Water Solvent Method for Esterification and Amide Formation between Acid Chlorides and Alcohols Promoted by Combined Catalytic Amines: Synergy between N‐Methylimidazole and N,N,N′,N′‐Tetramethylethylenediamine (TMEDA)

Abstract

An efficient method for esterification between acid chlorides and alcohols in water as solvent has been developed by combining the catalytic amines, N-methylimidazole and N,N,N',N'-tetramethylethylenediamine (TMEDA). The present Schotten-Baumann-type reaction was performed by maintaining the pH at around 11.5 using a pH controller to prevent the decomposition of acid chlorides and/or esters and to facilitate the condensation. The choice of catalysts (0.1 equiv.) was crucial: the combined use of N-methylimidazole and TMEDA exhibited a dramatic synergistic effect. The catalytic amines have two different roles: (i) N-methylimidazole forms highly reactive ammonium intermediates with acid chlorides and (ii) TMEDA acts as an effective HCl binder. The production of these intermediates was rationally supported by a careful 1 H NMR monitoring study. Related amide formation was also achieved between acid chlorides and primary or secondary amines, including less nucleophilic or water-soluble amines such as 2-(or 4-)chloroaniline, the Weinreb N-methoxyamine, and 2,2-dimethoxyethanamine.

Kinetic Study of Michael Addition Catalyzed by N‐Methylimidazole in Ionic Liquids: Residual N‐Methylimidazole in Ionic Liquids as a Strong Base

“…[1] N-Methylimidazole is known to be an effective catalyst for the aza-Michael reaction of N-heterocycles, [8] the enzymatic acylation of ribavirin, [9] esterification and amide formation reactions, [10] aldol reactions of silyl enol ether with aldehydes, [11] the Baylis-Hillman reaction, [12] condensation [13] between carboxylic esters and acid chlorides or acids, and other [14] reactions. Small amounts (1-5 mol-%) of N-methylimidazole, as a basic impurity significantly affected H/D exchange in the synthesis of perdeuterated ILs.…”

Selective Monobenzoylation of 1,2- and 1,3-Diols Catalyzed by Me2SnCl2 in Water (Organic Solvent Free) under Mild Conditions

“…However, the polyols that can be effectively targeted in such reaction sequences are limited because most polyols are not sufficiently soluble in organic solvents. Moreover, organic reactions in water have recently attracted considerable attention from the standpoint of green chemistry, and several acylation methods including the Schotten–Baumann-type reaction have been developed . However, their methods require special conditions such as pH control, and nonenzymatic methods for the selective acylation of polyols in water (organic solvent free) has not been reported so far.…”

Amphiphilic Organocatalyst for Schotten-Baumann-Type Tosylation of Alcohols under Organic Solvent Free Condition

“…Even though the method was well planned, it still requires an organic solvent. Tanabe reported an organic solvent-free Schotten-Baumann-type tosylation in water, but it requires control of the pH of water and slow addition of tosyl chloride to prevent hydrolysis of the chloride . The procedure reported by Kazemi without water and organic solvent seems to be attractive, but it should be performed under harsh conditions to use inorganic bases without water .…”