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  • Electronic Resource  (146)
  • 2020-2022
  • 1985-1989
  • 1975-1979  (146)
  • 1978  (146)
  • Physical Chemistry  (105)
  • pharmacokinetics
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 275-284 
    ISSN: 1432-1041
    Keywords: Diazepam ; pharmacokinetics ; pregnant women ; plasma clearance ; blood/plasma concentration ratio ; placental transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The disposition of diazepam has been studied in pregnant women at parturition. The plasma concentration of diazepam was monitored for at least 3 days in 18 women who received a single intravenous injection of 10 mg during the 10 h-period prior to delivery. Fourteen mothers had uneventful puerperia (Group I) and in 13 of these cases there was a pronounced postnatal increase in the plasma concentration of diazepam. The terminal phase half-life (t1/2) was significantly greater for Group I (mean = 65 h; range = 24–114 h) than for age-matched non-pregnant patients (mean = 29 h; range = 18–44 h from literature). The prolonged t1/2 appeared to be related to changes in the distribution of diazepam and not to a reduction in hepatic elimination since the total plasma clearance (Cltp) in these 14 pregnant patients (mean = 28 ml/min; range = 18–43 ml/min) was not reduced compared to that reported for non-pregnant controls (mean = 30 ml/min; range = 22–45 ml/min). Four mothers underwent postnatal surgery for tubal ligation (Group II) and the plasma concentration-time profiles for this group did not show the same postnatal phenomenon as did the profiles obtained for Group I. The t1/2 for Group II was shorter (mean = 31 h; range = 24–37 h) than for Group I and similar to that for the non-pregnant controls. The Cltp for Group II was greater (mean = 56 ml/min; range = 48–63 ml/min) than for both Group I and non-pregnant controls. These results suggest that delivery alters the disposition of diazepam and is generally associated with a postnatal re-distribution of diazepam into the systemic circulation. The blood/plasma concentration ratio was determined in 9 patients (mean = 0.62; range = 0.54–0.77). There was no difference in the total blood clearance between the pregnant patients of Group I and the non-pregnant controls. In most cases the umbilical venous plasma concentration (Cpuv) of diazepam was greater than the peripheral maternal venous plasma concentration (Cpmv) at delivery. The foetus appears to constitute a slowly equilibrating tissue-group in which diazepam does not reach equilibrium with the maternal systemic circulation for at least 5–10 h at which time the diazepam concentration in maternal and foetal plasma is similar.
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  • 2
    ISSN: 1432-1041
    Keywords: p-Chlorophenoxyisobutyric acid ; clofibrate ; steady-state plasma concentrations ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma concentrations and bioavailability of clofibrinic acid have been estimated under conditions approaching the steady-state during a ten-day period of administration as clofibrate or as a calcium clofibrinate-carbonate combination (1:1 w/w) at a dosage interval of 12 h. Formulation — related differences in bioavailability were not significant, and the 95% confidence limits of these differences were within −2% to +8% of the mean for the reference formulation of clofibrate. The mean steadystate plasma concentrations of clofibrinic acid measured on the tenth day of dosing were 116 µg/ml±22 S.D. and 119 µg/ml±23 S.D. after administration of 885 mg as clofibrate and the calcium clofibrinate-carbonate combination respectively. The peaks of mean plasma concentrations were 70 µg/ml±15 S.D., 119 µg/ml±32 S.D. and 131 µg/ml±26 S.D. on the first, fifth and tenth day of dosing with clofibrate, and 62 µg/ml±13 S.D., 127 µg/ml±S.D. and 143 µg/ml±25 S.D. on the corresponding days of dosing with the calcium clofibrinate-carbonate combination. After the last dose on the tenth day of dosing, the mean apparent half-lives of elimination of clofibrinic acid from plasma were 24.2 h±4.4 S.D. and 25.5 h±3.2 S.D. after administration of clofibrate and the calcium clofibrinate-carbonate combination respectively.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 69-72 
    ISSN: 1432-1041
    Keywords: Phenazone ; pharmacokinetics ; hydrocortisone ; elimination rate ; distribution volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of a high plasma concentration of hydrocortisone on the metabolism of phenazone in humans has been studied. Two series of experiments were carried out, Group A to demonstrate any enzyme-inducing effect of hydrocortisone, and Group B to study the immediate effect of hydrocortisone on the metabolism of phenazone. 9 subjects (Group A) received a total 250–400 mg hydrocortisone i.m. twice daily for three days and the 24-hour elimination of phenazone was studied before and afterwards. In a further 5 subjects (Group B) the elimination of phenazone was examined during administration of hydrocortisone or placebo. The elimination rate and the apparent volume of distribution of phenazone remained unchanged under both experimental conditions.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 97-101 
    ISSN: 1432-1041
    Keywords: Clonidine ; plasma level ; pharmacokinetics ; steady state ; urinary excretion ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A single oral dose of clonidine 300 µg was administered to 8 healthy, normotensive subjects and the time course of its plasma concentrations was followed for 24 h. The plasma concentration of clonidine rose to a peak of 1.17±0.12 ng/ml at about 2 h: the absorption half-life was 0.6±0.2 h. Elimination followed first order kinetics with a half-life of 7.7±2.0 h. The correlation between the two most common side-effects of clonidine, sedation and dryness of the mouth, with the time course of its plasma concentrations was highly significant, p〈0.01. All the subjects complained of severe sedation. During continuous administration of clonidine (75 µg t.i.d.) for one week a steady state serum level of 0.30–0.35 ng/ml was achieved. One 75 µg tablet of clonidine raised the serum level to about 0.69±0.13 ng/ml in two hours. After cessation of dosing, the serum level declined with a half-life of 7.5±1.5 h. The urinary excretion of unchanged clonidine was found to be about onethird of the administered dose in 24 h during continuous administration and in the first 24 h after the single oral dose.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 203-212 
    ISSN: 1432-1041
    Keywords: Mepivacaine ; pharmacokinetics ; neonates ; healthy adults ; metabolism ; renal excretion ; lignocaine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and metabolism of mepivacaine has been studied in premature neonates dosed subcutaneously and in healthy adults dosed intravenously. The pharmacokinetics of mepivacaine in four neonates (N) was compared with that in six adults (A). Newborns had a significantly longer terminal phase half-life than adults (N mean 8.69 h; A mean 3.17 h). Total plasma clearance normalized on body weight was significantly smaller in neonates (mean 2.34 ml/min/kg) than in adults (mean 5.47 ml/min/kg), as was the hepatic blood clearance (N mean 1.37 ml/min/kg; A mean 5.10 ml/min/kg). The renal plasma clearance, however, was significantly greater in neonates (mean 0.76 ml/min/kg) than adults (mean 0.20 ml/min/kg). There was an average six-fold increase in the fraction of the dose excreted unchanged in newborns (mean 43.3%) compared to adults (mean 7.1%) with acidified urine (pH 5.5–6.0). There was significantly more of the mono-N-demethylated metabolite of mepivacaine excreted by newborns (mean 11.4%) than by adults (mean 2.2%), but their capacity to carry out aromatic hydroxylation of mepivacaine was negligible. These results for mepivacaine were compared with those previously reported for lignocaine in premature infants. The immaturity of hepatic function appears to have diminished more profoundly the ability of premature infants to metabolize mepivacaine than lignocaine. These findings are discussed in terms of perfusion theory of hepatic drug elimination.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 143-147 
    ISSN: 1432-1041
    Keywords: Children ; leukemia ; high-dose methotrexate ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of intravenous high-dose methotrexate were studied in two groups of children being treated for malignant diseases, mostly acute lymphatic leukemia. The peak serum level of methotrexate of 2.32·10−5 mol/l was found in children given 500 mg methotrexate/m2 by a 24 h infusion, and another group given 2790 mg/m2 during a 6 h infusion had serum levels as high as 2.16·10−4 mol/l. The decay of serum concentration of methotrexate after completion of the infusion followed a diphasic curve, with an initial serum half-life of 4.8 h, followed by a second half-life of 34.4 h at distribution equilibrium. The apparent volume of distribution was 56.8 litres/m2. Significant levels of methotrexate were found in cerebrospinal fluid, but penetration into cerebrospinal fluid was slow. Urinary excretion of methotrexate was considerable. Four to five days after commencement of the infusion, urinary concentrations of methotrexate still exceeded the serum levels.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 335-340 
    ISSN: 1432-1041
    Keywords: Drug binding to muscle ; interindividual differences ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Binding of 22 drugs to human muscle tissue has been determined by ultrafiltration. All drugs tested were bound, the bound fraction ranging from 13% (aminophenazone) to 〉98% (desipramine). Both linear and nonlinear binding was observed. For chemically related substances, binding to muscle tissue correlated with plasma binding and lipid solubility. There were significant differences in binding to muscle from different individuals. With respect to pharmacokinetics of drugs, it is suggested that binding to muscle tissue may be at least as important as plasma binding.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 41-48 
    ISSN: 1432-1041
    Keywords: Furosemide ; pharmacokinetics ; anephric patients ; metabolism ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of furosemide 40 mg i.v. were compared in 7 anephric patients and in 7 normal subjects. The average serum clearance was 66 ml/min in the patients and 219 ml/min in the normal subjects, and the corresponding weight corrected clearances were 1.33 ml/min · kg and 2.96 ml/min · kg. Binding to serum proteins was significantly decreased in the anephric subjects, in whom a significant negative correlation was found between the percentage binding and the volume of distribution VDss. In the patients, but not in the normal subjects, there was a significant positive correlation between $$V_{D_{ss} } $$ and serum clearance. Both in normal and anephric individuals 4-chlor-5-sulphamoylanthranilic-acid (CSA) was found, but there was no evidence of special accumulation either of CSA or anthranilic acid in the anephric patients. In the patients the initial increase in serum concentration of sodium and protein followed by a more conspicuous decrease were more pronounced, but none of the changes were statistically significant.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 29-33 
    ISSN: 1432-1041
    Keywords: Microcrystalline theophylline ; chronic obstructive airways disease ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma theophylline concentrations have been measured in 9 patients with chronic obstructive airways disease following the oral administration of a microcrystalline theophylline preparation. Some measurements of FEV1 were also made. Four patients were given 375 mg as a single dose and then subsequently 375 mg stat and 125 mg 4 times daily for 3 days, (Group I). A further 5 patients took 250 mg as a single dose and then 250 mg 4 times daily for 3 days, (Group II). In both groups, following the single dose and again after the last dose of chronic administration, blood samples were obtained at frequent intervals up to 24 h for plasma drug estimation. During the 3-day course, blood samples were drawn before and 2 h after each morning dose. In Group I patients, substantial plasma theophylline concentrations were seen only after the loading dose. Thereafter, the mean concentrations before or 2 h after the morning doese were always less than 4.0 µg/ml. Trough concentrations were usually below 2.0 µg/ml. In contrast patients in Group II achieved substantially higher plasma theophylline concentrations, with mean peak concentrations always 10 µg/ml or greater, and trough concentrations greater than 5 µg/ml on at least one occasion in every subject. The elimination half-lives after chronic administration in both groups were not significantly different from those obtained after single doses. Mean drug accumulation, measured as AUCss/AUC1, was 0.87±0.07 in Group I and 0.72±0.14 in Group II, indicating that accumulation had not occurred with either regimen. The mean increase in FEV1 2 h after the administration of a single dose was 19.2% after 375 mg and 16.7% after 250 mg. These results indicate that the recommended dosage regimen for microcrystalline theophylline preparation (375 mg stat and 125 mg 4 times daily) produces inadequate plasma theophylline concentrations: 250 mg 4 times daily would appear to be likely to result in satisfactory theophylline levels in more patients.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 365-371 
    ISSN: 1432-1041
    Keywords: Etidocaine ; pharmacokinetics ; metabolism ; neonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The urinary elimination of etidocaine and several of its metabolites was investigated in neonates whose mothers had received one or more doses of etidocaine during labour. The urine collection period ranged among the neonates from 21.4 to 47.0 h post-partum. The total amounts of etidocaine and its metabolites recovered in neonatal urine represented a mean of 0.12 per cent of the maternal dose. Some differences in the pattern of urinary metabolites were observed between neonates and adults. Mean half-life of elimination of etidocaine calculated from sigma-minus plots of the neonatal urinary data was 6.42 h. This is greater than that previously reported following intravenous administration of etidocaine to adults (2.6 h). The slower rate of elimination in neonates is probably due to an increased neonatal volume of distribution since there is evidence to show that etidocaine is extensively metabolised by the neonate.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 379-383 
    ISSN: 1432-1041
    Keywords: Antipyrine ; pharmacokinetics ; phenzone ; posture ; immobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of a single dose of phenazone was studied in six subjects while ambulant and during bed rest for 3 days. Elimination of the drug was followed for 12 h after oral and intravenous administration. The elimination rate constant and total body clearance were significantly increased during bed rest as compared to the ambulant period, but the differences were small. The apparent volume of distribution decreased significantly. No consistent change due to bed rest was found in the rate of absorption or bioavailability of the oral dose.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 209-212 
    ISSN: 1432-1041
    Keywords: Paracetamol ; acetaminophen ; Gilbert's syndrome ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of paracetamol after intravenous and oral administration has been studied in 6 patients with Gilbert's syndrome, and 6 healthy controls. Paracetamol clearance was significantly less in the patients (255 ml/min SE±23 ml/min) than in the normal subjects (352 ml/min SE±40 ml/min). Moreover, whilst paracetamol concentrations declined monoexponentially in the patients, the decline was biexponential in the controls. No difference in the bioavailability of 500 mg paracetamol given orally was observed between the two groups. The results suggest that not only is paracetamol elimination impaired in Gilbert's syndrome, but that its distribution kinetics are also abnormal. Both these findings could be attributed to a decrease in hepatic glucuronyl transferase activity.
