Formation of secondary ozonides in the gas phase low-temperature ozonation of primary and secondary alkenes
作者:Radek Fajgar、Josef Vítek、Yehuda Haas、Josef Pola
DOI:10.1039/a807208f
日期:——
The gas-phase ozonation of a series of alkenes RCHCH2 (R = Et, Hex), trans-RHCCHR (R = Me, Et, Pri) and Me2CCMe2 at –40 to 20 °C, and that of ethene H2CCH2 at –120 to 0 °C at 10–4 v/v concentrations in N2 at atmospheric pressure have been studied. Using complementary product analysis by means of GC–FTIR and GC–MS techniques, we present conclusive evidence for the formation of secondary alkene ozonides as high-yield products in all instances except Me2CCMe2. It is shown that the stereoselectivity for the conversion of trans-RHCCHR (R = Me, Et, Pri) to trans-secondary ozonides in the gas phase is similar to that observed earlier in solution, and that the yields of secondary ozonides from RHCCH2, but not those from RHCCHR, significantly decrease with increasing temperature.
在-40至20摄氏度下,一系列烯烃(RCHCH2,其中R=Et, Hex),反式-RHCCHR(R=Me, Et, Pri)以及Me2CCMe2的气相臭氧化反应,以及在-120至0摄氏度下乙烯H2CCH2的臭氧化反应,在氮气中体积分数为10-4的条件下、常压下进行了研究。通过GC-FTIR和GC-MS技术进行的补充产物分析,我们提供了确凿证据,表明在除Me2CCMe2外的所有情况下,次级烯烃臭氧化物都是高产率的主要产物。研究表明,反式-RHCCHR(R=Me, Et, Pri)在气相中转化为反式次级臭氧化物的立体选择性,与先前在溶液中观察到的相似,并且从RHCCH2(而非RHCCHR)生成的次级臭氧化物的产率随着温度的升高显著下降。