已经研究了几种取代的磺酰胺的亚硝化反应的动力学以及所得产物的脱亚硝化的动力学。相对于亚硝基化合物和酸浓度而言,脱亚硝化速率是一级的,并且未观察到添加亲核试剂的影响。所述denitrosation反应是一般酸催化,用布朗斯台德参数,α d,0.7,它是独立于芳环上的取代基。动力学溶剂的同位素效应范围为k d H 3 O + / k d D 3 O + = 1.20±0.05到2.04±0.06(对于L 3 O +进行脱氮) 对于二氯乙酸进行的亚硝化,从k d AH / k d AD取值为1.5±0.2至2.3±0.3,这表明该反应涉及速率确定的质子转移。进行亚硝化反应,通过亲核阴离子的无催化的,所观察到的一般碱催化(β NO = 0.3)和取代基影响提供一个一致的亚硝化-denitrosation过程。对于N获得的莱弗勒参数··· H键的形成(α NUC = 0.7)以及对于N ···
已经研究了几种取代的磺酰胺的亚硝化反应的动力学以及所得产物的脱亚硝化的动力学。相对于亚硝基化合物和酸浓度而言,脱亚硝化速率是一级的,并且未观察到添加亲核试剂的影响。所述denitrosation反应是一般酸催化,用布朗斯台德参数,α d,0.7,它是独立于芳环上的取代基。动力学溶剂的同位素效应范围为k d H 3 O + / k d D 3 O + = 1.20±0.05到2.04±0.06(对于L 3 O +进行脱氮) 对于二氯乙酸进行的亚硝化,从k d AH / k d AD取值为1.5±0.2至2.3±0.3,这表明该反应涉及速率确定的质子转移。进行亚硝化反应,通过亲核阴离子的无催化的,所观察到的一般碱催化(β NO = 0.3)和取代基影响提供一个一致的亚硝化-denitrosation过程。对于N获得的莱弗勒参数··· H键的形成(α NUC = 0.7)以及对于N ···
Nitroso Group Transfer from Substituted <i>N</i>-Methyl-<i>N</i>-nitrosobenzenesulfonamides to Amines. Intrinsic and Apparent Reactivity
作者:Luis García-Río、José Ramón Leis、José A. Moreira、Fátima Norberto
DOI:10.1021/jo0006730
日期:2001.1.1
between log ktr (rate constant for nitrosogrouptransfer) and pKaR2NH2+ and pKaleaving group. The study of the nitrosation processes of secondary amines catalyzed by ONSCN and denitrosation catalyzed by SCN-, in combination with the formation equilibrium of ONSCN, has enabled us to calculate the value of the equilibrium constant for the loss of the NO+ group from a protonated N-nitrosamine (pKNOR2N+HNO)
Determination of N−NO Bond Dissociation Energies of <i>N</i>-Methyl-<i>N</i>-nitrosobenzenesulfonamides in Acetonitrile and Application in the Mechanism Analyses on NO Transfer
heterolytic and homolytic N-NO bonddissociationenergies of G-MNBS in acetonitrile solution cover the ranges from 44.3 to 49.5 and from 33.0 to 34.9 kcal/mol for the neutral G-MNBS, respectively, which indicates that N-methyl-N-nitrosobenzenesulfonamides are much easier to release a NO radical (NO(*)) than to release a NO cation (NO(+)). The estimation of the heterolytic and homolytic (N-NO)(-)(*) bond dissociation
A series of substituted N-methyl-N-nitrosobenzenesulfonamides [2,4,6-(CH3)(3), 4-CH3O, 4-CH3, 4-Cl and 4-NO2] were synthesized. All of them transfer their nitroso group to N-methylaniline in a quantitative manner, the more reactive being those substituted with electron-withdrawing groups, thus resembling some of the known alkyl nitrites. Studies of their acid denitrosation and base-catalysed hydrolysis demonstrated that the nitrosobenzene-sulfonamides are fairly stable in aqueous media between pH 2 and 11. Their relative stability in aqueous media together with their ability to transfer the nitroso group to nucleophiles suggest their use as excellent alternatives to alkyl nitrites in both neutral and basic media. (C) 1998 John Wiley & Sons, Ltd.
Nitroso group transfer from N-nitrososulfonamides to thiolate ions. Intrinsic reactivity
作者:C. Adam、L. García-Río、J.R. Leis、J.A. Moreira
DOI:10.1016/j.tet.2006.06.060
日期:2006.9
The nitroso group transfer from N-nitrososulfonamides to thiolate ions was studied. Based on the results, the reaction rate is strongly dependent on the nature of the leaving group (alpha(1g) approximate to -1.30), but virtually independent of the basicity of the thiol (beta(nuc) approximate to 0-10)This dependence is ascribed to the presence of a nucleophile desolvation equilibrium (beta(d)) that is followed by the attack of the thiolate ion on the nitroso group (beta'(nuc)) via a concerted mechanism. The equilibrium constants for the loss of a nitroso group from a nitrosothiol and an N-nitrososulfonarni de were used to obtain the equilibrium constants for the different reactions involved. By using rate-equilibrium correlations, the parameters alpha(norm)(1g) ,beta(d), and beta('norm)(nuc) were obtained. (c) 2006 Elsevier Ltd. All rights reserved.
de Boer, Recueil des Travaux Chimiques des Pays-Bas, 1954, vol. 73, p. 677,679