Ammonia reactivity in the acylation with 4-nitrophenyl benzoate in a water-2-propanol system

Acylation of piperidine and morpholine with phenyl benzoates in the mixtures water-2-propanol and water-dioxane

“…For equal amounts of water in the system the values of k for all studied reactions in the mixture water-dioxane are considerably larger than the k values for the same reactions in aqueous 2-propanol (Tables 1-3). The accelerating effect of aqueous dioxane as compared to aqueous 2-propanol on the rate constants of Nacylation was observed also in other reactions, for example, in the reactions of ammonia, aliphatic amines and α-amino acids with esters and sulfonyl chlorides [7,[10][11][12][13].…”

“…2), which is indicative of an important role of specific solvation of amines and transition states of the reaction of acylation. The solvation of the acylation reagents in the reaction of the acyl group transfer, according to the available data [7,[10][11][12][13], plays a subordinate role. Table 3 presents the results of the kinetic study of the reactions of piperidine and morpholine with compounds I and II in the system water (40 wt %)dioxane.…”

“…Apparently, the main factor affecting the rates of the studied reactions is the interaction of the components of the binary solvent with the transition states of the reactions. This assumption is based on the results of previous calculations [11] of the potential energy surface for the reaction of ammonia with phenyl benzoate. The simulation has shown that the increase in the number of water molecules in the transition state decreases the activation energy and increases the acylation rate constants when the fraction of water in the binary solvent is increased.…”