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Two‐Phase Reactions in Microdroplets without the Use of Phase‐Transfer Catalysts
Author(s) -
Yan Xin,
Cheng Heyong,
Zare Richard N.
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201612308
Subject(s) - catalysis , sodium hypochlorite , phase (matter) , chemistry , hypochlorite , chemical engineering , polymer , alcohol , phase transfer catalyst , combinatorial chemistry , organic chemistry , engineering
Many important chemical transformations occur in two‐phase reactions, which are widely used in chemical, pharmaceutical, and polymer manufacturing. We present an efficient method for performing two‐phase reactions in microdroplets sheared by sheath gas without using a phase‐transfer catalyst. This avoids disadvantages such as thermal instability, high cost, and, especially, the need to separate and recycle the catalysts. We show that various alcohols can be oxidized to the corresponding aldehydes and ketones within milliseconds in moderate to good yields (50–75 %). The scale‐up of the present method was achieved at an isolated rate of 1.2 mg min −1 for the synthesis of 4‐nitrobenzylaldehyde from 4‐nitrobenzyl alcohol in the presence of sodium hypochlorite. The biphasic nature of this process, which avoids use of a phase‐transfer catalyst, greatly enhances synthetic effectiveness.