CAS号 [583-39-1] 生产工艺。   2-巯基苯并咪唑（防老剂MB）

CAS名：2H-benzimidazole-2-thione, 1,3-dihydro-   历史参考文献：Beil. 24, 119; E2, 65; E3/4, 287.

用途：橡胶防老剂。医用抗麻风药。LookChem网登录生产与经营单位186家。

BIOS 661, 12.（=胶卷PB  ）。 Antioxidant MB.  英国人译自德文（无资料来源）。本人手工抄录如下。

反应式：本人有加注，暂未找到德文原件。（这是早期本人在沈阳院抄录的英文，原书未收藏。）。

Properties:  Yellowish white powder. M.P. 2900. Non- or very slight discolouring antioxidant.

Process:

Is made by reduction of o-nitraniline, followed by reaction of the resulting o-phenylene diamine with carbon disulfide, giving o-phenylene thiourea.  500 l. water, 4 kg. Neckal BX and 400 kg. o-nitraniline are placed in the stirring equipment used for Vulcacit P etc., and are brought to 95℃. 376 kg. sodium sulfide (as 10% solution) are added with stirring, over 6 hrs.  Stirring is continued for 5 hrs longer, by which time there should be no reaction on lead acetate paper, and a sample of the mixture on boiling should be no reaction yellow vapor (absence of nitraniline).  The mixture is cooled to 20-25℃, and 290 kg. carbon disulfide added over 4 hrs. at about that temperature.  The temperature is allowed to rise to 40℃ in a further 4 hrs. and maintained at 40-45℃ for 12 hrs.  Finally it is raised to 90℃ as quickly as the very low pressure steam will allow.  The batch is cooled to 50℃ and precipitated with sulfuric acid (600Be’), filtered and washed until there is no further smell of sulfur dioxide.

About 1000 kg. of the filtered material containing 250-300 kg. dry product are transferred to a 15 cbm kettle (also used for making Vulcacit DM), made up to 10,000 l. with water and about 1500 l. milk of lime added to bring the pH to 11-12 (triazine indicator).  The batch is stirred for 4 hrs., filtrate treated with 35 kg. activated charcoal, a laboratory test being made to ensure that decolourising is complete.  After filtering, the filtrate is acidified with HCl to a brown tint on Congo Red paper.  The precipitate is filtered off, washed free from chlorides, and dried at about 95℃.  The dry product is milled without air flotation.  Yield 75-80% theory. M.P. about 300℃.

Antioxidant MB:-

Solubility: chloroform, benzene and petro-insoluble, alcohol-su=oluble.  White powder.  Medium strength antioxidant for all purposes.  Absolutely non-discolouring, even reduces discolouration due to curing.  In sulfurless Thiuram mixes, gives excellent heat ewsistance.  Can be used in latex mixes and trandparent stooks.  Acts as antiscorcher for Thiuram, P Extra N and M, and in higher percentages also for P and 774.

张澍声 《精细化工中间体及产品生产工艺》2006年。 P. 719.  2-巯基苯并咪唑。  译自BIOS 661, 12.

在适宜的搅拌锅中加入500 L水，4 kg Nekal BX和400 kg 邻硝基苯胺，加热到95℃. 然后于6小时内加入376 kg 硫化钠（配成10% 溶液），搅拌5小时，取样用醋酸铝试纸检验，或者沸腾挥发出邻硝基苯胺的黄色蒸汽。如果两项试验结果都是否定的，冷却到20-25℃, 于4小时内加入290 kg 二硫化碳，在随后的4小时内反应温度升至40℃，再在40-45℃保持12小时。最后过量的低沸点二硫化碳（bp 46.2℃）缓缓加热蒸馏出来，直至达90℃。冷却到50℃后，用78% 硫酸使2-巯基苯并咪唑沉淀出来，过滤，洗涤至不含SO2 气味。

精制：1000 kg 过滤产品约含250-300 kg干产品，加到15000 L锅中，加水使总体积达10000 L. 用约1500 L石灰乳调节pH 为11-12. 锅内物搅拌4小时，过滤，滤液用35 kg 活性炭处理。过滤，滤液用盐酸酸化，以刚果红试纸为指示剂。过滤出沉淀，洗至不含氯，在95℃干燥，研磨。为黄白色粉末，凝固点约300℃（纯品301-302℃）。收率75-80%。 抄注：本书为非正式出版物。

张林栋 编 《化工产品手册，第五版 – 橡塑助剂》 化学工业出版社 出版 2008年。P. 470-471.  防老剂MB。

【制法】防老剂MB的制备：在还原槽内加入邻硝基苯胺和21% 硫化钠溶液，升温至90℃，再密闭升温至105-110℃，压力自升为0.1-0.2 MPa，搅拌还原5 h，降温至30℃以下，再加入二硫化碳进行反应，温度保持在40℃左右，反应数小时后，升温回收二硫化碳。然后投入适量的碳酸氢钠溶液，加活性炭脱色，过滤，滤液用稀盐酸或稀硫酸酸化，2-巯基苯并咪唑以固体析出，经离心分离，洗涤，干燥，粉碎，即得成品。

抄注：无资料来源！本书的序提到资料新且翔实，至少本人无法理解！

陈忠源 2018年9月16日。