相转移催化合成2,4-二氯苯氧乙酸新工艺研究

Phase transfer catalytic synthesis of 2,4-dichlorophenoxyacetic acid

以2,4-二氯苯酚和氯乙酸为原料,在碳酸钾作用下筛选相转移催化剂(四丁基溴化铵、四乙基溴化铵和PEG-600)进行醚化反应,制备2,4-二氯苯氧乙酸。所获得的最佳工艺条件是:催化剂选PEG-600/KI为最佳,二氯苯酚和氯乙酸原料物质的量比1∶2,相转移催化剂PEG-600用量为二氯苯酚的6%,KI用量为二氯苯酚量的10%。在此合成条件下,2,4-二氯苯氧乙酸收率达94.2%。

2,4-Dichlorophenoxy acetic acid is synthesized by etherification of chloroacetic acid and 2,4-dichlorophenol with phase transfer catalyst which selected from tetrahutylammonium bromide （TBAB）, tetraethylammonium bromide （TEAB） and polyethylene gtycol-600 （PEG-600） by potassium carbonate. The effect of different catalysts on yield of 2,4-dichlorophenoxy acetic acid is studied. As a result, the optimal conditions are obtained as following= using PEG-600/KI as the most suitable cat- alyst, the molar ratio of 2,4-dichlorophenol, chloroacetic acid, PEG-600 and KI is 1： 2 ： 0.06 ： 0.1. Under these conditions, the yield of 2,4-dichlorophenoxy acetic acid reaches 94.2%.