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  • 13
    ISSN: 1432-1041
    Keywords: Aminopyrine ; pharmacokinetics ; 14CO2 breath test ; hepatic disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The time-course of aminopyrine in plasma and of14CO2 in breath was determined for 6 hours after oral administration of (14C-methyl) aminopyrine to healthy controls and to patients with hepatitis and hepatic fibrosis, cirrhosis and hepatic bilharziasis.14CO2 in breath declined about 1.8 times more slowly than aminopyrine plasma levels, which suggests the occurrence of metabolite demethylation. This was confirmed by the slow elimination of14C from plasma, the formation of14CO2 after aminopyrine had disappeared and the presence of a considerable amount of monomethyl-aminopyrine in plasma. The mean14CO2 concentration in breath was correlated with but was not proportional to aminopyrine clearance, which was attributed to individual differences in aminopyrine half-life. Both a correlation and proportionality were found when14CO2 extrapolated to zero time was used as a parameter of14CO2 production. Hepatic disease affected aminopyrine clearance to a variable extent. In the hepatitis and fibrosis group, aminopyrine clearance was affected in 2 out of five subjects. In all except one cirrhotic subject aminopyrine clearance was markedly decreased. Moreover, in three out of seven cases aminopyrine absorption was impaired, presumably due to decreased gastrointestinal blood-flow. This may produce an erroneously low14CO2 concentration in breath during the first two hours after aminopyrine administration. Hepatic bilharziasis was accompanied by very low aminopyrine clearance in all four cases. In two patients high apparent Vd values were observed, probably due to “first-pass” metabolism. Patients with ascites had Vd values within normal limits.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 57-67 
    ISSN: 1432-1041
    Keywords: Chemotherapy ; sulfadiazine ; trimethoprim ; pharmacokinetics ; acetylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Sulfadiazine (SDZ) 800 mg and trimethoprim (TMP) 160 mg were given orally to 10 normal subjects and the concentration of SDZ and TMP in serum and urine was followed for 24 h. Both drugs showed a significant negative correlation between individual “peak” concentrations in serum and the body weight of the subject. Twelve hours after dosing the serum concentration was 12 to 25 µg/ml for SDZ and 0.3 to 1.1 µg/ml for TMP. Individual concentration ratios between SDZ and TMP in serum were 4.8 (1 h) – 145 (24 h), and in the urine the ratio was close to 6 throughout the 24 h collection period. The range of urinary concentrations was from 65 to 400 µg/ml for SDZ and from 13.8 to 93.4 µg/ml for TMP. The fraction acetylated SDZ/acetylated SDZ + SDZ was 21% during the 0–8 h period, 33% during the 8–15 h period and 41% during the 15–24 period. The average values for the notional volume of distribution, Vd, were 0.36±0.13 1/kg for SDZ and 1.39±0.25 1/kg for TMP. The average “t1/2” was 15.2±7.4 h for SDZ and 7.4±1.9 h for TMP. Individual subjects showed a significant correlation between the serum clearance of TMP and SDZ (p〈0.01) and also between the renal clearance of the two drugs (p〈0.05). The serum clearance was significantly correlated with the renal clearance for TMP but not for SDZ. For SDZ Vd was significantly negatively correlated with the elimination constant; for TMP no such correlation was found. The serum clearance of SDZ was significantly correlated with the percentage of SDZ which was excreted as the (presumably) acetylated compound. The renal clearance of SDZ was independent of the serum concentration of SDZ. There was a highly significant negative correlation between the renal clearance and serum concentration of TMP, as well as for “acetylated SDZ”. The renal clearance of “acetylated SDZ” averaged more than six times that of unconjugated SDZ. With increased urine flow the renal clearances of TMP and SDZ were significantly increased.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 237-244 
    ISSN: 1432-1041
    Keywords: Furosemide ; arterial hypertension ; protein binding ; sodium excretion ; renal function ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Furosemide 40 mg was injected intravenously in 7 patients with severe hypertension and vascular complications. A two compartment, open model was used to describe the disappearance of the drug from serum. The mean serum clearance (Cls=1.83 ml/min · kg) was significantly reduced compared to the mean Cls-value of a group of normals (2.96 ml/min · kg). A significant correlation was found between Cls and mean blood pressure, as well as between Cls and renal clearance (mean Clr=0.83 ml/min · kg); extrapolation of the regression line yielded a Cls-value of 50 ml/min for Clr=0. The Clr was also significantly negatively correlated with mean blood pressure. Protein binding of furosemide was normal, except in one patient, who had considerable impairment of renal function. Apparently more than 90% of unchanged furosemide passed in urine was excreted by tubular transport. A highly significant negative correlation was found between Cls and the fraction of furosemide excreted as a glucuronide. During the first two hours, significantly less sodium was excreted by the patients than by a comparable group of normal subjects. The correlation between serum concentration of furosemide and the amount excreted of sodium was not significant, but highly significant correlations were found between the amounts of furosemide and sodium excreted by the kidney in 0–30 and 0–60 min. In all the individual patients an approximately linear relationship with wide variation in the slope was found between the cumulative excretion of furosemide and sodium from 0–30 min to 0–60 and to 0–120 min. After 120 min deviations were observed in the curves from 4 of the patients, which indicated that smaller and smaller additional amounts of sodium were excreted with constant additional amounts of furosemide.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 267-271 
    ISSN: 1432-1041
    Keywords: Lithium ; sustained-release ; pharmacokinetics ; manic patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An ordinary and a sustained-release lithium carbonate preparation were administered acutely at equivalent dosage (1.80 g=24.3 mmol) in a crossover fashion to manic patients. Serum lithium levels were determined by atomic absorption spectroscopy and pharmacokinetic parameters were calculated. Maximum mean serum levels of 1.13 mmol/l and 0.78 mmol/l were achieved at 6 h and 12 h respectively with the ordinary and sustained-release forms. The mean half-lives of absorption, redistribution and elimination were 0.78 h±0.05 (SE), 5.06 h±0.23, 26.8 h±4.5 and 3.73 h±0.37 (SE), 4.42 h±0.28 and 25.6 h±5.5 for the ordinary and sustained-release forms respectively. In healthy volunteers the ordinary preparation was completely absorbed but only 85% of the sustained-release form was absorbed in the manic subjects. Lithium ion distributed into two kinetic compartments and the final compartment appeared to correspond to total body water.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 277-280 
    ISSN: 1432-1041
    Keywords: Doxycycline ; iron ; charcoal ; enteral cycling ; man ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In order to study the intestinal interactions of doxycycline (DC) with Fe++ and charcoal, two groups of healthy volunteers were given either 200 mg or 100 mg DC in capsules at 2 p. m. and 9 p. m., and blood samples for fluorimetric assay of DC were collected for 24 h starting at 8.30 a. m. on the following morning. A 24-h-urine was also collected. The test was subsequently repeated at one-week intervals, when the volunteers also ingested either ferrous sulphate (80 mg Fe++) or charcoal (4.0 g) immediately after the zero-time sample of DC and at 3, 8 and 12 h. Charcoal completely adsorbed DC in vitro in an artificial small intestinal fluid. Ferrous sulphate or charcoal did not modify the serum level or urinary excretion of DC after the 200 mg+200 mg dose, but ferrous sulphate did reduce the 24-h urinary excretion of DC after the 100 mg+100 mg dose. The serum half-life and AUC of DC were reduced by ferrous sulphate given after the 100 mg+100 mg dose of DC. Charcoal did not modify any parameter, even after the 100 mg+100 mg dose of DC. The results do not support existence of important enteral cycling of DC. Although oral ferrous sulphate can lower the serum level and shorten the serum half-life of DC, the acute experiment suggested that a therapeutic serum level of DC can be maintained despite treatment with iron in the doses used in iron-deficiency, and charcoal in the doses used in diarrhoeic states, if the drugs are administered several hours apart.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 69-73 
    ISSN: 1432-1041
    Keywords: Citalopram ; pharmacokinetics ; man ; steady state levels ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma concentrations of citalopram, a potent serotonin reuptake inhibitor, and its demethylated metabolite have been determined by a specific fluorescence coupling technique during single dose experiments in volunteers and in clinical tests. Citalopram was found to have linear kinetics within the dose range investigated, which were characterized by fairly rapid absorption and slow elimination (biological half-life 1–21/2 days). Steady state levels in the range 120–340 nM (i.e. slightly above those associated with pharmacodynamic activity in animals) were attained within a week. A drug/metabolite ratio of 2–3 was recorded.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 431-434 
    ISSN: 1432-1041
    Keywords: Timolol ; pharmacokinetics ; oral and intravenous dosing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma kinetics of timolol administered orally and intravenously to 5 male subjects were examined. Bioavailability was reduced by 25% when the drug was taken orally. Mean plasma half-life after oral dosing was 4.86 h, and after intravenous administration it was 4.56 h; the difference was not significant. The volume of distribution was 3.5 l/k. It is suggested that timolol is little affected by the ‘first pass effect’, even though there is marked interindividual variation in availability and peak plasma level.
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  • 20
    ISSN: 1432-1041
    Keywords: Lignocaine ; pharmacokinetics ; neonates ; metabolism ; renal excretion ; plasma concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and metabolism of lignocaine in premature neonates was studied after subcutaneous administration. The collection of serial urine together with a limited number of blood samples from neonates enabled simultaneous computer fitting of data to a pharmacokinetic model. The disposition kinetics of lignocaine in four neonates were compared with similar data reported for adults. Neonates had prolonged t1/2 (neonate mean: 3.16 h; adult mean: 1.80 h), and an increased total volume of distribution (neonate mean: 2.75 l/kg; adult mean: 1.11 l/kg) compared with adults. Total plasma clearance (Cltp) normalised on body weight showed no significant difference between neonates (mean: 0.610 l/h/kg) and adults (mean: 0.550 l/h/kg). The urinary excretion of lignocaine and several of its metabolites was studied in 8 neonates and 11 adults. Neonates were shown to excrete much more unchanged lignocaine (mean: 19.67%) compared with adults (mean: 4.27%) and the proportion of the dose excreted as 4-hydroxyxylidine is considerably reduced in neonates (neonate mean: 8.89%; adult mean: 63.78%). The use of the two pharmacokinetic parameters, t1/2 and Cltp, as indices of drug elimination ability are discussed.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 219-222 
    ISSN: 1432-1041
    Keywords: Glaziovine ; pharmacokinetics ; plasma levels ; urinary excretion ; biliary excretion ; enteral absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic parameters of Glaziovine, a pro-aporphine alkaloid with neuropharmacological properties, were investigated in healthy human volunteers. Glaziovine-14C 20 mg was administered in capsules (oral route) and in vials (i.v. route). Total radioactivity was measured in plasma, urine and faeces. When administered orally, peak plasma levels were encountered at 2 h. The cumulative urinary excretion of total radioactivity over a 24 h period was 38% after oral and 50% after i.v. administration. Investigation of metabolites in urine revealed Glaziovine glucuronide as the sole metabolite of the drug. By comparing the percentage of urinary excretion or the area under the plasma level-time curve (AUC) obtained in the first 24 hours after i.v. and oral administration, enteral absorption was found to range from 78 to 84%. Thus, glaziovine appears to show very high enteral absorption.
