CONJUGATION IN ALKADIENES AND ALLYLIC SYSTEMS 231 Not an allylic carbocation 5-chloro CH CH ot an 10.3 The allylic hydrogens are the ones shown in the structural formulas. I-Methylcyclohexene 2, 3, 3-Trimethyl-1-butene 1-Octene 10.4 The statement of the problem specifies that in allylic brominations using N-bromosuccinimide the active reagent is Br,. Thus, the equation for the overall reaction is H Br2 B 3-Bromocyclohexene Hydrogen The propagation steps are analogous to those of other free-radical brominations. An allylic hydrogen is removed by a bromine atom in the first step ·Br: H+H—Br Cyclohexene Bromine Hydrogen Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website10.3 The allylic hydrogens are the ones shown in the structural formulas. (b) (c) (d) 10.4 The statement of the problem specifies that in allylic brominations using N-bromosuccinimide the active reagent is Br2. Thus, the equation for the overall reaction is The propagation steps are analogous to those of other free-radical brominations. An allylic hydrogen is removed by a bromine atom in the first step. H H Cyclohexene Bromine atom H 2-Cyclohexenyl radical Hydrogen bromide Br H Br Br2 H H Cyclohexene Bromine Br H 3-Bromocyclohexene Hydrogen bromide HBr 1-Octene H H 2,3,3-Trimethyl-1-butene CH3 H H H H CH3 1-Methylcyclohexene CH3 1-Bromo-3- methylcyclohexene Not an allylic carbocation CH3 Br CH3 5-Chloro-1- methylcyclohexene Not an allylic carbocation CH3 Cl CONJUGATION IN ALKADIENES AND ALLYLIC SYSTEMS 231 Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website