Kinetics and mechanism of hydrolysis of N-arylimidic esters

Abstract

The influence of aryl substituents, pH, temperature, general acid-base catalysts, and solvent polarity on the kinetics of hydrolysis of ethyl A-arylformimidates and ethyl A-arylacetimidates was studied in aqueous and aqueous dioxane solutions. The data indicate that hydrolysis of these imidates involves rate-limiting reaction of the conjugate acids of the imidates with water in acidic solutions, and with hydroxide ion in alkaline solutions. Although alkoxyanilinocarbinols are probably intermediates in alkaline solutions, they may not be intermediates in acidic solutions. Hydrolysis at low pH may be a concerted process involving simultaneous C-0 bond formation and C-N bond cleavage. The falloff in hydrolysis rate in strongly acidic solutions may be due to the diminished water activity of the solvent, rather than to a change in the rate-limiting step. The two sets of products formed in alkaline imidate hydrolyses may arise from competing reactions of a single intermediate, rather than from reactions of two different intermediates in acid-base equilibrium.

The Alkylation of Ambident Anions. IV. The Alkali Metal and Silver Salts of Formanilides

“…Imidates thermally rearrange to the corresponding Nsubstituted amide, a reaction known as the Chapman rearrangement (1 3). Under conditions where the amide is comparatively stable, imidates rapidly hydrolyze (14). Calorimetric studies have not been done but bond strength or bond dissociation energy values can be used to estimate the difference in stability between the imidate and amide.…”

“…While the amide is quite inert, the imidate is very susceptible to hydrolysis (14). Removal of the products, especially the imidate, from the solid, unreacted silver formanilide and the silver halide co-product was difficult and especially so in the less polar hydrocarbon soivents.…”

“…Since the formimidates are known to be much more sensitive to hydrolysis than are the N-alkylation products (14) controls with added water were performed. A series of four reactions were done in each of D M F and DME.…”

Addition of dimethyl acetylenedicarboxylate to imino ethers. Trapping of a 1,4-dipolar intermediate

“…5), 224 (3.5),198 (3.5),197 (16),196 (100),186 (3.5), 185 (16), 168 (4.5), 164 (8),160 (3.5), 154 (7), 140 (3.5), 128 (6), 127 (6), 126(35),113 (3.5), 112 (7), 108 (6), 101 (4.5), 100 (7), 99 (3.5), 98 (28), 96 (6), 84 (6), 82 (3.5), 81 (4.5), 69 (7), 68 (6), 67 (6),59 (6), 56 (6), 55 (14), 53 (4.5), 45 (4.5), 44 (6), 43 (3.5), 42(19), 41 (29), 40 (4.5), 39 (8); mass spectrum (70 eV) m/e 255.1113 (caled for C12H17NO5, 255.1107).…”