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  • 22
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    European journal of clinical pharmacology 13 (1978), S. 55-60 
    ISSN: 1432-1041
    Keywords: Valproic acid ; pharmacokinetics ; liver disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The disposition of valproic acid (di-n-propylacetate; VA) has been studied after a single oral dose of a solution of 450 mg in 7 patients with alcoholic cirrhosis and in 4 patients recovering from acute hepatitis. The diagnosis was based on biochemical function tests and histological findings. The pharmacokinetic parameters were compared with those reported for healthy volunteers. VA in therapeutic concentration (80 µg/ml) in plasma was less bound to plasma proteins in patients with alcoholic cirrhosis (70.7±11.3%) and in patients recovering from acute hepatitis (78.1±14.1%) than in controls (88.7±5.2%). The reduced binding affected the blood/plasma concentration ratio and the apparent distribution volume Vd(β); the latter was increased from the normal value of 0.14±0.05 l/kg to 0.22±0.09 (p〈0.05) in alcoholic cirrhotics, and to 0.20±0.07 (p=0.056) in patients recovering from acute hepatitis. The half-life of elimination T1/2 (β) (controls=12.2±3.7 h) was significantly (p〈0.05) prolonged in cirrhotics (18.9±5.1 h) and in patients recovering from acute hepatitis (17.0±3.7 h). The plasma $$\overline {Cl} $$ of total drug was not impaired, which can best be explained by the lower plasma protein binding, which might have increased the $$\overline {Cl} $$ of this drug which shows restricted clearance. In addition, the plasma $$\overline {Cl} $$ of free drug was significantly (p〈0.02) reduced in alcoholic cirrhotics. During a two day urine collection no measurable amount of unchanged VA was recovered. There was considerable excretion of VA-conjugates, which could be hydrolyzed either by HCl or by β-glucuronidase/arylsulphatase (4–23% of the dose). These percentages were in the same range as in normals (26.7±16.1%). The study indicates that elimination of VA is slightly impaired in patients with dysfunction of the liver.
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  • 23
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    European journal of clinical pharmacology 13 (1978), S. 267-274 
    ISSN: 1432-1041
    Keywords: Chlordiazepoxide ; benzodiazepines ; pharmacokinetics ; bioavailability ; intramuscular injection ; alcohol withdrawal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of oral and intramuscular (i. m.) chlordiazepoxide hydrochloride (CDX · HCl) was compared in two pharmacokinetic studies. In Study One, single 50-mg doses of CDX · HCl were administered orally and by i. m. injection to 14 healthy volunteers using a crossover design. Whole-blood concentrations of chlordiazepoxide (CDX) and its first active metabolite, desmethylchlordiazepoxide (DMCDX), were determined in multiple samples drawn after the dose. Mean pharmacokinetic variables for CDX following oral and i. m. administration, respectively, were: highest measured blood concentration, 1.65 vs 0.87 µg/ml (p〈0.001); time of highest concentration, 2.3 vs 7.6 h after dosing (p〈0.001); apparent absorption half-life, 0.71 vs 3.39 h (p〈0.001). Biphasic absorption after i. m. injection, consistent with precipitation at the injection site, was observed in 9 of 14 subjects. Based upon comparison with previous intravenous data, the completeness of absorption was 100% for oral vs 86% for i. m. CDX · HCl (p〈0.1). In Study Two, 28 male chronic alcoholics with clinical manifestations of the acute alcohol withdrawal syndrome were randomly assigned to one of four treatment conditions: 50 or 100 mg doses of CDX · HCl, by mouth or by i. m. injection. Concentrations of CDX and DMCDX, determined in plasma samples drawn every 20 min for 5 h following the dose, were significantly higher after oral administration of a given dose than at corresponding points in time after i.m. injection after the same dose. Thus absorption of oral CDX is reasonably rapid and complete, whereas the absorption rate of i. m. CDX is slow.
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  • 24
    ISSN: 1432-1041
    Keywords: Phenylbutazone ; pharmacokinetics ; model ; retrospective analysis ; digestive-tract hemorrhage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Phenylbutazone treatment can cause digestive-tract hemorrhages, but its concentration in the blood at the time of hemorrhage is generally not known. In two patients who had had digestive tract hemorrhages, the variation in the serum phenylbutazone concentration throughout treatment and just before hemorrhage was simulated by a two-compartment model based on assays (gas-liquid chromatography) made after the hemorrhage. Identification of the parameters of the model and simulation of changes in concentration during therapy suggested that the phenylbutazone level in serum at the time of hemorrhage was 101 and 125 µg/ml respectively.
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  • 25
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    European journal of clinical pharmacology 14 (1978), S. 29-37 
    ISSN: 1432-1041
    Keywords: Hydroflumethiazide ; pharmacokinetics ; cardiac failure ; renal drug excretion ; metabolism ; 2,4-disulfamyl-5-trifluoro-methylaniline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of hydroflumethiazide (HFT) were investigated after single oral doses of 6 µmoles/ per kg body weight in five healthy subjects and in nine patients with moderate cardiac failure. HFT was excreted in urine together with 2,4-disulfamyl-5-trifluoromethylaniline (DTA), which was also present in the blood after administration of HFT. HFT and DTA were determined by TLC and spectrofluorodensitometry. Mean cumulative urinary excretion of HFT was 46.5 and 47.5 per cent of the dose both in healthy subjects and in patients. Distribution half-life (t1/2α) was about 2 h in both groups of subjects, while biological half-life (t1/2β) ranged from 12.4 to 26.9 h (mean 16.6) in healthy subjects, and from 6.3 to 13.7 h (mean 9.6) in patients. Mean renal clearance was 0.33 and 0.211 · h−1 · kg−1 in normal subjects and patients, respectively, and was almost equal to the total body clearance. HFT had a large apparent volume of distribution (Vβ), with mean values of 6.4 and 3.11 · kg−1 in normal subjects and patients. Mean cumulative urinary excretion of DTA was 1.8 and 1.9 per cent in healthy subjects and patients with cardiac failure. The apparent half-life of DTA, determined from urinary excretion rate in eleven subjects, ranged from 16 to 56 h but half-lives in three others were more than 100 h. The results indicate that HFT is partly metabolized in the body to DTA, and DTA and HFT are excreted in urine. The half-life of DTA was longer than that of the parent drug. The apparent volume of distribution, clearance and biological half-life of HFT were lower in patients with cardiac failure than in healthy subjects.
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  • 26
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    European journal of clinical pharmacology 14 (1978), S. 361-366 
    ISSN: 1432-1041
    Keywords: Furosemide ; gestosis of pregnancy ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Furosemide 50 mg was administered orally and intravenously to twelve gestotic women for brief periods as a part of a randomized, multicentre clinical trial comparing the efficacy of bed rest and pharmacological treatment. The pharmacokinetic profile was investigated using a gas-liquid chromatographic technique. The plasma half-life after oral and intravenous administration was 115±37.1 and 71.8±26.3 min and plasma clearance was 153±48 and 152±23 ml/min, respectively (mean±SD). Comparative data from healthy pregnant women cannot be obtained for ethical reasons. The results show that gestosis has only a marginal if any effect on the kinetics of furosemide in comparison with published kinetic parameters in healthy volunteers and patients with renal failure. The new-born babies where checked for side effects according to a protocol in use in a larger regional surveillance programme. No clinical side-effects were attributable to furosemide, but the small size of the group does not permit any definitive conclusions about this aspect.
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  • 27
    ISSN: 1432-1041
    Keywords: Phase I clinical trial ; complex protocol ; tolerance ; pharmacokinetics ; praziquantel ; anthelmintic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The tolerance of Praziquantel (2-cyclohexylcarbonyl-1, 3, 4, 6, 7, 11b-hexahydro-2H-pyrazino-[2, 1-a]isoquinoline-4-one) in oral doses of 1×20 mg/kg, 1×50 mg/kg, 3×10 mg/kg and 3×25 mg/kg body weight (τ=4 h) was tested in a complex study involving 36 healthy volunteers. In addition to the usual assessment of clinical chemistry, haematology, coagulation physiology, urinalysis, clinico-physiological examination including EEG, and medical examination, clinico-psychological parameters were also recorded and special neurological investigations were performed. No clinically relevant changes were found in any of the laboratory parameters, nor in the medical-neurological or clinico-physiological examinations. Based on a few clinicopsychological parameters and subjective comments, the largest daily dose tested (3×25 mg/kg=75 mg/kg) produced a slight, transient disturbance in general well-being, which was barely detectable on objective clinical examination. The pharmacokinetic behaviour was dominated by rapid metabolism and pronounced first-pass metabolism of praziquantel, which greatly limits the value of results obtained by GC analysis of unchanged drug in serum. The peak concentration in serum was reached after 1– h, and the elimination half-life for the period 2–8 h was 1–1.5 h.
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  • 28
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    European journal of clinical pharmacology 13 (1978), S. 35-39 
    ISSN: 1432-1041
    Keywords: Norethindrone ; bioavailability ; man ; competitive protein binding ; sex differences ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A competitive protein binding assay for norethindrone was developed to measure plasma levels in human subjects. The plasma levels were considerably higher in women than in men, especially at low dose levels. The plasma levels were directly related to the dose in men; but greater variations in the plasma levels were observed in women. The plasma half-life was about 5 h in both sexes with single oral doses of 5 to 20 mg. A comparative bioavailability study with norethindrone from 2 different manufacturers, formulated in the same manner, showed no significant differences in absorption characteristics and provided sufficient data for pharmacokinetic analysis.
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  • 29
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    European journal of clinical pharmacology 13 (1978), S. 119-124 
    ISSN: 1432-1041
    Keywords: Bendroflumethiazide ; pharmacokinetics ; hypertension ; renal clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary After four weeks on placebo treatment, 8 hypertensive patients (WHO stage I) were treated for 2 weeks with bendroflumethiazide (bft) 2.5 mg and KCl 1.5 g daily. Subsequently they received bft 5 mg and KCl 1.5 g daily for a further fortnight. At the end of each period of treatment blood pressure was recorded and blood samples and urine were collected for analysis of bft by GLC. Before taking the daily dose of bft, no trace of the drug was found in plasma. Peak levels of bft were seen after 2.3 h and averaged 23 and 50 ng · ml−1 after 2.5 and 5 mg, respectively. After bft 2.5 mg the plasma level was too low for kinetic analysis. The plasma half-life after 5 mg averaged 4.1 h. The mean apparent volume of distribution was 1.18 l · kg−1. Non-renal clearance averaged 200 ml · min−1. The renal clearance of bft was significantly lower (p〈0.05) after 5 mg (48 ml · min−1) than after 2.5 mg bft (93 ml · min−1), although the creatinine clearance remained unchanged. No correlation was found between the plasma level of bft and its effect on blood pressure.
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  • 30
    ISSN: 1432-1041
    Keywords: Cephacetrile ; pharmacokinetics ; renal Impairment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of cephacetrile, administered as a single i. v. injection of 15 mg/kg, have been determined in 8 patients with normal renal function and in 12 patients with a varying degree of renal impairment. A two-compartment model was used to describe the biphasic decline in serum concentrations and to calculate the amount of antibiotic in the central and peripheral compartments. In patients with normal renal function the following values were obtained for various pharmacokinetic parameters: α=3.971 h−1; β=0.343 h−1; K12=1.745 h−1; K21=0.763 h−1; Kel=1.793 h−1; Vc=8.181; Vp=18.401 and Vdss=26.581. Cephacetrile had some of the highest apparent distribution volumes of all the cephalosporins. Impaired renal function significantly affected α, β, K12, and Kel. A linear relationship between Kel of cephacetrile and creatinine clearance was demonstrated. The elimination of cephacetrile in anuric patients was about ten times slower than in patients with normal renal function.
