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  • 1
    Electronic Resource
    Electronic Resource
    Nucleophilic substitution reactions of isopropyl benzenesulphonates with anilines and benzylamines (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 357-360 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nucleophilic substitution reactions of isopropyl arenesulphonates with anilines and benzylamines in acetonitrile at 65·0°C were investigated. The cross-interaction constants ρxz (and βxz) between substituents in the nucleophile (X) and leaving group (Z) are positive and relatively small. The transition state (TS) variation is consistent with that predicted by the More O'Ferrall-Jencks diagram, as expected from the positive ρxz. The small magnitude of ρxz correctly reflects a relatively loose TS structure, in contrast to the tight TS for ethyl (or methyl) derivatives under similar reaction conditions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060607
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetic studies on the aminolysis of 1-(trimethylsilyl)ethyl arenesulphonates in acetonitrile and methanol (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 359-363 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nucleophilic substitution reactions of 1-(trimethylsilyl)ethyl arenesulphonates with anilines and benzylamines in acetonitrile and methanol at 65·0°C were studied. The cross-interaction constants, ρXZ, between substituents in the nucleophile (X) and leaving group (Z) are relatively small (0·10 for XC6H4NH2 in MeCN) but similar to those for other SN2 processes at a secondary carbon atom. This provides further evidence for an approximately constant, loose SN2 transition state at a secondary carbon regardless of the size of the Cα substituent. The transition-state variations with substituents X and Z are in accord with that expected from the positive ρXZ value observed: a stronger nucleophile and/or nucleofuge leads to an earlier transition state, i.e. a lower degree of bond making and breaking.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610070705
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of aminolysis of propargyl and 1-methyl-propargyl arenesulphonates (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 629-633 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies were carried out on the aminolysis of propargly and 1-methylpropargyl arenesulphonates in acetonitrile at 45·0°C. The cross-interaction constants, ρxz and βxz, are similar to, but smaller than, those for the SN2 processes at other primary and secondary carbon centers. Compared with the allyl series, the smaller magnitude of ρxz and βxz reflects a looser transition state, which in turn leads to a lower rate despite the greater Taft's σ* value and the lower intrinsic (ΔE0≠) and thermodynamic barriers (ΔE0).
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610071107
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  • 4
    Electronic Resource
    Electronic Resource
    Nucleophilic substitution reactions of methallyl arenesulphonates with anilines and N, N-dimethylanilines (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 731-735 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies of the reactions of methallyl arenesulphonates (II) with anilines and N,N-dimethylanilines in acetonitrile at 45.0°C are reported. The sign and magnitude of the cross-interaction constants pxz (and βxz) between substituents in the nucleophile (X) and leaving group (Z) suggest that the transition state (TS) is slightly tighter than that for the corresponding reactions of allyl arenesulphonates (I). This is also supported by the observation that the magnitudes of ρx and ρz for II are uniformly greater than those for the reactions of I. These results are in line with the simple MO theory that the 2-position of the allyl system is inactive electronically. The steric effect of the 2-methyl group in II causes a rate retardation and a shift of the TS toward a later position along the reaction coordinate with a slight increase in the overall tightness of the TS structure. The large |ρxz| value obtained eliminates the possibility of an SN2′ mechanism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051104
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  • 5
    Electronic Resource
    Electronic Resource
    Cross interaction constants as a measure of the transition state structure. 13. Steric effects of the N,N-dimethyl group on the transition state structure in aminolysis of alkyl benzenesulphonates (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 751-756 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies on the reactions of methyl (MBS) and ethyl benzenesulphonates (EBS) with N,N-dimethylanilines (DMA) in methanol and acetonitrile are reported. The cross interaction constants ρXZ and βXZ, between the substituents in the nucleophile (X) and the leaving group (Z) indicated that the transition states (TS) are looser than those for the reactions with anilines, but the relative tightness between the two substrates was the same; the TS was tighter for EBS despite the increase in steric effect leading to looser TSs for MBS and EBS alike. The TS variation between two different reaction series expected from the simple Hammett and Brønsted coefficients, ρX, ρZ, βX and βZ, was incompatible with that predicted by the cross interaction constants, demonstrating again the unreliability of the simple parameters.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031109
