Novel process for purifying crude product and commercial 2-mercaptobenzothiazole by CO2 method

Abstract

The invention discloses a novel process for purifying a crude product and commercial 2-mercaptobenzothiazole by a CO2 method, which belongs to the technical field of refining of 2-mercaptobenzothiazole. The process comprises the following steps: adding 2-mercaptobenzothiazole (M) to be purified into ammonia water in batches for mixing and dissolving; heating and stirring such that the solution isgradually clarified until obvious precipitates or brown suspended particles appear; filtering to remove the precipitates or the suspended particles to obtain colored clarified liquid containing M ammonium salt; diluting the clarified liquid with water, introducing CO2 with a certain pressure, acidifying, continuously stirring to obtain a light yellow suspension, and keeping the pressure unchangedafter a period of time; sampling the suspension, detecting the pH value, and judging whether the reaction reaches the end point or not; carrying out solid-liquid separation on the suspension by filtering, and washing, dehydrating and drying the obtained solid to obtain refined M. According to the process, refined M can be obtained, and a generated ammonium bicarbonate solution is applied to agricultural fertilizers and biochemical treatment pools, so that the process is environment-friendly and economic.

Description

technical field [0001] The invention relates to the technical field of refining 2-mercaptobenzothiazole, in particular to CO 2 A new process for purifying crude product and commercial 2-mercaptobenzothiazole by method. Background technique [0002] The rubber accelerator 2-mercaptobenzothiazole is referred to as Accelerator M or MBT. It is a commonly used accelerator in the rubber industry. As a general-purpose accelerator, it has excellent accelerating effect. It can not only be used together with other accelerator systems, It can also synthesize various other excellent accelerators, such as NS (N-tert-butyl-2-benzothiazole sulfenamide), NOBS (N-(oxyethylene)-2-benzothiazole sulfenamide) , CBS (N-cyclohexyl-2-benzothiazole sulfenamide), DM (2,2-dithiodibenzothiazole), etc., are widely used in natural rubber, various synthetic rubber and other industries. Demand huge. The existing refining methods of 2-mercaptobenzothiazole mainly include acid-base conversion method, solv...

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Problems solved by technology

[0003] The traditional acid-base transformation method uses caustic soda to dissolve 2-mercaptobenzothiazole in alkali, and then replaces 2-mercaptobenzothiazole with sulfuric acid. Before the precipitation, the pH value needs to be adjusted many times. The production process will consume a lot of acid and alkali, and A large amount of refractory wastewater with high COD and high salt content is produced, but it is widely used because of its simple operation, and some factories still use this method so far; the solvent extraction method is relatively green and environmentally friendly, and no wastewater is generated, but the extracted product The initial melting point is low, the resin removal rate is low, and it is difficult to be widely used because of its high technical requirements and low safety guarantee; the solvent-acid-base method is a composite refining method that combines solvent extraction and acid-base conversion. Products with a higher initial melting point will also produce waste water, and the solvent used is difficult to extract, and the production cost is very high, so it cannot be widely used; the main effect of the hydrogen peroxide method is to use it in combination with other methods to achieve a more effective removal of impurities from the hardened resin. Complete effect, although the purification efficiency has been improved, but if the use conditions are not controlled accurately, it will easily cause excessive oxidation and affect the quality of the finished product

2-Mercaptobenzothiazole crude product needs to be purified twice at least to high-quality products, and the purification of medical grade 2-mercaptobenzothiazole will have more requirements in terms of technology and material consumption, because the current purification process is mainly solvent method and acid Alkali method, whether it is technically difficult or difficult to treat wastewater, will transfer the production capacity consumption and pollution of the accelerator 2-mercaptobenzothiazole to the downstream, increasing the burden on downstream enterprises, so the purification technology of the accelerator 2-mercaptobenzothiazole is urgently needed innovation

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