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  • 31
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    European journal of clinical pharmacology 14 (1978), S. 293-299 
    ISSN: 1432-1041
    Keywords: Breath analysis ; 14CO2 exhalation ; drug metabolism ; glycodiazine ; liquid chromatography ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Exhalation of14CO2 in breath has been used to assess the rate of hepatic demethylation of (14C-dimethyl)aminopyrine, but due to the complexity of aminopyrine metabolism the pharmacokinetics of the procedure are insufficiently understood. Therefore, studies were performed in five individuals after oral administration of (14C-methoxy)glycodiazine, a model substance with relatively simple kinetic properties. Plasma concentrations of the drug and urinary output of its metabolites measured by high pressure liquid chromatography were analysed by a two-compartment open model. The terminal disappearance of14CO2 from breath was practically identical with the terminal disappearance of glycodiazine from plasma, which could be correlated with the plasma clearance of free glycodiazine. The mean transit time of14C-atoms from plasma to breath was 3 h. These results contribute to the pharmacokinetic basis for use of14C-demethylation breath tests. In particular, they are consistent with the hypothesis that14CO2-breath analysis may be used to assess certain pharmacokinetic parameters of appropriately labelled test compounds. These parameters may not necessarily be a direct reflection of the rate of demethylation.
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  • 32
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    European journal of clinical pharmacology 14 (1978), S. 405-412 
    ISSN: 1432-1041
    Keywords: Colloidal plasma substitutes ; cross-linked polypeptides ; Haemaccel® ; pharmacokinetics ; renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Infusions of 3.5% isocyanate cross-linked polypeptide solution 500 ml were given to 52 patients with normal or impaired renal function: glomerular filtration rate (GFR)=0–133 ml/min. The serum concentration and urinary excretion of hydroxyproline were measured and the equivalent polypeptide concentrations were calculated from the results. In patients with normal renal function (GFR〉90 ml/min) the proportion of polypeptide excreted in the urine up to 12 h was 45.4±2.6% ( $$\bar X$$ ±SEM), up to 24 h 47.7±2.9% and up to 48 h 49.3±3.4%. In patients with moderate renal insufficiency (GFR=30–90 ml/min) there was no decrease in polypeptide excretion and even in patients with more serious impairment of GFR (11–30 ml/min) 48-h urinary polypeptide excretion was still 40.6±5.9%. In patients with GFR of 2–10 ml/min polypeptide excretion fell to 10.7±3.2% during the first 12 h, although there was an increase in later collection periods as compared to patients with normal renal function −19.9±3.9% in 24 h and 27.0±3.5% in 48 h. The elimination half-life (t1/2) calculated from serum concentrations was 505±30 min ( $$\bar X$$ ±SEM) in patients with normal renal function (GFR〉90 ml/min). Only when the GFR fell below 30 ml/min did it slowly begin to increase. In patients with minimal residual renal function (GFR=0–0.5 ml/min), who were on haemodialysis, the elimination half-life was 985±49 min, i.e. approximately twice the normal. Twice weekly infusion of 3.5% polypeptide solution 500 ml over a period of 6 weeks did not produce any significant cumulation in haemodialysis patients (GFR=0–0.5 ml/min). A weekly dose of polypeptide 35 g appeared to be quite safe when given for several weeks, even to anuric patients. As no significant amount of polypeptide was lost during haemodialysis, the dose can be chosen without taking into account any effect of intermittent haemodialysis.
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  • 33
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 505-519 
    ISSN: 1573-8744
    Keywords: morphine ; first-pass elimination ; pharmacokinetics ; enterohepatic recirculation ; availability ; routes of administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Morphine was administered to rats by oral, intraportal, and intravenous routes in a dose of 7.6 mg · kg −1.From the serum concentration data after intraportal administration it was calculated that the first-pass elimination of morphine in the liver amounts to 72±2% (sd). The first-pass fraction eliminated after oral administration was 85±7% (sd), thus yielding a contribution by the gut mucosa of 46% to the overall first-pass elimination after an oral dose. The results were obtained with a general compartmental model which included the kinetics of enterohepatic recirculation. The oral availability was also estimated with the aid of pharmacological effect data. This availability was in good agreement with the corresponding value determined from the serum concentration data. The results suggest that morphine is subjected to enterohepatic recirculation and that the slowest phase of decline of morphine concentrations in serum might be due to this physiological process.
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  • 34
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 265-282 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; linear systems analysis ; in vivo dissolution rates ; absorption rates ; metabolic rates ; bioavailability ; numerical desconvolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The application of certain aspects of linear systems analysis to pharmacokinetic-problems is described. Topics covered include the evaluation of in vivodissolution rates, absorption rates, and metabolic rates, and the use of pharmacological data. Relevant numerical procedures are also discussed.
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  • 35
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 315-325 
    ISSN: 1573-8744
    Keywords: percutaneous penetration ; methotrexate ; compartmental models ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Compartmental models were developed to describe the penetration of a drug from a topically applied vehicle through the skin. Data for in vitro penetration of methotrexate through hairless mouse skin from vehicles varying in PH from 3.5 to 6.5 were computer- fitted to estimate model parameters. Comparison of lag time and the exponential coefficient suggested that parallel penetration pathways exist. The fraction of drug penetrating through the shunt pathway increased as vehicle pH and ionization increased. Penetration curves were quantitatively partitioned into bulk tissue and shunt contributions. At pH 6.5, flux through the shunt pathway predominated.
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  • 36
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 521-537 
    ISSN: 1573-8744
    Keywords: compartmental analysis ; doxantrazole ; drug distribution ; mathematical prediction ; pharmacokinetics ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A pharmacokinetic model incorporating 14 compartments and 29 transfer coefficients has been developed from experimental data obtained after intravenous administration of a single dose to describe the distribution of doxantrazole in the rat. The distribution calculated from the model agreed closely with that determined experimentally. In addition, the model was able to predict with considerable accuracy the distribution of doxantrazole after repeated dosing.
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  • 37
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 187-196 
    ISSN: 1573-8744
    Keywords: Chlorpromazine ; pharmacokinetics ; oral absorption ; single dose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A single oral dose (120 mg/m2) of Chlorpromazine hydrochloride was administered to four healthy subjects and the blood levels of Chlorpromazine were determined with time. Appropriate equations describing the two-compartment open model with zero-order absorption and the two-compartment model with first-order absorption, both with a lag time, were fitted to the observed data using weighted nonlinear least-squares regression analysis. Fitting the two-compartment model with zero-order absorption and a lag time to the observed data resulted in a significant reduction of the weighted sum of squared deviations, i.e., better correlation between the observed and calculated data, and a closer random scatter of the observed concentration data around the calculated curve with no apparent systematic deviations from the curve. These results suggest that Chlorpromazine absorption is zero order. Chlorpromazine began to appear in the systemic circulation after a mean lag time of 0.4 hr and continued to be absorbed for approximately 2.9 hr. The mean half-lives of the distribution and elimination phases were 1.63 and 17.7 hr, respectively.
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  • 38
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 547-558 
    ISSN: 1573-8744
    Keywords: statistical moments ; network theory ; pharmacokinetics ; bioavailability ; deconvolution ; plasma concentration-time curve ; urinary excretion rate-time curve ; compartment models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Statistical moments are parameters that describe the characteristics of the time courses of plasma concentration (area, mean residence time, and variance of residence time) and of the urinary excretion rate that follow administration of a single dose of a drug. The relationship between the moments of a time-course curve and pharmacokinetic profiles of drug disposition, i.e., absorption, distribution, metabolism, and excretion, is described. The moments are related to the extent and rate of bioavailability, and it is shown that they can be effectively applied to the deconvolution operation.
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  • 39
    ISSN: 1573-8744
    Keywords: trapezoidal rule ; area under the curve ; pharmacokinetics ; clearance ; bioavailability ; integration method ; sulfisoxazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The linear trapezoidal rule method is commonly used for the estimation of the area under the plasma level-time curve. Error analyses are performed when the method is used in first-order absorption and first-order elimination kinetics in the one-compartment system. It is found that significant underestimations and overestimations in area during the absorption phase and postabsorption phase, respectively, can occur when the method is improperly used. During the exponential postabsorption phase the relative error is only a function of the ratio (n)of the time interval over the half-life of the two plasma data points in the interval. The error from the linear trapezoidal rule method at n=0.5 is about 1%. The error increases to 15.5% and 57.1 % when nis increased to 2 and 4, respectively. It is recommended that for most absorption studies the linear trapezoidal method be used for prepeak and plateau plasma data and the logarithmic trapezoidal method for postpeak plasma data.
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  • 40
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 295-303 
    ISSN: 1573-8744
    Keywords: tetracycline ; antibiotics ; Billroth-II gastrectomy ; gastrectomy ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The bioavailability of a single 250-mg oral dose of tetracycline hydroghloride was studied in seven patients following Billroth-II gastrectomy in comparison with seven control subjects matched for age and body weight. There were no significant differences between control subjects and gastrectomized patients in the apparent lag time prior to the start of absorption (23.6 vs. 22.8 min), peak serum tetracycline concentration (1.72 vs. 1.75 μg/ml), the time of attainment of peak concentrations (3.35 vs. 3.42 hr), the apparent first-order absorption half-life (1.8 vs. 1.4hr), or the apparent first-order elimination half-life (8.0 vs. 8.7hr). Completeness of tetracycline absorption, as judged by area under the 24-hr serum concentration curve, did not differ significantly between the two groups, nor did 24-hr urinary excretion of tetracycline. Thus the abnormalities of gastrointestinal structure and function produced by Billroth -II gastrectomy do not result in impairment of the rate and completeness of tetracycline absorption.
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  • 41
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    Journal of pharmacokinetics and pharmacodynamics 6 (1978), S. 369-387 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; dog ; diethyldithiocarbamate metabolite of disulfiram ; presence of methyl ester ; kinetic evaluation of prior studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Following the intravenous infusion of sodium diethyldithiocarbamate to dogs, the disposition kinetics of diethyldithiocarbamate (DDC), a metabolite of disulfiram, were assessed. Approximately 27% of the administered dose was S-methylated, this process exhibiting a mean first-order rate constant of 0. 0569 min−1 (t1/2=12.2 min), while the remainder was eliminated by other routes having a rate constant of 0.148 min−1 (t1/2=4.68 min). The methyl diethyldithiocarbamate (MeDDC) formed from DDC showed an elimination rate constant of 0.0141 min−1 (t1/2=49.2 min). These observations are discussed in the light of previous investigations where the presence of MeDDC has rarely been sought or reported. A few comparisons with prior studies, in which DDC or disulfiram was administered, are made by retrospective kinetic evaluation of published data. The results are discussed in relation to the duration of action of disulfiram in man.
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  • 42
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 43
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 31-39 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flash photolysis-vacuum ultraviolet kinetic absorption spectroscopy technique has been used to measure the absolute rate constant for the reaction of ground state S(3P) atoms withnitric oxide,\documentclass{article}\pagestyle{empty}\begin{document}${\rm S}\left({^{\rm 3} P} \right) + {\rm NO}\mathop {\longrightarrow}\limits^{\rm M} {\rm SNO}\left({{\rm M} = {\rm CO}_2} \right)$\end{document} as a function of nitric oxide concentration and total pressure. The rateconstant was determined to be 1.9±0.1 × 1011 12/mol2.sec at 298°K, with a high-pressure limit of 9.3 ± 2.1×109 l/mol·sec-1. The observed kinetics are consistent with a termolecular energy transfer mechanism.
    Additional Material: 3 Ill.