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  • 6
    Electronic Resource
    Electronic Resource
    KINETICS AND MECHANISM OF THE AMINOLYSIS OF CYCLOALKYLMETHYL ARENESULFONATES (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 91-96 
    Details
    ISSN: 0894-3230
    Keywords: nucleophilic substitution reactions ; cycloalkylmethyl arenesulfonates ; positive ρXZ values ; secondary kinetic isotope effects ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Nucleophilic substitution reactions of cycloalkylmethyl arenesulfonates (CmH2n-1CH2OSO2C6H4Z) with anilines (XC6H4NH2) in methanol at 65.0 °C were studied. The reactivity order (n=4〉6〉7〉5) reflects largely the order of steric effect of the ring size (SEs term) except for n=5, which exhibits the least reactivity. This reversal of the order for n=5 is considered to result from large rate retardation due to polar effect of the ρ*σ* term. Application of the Taft equation to the rate data for n=5 and 6 gives ρ*=17·4 and S=2·3 with correlation coefficient of 0·90. The σ* values for n=4 and 7 are estimated to be -0·23 and -0·11, respectively. The positive ρXZ values of ca 0·3 are consistent with previous results for the reactions at primary reaction centers. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bimolecular nucleophilic displacement at tertiary carbon centers: Aminolyses of 2-cyano-2-propyl and 1-cyanocyclooctyl arenesulfonatesDetermination of Reactivity by MO Theory, Part 100. For Part 99, see Ref. 1. (1996)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 9 (1996), S. 683-688 
    Details
    ISSN: 0894-3230
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies were carried out on the reactions of anilines with 2-cyano-2-propyl and 1-cyanocyclooctyl arenesulfonates in acetonitrile at 50·0°C. The second-order rate constants for the former are in general greater than those for the latter but the rates of the two become comparable for a strong nucleofuge. The cross-interaction constants, ρXZ (and βXZ), are considerably smaller (ca -0·04) than those for the primary (ca 0·33) and secondary (ca 0·12) compounds. The negative sign and small magnitude are consistent with a dissociative SN2 mechanism with a loose transition state structure. The ab initio MO theoretical results for Cl- + RCl ClR + Cl- at the MP2 level (MP2/6-31 + G*//MP2/6-31 + G*) confirm the looseness of the transition state for the tertiary (R) alkyl compounds. The average r(Cl…Cl) value is 47middot;88 ± 0·03 Å, which is larger than those for the reactions at primary (4·68 ± 0·02 Å) and secondary (4·80 ± 07middot;02 Å) carbon centers. Thus a looser transition state with a smaller magnitude of ρXZ for the tertiary carbon centers has a larger theoretical r(Cl…Cl) value.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Aminolysis of aryl dithio-2-thiophenates and dithio-2-furoates in acetonitrile (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 30 (1998), S. 849-857 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aminolyses of the title substrates with anilines and benzylamines are investigated in acetonitrile. A clean second-order kinetics is obtained with a first-order rate law in the amine concentration, which is uncomplicated by the fast proton transfer step. The large magnitude of ρZ (ρ1g) as well as ρX (ρnuc) together with relatively large positive ρXZ values is consistent with a stepwise mechanism in which thiophenolate ion expulsion from the intermediate is rate limiting. For the reactions of aryl dithio-2-thiophenates with benzylamines the magnitude of ρX and ρZ values is relatively smaller suggesting that both the addition and expulsion of thiophenolate are partially rate determining. Relatively large secondary kinetic isotope effects, kH/kD≥1.7, with deuterated nucleophiles, support involvement a concurrent proton transfer to the departing thiophenolate ion in the transition state. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 849-857, 1998
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the aminolysis of O-ethyl S-aryl dithiocarbonates in acetonitrile (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 30 (1998), S. 419-423 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aminolysis reactions of O-ethyl S-(Z-phenyl) dithiocarbonates (Z=p-CH3, H, p-Cl, and p-NO2) with anilines (AN) and N,N-dimethylanilines (DMA) in acetonitrile at 30.0°C are investigated. Relatively small values of βX (βnuc,0.4 ca. 0.7) and βZ (βlg -0.1 ca. -0.4) for both ANs and DMAs, significantly large kH/kD values (1.1 ca. 1.9) involving deuterated anilines, and large negative ρXZ values for ANs (-0.56) are interpreted to indicate a concerted mechanism for both ANs and DMAs but with a hydrogen bonded four-center type transition state (TS) for ANs. The relative leaving ability, k(Z=p-NO2)/k(Z=p-CH3), is smaller for ANs than for DMAs, especially for a weaker nucleophile (1.9 and 4.7 for AN and DMA, respectively, with X=p-Cl). This suggests that the rate enhancement by the hydrogen-bond formation in the four-center type TS for AN is greater for a weaker nucleofuge (Z=p-CH3), especially when the nucleophile (X=p-Cl) is weaker. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 419-423,1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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