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  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (o-Hydroxyphenyl)methylphosphonic acids are readily obtained from o-(bromomethyl)- or o-(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pKa values have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric effects.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: UV/VIS Absorption spectra of nitrosubsituted (o-hydroxyphenyl)methylphosphonic acids (o-(phosphonomethyl)phenols) were measured as a function of pH at 25° in 0.1M NaClo4 solutions. Computational treatment of the whole set of optical density data between 200 and 500 nm resulted in the determination of the dissociation constants of these polyacids and also of the individual electronic spectra of all the species involved in the deprotonation sequence. The spectral behavior gives information on the structure of the anions formed and consequently the order of the subsequent deprotonation steps could be deduced. For the (2-hydroxy-3-nitro(or 5-nitro)phenyl)methylphosphonic acid and the 2-hydroxy-5-nitro-1,3-phenylenebis(methylphosphonic acid), the phenolic proton dissociates in the last step, while, in the case of (2-hydroxy-3,5-dinitrophenyl)methylphosphonic acid, the last dissociating proton comes from a P—OH group. An intermediate situation is found for (3-chloro-2-hydroxy-5-nitrophenyl)methylphosphonic acid. Generally, the deprotonation sequence is governed by intramolecular H-bonds involving the phenolic OH group.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: Phosphonium compounds ; Phosphorus-phosphorus bonds ; Phosphorus-arsenic bonds ; Phosphorus-tin bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation, Structure, and Properties of Urea-Bridged Cyclic Phosphonium Salts with Phosphorus-Phosphorus, Phosphorus-Arsenic, Phosphorus-Antimony, and Phosphorus-Tin BondsN-[tert1-Butyl(phenyl)phosphanyl]-N,N′-dimethyl-N′-(trimethylsilyl)urea (2) reacts with organodichlorophosphanes with cleavage of the Si - N bond to form the cyclic phosphanylphosphonium chlorides 3a - i containing the grouping [λ3P - λ4P+]Cl-. Evidence was obtained for the existence of an equilibrium in solution between the ionic phosphonium structure 3 and a covalent form. The position of the equilibrium is determined by the nature of the group R at λ3P. Reaction of the phosphonium salts 3a - i with Na[BPh4] furnished the phosphonium tetraphenylborates 4a - i containing the grouping [λ3P - λ4P+][BPh4]-. In the reaction of 2 with organodichloroarsanes the arsanyl-phosphonium chlorides 5a and 5b with the grouping [λ3As - λ4P+] were formed. By treatment of 5a and 5b with Na[BPh4] the corresponding tetraphenylborates 6a and 6b were produced. Further cyclic phosphonium salts containing a heteroatom-phosphorus bond with the complex chloro anions [AsCl4]-, [SbCl4]-, and [Me2SnCl4]2- were formed in the reaction of 2 with the chlorides AsCl3, SbCl3 and Me2SnCl2. - The structures of 4h and 6a were confirmed by low-temperature X-ray crystal structure determination; the P - P bond length of 4h is 222.3(2) pm, the P - As bond length of 6a 234.6, 234.1(2) pm in two independent cations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1719-1727 
    ISSN: 0009-2940
    Keywords: Isoindoles, symmetrically substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies on the Chemistry of Isoindoles and Isoindolenines, XXXVII1) - Symmetrically Substituted 2-Alkyl-2H-isoindoles2-Alkyl-Rn-2H-isoindoles (1; Rn=4,5,6,7-tetramethyl, 4,5,6,7-tetrachloro) have been prepared efficiently by the N-oxide route and characterized by spectroscopic means.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0009-2940
    Keywords: Oxaquadricyclanes ; Donor-acceptor cyclopropanes ; Calculations, AM1, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Medium and Large Rings, XXX1). - Regioselective Thermolysis of Oligomethylene Oxaquadricyclanedicar-boxylic Esters to 3,6-Alkanooxepinedicarboxylic Esters - X-ray Structural Analyses and Semiempirical CalculationsX-ray structural analyses and semiempirical calculations for the oxaquadricyclanes 1 - 3 are discussed. The regioselectivity observed for the thermolyses of 1 - 3 (exclusive formation of 3,6-alkanooxepines 6) is in line with the assumption that preferential cleavage of the long C - C bonds between the donor and acceptor substituents of the cyclopropane rings determines the reaction course.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0009-2940