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  • 44
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 101-110 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction has been investigated in the temperature range 667-715K. The only reaction products were trifluorosilyl iodide and hydrogen iodide. The rate law \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d\left[{{\rm I}_2} \right]}}{{dt}} = \frac{{k\left[{{\rm I}_2} \right]^{1/2} \left[{{\rm F}_3 {\rm SiH}} \right]}}{{1 + k\prime \left[{{\rm HI}} \right]/\left[{{\rm I}_2} \right]}} $$\end{document} was obeyed over a wide range of iodine and trifluorosilane pressures. This expression is consistent with an iodine atom abstraction mechanism and for the step \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm I}^ \cdot + {\rm F}_3 {\rm SiH}\mathop {\longrightarrow}\limits^1 {\rm F}_3 {\rm Si}^\cdot + {\rm HI} $$\end{document} log k1(dm3/mol·sec) = (11.54 ± 0.17) - (130.5 ± 2.2 kJ/mol)/RT In 10 has been deduced. From this the bond dissociation energy D(F3Si—H) = (419 ± 5) kJ/mol (100.1 kcal/mol) is obtained. The kinetic andthermochemical implications of this value are discussed.
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  • 45
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 155-169 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The recombination of bromine atoms at room temperature has been studied by flash photolysis in the range of 1-100 atm of the inert diluent He, leading to a value for the third-order rate constant of (1.5 ± 0.2) × 1015 cm6/mol2.sec. In the presence of NO the recombination is considerably accelerated. The falloff curve of the recombination Br + NO (+He) → BrNO (+He) was also measured resulting in a value for the limiting low-pressure rate constant of (3.4 ± 1.3) × 1015 cm6/mol2.sec. In experiments with excess NO, rate constants of (2.2 ± 1) × 1014 cm3/mol·sec for the reaction Br + BrNO → Br2 + NO, and (6.1 ± 0.4) × 109 cm6/mol2.sec for the reaction Br2 + 2NO → 2BrNO were obtained.
    Additional Material: 6 Ill.
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  • 46
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 47
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 233-248 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A previously developed model for active species concentration profiles in infinite cylindrical systems has been extended to include the spherical system. The model couples the processes of diffusion to and reaction at the wall. Predictions of time buildup under conditions of homogeneous production by light, and time decay after extinguishing the light source, are made for H atoms. Such predictions require a knowledge of the wall recombination coefficient and the binary diffusion coefficient for H in heat bath gas. The model is experimentally tested by measuring the first-order decay constants of H at room temperature in various pressures (10-1500 torr) of six heat bath gases. The atomic concentration is monitored by Lyman-α absorption photometry. The results show good agreement with model predictions in the various heat bath gases up to ∼400 torr and depend only on one parameter,γ, the recombi-nation coefficient. This should be contrasted with the earlier work where slight variation in γ was invoked. The rate constants at pressures higher than 400 torr are consistently higher than model predictions.
    Additional Material: 6 Ill.
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  • 48
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 49
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    International Journal of Chemical Kinetics 10 (1978), S. 367-387 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Atomic resonance absorption spectrometry with a nonreversed fluorine resonance lamp (∼95 nm) has been used to study the kinetics of elementary reactions of ground state F2PJ atoms in a discharge-flow system. The following rate constants (in cm3/molec·sec)All rate constants are given with 1.5 σ. were determined at 298° K: The reaction F 2PJ + HCl(1) was found to give J-excited Cl 2P1/2 atoms with a product branching ratio [Cl 2P1/2]/[Cl 2P3/2] = 0.10.
    Additional Material: 8 Ill.
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  • 50
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 51
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    International Journal of Chemical Kinetics 10 (1978), S. 171-183 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equations for the average energy of chemically activated species are developed, and uncertainties in the various energy quantities involved are discussed. Various approaches to the energy distribution function of chemically activated species are discussed. Trial calculations on methylcyclobutane are presented.
    Additional Material: 4 Ill.
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  • 52
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    International Journal of Chemical Kinetics 10 (1978), S. 197-212 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrogen-atom recombination reaction has been simulated using a molecular dynamics technique recently formulated by the authors [1]. The rate of recombination has been calculated over a range of temperatures and inert gas concentrations (He and Ar) and agrees well with available experimental data. The calculations reproduce the negative activation energy characteristic of an atom recombination process. Over the range of conditions studied recombination was found to proceed via the energy transfer mechanism only, no evidence of bound HAr or HHe species was observed. Recombination was found to occur through an intermediate metastable diatomic molecule which is in equilibrium with its environment and from which there is a bottleneck to the formation of a stable molecule. The initial formation of a metastable species is sensitive to the hydrogen-inert gas potential, but relaxation of the total energy is primary determined by the mass of the third-body and the collision frequency.
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  • 53
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    International Journal of Chemical Kinetics 10 (1978), S. 249-275 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction, displaying peculiar characteristics as to relative rates and isomer distributions, has been studied in detail. Prior to this study, different mechanisms had been advanced by several groups. Kinetic features (isomer patterns, relative and absolute rates, reaction orders, influences of additives, H/D isotope effects) strongly point to a free-radical (chain) process, in which (1) is a crucial step. This abstraction reaction, endothermal by about 6 kcal/mol, apparently proceeds via a transition state closely resembling the free aryl radical. Relative rates and isomer distributions therefore reflect differences in stabilization energies, or in DH°(Ar - H). With high arene-Cl2 intake ratios or, more pronounced, with CCl4 as the reagent, aryl radicals also lead to biaryl, where arene successfully competes with the halogenating agent. This interpretation is quantitatively supported by our observation that “added,˝” recognizable aryl radicals yield the same chlorination-arylation product ratio, and by the results of competitive chlorination of benzene and chloroform over a temperature range of 200°C, where the latter study substantiates the value DH0(C6H5 - H) ≈ 109 kcal/mol.
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  • 54
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    International Journal of Chemical Kinetics 10 (1978), S. 307-324 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of ethylene-butene-2 mixtures has been studied in a static system over the temperature range of 689°-754°k and for initial pressures of each olefin of 20-200 torr. The two main addition products were cyclopentene and 3-methylpentene-1. Kinetic evidence indicated that cyclopentene was formed from radical processes while 3-methylpentene-1 was formed by the molecular “ene¨” addition of ethylene to butene-2 through a six-center transition state. The following rate constants were obtained: The pyrolysis of 3-methylpentene-1 has been studied over the same temperature range and for initial pressures of 20-100 torr. Kinetic evidence showed that the products ethylene and butenes were formed in both radical and molecular processes. Estimates of the rate constant k-1t and k-1c were, however, in reasonable agreement with the measurements of k1t and k1c. The mechanism of the ene reaction is discussed, and it is concluded that the transition state does not involve the formation of a biradical.
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  • 55
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    International Journal of Chemical Kinetics 10 (1978), S. 389-405 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of ethylene-propylene and ethylene-isobutene mixtures has been studied in a static system over the temperature range of 682°-754° K and for initial pressures of each olefin of 33-300 torr. The following molecular ene reactions were observed and the rate constants measured: Using thermodynamic data, rate constants for the corresponding retro-ene decomposition reactions were calculated and compared to kinetic data reported for similar compounds. Other products were formed by radical chain processes, the main higher molecular weight ones being cyclopentene and 1-methylcyclopentene. A mechanism involving addition of allyl radicals is suggested for the formation of these products.
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  • 56
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    International Journal of Chemical Kinetics 10 (1978), S. 425-425 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 57
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    International Journal of Chemical Kinetics 10 (1978), S. 461-469 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A program system is described for the integration of the rate equations resulting from large systems of elementary reactions. The Gear integration method is used for this problem, which frequently may exhibit stiffness instability when other integration methds are employed. No usage of the quasi-steady-state approximation is necessary. Ease in varying the reaction mechanism and simplicity of input structure are coupled with efficient execution and minimal demands for program storage as key features. The input-output structure, method of operation, and implementation are summarized, along with core storage requirements and execution times for trials using an IBM 360/44 computer.
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  • 58
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    International Journal of Chemical Kinetics 10 (1978), S. 529-544 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal reaction of 2-pentene (cis or trans) has been performed in a static system over the temperature range of 470°-535°C at low extent of reaction and for initial pressures of 20-100 torr. The main products of decomposition are methane and 1,3-butadiene. Other minor primary products have been monitored: trans-2-pentene, trans- and cis-2-butenes, ethane, 1,3-pentadienes, 3-methyl-1-butene, propylene, 1-butene, hydrogen, ethylene, and 1-pentene. The initial orders of formation, 0.8-1.1 for most of the products and 1.5-1.8 for 1-pentene, increase with temperature. The formation of the products and the influence of temperature on their orders can be essentially explained by a free radical chain mechanism. But cis-trans or trans-cis isomerization and hydrogen elimination from cis-2-pentene certainly involve both molecular and free radical processes. The formation of 1-pentene mainly occurs from the abstraction of the hydrogen atom of 2-pentene by resonance stabilized free radicals (C5H9.).
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  • 59
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    International Journal of Chemical Kinetics 10 (1978), S. 591-598 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the thermal bromination reaction have been studied in the range of 261°-391°C. The observed rate law is compatible with initiation by the step for which we obtain \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_6 (cm^3 /mol - \sec) = (13.41 \pm 0.26) - (11700 \pm 700)/\theta $$\end{document} where Θ = 2.303RT cal/mol. Using the above value of E6, we have \documentclass{article}\pagestyle{empty}\begin{document}$$ {D(C}_{\rm 6} {\rm F}_{{\rm 5}^{\rm -}} {\rm I)} \to {\rm 53.5}\ {\rm kcal/mol} $$\end{document}This result disagrees with values of D(C6F5-I) obtained in other ways and we conclude that reaction (3) probably does not involve initiation by reaction (6). Instead, initiation may involve an addition of Br to the ring in C6F5I followed by decomposition of the adduct to give C6F5Br. If correct, this implies that the Arrhenius parameters above refer to the addition reaction rather than to reaction (6).
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  • 60
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    International Journal of Chemical Kinetics 10 (1978), S. 657-667 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants and modes of reaction of NO2+ and C2H5ONO2NO2+ with aromatic compounds and alkanes have been determined in a pulsed ion cyclotron resonance mass spectrometer. Both ions undergo competing charge transfer and substitution reactions (NO2+ + M → MO+ + NO; C2H5ONO2NO2+ + M → MNO2+ + C2H5ONO2) with aromatic molecules. In both cases, the probability that a collision results in charge transfer increases with increasing exothermicity of that process. The C2H5ONO2NO2+ ion does not undergo charge transfer with molecules having an ionization potential greater than about 212 kcal/mol (9.2 eV); this observation leads to an estimate of 13 kcal/mol for the binding energy between NO2+ and C2H5ONO2. The importance of the substitution reaction depends on the number of substituents on the aromatic ring and the molecular structure, and, in the case of C2H5ONO2NO2+ ions, on the energetics of the competing charge transfer process. Both NO2+ and C2H5ONO2NO2+ undergo hydride transfer reactions with alkanes. For both these ions, k(hydride transfer)/k (collision) increases with increasing exothermicity of reaction, but in both cases the rate constants of reaction are unusually low when compared with other hydride transfer reactions of comparable exothermicity which have been reported in the literature. This is interpreted as evidence that the attack on the alkane preferentially involves the nitrogen atom (where the charge is localized) rather than one of the oxygen atoms of NO2+.
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  • 61
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    International Journal of Chemical Kinetics 10 (1978), S. 745-757 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general competitive method is described for the study of the kinetics of the reactions of radicals with halogens and interhalogen compounds in the gas phase. The method is applied to the reactions over the temperature range of 48°-199°C. It is found that \documentclass{article}\pagestyle{empty}\begin{document}$$ \log (k_6 /k_5) = \log (k_\varepsilon /k_7) = (- 0.042 \pm 0.060) - (8700 \pm 1300)/\theta $$\end{document} where Θ=2.303RT J/mol. Also \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} A_7 = 1/2A_{5,} \,\,\,\,\,\,\,\,\,\,\,\,E_7 = E_5 \\ A_8 = 1/2A_{6,} \,\,\,\,\,\,\,\,\,\,\,\,E_8 = E_6 \\ \end{array} $$\end{document}There is no correlation between differences in activation energies and differences in enthalpy changes for these reactions, but polar effects may be important in reactions (7) and (8).
