Method for preparing sulfur-containing bisphenol compound antioxidant by means of recycling mother liquor

Abstract

The invention relates to a method for preparing sulfur-containing bisphenol compound antioxidant by means of recycling mother liquor, which belongs to the field of synthetic rubber, polyolefin plastics and lubricating oil. Ethanol water is used as a reaction solvent, 2, 6-di-tert-buty phenol, paraformaldehyde and hydrogen sulfide or sodium hydrosulfide are used as raw materials, sodium hydroxide is used as a catalyst, and reaction is performed in a closed reactor to prepare a methylene-4426-S product. The product is separated by means of filtration and washed by the ethanol water to obtain a white crystal product. Residual reaction mother liquor mainly includes ethanol water and contains organic matters such as formaldehyde, the sodium hydroxide, Na2S, the methylene-4426-S product and the like. The reaction mother liquor is collected to serve as the reaction solvent, and condensation reaction is continued to prepare the methylene-4426-S product. The reaction mother liquor is recycled, consumption of paraformaldehyde and hydrogen sulfide or sodium hydrosulfide is reduced, and 2,6-phenol raw material conversion rate, target product yield and target product quality can be kept.

Description

technical field [0001] The invention belongs to the field of synthetic rubber, polyolefin plastic and lubricating oil. It relates to a method for preparing a sulfur-containing bisphenol compound antioxidant by circulating mother liquor. The product of the sulfur-containing bisphenol compound antioxidant specifically refers to the following formula (I), (referred to as methylene-4426-S). [0002] [0003] (I) [0004] (I) Chemical name: bis(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide. Background technique [0005] Methylidene-4426-S is a sulfur-containing bisphenol compound antioxidant product, which is mainly used as an antioxidant for synthetic rubber, polyolefin plastics and other polymer materials, as well as oil products such as lubricating oil and fuel oil. [0006] The Guangzhou Synthetic Materials Aging Research Institute has disclosed the synthesis method of methylene-4426-S products, using 2,6-tert-butylphenol (referred to as 2,6-phenol), 36% formaldehyde aqueo...

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Problems solved by technology

[0008]2. Due to the fact that there is a large amount of washing wastewater from dark brown to dark yellow to light yellow in the process of washing crude products in this production process, the production of one ton of products produces approximately 12-15 tons of waste water, yellow and turbid, containing a small amount of phenolic compounds, Na2S, formaldehyde, ethanol, etc., usually discharged directly, causing serious pollution to the environment

Washing waste water is discharged into the groundwater system, and some highly toxic hydrogen sulfide gas will be released after encountering acid, which will cause poisoning and injury to personnel if you are not careful

[0009]3. Poor product quality

After the reaction, the crude product is washed with water or ethanol aqueous solution to neutrality, but the alkaline substance wrapped inside the crystal grains cannot be removed, so the product is easy to turn yellow during storage, usually within three weeks, forming a yellowish powder Bulk products, affect its performance in polymers, and even cause the appearance of white polymers to turn yellow

[0010]4. If you want to obtain a product with a melting point > 140°C and granular white crystals, you must use absolute ethanol for recrystallization and refinement

[0012] 1. While neutralizing the alkali metal hydroxide catalyst in the reaction mixture with inorganic acid, the excess hydrogen sulfide raw material in the reaction mixture becomes a free gas again, during production It needs to be completely absorbed with lye and recycled. After absorption, the by-product composed of lye and Na2S needs to be further processed to obtain Na without alkali metal hydroxide 2S aqueous solution can be recycled, the process in production is longer, and the investment in equipment is larger;

[0013] 2. Use excess formaldehyde to increase the conversion rate of 2,6-phenol raw materials and product yield. The molar ratio of 2,6-phenol to formaldehyde raw materials is 1:1.85-2.0, and the excess formaldehyde is nearly 50%. Therefore, from the reaction mixture After removing the methanol or ethanol reaction solvent, add an aliphatic hydrocarbon solvent to dissolve the solid crude product of methylene-4426-S, let it stand for stratification, and separate the lower water layer; wash with water, combine the washing water and the lower layer separated by standing The water layer, which contains the excess formaldehyde and sodium sulfate fed, needs to be distilled, which consumes a lot of energy. During the production process, the company cannot bear such a high cost, so it has no choice but to choose to discharge directly, so the formaldehyde accumulates Still cause serious environmental pollution and waste of formaldehyde raw materials

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