    Keywords: 2,4-Diaza-1,5-diphosphapentan-3-ones, 2,4-dimethyl- ; Coordination compounds ; Chromium complexes ; Molybdenum complexes ; Tungsten complexes ; Iron complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Compounds with the 2,4-Dimethyl-2,4-diaza-1,5-diphosphapentan-3-one Skeleton; Synthesis, Structure, and Properties of 1,5-Di-tert-butyl-2,4-dimethyl-1,5-diphenyl-2,4-diaza-1,5-diphosphapentan-3-one and Its DerivativesN,N′-Dimethyl-N-N′-bis(trimethylsilyl)urea (1) reacts with tert-butylchlorophenylphosphane (2) to form the monophosphino/ trimethylsilyl-substituted urea 3. Under more vigorous conditions the bisphosphino-substituted derivative 4 was also obtained. The reaction of 4 with the tetracarbonyl norbornadiene derivatives of Cr, Mo, and W furnished the unusual chelate complexes 5-7, in which the ligand 4 is coordinated to the metal through one of the two phosphorus atoms and the oxygen atom of the carbonyl group. The free ligand 4 and the isostructural complexes 5 and 6 were subjected to X-ray structure analyses. The approximate twofold symmetry of 4 is lost as a result of a major conformational change on complex formation. In contrast, 4 reacts with Fe2(CO)9 and with (COD)-PtCl2 (COD=1,5-cyclooctadiene) to give the complexes 8 and 9. In both 8 and 9 the ligand 4 is coordinated by both phosphorus atoms. Reaction of 4 with sulfur and selenium led to the disulfide 10 and diselenide 11, whereas with tellurium no reaction was observed.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0009-2940
    Keywords: 2H-Isoindoles, 2-alkyl-, reactions with C=C dienophiles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies on the Chemistry of Isoindoles and Isoindolenines, XXXIX.  -  Reactions of 2-Alkyl-4,5,6,7-Rn-2H-isoindoles (Rn=tetramethyl, tetrachloro) with Activated C=C DienophilesSubstituted 2H-Isoindoles 2 react with maleic imides in absolute ether. Cycloaddition in 1,3-position leads to the formation of 1:1 adducts. The ratio between endo isomers 4 and exo isomers 5 depends on the substituents and the solvents. In the case of steric hindrance the Diels-Alder addition can be induced by Lewis acids. In the presence of oxygen-substituted 4,5,6,7-tetrachloro-2-methylisoindolin-1-ones 7 are formed as minor products.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 427-432 
    ISSN: 0009-2940
    Keywords: [1n]Metabiphenylophanes ; Calixarenes ; Spherands ; Diastereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation of 5,5′-di-tert-butyl-2,2′-dihydroxybiphenyl (1) with formaldehyde yields a cyclic trimer 2 (and tetramer 3) having three (four) methylene groups less than a calix[6]-arene (calix[8]arene). Alkylation of the (flexible) trimer with ethyl bromoacetate gives exclusively the stereoisomer 4 with C2 symmetry, while the isomer with D3 symmetry is not observed. Two isomers 6a and 6b (C2 and C1 symmetry) are obtained by treatment with tert-butyl bromoacetate which both are converted by transesterification with methanol into the same hexamethyl ester 5 having C2 symmetry. These results are rationalized by restricted rotation around Ar—Ar bonds for larger O-alkyl groups also around Ar—CH2—Ar bonds. The structure of the hexaethyl ester 4 is also confirmed by single crystal X-ray analysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 799-810 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phosphonomethyl-substituted phenols are readily obtained from o-hydroxymethylated phenols and trialkyl phosphites. The free acids, incorporated into phenol-formaldehyde resins, act as cation exchangers with remarkable selectivity for different metal ions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0887-624X
    Keywords: antenna effect ; photocatalytic activity ; solubilization ; distribution coefficient ; poly(sodium styrene sulfonate-co-N-vinylcarbazole) ; poly[sodium styrene sulfonate-co-N-(acryloyloxyhexyl)carbazole] ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new antenna polyelectrolytes, poly(sodium styrenesulfonate-co-N-vinylcarbazole) (PSSS-VCz) and poly[sodium styrenesulfonate-co-N-(acryloyloxyhexyl)carbazole](PSSS-AHCz) have been synthesized. Both polymers were found to solubilize large hydrophobic compounds such as perylene in aqueous solution, but PSSS-AHCz was much more efficient than PSSS-VCz. The distribution coefficients of perylene between the polymer pseudophase and water was determined to be (2.9 ± 0.1) × 106 and (4.0 ± 0.2) × 104 in PSSS-AHCz and PSSS-VCz, respectively. The greater solubilizing ability of PSSS-AHCz is attributed to the higher content of hydrophobic monomer units in the polymer. Both copolymers displayed photocatalytic activity, absorbing light in the UV-visible spectral region. Energy can then be transferred to a solubilized molecule or dissolved oxygen and induce photochemical reactions. The model reaction used in this study was the photosensitized oxidation of perylene solubilized in aqueous polymer solutions. PSSS-AHCz was found to be a much more efficient photocatalyst than PSSS-VCz. The enhanced photocatalytic activity of PSSS-AHCz is attributed to the greater concentration of carbazole chromophores, the higher local concentration of probe in the polymeric pseudophase and possibly to the elimination of the low-energy excimer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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