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  • 62
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    International Journal of Chemical Kinetics 10 (1978), S. 687-711 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Methylhexyne-1, 5-methylhexyne-1, hexyne-1, and 6-methylheptyne-2 have been decomposed in comparative-rate single-pulse shock-tube experiments. Rate expressions for the initial decomposition reactions at 1100°K and from 2 to 6 atm pressure are \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm HC} \equiv {\rm CCH}_{{\rm 2}^{{\rm -}}}s {\rm C}_{\rm 4} {\rm H}_{\rm 9} \to {\rm HC} \equiv {\rm CCH}_{\rm 2} \cdot + s{\rm C}_{\rm 4} {\rm H}_{\rm 9} \cdot) = 10^{15.9} \exp (- 35,000/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm HC} \equiv {\rm CCH}_{{\rm 2}^{{\rm -}}}i {\rm C}_{\rm 4} {\rm H}_{\rm 9} \to {\rm allene} + n{\rm C}_{\rm 4} {\rm H}_{\rm 8}) = 10^{12.9} \exp (- 28,000/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm HC} \equiv {\rm CCH}_{{\rm 2}^{{\rm -}}}i {\rm C}_{\rm 4} {\rm H}_{\rm 9} \to {\rm HC} \equiv {\rm CCH}_{\rm 2} \cdot + i{\rm C}_{\rm 4} {\rm H}_{\rm 9} \cdot) = 10^{16.1} \exp (- 36,700/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm HC} \equiv {\rm CCH}_{{\rm 2}^{{\rm -}}}i {\rm C}_{\rm 4} {\rm H}_{\rm 9} \to {\rm allene} + i{\rm C}_{\rm 4} {\rm H}_{\rm 8}) = 10^{2.3} \exp (- 27,500/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm HC} \equiv {\rm CCH}_{{\rm 2}^{{\rm -}}}n {\rm C}_{\rm 3} {\rm H}_{\rm 7} \to {\rm HC} \equiv {\rm CCH}_{\rm 2} \cdot + n{\rm C}_{\rm 3} {\rm H}_{\rm 7} \cdot) = 10^{15.9} \exp (- 36,300/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm HC} \equiv {\rm CCH}_{{\rm 2}^{{\rm -}}}n {\rm C}_{\rm 3} {\rm H}_{\rm 7} \to {\rm allene} + n{\rm C}_{\rm 3} {\rm H}_{\rm 6}) = 10^{12.7} \exp (- 28,400/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm CH}_3 {\rm C} \equiv {\rm CCH}_{2^{-}}i {\rm C}_4 {\rm H}_9 \to {\rm CH}_3 {\rm C}) \equiv {\rm CCH}_{\rm 2} \cdot + i{\rm C}_{\rm 4} {\rm H}_{\rm 9} \cdot) = 10^{16.2} \exp (- 36,800/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm CH}_3 {\rm C} \equiv {\rm CCH}_{2^{-}}i {\rm C}_4 {\rm H}_9 \to 1,2-butadiene + i{\rm C}_{\rm 4} {\rm H}_{\rm 8}) = 10^{12.3} \exp (- 28,700/T)\sec ^{- 1} $$\end{document} In combination with previous results, rate expressions for propargyl C—C bond cleavage are related to that for the alkanes by the expression \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{\rm B} (alkyne) = \frac{1}{{3 \pm 1.5}}\exp (+ 4.25/T)k_{\rm B} (alkane) $$\end{document} These results yield a propargyl resonance energy of D(nC3H7-H) - D(C3H3-H) = 36 ± 2 kJ, in excellent agreement with a previous shock-tube study. They also lead to D(CH3C≡CCH2-H) - D(C3H3-H) = 0.6 ± 3 kJ, D(sC4H9-H) - D(iC3H7-H) = 0 ± 3 kJ, D(iC4H9-H) - D(nC3H7-H) = 2 ± 3 kJ, and D(nC3H7-H) - D(iC3H7-H) = 13.9 ± 3 kJ (all values are for 300°K). The systematics of the molecular decomposition process are explored.
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  • 63
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    International Journal of Chemical Kinetics 10 (1978), S. 783-804 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of hydroxyl radicals with eight substituted aromatic hydrocarbons and four olefins were studied utilizing the flash photolysis-resonance fluorescence technique. The rate constants were measured at 298°K using either Ar or He as the diluent gas. The values of the rate constants (k × 1012) in the units of cm3/molec. sec are (a) OH + o-xylene → products: (12.9±3.8), 20 torr He; (13.0±0.3), 20 torr Ar; (12.4±0.1), 200 torr He;(b) OH + m-xylene → products: (15.6±1.4), 3 torr Ar; (19.4±0.8), 20 torr Ar; (21.4±0.2), 20 torr He; (20.3±1.9), 200 torr Ar; (20.6±1.3), 200 Torr He;(c) OH + p-xylene → products: (8.8±1.2), 3 torr Ar; (10.1±1.0), 20 torr He; (10.5±0.6), 200 torr He;(d) OH + ethyl benzene → products: (7.50±0.38), 3 torr He; (7.06±0.26), 20 torr He; (7.95±0.28), 200 torr He;(e) OH + n-propylbenzene → products: (6.40±0.36), 20 torr He; (5.86±0.16), 200 torr He;(f) OH + isopropylbenzene → products: (7.79±0.40), 200 torr He;(g) OH + hexafluorobenzene → products: (0.221±0.020), 20 torr He; (0.219±0.016) 200 torr He;(h) OH + n-propyl pentafluorobenzene → products: (2.52±0.54), 3 torr He; (3.01±0.76), 20 torr He; (3.06±0.24), 200 torr He;(i) OH + propylene → products: (25.6±1.2), 20 torr He; (26.3±1.2), 200 torr He;(j) OH + 1-butene → products: (29.6±1.9), 3 torr He; (29.4±1.4), 20 torr He;(k) OH + cis-2-butene → products: (43.2±4.1), 3 torr He; (42.6±2.5), 20 torr He;(l) OH + tetramethylethylene → products: (56.9±1.3), 20 torr He.
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  • 64
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    International Journal of Chemical Kinetics 10 (1978), S. 669-675 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first-order kinetics and hydrogen kinetic isotope effect of the decarboxylation of oxalic acid in acetophenone were studied in the temperature range of 109.6°-150.0°C. The rate constants, activation parameters, and hydrogen kinetic isotope effect were calculated. Detailed comparison and discussion of the results were made with the data reported in the literature. Kinetic isotope effects and solvent effects on rates should be considered similar in mechanistic and/or theoretical studies in the sense that kinetic isotope effects result from a small perturbation of the reaction coordinate, while the solvent effect causes a general overall variation on the potential energy surface (thereby resulting in a change in the reaction coordinate).
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  • 65
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    International Journal of Chemical Kinetics 10 (1978), S. 713-732 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the photolysis of formaldehyde was studied in experiments at 3130 Å and in the pressure range of 1-12 torr at 25°C. The experiments were designed to establish the quantum yields of the primary decomposition steps (1) and (2), CH2O + hν → H + HCO (1): CH2O + hν → H2 + CO (2), through the effects of added isobutene, trimethylsilane, and nitric oxide on ΦCO and ΦH2. The ratio ΦCO/ΦH2 was found to be 1.01 ± 0.09(2σ) and (ΦH2 + ΦCO)/2 = 1.10 ± 0.08 over the range of pressures and a 12-fold change in incident light intensity. Isobutene and nitric oxide additions reduced ΦH2 to about the same limiting value, 0.32 ± 0.03 and 0.34 ± 0.04, respectively, but these added gases differed in their effects on ΦCO. With isobutene addition ΦCO/ΦH2 reached a limiting value of 2.3; with NO addition ΦCO exceeded unity. The addition of small amounts of Me3SiH reduced ΦH2 to 1.02 ± 0.08 and lowered ΦCO to 0.7. These findings were rationalized in terms of a mechanism in which the “nonscavengeable,” molecular hydrogen is formed in reaction (2) with φ2 = 0.32 ± 0.03, while the “free radical” hydrogen is formed in reaction (1) with φ1 = 0.68 ± 0.03. In the pure formaldehyde system these reactions are followed by (3)-(5): H + CH2O → H2 + HCO (3); 2HCO → CH2O + CO (4); 2HCO → H2 + 2CO (5). The data suggest k4/k5 ≅ 5.8. Isobutene reduced ΦH2 by the reaction H + iso-C4H8 → C4H9 (20), and the results give k20/k3 ≅ 43 ± 4, in good agreement with the ratio of the reported values of the individual constants k3 and k20.
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  • 66
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    International Journal of Chemical Kinetics 10 (1978), S. 883-891 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidative cleavage of some aliphatic ketoximes by thallium(III) acetate was studied in the temperature range of 20-40°C. The reactions were followed by determination of the rates of disappearance of thallium(III) acetate for variations in [substrate], [Tl(III)], [H+], ionic strength, temperature, etc. The reactions were found to be totally second order-first order with respect to each reactant. The second-order rate constants and thermodynamic parameters were evaluated and discussed. The mechanism proposed involves one-electron oxidation to the iminoxy radical followed by an another one-electron oxidation to the hydroxynitroso compound which dimerizes and decomposes to give the carbonyl compounds and hyponitrous acid.
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  • 67
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    International Journal of Chemical Kinetics 10 (1978), S. 899-904 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate of disappearance of C2N2 in the presence of a large excess of H atoms has been measured in a discharge-flow system at pressures near 1 torr and temperatures in the range of 282-338 K. Under these conditions the reaction has a small negative temperature coefficient. A transition from second-order to third-order kinetics with decreasing pressure occurs at pressures near 1 torr. The results are discussed in terms of the mechanism where k7 = (1.5 ± 0.2) × 10-15 cm3/molec1·sec is found for the forward rate of reaction (7). The results also give k7k8/k-7 = 3.7 × 10-31 cm6/molec2·sec and k7k9/k-7 = 3.0 × 10-32 cm6/molec2·sec, the first being probably an upper limit and the second probably a lower limit; hence k8/k9 = 12 is found as an upper limit.
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  • 68
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    International Journal of Chemical Kinetics 10 (1978), S. 995-1002 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative kinetics of diethyl ketone in perchloric acid media in the presence of mercuric acetate have been studied by using N-bromosuccinimide (NBS) as oxidant in the temperature range of 25°-50°C. It has been found that the order with respect to NBS is zero while with respect to diethyl ketone and [H+], it is unity. Succinimide, sodium perchlorate, and mercuric acetate have an insignificant effect on the reaction rate, while the dielectric effect was negative. A solvent isotope effect (k0D2O/k0H2O = 1.6-1.8) at 35°C has been observed. On the basis of the available evidences a suitable mechanism consistent with the experimental results has been proposed in which it is suggested that the mechanistic route for NBS oxidation in an acidic medium is through the enol form of the ketone. The magnitude of the solvent effect also supports the mechanism. Various activation parameters have been calculated, and the 1,2-dicarbonyl compound has been identified as the end product of the reaction.
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  • 69
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    International Journal of Chemical Kinetics 10 (1978), S. 67-87 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of N2O, H2, O2, and trace amounts of NO and NO2 were photolyzed at 213.9 nm, at 245°-328°K, and at about 1 atm total pressure (mostly H2). HO2 radicals are produced from the photolysis and they react as follows:Reaction (1b) is unimportant under all of our reaction conditions. Reaction (1a) was studied in competition with reaction (3) from which it was found that k1a/k31/2 = 6.4 × 10-6 exp { z-(1400 ± 500)/RT} cm3/2/sec1/2. If k3 is taken to be 3.3 × 10-12 cm3/sec independent of temperature, k1a = 1.2 × 10-11 exp {-(1400 ± 500)/RT} cm3/sec. Reaction (2a) is negligible compared to reaction (2b) under all of our reaction conditions. The ratio k2b/k1 = 0.61 ± 0.15 at 245°K. Using the Arrhenius expression for k1a given above leads to k2b = 4.2 × 10-13 cm3/sec, which is assumed to be independent of temperature. The intermediate HO2NO2 is unstable and induces the dark oxidation of NO through reaction (-2b), which was found to have a rate coefficient k-2b = 6 × 1017 exp {-26,000/RT} sec-1 based on the value of k1a given above. The intermediate can also decompose via Reaction (10b) is at least partially heterogeneous.
