Complete the following reaction- → Conc . H 2 SO 4 HNO 3

It is the nitration process which is carried by heating haloarene with mixture of concentrated acid. Therefore, the following chemical reaction will take place when chlorobenzene is treated with conc. nitric acid and conc. sulphuric acid to form ortho and para nitrochlorobenzene.

Complete the following reaction- CH 3 CH 2 Br → aq ethanol AgCN

It is one of the method to form carbylamines from alkyl halide.Therefore, the following reaction will take place when ethyl bromide is treated with silver cyanide to form ethyl carbylamine and silver bromide. CH 3 CH 2 Br → aq ethanol AgCN CH 3 - CH 2 - NC + AgBr

Complete the following reaction- CH 3 - CH = CH 2 + HI →

Haloalkanes are prepared by electrophilic addition of halogen acids to unsymmetrical alkenes. Therefore, the Markovnikov rule is applied which states that, during the addition across unsymmetrical double bond, the negative part of the attacking reagent attaches itself to the carbon atom carrying a lesser number of hydrogen atoms while the positive part goes to the carbon atom with more number of hydrogen atoms. Hence, in the case of propene, the major product formed is 2 -Iodopropene.

Explain S N 1 mechanism for the conversion of tertiary butyl bromide to tertiary butyl alcohol.

The mechanism involved in the conversion of tertiary butyl bromide to tertiary butyl alcohol is S N 1 . Therefore, it is a nucleophilic first order reaction. It is a two-step process- Step 1- Formation of carbocation. Step 2- The carbocation is attacked by a nucleophile to form alcohol.

Give reason. In case of optically active alkyl halides S N 1 reaction are accompanied by racemization.

It is mainly due to the inversion of configuration that optically active alkyl halides S N 1 reaction are accompanied by racemization.

Name the reagent used in the dehydrohalogenation of haloalkanes.

The reagent used for dehydrohalogenation of haloalkanes is Alcoholic potassium hydroxide. The reaction occurs as: CH 3 CH 2 Br + KOH ( alc . ) → Heat H 2 C = CH 2 + KBr + H 2 O When Alcoholic potassium hydroxide is taken as a reagent, the negative part of the reagent OH - acts as a base and abstracts the beta hydrogen from the saturated substrate (alkyl halide) present and transforms it to an alkene in the product, thereby undergoing elimination reaction.

Explain Fittig reaction.

Aryl halides give analogous compounds when treated with sodium in dry ether, in which two aryl groups are joined together. It is known as fittig reaction. For example, 2 -Chlorobenzene reacts with sodium in dry ether medium to form diphenyl in which two phenyl rings combine through a bond.

Write an expression for the steps in S N 1 mechanism of the conversion of tert-Butyl bromide into tert-Butyl alcohol.

The reaction between tert-butyl bromide and hydroxide ion yields tert-butyl alcohol and is a substitution nucleophilic unimolecular S N 1 reaction. That means it follows the first order kinetics where the rate of reaction depends upon the concentration of only one reactant, i.e., tert-butyl bromide. It happens in two steps. In the first step, the polarised C - Br bond undergoes slow cleavage to produce a carbocation and a bromide ion. The carbocation thus formed is then attacked by nucleophile in the second step to complete the substitution reaction.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter -1 - Haloalkanes and Haloarenes>Karnataka Board-2019>Q 7

EASY

12th Karnataka Board

IMPORTANT

Earn 100

Name the product formed for the reaction of isopropyl iodide on alcoholic $KOH$ .

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