Novel preparation method of 3-alkenyl benzyne liquid crystal compound

Abstract

The invention relates to a new preparation method of a 3-alkenyl benzyne liquid crystal compound, comprising the following steps of: by using phenylpropionic acid as a raw material, carrying out a halogenation reaction to prepare an intermediate I-1; carrying out an esterification reaction on the intermediate I-1 and alcohol under the catalysis of acid or acyl chloride to prepare an intermediate I-2; letting the intermediate I-2 react with an ethynylation reagent under an alkaline condition and a transition metal catalyst to obtain I-3; preparing I-4 from I-3 under the reduction of hydroboron;preparing I-5 from I-4 through selective oxidation under the action of an oxidizing agent; and carrying out a wittig reaction on the I-5 to prepare the 3-alkenyl benzyne liquid crystal compound. According to the novel preparation method, generation of by-products in the synthesis process can be avoided, the synthesis efficiency is high, the product quality is high, the cost is low, the post-treatment method is simple and easy to implement, industrial mass production is facilitated, and the product completely meets the requirements for high quality of liquid crystal materials at present.

Description

technical field [0001] The invention relates to a new method for preparing a 3-alkenyl benzyl liquid crystal compound, which belongs to the technical field of liquid crystal compounds. Background technique [0002] Liquid crystal displays have been widely used in various aspects of social life. Since the development of liquid crystal display technology, various liquid crystal compounds have been practically applied. Some general requirements for liquid crystal compounds, including phase transition temperature, optical anisotropy, dielectric anisotropy, viscosity, etc. of liquid crystal compounds, all have a great influence on the final application of liquid crystal materials. [0003] 3-alkenyl phenylene liquid crystal compounds can be widely used in STN-LCD, this type of liquid crystal has high birefringence, wide nematic phase transition temperature, low viscosity, low temperature miscibility, large K33 / K11 Value, with a good steepness, is a liquid crystal compound with e...

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Problems solved by technology

[0009] The synthetic route of scheme 2 has relatively greater improvement, but in research process, finds that this synthetic route has following two defectives: (1) in p-iodobenzoic acid ethyl ester as raw material preparation During the process, due to the existence of CuI, a Glaser side reaction occurs, producing 2% to 10% 1,3-diyne impurities, which are very difficult to purify and affect the product quality and effective utilization of raw materials; (2) final format coupling reaction, there is a small amount of migration of terminal olefinic double bonds, which will also pose a greater challenge to the purification of products

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