一步法高压合成硫化异丁烯产物分析及反应机理

以正辛胺为催化剂,硫磺和异丁烯为原料在160~190 ℃条件下通过一步法高压合成硫化异丁烯。 采用气相色谱、红外光谱和¹H NMR谱等技术手段分析了产物硫化异丁烯的化学组成。 分析结果表明,产物中含有链状和环状的叔丁基多硫醚,其中链状多硫醚是主产物,同时伴有副产物4-甲基-3H-1,2-二硫杂茂-3-硫酮(MDTT)、叔丁基硫醇和少量的尾气如H₂S产生。 硫化过程中主要的副反应是碱催化下硫磺与异丁烯的脱氢反应,生成MDTT和H₂S,H₂S与异丁烯进行马氏加成反应生成叔丁基硫醇,叔丁基硫醇与硫磺反应生成链状的叔丁基多硫醚。

Product Analysis and Reaction Mechanism of High-Pressure Synthesis of Sulfurized Isobutylene by One-Step Method

Sulfurized isobutylene was prepared from sulfur and isobutylene via high pressure one-step method at 160~190 ℃ with n-octylamine as catalyst. GC, FT-IR and ¹H NMR analyses of the final products show that it contains chain-like and cyclic polysulfides, chain-like polysulfides are main products, accompanied with the byproducts 4-methyl-3H-1,2-dithiole-3-thione (MDTT), tert-butyl mercaptan, and a small amount of exhaust gas such as H₂S. The formation of MDTT and H₂S is the result of the hydrogen abstraction reaction from isobutylene catalyzed by alkali in the sulfurization process. H₂S then reacts with isobutylene by Markovnikov addition to the formation of tert-butyl mercaptan which is converted to linear polysulfides by reaction with sulfur.