In the photo-bromination of pentane, hexane and heptane with bromine, N-bromo-diethylamine or N-bromo-succinimide, the authors found that the mono-bromo-pentanes, -hexanes and-heptanes obtained contain the isomers in the same proportions disregarding whatever brom-inating reagent is used. Among the isomers, 2-bromo-compounds occur in dominant quantitieswhile 1-bromo-compounds are nearly nil. The authors attributed these phenomena mainly tothe low mobility of bromine molecules but the rearrangement of the alkyl free radicals fromprimary to the secondary. Compared with chlorination, chlorine molecules are more mobileand combine with alkyl free radicals rather rapidly before rearrangement occurs, which makes1-chloro-isomer more abundant. In the photo-bromination of pentane, hexane and heptane with bromine, N-bromo-diethylamine or N-bromo-succinimide, the authors found that the mono-bromo-pentanes, -hexanes and-heptanes gave contain the isomers in the same proportions Among the isomers, 1-bromo-compounds are nearly nil. The authors attributed these phenomena mainly tothe low mobility of bromine molecules but the rearrangement of the alkyl free Compared with chlorination, chlorine molecules are more mobile and combine with alkyl free radicals rather rapid before rearrangement occurs, which makes 1-chloro-isomer more abundant.