Novel synthesis method of clean and safe photoinitiator (2,4,6-trimethylbenzoyldiphenyl-diphenylphosphine oxide)

Abstract

The invention relates to the technical field of synthesis of photoinitiators, in particular to a novel synthesis method of a clean and safe photoinitiator (2,4,6-trimethylbenzoyldiphenyl-diphenylphosphine oxide). The method includes the steps of evenly mixing anhydrous alcohol with N-methylimidazole at the room temperature, raising the temperature to 30-50%, controlling the temperature, dropwise adding diphenylphosphine oxide, raising the temperature to 50-100 DEG C, conducting the constant-temperature reaction for 2-3 h, conducting standing and layering to take supernatant liquid for decompressing and distilling to obtain diphenyl alkoxylphosphine, making the diphenyl alkoxylphosphine start to react with 2,4,6-trimethylbenzoyldiphenyl chloride at the controlled temperature of 50 DEG C under the vacuum condition of -0.098 Mpa, raising the temperature by 10 DEG C every 20 minutes until the temperature is raised to 90 DEG C, conducting the constant-temperature reaction for 4-8 h, and adding 50% ethyl alcohol crystals to obtain a target product. The produced byproduct is subjected to vacuum removal and then enters a tail gas recovery system to be recovered through two stages of condensation. The synthesis method is simple in step, safe, clean, low in running cost and high in byproduct recovery rate.

Description

technical field [0001] The invention relates to a new synthesis method of a clean and safe photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and belongs to the technical field of photoinitiator synthesis. Background technique [0002] 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide (TPO) is a highly efficient free radical photoinitiator, which is widely used due to its large absorption in the ultraviolet and visible light regions. It is used in the field of curing of colored systems and film thickness. In recent years, the research on the synthesis process of this compound has become a focus of attention. [0003] U.S. Patent No. 4,298,738 discloses a method for synthesizing TPO, which uses diphenylethoxyphosphine and acid chloride as raw materials, and uses toluene, petroleum ether, etc. as solvents, and reacts for 6 hours under normal pressure at 50°C to obtain a crude product, which is washed with water. , pickling, alkali washing, and crystallization with 5...

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Problems solved by technology

And in this patent and above-mentioned U.S. patent same, all do not mention the reclamation processing method of ethyl chloride

[0005] A method for synthesizing TPO disclosed in Chinese patent CN109336925A, in which the by-product ethyl chloride is recovered by vacuum removal collection and compression filling system, but the system has a large investment and is complicated, which restricts the promotion of the system. It also restricts the industrial production of utilizing 2,4,6-trimethylbenzoyl chloride as raw material to synthesize TPO

[0006] In addition, when preparing diphenylalkoxyphosphine, alcohol reacts with diphenylphosphine chloride, and hydrogen chloride is generated, which is easy to affect the progress of the reaction. Therefore, the reaction must have a fuacid agent; Amines, dimethylaniline, etc. are acid-binding agents. Such amines and hydrogen chloride form hydrochloride, which is solid at low temperature. In order to completely separate the hydrochloride from diphenylalkoxyphosphine, it is necessary to add Such as toluene, petroleum ether and other low-polarity solvents, the hydrochloride cannot be separated from diphenylalkoxyphosphine at high temperature

This method uses dangerous toluene, petroleum ether, etc., which are low-flash point solvents, and the reaction process is relatively dangerous.

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