Question

the weakest base: CH3 HO HS the fastest in an Syl reaction: (CE)_CACHOSCH (CH3CB (CH.) CHCH(Br)CH, (CH),C(Br)CH (CH3)2CHCH Br 2. For each pair of reactions given below indicate which is faster and explain your reasoning. + CHỊ N + C CH3Cl + N CH3 + Ng CH₃N₂ + i CHg. + NaCN CH, CN + Nal DMSO CH3-1 + NaCN C H, CN + Nal Cho (c) CH,0 + CH,CH,Br - HƠ + CHỊCH,Br CH,CH,OCH, + Bril CH,CH,OH + Br (CH),CHBr + Nal acetone (CH),CH-1 + NaBr CH,CH,CH,Br + Nal acetone CH,CH,CH4 + NaBr

Answer 1

the weakest base: CH3 HO HS the fastest in an Syl reaction: CH3- is weakest base because it 'C" has least electronegativity and cant stabilize negative charge Snl reactione] is slowened by steric hindrance. Lowest steric hindrance is in third compound so it will have fastest SN1 (CH.) CHCH(Br)CH, (CH),C(Br)CH (CH3)2CHCH Br 2. For each pair of reactions given below indicate which is faster and explain your reasoning. CH3Cl + N CH₃y + No CH₃N₂ + i Iodine is good leaving group due to high size and low elecctronegativity. SO 2nd reaction is faster CH3-1 + NaCNCH Сн, он CH3 + NaCN DMSO CH, CN + Nal CH, CN + Nai Polar protic solvents actually speed up the rate of the unimolecular substitution reaction because the large dipole moment of the solvent helps to stabilize the transition state. so first reaction is faster CH30- is stronger nucleophile due to +I effect from CH3 group so gives faster reaction CH, O + CH,CH,Br- HƠ + CHỊCH,Br - - CH,CH,OCH, + Br CHỊCH,OH + Bi acetone (CH),CHBr + Nal (CH),CH4 + NaBr (d) The first structure has some steric hindrance (secondary carbon) so gives slower reaction. acetone CH,CH,CH, Br + Nal CH,CH,CH,+ NaBr