溶液中烯烃自由基加成反应的绝对速率常数。全氟取代对正烷基自由基反应活性的协同效应。

Absolute Rate Constants for Radical Additions to Alkenes in Solution. The Synergistic Effect of Perfluorination on the Reactivities of n-Alkyl Radicals.

作者信息

Avila David V, Ingold K U, Lusztyk J, Dolbier W R, Pan H-Q

机构信息

Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A OR6, and the Department of Chemistry, University of Florida, Gainesville, Florida 32611.

出版信息

J Org Chem. 1996 Mar 22;61(6):2027-2030. doi: 10.1021/jo951782v.

DOI:10.1021/jo951782v

PMID:28616983

Abstract

Laser flash photolysis has been used to determine the absolute rate constants for addition of several partially fluorinated n-alkyl radicals to three styrenes at 25 °C in Freon 113. Fluorination at the γ-position (RCFCHCH) gives radicals with essentially the same reactivity as non-fluorinated n-alkyls. The RCHCFCH and RCHCHCHF radicals are both about three times as reactive as RCFCHCH, but the RCHCHCF radical is ca. five to six times rather than ca. three times as reactive as RCHCHCHF. Similarly, the perfluorinated radical CFCFCF is much more reactive than would be expected on the basis of the reactivities of the RCHCFCH and RCHCHCF radicals. Thus, perfluorinated n-alkyl radicals are very considerably more reactive than would be predicted from the individual effects of α-, β-, and γ-fluorination.

摘要

激光闪光光解已被用于测定几种部分氟化的正烷基自由基在25℃下于氟利昂113中与三种苯乙烯加成反应的绝对速率常数。在γ位（RCFCHCH）进行氟化得到的自由基，其反应活性与未氟化的正烷基自由基基本相同。RCHCFCH和RCHCHCHF自由基的反应活性均约为RCFCHCH的三倍，但RCHCHCF自由基的反应活性约为RCHCHCHF的五到六倍，而非约三倍。同样，全氟自由基CFCFCF的反应活性比基于RCHCFCH和RCHCHCF自由基反应活性所预期的要高得多。因此，全氟正烷基自由基的反应活性比由α-、β-和γ-氟化的单独影响所预测的要高得多。