960. Nucleophilic displacements in organic sulphites. Part III. Comparison of alkaline and acidic hydrolyses of trimethylene sulphite and related compounds

Abstract

Trimethylene and 1 : 3-butylene sulphites are hydrolysed in alkaline solution a t rates which can be followed by conventional techniques at 0". The reactions are of the second kinetic order, and have the same rates whether measured by the uptake of alkali or the liberation of sulphur dioxide. The possible intermediate (e.g., HO*CH,*CH,*CH,*O-SO,H or its anion) does not build up to high concentration during reaction. Alkyl substitution in the carbon chain seems to have little effect on the rate of alkaline hydrolysis, but 1 : 2-sulphites are in this process very much more rapidly hydrolysed. These results, in conjunction with studies of bond-fission (Part I) allow comparison with the corresponding data for acid-catalysed hydrolysis (Part 11). In the latter reaction also, the possible intermediate does not build up in concentration; and alkyl substitution in the carbon chain has little influence on the rate, which now is little changed when the ring-size is altered.THE detailed courses of hydrolyses of cyclic sulphites, and the kinetic effects of structural changes, are considered. In contrast to the acid-catalysed hydrolyses of cyclic sulphites discussed in Part 11, those in alkaline solution are very rapid. Possible stages in the reaction (e.g., of trimethylene sulphite) are as follows:* Parts I and 11, preceding papers.

Deuterium Oxide Solvent Isotope Effects in the Nucleophilic Reactions of Phenyl Esters

“…The aspirin hydrolysis has been shown, on the basic of kinetic and isotopic expeirments, to involve an intramolecular nucleophilic-catalyzed hydrolysis involving an anhydride intermediate.18 '19 The methyl hydrogen phthalate hydrolysis has been shown on the basis of kinetic experiments to involve a similar intramolecular nucleophilic-catalyzed hydrolysis.19 The reaction of 2,4-dinitrophenyl acetate with acetate ion is an analogous intermolecular nucleophilic-catalyzed hydrolysis involving an anhydride intermediate. 14 Evidence for an anhydride intermediate in this reaction stems from the isotopic experiment involving acetate-180 (18) E. S. Garrett, J. Am.…”

Nucleophilic substitution at tricoordinate sulfur

“…Darwish and Tourigny,216 however, proposed that the racemization of p-methoxybenzylethylmethylsulfonium perchlorate occurred via carbon-sulfur heterolysis to give an unusual ionneutral molecule pair which can react to give either solvolysis products or return to racemic sulfonium salt (eq 130). ;s-R (130) solvolysis products ative amounts of olefin and substitution product resulting from solvolysis vary considerably with the nature of the counterion. Brower and Wu34 concluded that the volume of activation for the racemization of the phenacylethylmethylsulfonium ion ( * 0) is consistent with a pyramidal inversion mechanism while the value for the ferf-butylethylmethylsulfonium ion ( * = +6.4 ml/mol) is more compatible with a transition state in which partial dissociation has occurred.…”

Organic Sulfites.

“…Reaction rates and mechanisms have been studied in a series of investigations by de la Mare, Bunton, Tillett, and others (30,31,32,33,34,62,151,152,220,221). From hydrolyses carried out in isotopically enriched water it appeared that for open-chain as well as cyclic aliphatic sulfites reactions take place with sulfur-oxygen bond fission only.…”