Butyl bromide, photolysis

The photolysis of (Me3Si)3SiPh in the presence of functional substituted olefins is of considerable interest (55). Irradiation of 20 with a low-pressure mercury lamp in the presence of vinyl chloride or l-bromo-2-methyl-propene affords the respective 1-alkenyl-1-halo-1-phenyltrimethyldisilanes as the sole volatile product. The fact that the reaction of trimethylsilylphenylsilylene with butyl bromide does not give any volatile products suggests that compound 23 and 24 must come from a 1,2-halogen shift of... 

A teehnique that is a convenient source of radieals for study by EPR involves photolysis of a mixture of di-t-butyl peroxide, triethylsilane, and the alkyl bromide corresponding to the radieal to be studied. Photolysis of the peroxide gives t-butoxy radieals, whieh selectively abstract hydrogen from the silane. This reactive silicon radieal in turn abstracts bromine, generating the alkyl radieal at a steady-state eoncentration suitable for EPR study. 

In order to determine the sensitivity of coumarin dimerization to heavy-atom perturbation, the direct photolysis was carried out in butyl chloride, propyl bromide, and ethyl iodide. Comparison of these results with those obtained in nonpolar solvents indicated that there was no significant change in the amount of the triplet-derived product (80) formed in the heavy-atom solvents as would be expected if heavy-atom perturbation were important.<90) More recent investigations,<93W however, of the formation of (79) in carbon tetrachloride indicate that halocarbon enhancement of the formation of this isomer exists. A direct measure of the intersystem quantum... 

Free radical reagents usually react with tetraalkyltin compounds at a hydrogen centre in one of the alkyl ligands to give a stannylalkyl radical. P-Stannylalkyl radicals prepared in this way can then undergo P-scission to break the Sn-C bond. Thus the photolysis of di-t-butyl peroxide in the presence of trimethylisobutyltin and ethylene or an alkyl bromide, gives rise to the ESR spectrum of the P-stannylethyl radical or of the alkyl radical respectively, which are formed by the sequence of reactions shown in equations 5-38.50... 

The fluoro-chloroalkyl radicals and the fluorobromoalkyl radicals have both been produced by the photolysis of appropriate iodides or bromides (11). The photolysis of di-bromodifluoromethane has been investigated in some detail (12). An alternative method of production of fluorochloromethyl and fluorobromomethyl radicals has been the use of benzoyl peroxides as an initiator (13). More recently di- t-butyl-peroxide has been used in orientation studies (14). 

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