Question

To which compound is the addition of HBr more highly regioselective? Сн, сн, H₂ C- & C=CH2 H3C c1 H2 CH3 H₂C - C нс ΙΩ CH

Answer 1

Bengal Addition of HBr is highly regio selective in CH₃ CH3 1 H₂C- CH₃ a=CH2 H₂ mechanism for compound CH3 CH3 CH₃ CH3 - HBr =CH2 -CH3 С(43 CH3 c H₂ A Bocanbocation CH₃ CH3 CH3 " to с. •CHz - ctz CH3 C H2 CH₃ Again, CH3 CH3 HBr C=CH2 7 .C CH₂ H2 HC - C 7 с 1 H Cutz CH3 1 CH3 locambocation CH3 CHI с. . e c H₂ - -CH H3C CH3 H CH2 By CH3 11 As we 30 can bo cation is very meich stable than 2 carbo cation. hence the prodent fooms exclusively than the produit 6.

mechanism for Compound B CH3 CH3 CH3 е на H₂ C Hor C — С. 7 9 cta C- CH3 c CH3 3 H2 3 'Carbocation CH3 CH3 CH3 CH3 1 C •CH3 e-CHI H₂ C H2 CH₃ Br Again CH₂ CH₃ CH₃ CH3 Hor 1 che c c. 7 14ge Н CH₂ CH3 & -CH3 CH3 CH3 CH3 2o carbocation. CH3 CH₃ с # Br - CH3 # .. - CH3 CH3 H CH с 1 By 'H IT 3 cambocation is much more stable, but 20 carbocation also gets some stability, so compound also forms good yield So compound a has highly regio selectivity re. bromide adds to a 30 carbocation & not in 10 Carbocation