Preparation process of tert-butylhydroquinone

Abstract

The invention relates to the technical field of antioxidant preparation methods, and particularly relates to a preparation process of tert-butylhydroquinone (TBHQ). The preparation process comprises the following steps of (1) simultaneously adding excessive dilute sulphuric acid, equimolar hydroquinone and tertiary butyl acetate to a reaction still, wherein the weight ratio of the dilute sulphuric acid to the tertiary butyl acetate is 1:(3 to 6); (2) stirring and heating to 85 to 95 DEG C, and reacting for 1 to 8 hours; (3) stopping stirring, cooling to 65 to 75 DEG C, and then performing centrifugal filtration, wherein filtrate of sulphuric acid is recycled, and obtained filter residues are washed with 1 to 3 times warm water, so as to obtain a crude product of the TBHQ. Compared with the prior art, the preparation process has the advantages that the hydroquinone and the tertiary butyl acetate are used as raw materials, and the dilute sulphuric acid is used as a catalyst and a reaction solvent, so as to promote a reaction; tertiary butyl is supplied by the tertiary butyl acetate, so that side reactions are reduced; the crude product contains 70% to 75% of TBHQ, the content of DTBHQ (Di-Tert-Butylhydroquinone) as a by-product is low, the yield can reach 65 to 70% after purification, the yield is greatly increased, and great economic benefits are obtained.

Description

technical field [0001] The invention relates to the technical field of antioxidant preparation methods, in particular to a preparation process of tert-butyl hydroquinone. Background technique [0002] TBHQ is a low toxicity, high-efficiency antioxidant. It was approved for use in the United States in 1972. By 195, more than 20 countries and regions had allowed its use. It was approved for use in my country in 1991. It has good safety and high antioxidant performance, and is more effective for unsaturated oils than other commonly used antioxidants. TBHQ has excellent oil solubility, and does not change in color and flavor when it encounters copper and iron metals; it does not produce peculiar smell and odor when added to any oil and grease food. This makes it widely used in edible oil and oil-containing food. In addition, TBHQ can also be used as an intermediate of organic synthesis, polyester raw material, photosensitizer, cosmetic additive, and can also synthesize another ...

AI Technical Summary

Problems solved by technology

[0003] The existing patents for the preparation of TBHQ mostly use acid as a catalyst, and use tert-butyl or isobutylene to react with hydroquinone, such as patent GB761613, which uses phosphoric acid or sulfuric acid as a catalyst to prepare TBHQ in toluene solvents, and patent WO9716402 is in the water alloy Alkylation with benzenesulfonic acid in methanol, these methods will use organic solvents, which is likely to cause relatively large pollution, and the problem of solvent residues must be solved when the product is purified

Patent WO0198242 purifies TBHQ with a mixed solvent of water and toluene, they all utilize non-polar solvents to dissolve 2,5-di-tert-butylhydroquinone DTBHQ but its content is lower than 0.2%, but there is a shortage of using organic solvents , and the process efficiency is not high; Chinese patent CN1583698A discloses the preparation method of TBHQ, using hydroquinone and tert-butanol as raw materials to synthesize TBHQ by dehydration and alkylation under acid catalysis, and utilizing a small amount of sodium sulfite and hydrogen sulfite in water Sodium and zinc powder and other reducing agents and acids separate and purify TBHQ. The yield of the above method is low. The crude product contains about 50% of TBHQ, and the content of by-product DTBHQ is high, resulting in low yield.