Preparation of the Liquid Crystal Intermediate via Bromo-Reaction of Phenylacetylene and N-bromosuccinimide

摘要

An important liquid crystal intermediate of 4'-Bromoethynyl-4-pentyl-biphenyl was synthesized by bromo-reaction using N-bromosuccinimide as brominating agent, 4-Ethynyl-4'-pentyl-biphenyl as raw material, benzoyl peroxide (BPO) as catalyst and carbon tetrachloride (CCl_4) as reaction solvent. The effects of reaction variables were systematically optimized to achieve product with yield as high as possible. Under the optimal synthesis condition, where the temperature was 80°C, the mol ratio between 4-Ethynyl-4'- pentyl-biphenyl and NBS was 1:2, the weight rate of BPO to 4-Ethynyl-4'-pentyl-biphenyl was 2.5%, and the reaction time was 8 h, the product attained the best yield of 93.1%.