Kinetic and equilibrium studies of anilinoalkanesulfonate formation.

(1)H NMR studies of the reactions of some hydroxyalkanesulfonates, 1, with aniline derivatives, 2, show the formation at equilibrium of anilinoalkanesulfonates, 3. Kinetic studies in water are consistent with a mechanism involving dissociation of 1 to give the parent aldehyde, which reacts with 2 to give a carbinolamine. Acid-catalysed dehydration of the carbinolamine yields an iminium ion which reacts rapidly with sulfite to give the product 3.

Carbanion reactivity, kinetic and equilibrium studies of sigma-adduct formation and elimination in the reactions of 4-nitrobenzofurazan derivatives with nitroalkane anions.

1H NMR studies are reported of the reactions in [2H(6)]-DMSO of 4-nitrobenzofurazan, 2a, and its 7-chloro- and 7-methoxy-derivatives, 2b and 2c respectively, with anions derived from nitromethane, 3, nitroethane, 4, and 2-nitropropane, 5. The initial reactions result in sigma-adduct formation by carbanion attack at the 5-position of 2a-c and in the case of reaction of 2a with 5 the adduct at the 7-position is also observed. These reactions may be followed by base catalysed elimination of nitrous acid to yield anionic alkene derivatives.

Rate-limiting proton-transfer in the sigma-adduct forming reactions of 1,3,5-trinitrobenzene and 4-nitrobenzofuroxan with substituted anilines in dimethyl sulfoxide.

Kinetic and equilibrium results are compared for the reactions in dimethyl sulfoxide of 1,3,5-trinitrobenzene, 1, and 4-nitrobenzofuroxan, 4, with a series of substituted anilines in the presence of Dabco or in, some cases, quinuclidine. pKa values for the corresponding anilinium ions are reported. The reactions of 1and 4 are likely to proceed through nucleophilic attack by the aniline to yield zwitterionic intermediates which may transfer an acidic proton to the bases present to yield the anionic adducts 9 or 12 respectively.

The Strecker reaction: kinetic and equilibrium studies of cyanide addition to iminium ions.

Kinetics studies are reported of the reactions of benzylidene benzylamine 4a, and of benzylidene allylamine 4b, with cyanide in aqueous buffers to give the corresponding [small alpha]-aminonitriles. The results allow the calculation of values of rate and equilibrium constants for reaction of the iminium ions formed from 4a and 4b with cyanide ions. These values are compared with those, obtained from the hydrolysis reactions, for reaction of the iminium ions with hydroxide ions and with water.

Sigma-adduct formation and oxidative substitution in the reactions of 4-nitrobenzofurazan and some derivatives with hydroxide ions in water.

The reactions of hydroxide ions with 4-nitrobenzofurazan, 1a, 4-nitrobenzofuroxan, 1b, and with three 4-nitro-7-substituted benzofurazans have been examined using 1H NMR and UV-visible spectroscopies. In each case initial reaction is at the 5-position to give an anionic sigma-adduct. Kinetic and equilibrium results are reported.

Kinetic and equilibrium studies of sigma-adduct formation and nucleophilic substitution in the reactions of 2-phenoxy-3,5-dinitropyridine and 2-ethoxy-3,5-dinitropyridine with aliphatic amines in dipolar aprotic solvents.

The reactions of aliphatic amines with 2-phenoxy-3,5-dinitropyridine, 4, and 2-ethoxy-3,5-dinitropyridine, 5, in DMSO result in the rapid reversible formation of anionic sigma-adducts at the 6-position. Kinetic studies show that proton transfer from the initially formed zwitterions to base may be rate-limiting. Slower reactions result, except in the case of 5 and piperidine, in displacement of the 2-substitutent via intermediates which have lower thermodynamic stabilities than their 6-isomers.