The Mercury Photo-Sensitized Hydrogenation of the Butenes and the Photolysis of Di-n-butylmercury

Abstract

The Hg–³P₁ photo‐sensitized hydrogenations of isobutene, butene−1, and butene−2 have been studied from 24 to 300°C at an H₂:C₄H₈ ratio of 10:1. Mass spectrometer analyses of the products have led to the following conclusions: (1) When a H atom adds to isobutene, the tertiary butyl radical is formed. Any isobutyls decompose immediately into methyl and propene. (2) Addition of a H atom to butene−2 produces little sec.‐butyl, mostly methyl plus propene. (3) Addition of a H atom to butene−1 produces considerable sec.‐butyl. Any n‐butyls decompose into ethyl and ethene. (4) The isomeric constitution of the octanes suggests that radicals add to olefinic double bonds at the carbon atom with highest electron density. Products from the photolysis of di‐n‐butylmercury at λ=2537A indicate that n‐C₄H₉=C₂H₅+C₂H₄ has an activation energy of around 35 kcal.