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  • 70
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    International Journal of Chemical Kinetics 10 (1978), S. 41-66 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tertiary-amyl amine has been decomposed in single-pulse shock-tube experiments. Rate expressions for several of the important primary steps are \documentclass{article}\pagestyle{empty}\begin{document}$$ k(t{\rm C}_5 {\rm H}_{11 - {\rm NH}_2} \to t{\rm C}_5 {\rm H}_{11}\!\!\cdot + {\rm NH}_2\cdot) = 10^{15.9} \exp (-39,700/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm C}_2 {\rm H}_5- {\rm C}({\rm CH}_3)_2{\rm NH}_2 \to {\rm C}_2 {\rm H}_5 \cdot + \cdot{\rm C}({\rm CH}_3)_2{\rm NH}_2) = 10^{16.5} \exp (- 38,500/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(t{\rm C}_5 {\rm H}_{11} {\rm NH}_2 \to {\rm C}_5 {\rm H}_{10} + {\rm NH}_3) 〈10^{14.5} \exp (- 37,200/T)\sec ^{- 1} $$\end{document}This leads to D(CH3—H) - D(NH2—H) = -10.5 kJ and D[(CH3)3C—H] - D[(CH3)2NH2C—H] = + 6 kJ.The present and earlier comparative rate single-pulse shock-tube data when combined with high-pressure hydrazine decomposition results-(after correcting for fall off effects through RRKM calculations) gives \documentclass{article}\pagestyle{empty}\begin{document}$$ [k_r^2 (t{\rm C}_5 {\rm H}_{11} \cdot,{\rm NH}_2 \cdot)/k_r (t{\rm C}_5 {\rm H}_{11} \cdot,t{\rm C}_5 {\rm H}_{11} \cdot)k_r ({\rm NH}_2 \cdot,{\rm NH}_2 \cdot)]^{1/2} \sim 2\,{\rm at}\,1100^o {\rm K} $$\end{document} where kr(…) is the recombination rate involving the appropriate radicals. This suggests that in this context amino radical behavior is analogous to that of alkyl radicals. If this agreement is exact, then \documentclass{article}\pagestyle{empty}\begin{document}$$ k_\infty ({\rm N}_2 {\rm H}_4 \to 2{\rm NH}_2 \cdot) = 10^{16.25} \exp (- 32,300/T)\sec ^{- 1} $$\end{document} Rate expressions for the primary step in the decomposition of a variety of primary amines have been computed. In the case of benzyl amine where data exist the agreement is satisfactory. The following differences in bond energies have been estimated: \documentclass{article}\pagestyle{empty}\begin{document}$$ D(i{\rm C}_3 {\rm H}_7 {-\!-} {\rm H}) {-\!-} D[{\rm CH}_3 ({\rm NH}_2){\rm CH} {-\!-} {\rm H}] = 14.3\,{\rm kJ} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ D({\rm C}_2 {\rm H}_5 {-\!-} {\rm H}) - D({\rm NH}_2 {\rm CH}_2 {-\!-} {\rm H}) = 15.9\,{\rm kJ} $$\end{document}
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  • 71
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    International Journal of Chemical Kinetics 10 (1978), S. 111-116 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of F5SOOSF5, P, in the presence of CO has been investigated between 130.1° and 161.9°C at total pressures between 50 and 600 torr. The reaction is homogeneous, and the only final products formed are CO2 and S2F10. The rate of reaction is proportional to the pressure of P. The partial pressures of CO and O2 and the total pressure have no influence on the course of reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d\left[P \right]}}{{dt}} = k\left[P \right] $$\end{document}The results are explained by the following mechanism:
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  • 72
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    International Journal of Chemical Kinetics 10 (1978), S. 117-123 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The unimolecularity of the thermal dehydrogenation of cyclopentene has been confirmed using the technique of very low-pressure pyrolysis (VLPP). Application of RRKM theory shows that the experimental unimolecular rate constants obtained over the temperature range of 942°-1152°K are consistent with the high-pressure Arrhenius parameters given by\documentclass{article}\pagestyle{empty}\begin{document}$$ \log (k/\sec ^{-1}) = 13.35 - 61/\theta $$\end{document} where θ = 2.303 RT kcal/mol. These parameters are in good agreement with static and shock tube studies. No firm evidence could be found for any side reactions or reversibility under the experimental conditions used.
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  • 73
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    International Journal of Chemical Kinetics 10 (1978), S. 185-195 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of isopropyl peroxide in solvents is shownto be a competition between unimolecular homolysis (kr) and an electrocyclic reaction yielding H2 plus acetone (kH). The value of kH increases markedly with increasing solvent polarity: PhCH3 〈 i-PrOH 〈 MeOH 〈 H2O. Log kH correlates linearly with Et (or Z). The effect on kr is similar but less pronounced. Log kr's for both i-Pr2O2 and t-Bu2O2 are shown to correlate with the molar solubility parameter δ. The negligible contribution of the electrocyclic reaction to thermal decompositions of peroxides in the vapor phase is thus not due to peculiar behavior of that reaction, which clearly has a polartransition state. It is argued that the transition state for unimolecular homolysis has no polar character despite the apparent sensitivity of homolysis rates to solvent polarity.
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  • 74
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    International Journal of Chemical Kinetics 10 (1978), S. 227-231 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the gas-phase decomposition of 1-methylcyclohex-1-ene has been studied over the temperature range of 1000°-1180° K in a single-pulse shock tube using a comparative-rate technique. The retro Diels-Alder reaction to ethylene and isoprene accounts for the bulk of the products with a rate constant given by \documentclass{article}\pagestyle{empty}\begin{document}$$ k = 10^{15.57} \exp \left({- 35,000/T} \right)\sec ^{- 1} $$\end{document}
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  • 75
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    International Journal of Chemical Kinetics 10 (1978), S. 295-306 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decomposition of acetonyl bromide, isopropenylmethylether, and hexanedione-2,5 was studied using the very-low-pressure pyrolysis (VLPP) technique. The acetonyl radical is a product of each reaction. Arrhenius parameters determined are or acetonyl bromide ← acetonyl + Br: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k\left({\sec ^{- 1}} \right) = 16.0 - 62.5/\theta\,{\rm at}\,300^{\rm o} {\rm K} $$\end{document} and for isopropenylmethylether ← acetonyl + CH3: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k\left({\sec ^{- 1}} \right) = 15.8 - 66.3/\theta\,{\rm at}\,300^{\rm o} {\rm K} $$\end{document} These lead to values of acetonyl stabilization energy (SE) of 0.8 and -4.0 kcal/mol, respectively. Comparison of the pyrolyses of hexanedione-2,5 and 2,5-dimethylhexane indicate a value of SE ∼ 2 kcal/mol. The total of these results is taken, along with previous work, to indicate that 0 ≲ SE ≲ 2 kcal/mol.
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  • 76
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative Arrhenius parameters have been determined for the addition of trifluoromethyl radicals to vinyl chloride (X=Cl), vinyl bromide (X=Br), acrylonitrile (X=CN), methyl vinyl ketone (X=COCH3), 2-methylbut-2-ene, and to iso-butene, taking the rate of addition to ethylene as standard. Addition occurred virtually exclusively at the unsubstituted end of all the olefins. The relative rates of addition at 164°C show very little variation. The preexponential terms for addition to the CH2 ends are constant within experimental error, and the small variations in rate are due principally to the activation energy term. The present results are put on an absolute scale using the previously determined Arrhenius parameters for addition to ethylene and are compared with data for other similar monomers determined previously.
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  • 77
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    International Journal of Chemical Kinetics 10 (1978), S. 407-415 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the deprotonation of tropaeolin O by OH- ions was investigated between 9° and 30°C, and by OD- ions at 24.7°C. The pH range was 10.7-12.5, and the ionic strength 0.1M throughout. All results were obtained by the temperature jump method. On the basis of a mechanism suggested earlier, rate constants k31 for the reaction between OL- and the internally bonded weak acid and k32 for the opening of the internal hydrogen bond were evaluated. The activation energies in ordinary water were found to be ΔH≠31 = 3.6 kcal/mol, ΔS≠31 = -19 eu, and ΔH≠32 = 27 kcal/mol, ΔS≠32 = 46 eu. The kinetic isotope effect was k31H2O/k31D2O ∼ 1.5 and k32H2O/k32D2O ∼ 0.9. The unusual results for reaction path are discussed in terms of solvent participation.
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  • 78
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    International Journal of Chemical Kinetics 10 (1978), S. 433-452 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The autoinhibiting reaction of ozone with dimethyl sulfide (DMS), has been studied at 296°K and 1.1 kPa (8 torr) as a function of the concentrations of both reactants. The major products of the reaction are H2CO, H2O, CO, and SO2. The specific rate of primary attack of O3 on DMS is immeasurably slow. It is suggested that the rapid overall rate observed for this reaction is due to a chain reaction initiated by the very slow primary reaction. It is concluded that reaction (1) cannot be important under atmospheric conditions and that the major loss process for DMS in the atmosphere is probably reaction with photochemically generated free radicals.
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  • 79
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    International Journal of Chemical Kinetics 10 (1978), S. 637-648 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl radical reactions with matrix molecules in glasses C2H5OH, (CH2OH)2, n- and i-C3H7OH, n- and i-C4H9OH, n- and i-C5H11OH, C2D5OH, and i-C3D7OD, and the reactions of Ċ2H5, Ċ3H7, Ċ4H9, Ċ5H11 with methanol glasses have been studied. Alkyl radicals were produced by photolysis of diphenylamine-alkylhalide-alcohol mixtures using ultraviolet light. In all cases the alkyl radical decay follows the law c = c0 exp(-k √t). The √t law should not be associated with alkyl radical diffusion in a matrix. A method of processing the kinetics of those reactions in which one paramagnetic species changes into another with the total concentration being constant and the electron spin resonance spectra of both species overlapping, is described.
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  • 80
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    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 81
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    International Journal of Chemical Kinetics 10 (1978), S. 1099-1117 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study has been made of the 3130-Å photolysis of CH2O (8 torr) in O2-containing mixtures (0.02-8 torr) and in the presence of added CO2 (0-300 torr) at 25°C. Quantum yields of formation of H2, CO, and CO2 and the loss of O2 were measured. ΦH2 and ΦCO were much above unity. In an explanation of these unexpected results, a new H-atom-forming chain mechanism was postulated involving HO2 and HO addition to CH2O: CH2O + hν → H + HCO (1) H + CH2O → H2 + HCO (3) H + O2 + M → HO2 + M (6) HCO + O2 → HO2 + CO (8) HO2 + CH2O → (HO2CH2O) → HO + HCO2H (15) HO + CH2O → H2O + HCO† (16); HCO† → H + CO (19) HO + CH2O → H2O + HCO (17) and HO + CH2O → HCO2H + H (18). When the results are rationalized in terms of this mechanism, the data suggest k16 ≫ k17 and k16/k18 ≅ 0.5. The data require that a reassessment of the relative rates of reactions (7) and (8) be made, since in the previous work HCO2H formation was used as a monitor of the rate of reaction (7) HCO + O2 + M → HCOO2 + M (7). The present data from experiments at PCH2O = 8 torr and PO2 = 1-4 torr give k7[M]/(k7[M] + k8) ≥ 0.049 ± 0.017. These data coupled with the k8 estimates of Washida and coworkers give k7 ≥ (4.4 ± 1.6) × 1011 l2/mol2·sec for M = CH2O. The reaction sequence proposed here is consistent with the observed deterimental effect of O2 addition on the laser-induced isotope enrichment in HDCO. In additional studies of CH2O-O2-isobutene mixtures it was found that ΦH2 was equal to φ2 as estimated in O2-free CH2O-isobutene mixtures. These results suggest that the increase in CO (ν = 1) product observed with O2 addition in CH2O photolysis does not result from perturbations in the fragmentation pattern of the excited CH2O, but it is likely that it originates in the occurrence of the exothermic reaction HCO + O2 → HO2 + CO (ν = 1).
