117135-59-8Relevant articles and documents
Rate constants for abstraction of bromine from bromotrichloromethane by butyl, cyclopropylmethyl, and phenyl radicals in solution
Mathew, Lukose,Warkentin, John
, p. 11 - 16 (2007/10/02)
The radical chain decomposition of cyclopropylmethyl(1-hydroxy-1-methylethyl)diazene ((CH3)2C(OH)N=NCH2- 1) at 253-341 K in hexafluorobenzene or in dichloromethane solution containing bromotrichloromethane affords cyclopropylmethyl bromide, 4-bromo-1-butene, 1-bromo-5,5,5-trichloro-2-pentene, and 3,5-dibromo-1,1,1-trichloropentane from the cyclopropylmethyl portion of 1.Other major products are nitrogen, acetone, and chloroform.The rate constant for formation of cyclopropylmethyl bromide by attack of cyclopropylmethyl free radicals from 1 at bromine of BrCCl3 (kBrcpm) was calculated from the product composition using the known rate constant for rearrangement of cyclopropylmethyl radicals to 3-buten-1-yl radicals.At 25 deg C, kBrcpm = 6.5 x 1E8 M-1s-1 and the temperature dependence is given by log (kBrcpm/M-1s-1) = (10.6 +/- 0.3) - (2.4 +/- 0.4)/θ, where θ = 2.3RT kcal/mol-1.Non-chain decomposition of (CH3)2C(OH)N=N-R (2, R = Bu, and 3, R = Ph) in the presence of excess 1,1,3,3-tetramethylisoindolin-2-yloxyl (4) and bromotrichloromethane afforded BuBr and PhBr, respectively, in yields determined by the relative concentrations of 4 and BrCCl3.Rate constants for coupling (kc) of Bu. and Ph. with 4 were assumed to be proportional to rate constants for diffusion controlled reactions, kd, which were estimated from measured viscosities.Values of kBrBu and kBrPh, calculated from kc and product yields for reactions at 80 deg C, are 0.26 x 1E9 and 1.55 x 1E9 M-1s-1, respectively.The relative radical reactivities toward BrCCl3 at 80 deg C are Ph, 6; cpm, 5; Bu, 1.
