Experiments and quantum chemistry calculations were performed to study the decomposition mechanism of isopropylthiobenzene, the role of supercritical water (SCW) and the effects of alkanes on the decomposition of isopropylthiobenzene. In this study, three possible decomposition paths in SCW were described. The most feasible decomposition path involves four steps. First, hydrocarbon radicals attack the α-H on the isopropyl group of isopropylthiobenzene, leading to cleavage of one C–S bond to form thioacetone. Second, a cycloaddition of water to thioacetone occurs to form a mercaptoalcohol. Third, mercaptoalcohol decomposes into H₂S and acetone either directly or via the catalysis of water. Finally, acetone decomposes into CO₂ via free radical reactions. During the decomposition process, SCW partakes mainly as an H-transfer catalyst and a reactant by forming a n-membered ring transition state (n = 4, 6). The alkanes cause selective cleavage of the C–S bond and promote desulfurization by forming free radicals. In addition, isopropyl from isopropylthiobenzene could act in the same way as an alkane to promote the decomposition of isopropylthiobenzene in SCW.

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超临界水中异丙基硫苯分解的新见解

通过实验和量子化学计算研究了异丙基硫苯的分解机理，超临界水（SCW）的作用以及烷烃对异丙基硫苯分解的影响。在这项研究中，描述了SCW中的三种可能的分解路径。最可行的分解路径包括四个步骤。首先，烃基攻击异丙基硫代苯的异丙基上的α-H，导致一个C–S键断裂形成硫代丙酮。第二，发生水与硫代丙酮的环加成反应，形成巯基醇。第三，巯基醇直接或通过催化水分解成H ₂ S和丙酮。最后，丙酮分解成CO ₂经由 自由基反应。在分解过程中，SCW主要通过形成n元环过渡态（n = 4、6）而作为H-转移催化剂和反应物。烷烃导致C–S键的选择性裂解，并通过形成自由基促进脱硫。另外，异丙基硫苯中的异丙基可以与烷烃以相同的方式起作用，从而促进SCW中异丙基硫苯的分解。