Thermal Curtius Rearrangement of<i>N</i>-Acyl-<i>S</i>,<i>S</i>-diphenylsulfilimine
作者:Naomichi Furukawa、Mitsuo Fukumura、Takehiko Nishio、Shigeru Oae
DOI:10.1246/bcsj.51.3599
日期:1978.12
Several N-acyl-S,S-arylphenylsulfilimines were prepared and subjected to thermal decomposition. They decomposed readily at 130–190 °C to give isocyanates together with diphenyl sulfide, quantitatively. However, N-tosyl-S,S-diphenylsulfilimine did not decompose even upon heating at 200 °C for 24 h. A kinetic study revealed that the rates of pyrolysis of N-aroyl-S,S-arylphenylsulfilimines (p-Y–C6H4(Ph)S→NCOC6H4–X-p) are nicely correlated with the Hammett σ-values, ρX=−1.2 and ρY=+0.92, respectively, being obtained. The activation enthalpies and entropies were ΔH\eweq=38.7 kcal/mol and ΔS\eweq=6.0 e.u. for Ph2S→NCOPh and ΔH\eweq=32.3 kcal/mol and ΔS\eweq=5.5 e.u. for (Remark: Graphics omitted.), respectively. The rearrangement was accelerated considerably by o-methyl substituent in the aryl group. The effect of solvent on the rate of pyrolysis was small. The results indicate that the pyrolysis of sulfilimine proceeds via a concerted migration of the R group from carbonyl carbon to imino nitrogen similar to the Curtius type rearrangement of acid azide.
制备了几种N-酰基-S,S-二苯基亚砜亚胺,并进行了热分解实验。它们在130-190°C下容易分解,定量地生成异氰酸酯和二苯基硫醚。然而,N-对甲苯磺酰基-S,S-二苯基亚砜亚胺即使在200°C下加热24小时也不分解。动力学研究表明,N-芳酰基-S,S-芳基苯基亚砜亚胺(p-Y-C6H4(Ph)S→NCOC6H4-X-p)的热解速率与Hammett σ值很好地相关,分别得到ρX=-1.2和ρY=+0.92。活化焓和熵分别为ΔH\eweq=38.7 kcal/mol和ΔS\eweq=6.0 e.u.(对于Ph2S→NCOPh)以及ΔH\eweq=32.3 kcal/mol和ΔS\eweq=5.5 e.u.(注:图形省略)。芳基的邻位甲基取代基明显加速了重排反应。溶剂对热解速率的影响很小。结果表明,亚砜亚胺的热解是通过R基团从羰基碳向亚胺氮的协同迁移进行的,类似于酸叠氮的Curtius型重排。