CBSE Class 12 Chemistry 2020 Outside Delhi Set 1 Solved Paper

Question : 32 of 37

Marks: +1, -0

(i) Write the structure of major alkene formed by

β

-elimination of 2, 2, 3-trimethyl-3bromopentane with sodium ethoxide in ethanol.
(ii) Which one of the compounds in the following pairs is chiral?

(iii) Identify (A) and (B) in the following:

OR
How can you convert the following?
(i) But-1-ene to 1-iodobutane
(ii) Benzene to acetophenone
(iii) Ethanol to propanenitrile

Solution:

(i)

{\CH}_3- {\C}↖{|}↖{{\CH}_3}↙{|}↙{{\CH}_3}- {\C}↖{|}↖{\Br}↙{|}↙{{\CH}_3}- {\CH}_2- {\CH}_3

{{──────────▸} }↙{-\HBr}↖{ {\C}_2 {\H}_5 {\ONa} \/ {\C}_2 {\H}_5 {\OH}} {{\CH}_3-C ↖{|}↖{{\CH}_3}↙{|}↙{{\CH}_3}- {\C} ↙{|}↙{{\CH}_3}= {\CH}- {\CH}_3}↙{3,4,4-\Trimethylpent-2-\ene (\major)}

+{ {\CH}_3- {\C}↖{|}↖{{\CH}_3}↙{|}↙{{\CH}_3}- {\C}↖{∥}↖{\CH_2}- {\CH}_2- {\CH}_3}↙{2-\ethyl-3, 3-\dimethylbut-1-\ene}

(iii)

{\C}_2 {\H}_5 {\OH} {{────▸} }↖{ {\RedP} \/ {\Br}_2} {\CH}_3- {\CH}_2- {\Br} \;{{────▸} }↖{\KCN}↙{\;\text " Aq. ethanol "\;}

{ {\CH}_3 {\CH}_2 {\CN}}↙{\;\text " Propanenitrile "\;}

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