One-pot oximation–Beckmann rearrangement of ketones and aldehydes to amides of industrial interest: Acetanilide, caprolactam and acetaminophen

Abstract

High yielding one-pot oximation-Beckmann rearrangement of ketones to amides in ktrifluoroacetic acid has been conducted on several ketones and aldehydes. The substrate reactivity showed to depend on both oximation and Beckmann rearrangement reaction rate. In this synthetic procedure, trifluoroacetic acid acts as solvent, acid catalyst and organocatalyst and can be easily recycled.

Direct catalytic synthesis of ε-caprolactam from cyclohexanol using [n-C16H33N (CH3)3]H2PW12O40 as a catalyst

“…A single peak at −15.6 ppm (shown in Fig. 4a) was attributed to the structure of [PW 12 O 40 ] 3 − [19]. The spectrum of the recovered catalysts in oxidation stage (Fig.…”

“…Our previously work reported the utilization of the novel (NH 2 OH) 2 -IL in the one-step, solvent-free synthesis of CL from cyclohexanone with the 91% yield of CL, but using ZnCl 2 as a catalyst [11]. High yielding one-pot oximation-Beckmann rearrangement of ketones to amides using trifluoroacetic acid or FeCl 3 ·6H 2 O as a catalyst was reported by Aricò and Mahajan respectively [12,13]. More recently, Lee reported a multifunctional Pd/Sc(OTf) 3 /ionic liquid catalyst for the tandem onepot conversion of phenol to CL, in 67% overall yield, using 300 mol% 1-butyl-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]) as an additive [14].…”

“…However, the maximum yield of ε-caprolactam was 19.1% with CTAPMo as a catalyst. The order of softness of heteropoly anions in aqueous solution was estimated as follows: PW 12 . The softness of heteropoly anions is assumed to play an important role in stabilizing organic intermediates [28].…”

“…PW12 O 40 effectively promotes tandem reactions without the requirement of any additional catalyst and the final products are easily separated by simple extraction. DTAW) were synthesized according to previously reported methods respectively[18].…”

Carbonyl Compounds′ Journey to Amide Bond Formation

“…Aricò et al. reported an efficient one‐pot oxidative reaction for the synthesis of aromatic and aliphatic amides from ketones and hydroxylamine hydrochloride in the presence of trifluoroacetic acid (Scheme ) . This reaction was sensitive to steric hindrance and proceeded through a Beckmann rearrangement.…”