Question

15. An SMU graduate student attempted a collection of nucleophilic-substitution-at-a- chirality-center reactions, in order to have some quick data to present at the annual American Chemical Society Meeting in Miniature. (It was in San Diego that year.) The starting material was R-2-bromo-1,1-dimethylcyclohexane, and the nucleophiles for the three reactions were: CH, OH CH,0 (CH3),C-o tert-butoxide methanol methoxide However, instead of the expected outcomes, the following results were obtained HCOCH HB CH3 CHE Reaction A ...CH (S) Reaction B HU Reaction C H.COCH Y CH₂ . CH YCH (R) (S) achiral For each of the reactions depicted, indicate which nucleophile was used, and by which reaction mechanism (SNI, SN2, elimination or free radical halogenation) the obsevered results were obtained: Reaction A Nucleophile = Mechanism - SN 2 * ? Maybe Reaction B Nucleophile = Mechanism = SNI Reaction C Nucleophile = Mechanism Gelimination

Answer 1

CH3OH is weak base and undergoes the SN1 and the -CH# is strong base and undergoes the SN2 and the (CH3)3CO is strong hindered base so undergoes the E2 elimination reaction

# BT C4200 HO CH3 CH₂ Tu Cao TU CH3 Tort w achts PICH Racemic mixtune 62 Eliminating (SNI d.. Citso- B-CH₂OH C-(CH3),co » SN? ) SNI > E2