ChemInform Abstract: RK. EINIGER 1‐(CARBOXYALKYL)‐NITRO‐IMIDAZOL‐DERIVATE IN POLYPHOSPHORSAEURE

Abstract

Bei der Behandlung mit Hydroxylamin/Alkali erhält man aus den Nitro‐ imidazol‐carbonsäuren (IIa)‐(IIc) die Amino‐Verbindungen (IIIa)‐(IIIc), die durch Polyphosphorsäure (PPA) zu den Lactamen (IV) cyclisiert ′werden i können.

Proton inventories of the basic methanolysis of phenyl methyl carbonate and diphenyl carbonate

“…determined to be 0.690 M"1 s"1, and this compares favorably with the value 0.70 M"1 s_1 reported by Mitton and Schowen. 4 The second-order rate constant at 25.1 °C in pure methanol-d was found to be 1.26 M"1 s"1, which also compares favorably with the literature value of 1.30 M"1 s'1.4 Table I lists these second-order rate constants at 25.1 °C for 10 different solutions containing varying atom fractions of deuterium.…”

“…The addition of methoxide to methyl-tritiated aryl methyl carbonates proceeded with no methoxide exchange, confirming that the addition of methoxide to carbonyl group is rate limiting in the methanolysis of these carbonates. 4 The proton inventory experiments in this study should thus provide information on the transition state leading to the formation of the tetrahedral intermediate. The observed inverse isotope effect of 1.83 clearly suggests that there is considerable solvent reorganization as the transition state is formed.…”

“…In the basic methanolysis of phenyl acetate, the addition of heavily solvated methoxide ion to the ester carbonyl proceeds with a substantial solvent reorganization but with little bond formation between the methoxide ion and the carbonyl group.3 Aryl carbonates have been shown to undergo basic methanolysis with rate-limiting addition of methoxide ion. 4 In these methoxide-catalyzed reactions, fractionation in the reactant state is confined to the three solvent sites around the nuclephilic oxygen. In the transition state, the solvation is likely to be confined to sites around the methoxide oxygen and possibly around the carbonyl oxygen.…”