硫化促进剂N-环己基-2-苯并噻唑次磺酰胺合成工艺过程探究

Study on synthesis process of vulcanization accelerator N-cyclohexyl-2-benzothiazole sulfonamide

以硫化促进剂2-巯基苯并噻唑(M)和环己胺为原料,采用次氯酸钠氧化法合成了N-环己基-2-苯并噻唑次磺酰胺(CBS),考察了合成工艺过程中反应体系的外观变化、液相中环己胺含量、固相中游离胺含量及固相熔点,同时提出了反应机理。结果表明,反应机理主要是促进剂M先与环己胺反应生成促进剂M环己胺盐,在氧化剂次氯酸钠的作用下胺盐中的硫氢键和氮氢键经交叉偶联反应和脱氢反应形成硫氮键,从而生成促进剂CBS。当氧化剂次氯酸钠加入量较少时,在反应前期阶段反应体系内液相相对较少,反应体系整体上呈膏状;随着次氯酸钠加入量的不断增加,固液两相逐渐分离,液相中环己胺质量浓度先由0.120 g/mL逐渐降低至0.045 g/mL,后又逐渐升高至0.092 g/mL,固相中游离胺质量分数由37.12%逐渐下降至0.15%;当次钠酸钠完全加入时,促进剂CBS质量分数可高达98.9%。

N-cyclohexyl-2-benzothiazole sulfenamide(CBS)was synthesized with vulcanization accelerator 2-mercaptobenzothiazole(M)and cyclohexylamine as raw materials via the oxidation ca-talyzed by sodium hypochlorite,the appearance change of the reaction system,the content of cyclohexylamine in the liquid phase and free amine in the solid phase,and the melting point of the solid phase were investigated during the synthesis process,and at the same time,the reaction mechanism was proposed.The results showed that the reaction mechanism was mainly the reaction of promoter M with cyclohexylamine to give promoter M cyclohexylamine salt,of which the sulfur hydrogen bond and nitrogen hydrogen bond underwent cross-coupling reaction and dehydrogenation reaction to form sulfur nitrogen bond under the action of oxidant sodium hypochlorite,followed by the generating of accelerator CBS.When the addition amount of oxidant sodium hypochlorite was small,there was relatively little li-quid phase in the reaction system in the early stage of the reaction and the overall reaction system was paste-like;with the increasing addition amount of sodium hypochlorite,the solid-liquid phases separated gradually and mass concentration of cyclohexylamine in liquid phase decreased gradually from 0.120 g/mL to 0.045 g/mL and then increased gradually to 0.092 g/mL,and mass fraction of free amine in the solid phase decreased gradually from 37.12%to 0.15%;when sodium hyponatrate was completely added,mass fraction of vulcanization accelerator CBS could be up to 98.9%.