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  • 82
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    International Journal of Chemical Kinetics 10 (1978), S. 1189-1193 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 83
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    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 84
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    International Journal of Chemical Kinetics 10 (1978), S. 1215-1223 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the ECR technique the electron scavenging properties of the halomethanes CHF3, CHClF2, and CHCl2F were investigated. A brief discussion is given on the evaluation of experimental data for inefficient polar scavengers. Absolute attachment rate constants were obtained from the decrease of the cyclotron resonance signal upon addition of the above scavengers. For the molecules CHF3 and CHCl2F the activation energies for the capture processes are given. Possible capture mechanisms are discussed.
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  • 85
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    International Journal of Chemical Kinetics 10 (1978), S. 945-954 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A nitrogen laser pumped tunable dye laser has been used to observe the three-photon ionization of NO through a two-photon resonance with the C2II state. Fluorescence is also observed from this state. The wavelength dependence of both signals have been measured. A reaction mechanism is postulated, which includes the initial two-photon excitation of the C2II state as the rate-limiting step. This mechanism predicts the observed second-order intensity dependence of the ionization signal and shows that the simple rate equation treatment is valid in this system.
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  • 86
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    International Journal of Chemical Kinetics 10 (1978), S. 955-970 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the activation energies E oF chlorine atom abstraction by cyclohexyl radicals and hydrogen atom abstraction by Cl atoms from polychloroalkanes can be correlated with the bond dissociation energies D and the Taft polar and steric substituent constants σ* and Es by the expression: \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta E = \alpha \Delta D + \rho \sigma ^* + \delta E_{\rm s} $$\end{document} where ΔE and ΔD represent the differences between the E and D values of a given substrate and those of a reference compound (CH3 substituted substrate) and α, ρ, and δ are the corresponding correlation coefficients. The use of this expression allows quantitative evaluation of the relative contribution of the various factors affecting the activation energies of these reactions and estimation of related thermochemical data.
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  • 87
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    International Journal of Chemical Kinetics 10 (1978), S. 1019-1041 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of ozone with propene and isobutene have been studied in the gas phase at 298°K and 530 Pa (4 torr) using a stopped-flow reactor coupled to a photoionization mass spectrometer. Reactant and product concentrations were followed as a function of reaction time. The major reaction products monitored were CH2O, CH3CHO, CO2, and H2O from the propene reaction, and CH2O, (CH3)2CO, CO2, and H2O from the isobutene reaction. The observations were interpreted on the basis of the Criegee mechanism for ozonolysis in solution: for which we find kA≈kB.In the gas phase the carbene peroxy radical is postulated to isomerize and decompose into molecular and free-radical products.
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  • 88
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    International Journal of Chemical Kinetics 10 (1978), S. 1081-1090 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the reaction O(3P) + SO2 + M have been determined over the temperature range of 299°-440°K, using a flash photolysis-NO2 chemiluminescence technique. For M=Ar, the Arrhenius expression \documentclass{article}\pagestyle{empty}\begin{document}$$ k_2 ^{{\rm Ar}} {\rm = 3}{\rm .1 \times 10}^{{\rm - 32}} e^{{\rm - (2005 \pm 300)/RT}} {\rm cm}^{\rm 6} {\rm /molec}^2 \cdot \sec $$\end{document} was obtained. At room temperature k2Ar = (1.05 ± 0.21) × 10-33 cm6/molec2·sec. In addition, the rate constants k2N2 = (1.37 + 0.27) × 10-33 cm6/molec2·sec, k2SO2 = (9.5 ± 3.0) ± 10-33 cm6/molec2·sec, k3N2 = (1.1 ± 0.2) ± 10-31 cm6/molec2·sec, and k3SO2 = (2.6 - 0.9) ± 10-31 cm6/molec2·sec were obtained at room temperature where k3M is the rate constant for the reaction O + NO + M → NO2 + M. The rate data are compared and discussed with literature values.
    Additional Material: 3 Ill.
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  • 89
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 821-837 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The experimental data on alkane decomposition from shock-tube and radical buffer studies and radical combination from very-low-pressure pyrolysis and modulation spectroscopy are shown to be consistent. They lead to experimental A factors which decrease by factors of 10-2000 from 300° to 1100°K. Heats of formation for ethyl, isopropyl, and t-butyl radicals have been found to be 10, 10 and 20 kJ higher than currently accepted numbers from metathesis reactions.
    Additional Material: 1 Ill.
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  • 90
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CO laser emission at 5 μm was detected when SO2 and CFBr3 were flash photolyzed in the vacuum ultraviolet above 165 nm. Over 40 vibrational-rotational transitions ranging from Δv = 2 → 1 to 14 → 13, with the exception of those between 8 → 7 and 11 → 10, were identified. The CO emission is believed to result from the O + CF reaction:The vibrational population of the CO has been measured by means of a CO laser resonance absorption method. The CO was found to be vibrationally excited to v = 24 with a vibrational temperature of about 1.4 × 104°K. The “surprisal analysis” of the observed CO distribution showed the possible occurrence of a minor process (presumably O + CFBr) that generated vibrationally colder CO. The effects of various additives on the CO emission were also examined. The addition of CO2 to a D2-SO2-CFBr3-He mixture resulted in a simultaneous osciallation at 3.6, 5, and 10.6 μm due to DF, CO, and CO2, respectively. Additionally, the utilization of the O + CFn (n = 1, 2, 3) reactions as F-atom sources for HF-laser operation in flash-initiated systems were demonstrated.
    Additional Material: 11 Ill.
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  • 91
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 893-897 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No. Abstract.
    Additional Material: 2 Tab.
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  • 92
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 905-909 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of gamma-radiation-induced free-radical chain reactions in solutions of carbon tetrachloride in mixtures of varying composition of cyclohexane and n-hexane was investigated in the temperature range of 296°-413°K. Trichloromethyl radicals were produced by the reaction of radiolytically generated alkyl radicals with the solute. The kinetics of the following reactions were studied: The following rate expression was obtained: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_4 /k_5 = 0.32 \pm 0.04 - (0.14 \pm 0.07)/\theta $$\end{document} The error limits are the standard deviation from the least mean-square Arrhenius plots. The present results, combined with previously measured activation parameters for hydrogen-atom abstraction from c-C6H12 and n-C6H14 by CCl3 radicals relative to CCl3 combination, afford experimental evidence that the decay of trichloromethyl species in alkane solutions is a diffusion-limited process. The thesis that activation energies of reactions (4) and (5) in the liquid phase are equal to their respective values in the gas phase is confirmed.
    Additional Material: 1 Tab.
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  • 93
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Permanganate ion rapidly oxidizes the thiol group in 2-thiouracils (2,3-dihydro-2-thioxo-4(1H)-pyrimidinones, 4-hydroxy-2-pyrimidinethiols) to the corresponding uracil-2-sulfonates in phosphate-buffered solutions. The oxidations, which are first order in oxidant and first order in reductants, are characterized by relatively small energies of activation (Ea ≅ 4.3-6.7kcal/mol) and relatively large negative entropies of activation (ΔS
    Additional Material: 2 Ill.
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  • 94
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 1005-1018 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decay kinetics of aryloxy and semiquinone radicals in the presence of copper ions in aqueous solutions has been studied by means of the flash photolysis technique. The radicals are involved in electron transfer reactions and those leading to the formation of intermediate complexes with copper ions. The complexes of p-benzosemiquinone anion radicals and 2-hydroxyphenoxy radicals with cupric ions decay in bimolecular self-reactions at a much slower rate than the original radicals. The increased stability of the complexes compared with the initial radicals is attributed to partial delocalization of the unpaired electron over the electron shell of copper and to steric hindrances in the self-reactions of complexes.
    Additional Material: 8 Ill.
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  • 96
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 1091-1097 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Beam attenuation and mass discrimination in effusive and quasieffusive molecular beams of gaseous mixtures have been studied experimentally in an instrument of conventional design, and have been rationalized in terms of transition flow effects and elastic scattering. Their implication in the quantitative monitoring of reacting chemical systems is examined, with particular emphasis in the case of the very-low-pressure pyrolysis technique.
    Additional Material: 3 Ill.
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  • 97
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 855-869 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This investigation presents a detailed examination of the relative reliability of the comparative and absolute rate methods as they are applied to kinetic studies in the single-pulse shock tube. For this purpose two previously studied reactions, the thermal elimination of HCl from ethyl chloride and n-propyl chloride, were selected and mixtures of these compounds were shock heated to temperatures in the range of 960°-1100°K. The experimental results were analyzed by both methods and the rate constants obtained from these analyses are compared with those of previous studies. The advantages and shortcomings of both methods are noted and it is concluded that reliable kinetic data can be obtained by the absolute rate (isolation technique) method with careful examination of the gas-dynamic flow conditions and taking cognizance of the incident shock deceleration. The limitations of the comparative rate technique encountered in the present study were similar to those detailed in previous investigations.
    Additional Material: 4 Ill.
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  • 98
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 871-882 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The adsorption/desorption and reactive behavior of formaldehyde was studied on clean single-crystal Ni(110) at adsorption temperatures down to 200 °K. For low exposures of the surface to formaldehyde, hydrogen and CO binding states were populated due to decomposition of the molecule upon adsorption. Higher exposures gave rise to a decomposition-limited hydrogen peak exhibiting an activation energy of 20 kcal/gmol and an apparent frequency factor of 1014 sec-1. At initial coverages of H2CO exceeding about 0.5, monolayer methanol was observed to form. The formation of methanol involved a hydrogen atom transfer between two adsorbed H2CO molecules and did not occur totally via surface hydrogen. Self-oxidation to form CO2 was also observed. The surface exhibited reaction heterogeneity, and the surface reactivity was observed to depend on the temperature of adsorption of reactants, suggesting strong adsorbate-induced surface “reconstruction.”
    Additional Material: 7 Ill.
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  • 99
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 759-772 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase photolysis of 2-fluorocyclohexanone at 313 nm and 120°C is reported. The primary dissociative step appears to be The 1-fluoropentanediyl species can disproportionate to form the 1- and 5-fluoro-1-pentenes, or cyclize to form vibrationally excited fluorocyclopentane. The latter molecule either undergoes collisional stabilization or decomposes unimolecularly to give cyclopentene and HF. The half-quenching pressure for the latter reaction was 2 torr. The disproportionation-to-combination ratic for the diradical was found to be 1.2. Some brief preliminary experiments on the liquid-phase photolysis of 2-chlorocyclohexanone and 2-fluorocyclohexanone are also described.
    Additional Material: 2 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 805-819 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum efficiencies of the primary processes in formaldehyde photolysis (φ1 and φ2) were determined as a function of wavelength in the range from 2890 to 3380 Å and at 25°C: CH2O + hν → H + HCO (1); CH2O + hν → H2 + CO (2). The estimates of φ2 were derived from ΦH2 values obtained in photolyses of CH2O-isobutene mixtures at high isobutene concentrations where H-atom scavenging was essentially complete. Values of φ1 + φ2, obtained from the ΦH2 values from the pure CH2O photolyses, were very near unity at all but the longest wavelengths employed: ΦH2 = φ1 + φ2 = 1.02 (2930 Å); 1.12 (3130 Å); 1.06 (3150 Å); 1.01 (3250 Å); 1.0 (3335 Å); 0.75 (3380 Å). Our results showed that the onset of photodissociation of CH2O by process (1) was at 3370 ± 10 Å; this corresponds to D(H-CHO) = 84.8 plusmn; 0.3 kcal/mol. The values of φ1 increased regularly with decreasing wavelength from 0 at 3370 Å to ∼0.7 at 3175 Å. Little further variation in φ1 occurred from 3175 to 2890 Å. For experiments at λ = 3300 Å, the addition of CO2 (∼300 torr) reduced φ2, while the effect on φ1 appeared to be small. The present results coupled with the solar irradiance estimates of Peterson [24] and the extinction data for CH2O from McQuigg and Calvert [7] were used to make new estimates of the apparent first-order rate constants (min-;1 × 103) of process (1) in the lower atmosphere at various solar zenith angles (in parentheses): 2.31 (0°); 2.17 (20°); 1.71 (40°); 0.92 (60°); and 0.17 (78°). The corresponding first-order rate constants (min-1 × 103) for solar light absorption by CH2O in the lower atmosphere are 7.74 (0°); 7.38 (20°); 6.18 (40°); 3.80 (60°); and 0.96 (78°).
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