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e) A substitution product from a unhindered primary substrate can be obtained by using most nucleophiles. This SN2 product can be obtained using sodium ethoxide in ethanol. f) The use of the strongly basic nucleophile, methoxide ion, with a secondary substrate results primarily in E2 elimination. To obtain the substitution product, use methanol, a weaker base, as both nucleophile and solvent. The mechanism will follow the SN1 pathway. 9.27 a) 1-Hexene can be prepared by reaction of 1-bromohexane with a hindered base. Note that 2-bromohexane cannot be used because it would give a mixture of 1-hexene and 2-hexene, with the latter as the major product. t-BuOH Br + t-BuOK b) 3-Heptene can be prepared by reacting 4-bromoheptane with sodium methoxide in methanol. The alkyl halide is symmetrical so only a single elimination product is formed. Br CH₃OH + CH₃ONa c) Cyclohexene can be prepared from chlorocyclohexane by E2 elimination using sodium methoxide in methanol. Cl + CH₃ONa d) This alkene can be prepared from 4-bromo-1,2- CH₃ dimethylcyclopentane by treating it with a strong base such as sodium CH₃ ethoxide in ethanol. Because the EtOH + EtONa bromide is symmetrical, only the desired alkene is produced. Br 142