Question

1. (a) Show the mechanism for the following substitution reaction. 3 pommes (b) Determine how the rate of reaction is affected in a solvent such as water. 1 point (CH.):C- Br+ OH -- -> (CH3), C-Brº tott +(CH3),

Answer 1

J@ CHI Given substitution reaction (CH3)₂C-Br tot ---> Here i (CH3) z C-Br is a tertiary alkyl halide and on (hydroxide ion) is nucleophile which attack alkyl- halide from backside and inversion OE Product take place.

So, this substitution reaction is known as nucleophilic substitution reaction (sy reaction). substtution reaction is as follows: (CH3)3C-Br + oH (CH3)3C-0H + B8 mechanismi сH3 DokuCH3 tu -CH3 CH3 B--- --OH B8 + CH3 Chigrenang CH3 сна сня transition state Product linversion) Rate of substitution reaction is affected by presence of solvents such as Polar Protic (ex-water, alcohols etc.) and Polar aprotic Solvent (ex- acetone, nitromethane etc.) • Polar Protic solvents such as water have hydrogen bonding capacity due to Strong hydrogen bond interaction between lone pairs (reactive done pairs) and protons of water solventi nucleophilic power of nucleophile such as ot e etc. decreases. Therefore rate of substitution

Reaction deareases. Hence, rate of substitution reaction. become slower in the presence of polar protic solventa such as water. since, polar aprotic solvents such as acetone, nitromethane have no capacity of hydrogen bonding so nucleophilic power of nucleophile not decreases and so rate of substitution reaction become faster in Presence of Polar a protic Solvents. Hence, Rare of substitution reaction become Slower in presence of Polar protic solvent such as water while rate of reaction faster substitution become in presence of Polar aprotic solvents.