The radical chain decomposition of cyclopropylmethyl (1-hydroxy-1-methylethyl)-diazeneat 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 of1. Other major products are nitrogen, acetone, and chloroform. The rate constant for formation of cyclopropylmethyl bromide by attack of cyclopropylmethyl free radicals from1at bromine of BrCCl3was calculated from the product composition using the known rate constant for rearrangement of cyclopropylmethyl radicals to 3-buten-1-yl radicals. At 25 °C,and the temperature dependence is given by, where θ = 2.3RT kcal/mol−1. Non-chain decomposition of (CH3)2C(OH)N=N—R (2, R = Bu, and3, 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 of4and BrCCl3. Rate constants for coupling (kc) of Bu• and Ph• with4were assumed to be proportional to rate constants for diffusion controlled reactions,kd, which were estimated from measured viscosities. Values ofand, calculated fromkcand product yields for reactions at 80 °C, are 0.26 × 109and 1.55 × 109 M−1s−1, respectively. The relative radical reactivities toward BrCCl3at 80 °C are Ph, 6; cpm, 5; Bu, 1.