Ethers Class 12 Notes | EduRev

Chemistry Class 12

Created by: Mohit Rajpoot

Class 12 : Ethers Class 12 Notes | EduRev

The document Ethers Class 12 Notes | EduRev is a part of the Class 12 Course Chemistry Class 12.
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ETHER 

Structure of ether 

Ethers Class 12 Notes | EduRev

Ethers Class 12 Notes | EduRev

Classification of Acyclic ethers:

Ethers Class 12 Notes | EduRev

IUPAC Nomenclature of ether "Alkoxy Alkane"

S.NO.CompoundIUPAC Name
1Ethers Class 12 Notes | EduRev2-Methoxy propane
2Ethers Class 12 Notes | EduRevChloromethoxy methane
3Ethers Class 12 Notes | EduRevMethoxy benzene (Anisole)
4Ethers Class 12 Notes | EduRev3-Ethoxy-1, 1-dimethyl cyclohexane
5Ethers Class 12 Notes | EduRevtrans-1-Chloro-2-methoxy cyclobutane
6Ethers Class 12 Notes | EduRev2-Ethoxy ethan-1-ol

 

Method of Preparation of Ether: 

(1) Williamson synthesis-

General reaction:

RX  + Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev R - OR'

e.g. (i) n-PrOH Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

(ii) MeOH Ethers Class 12 Notes | EduRev MeEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

(iii) t-BuOH Ethers Class 12 Notes | EduRevt-BuEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev t-Butyl ethyl ether

(This reaction produces a poor yield of ether because of the bulkiness of t-BuO-)

2. Williamson's Continuous Etherification process or by Dehydration of Alcohols-

(i) ROH + Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev RO + Ethers Class 12 Notes | EduRev

Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev ROR + H3O+

(ii) Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev ....Ethers Class 12 Notes | EduRev

Ethers Class 12 Notes | EduRev

e.g.

Ethers Class 12 Notes | EduRev

 

Mechanism 

Step-1:
Ethers Class 12 Notes | EduRev

This is an acid-base reaction in which the alcohol accepts a proton from the sulfuric acid.

Step-2 :
Ethers Class 12 Notes | EduRev

Another molecule of the alcohol acts as a nucleophile and attacks the protonated alcohol in an Ethers Class 12 Notes | EduRev reaction.

Step-3 :
Ethers Class 12 Notes | EduRev

Another acid-base reaction converts the protonated ether to an ether by transferring a proton to a molecule of water (or to another molecule of the alcohol).

Only one combination of alkylhalide and alkoxide is appropriate for the preparation of each of the following ethers by Willianson ether synthesis. What is the correct combination in each case ?

3. From alkenes: 

(a) By addition of alcohols in alkenes:

When alcohol is added to alkenes in presence of acid, we get ethers.

General reaction:

(I) Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev carbocation

(II) Carbocation alcohol Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

e.g. (I) Ethers Class 12 Notes | EduRev = CH2  + Ethers Class 12 Notes | EduRev(H2SO4) Ethers Class 12 Notes | EduRev Me3Ethers Class 12 Notes | EduRev

(II) Me3Ethers Class 12 Notes | EduRev + EtOH Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev Me3COEt

(b) Alkoxymercuration - demercuration:

Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

e.g.

(i) RCH=CH2 +R'OH Ethers Class 12 Notes | EduRev RCH(OR')CH3

(ii) CH2=CHCH3 +CH3CH(OH)CH 3 Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

(iii) CH3CH=CHCH3 +CH3CH(OH)CH 2CH3 Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

Reactions of ethers: 

1. With HX-

General reaction:

Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev X-R X-R'

e.g. (i) CH3CH2CH2CH3Ethers Class 12 Notes | EduRev 2CH3-CH2Br

2. Reaction with sulphuric acid-

Ethers dissolve in concentrated solutions of strong inorganic acids to from oxonium salts, i.e. ether behave as Bronsted Lowry bases.

R2O H2SO4Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev R-OH Ethers Class 12 Notes | EduRev

When heated with dilute H2SO4

R2O H2SO4Ethers Class 12 Notes | EduRev 2ROH

e.g. C2H5OC2H5 +H2SO4Ethers Class 12 Notes | EduRev C2H5OH +C2H5OHSO4Ethers Class 12 Notes | EduRev C2H5OH+ H2SO4

 

3. Autoxidation of ethers :

When ethers are stored in the presence of atmospheric oxygen, they slowly oxidize to produce hydroperoxides and dialkyl peroxides, both of which are explosive. Such a spontaneous oxidation by atmospheric oxygen is called an autoxidation.

General reaction:

Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev +Ethers Class 12 Notes | EduRev

Ex.

(i) Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev +Ethers Class 12 Notes | EduRev

(ii) Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

 

4. Reaction with acid chlorides and anhydrides:

Reagent : ZnCl2, AlCl3 etc.

General reaction: (i) R-O-R +R-CO-Cl Ethers Class 12 Notes | EduRev R-Cl +RCOOR

Mech.

RCOCl +AlCl3Ethers Class 12 Notes | EduRev RCO + AlCl4-

Ethers Class 12 Notes | EduRev RCO Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev RCOOR' + Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev R"Cl + AlCl3

e.g.

C2H5OC2H5 + CH3COCl Ethers Class 12 Notes | EduRev C2H5Cl + CH3COOC2H5

(ii) R2O + Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev 2CH3COOR

e.g. C2H5OC2H5  + (CH3CO)2O Ethers Class 12 Notes | EduRev 2CH3COOC2H5

5. Reaction with carbon monoxide :

Ether react with CO at 125-180oC and at a pressure of 500 atm, in the presence of BF3 plus a little water.

R2O  + CO Ethers Class 12 Notes | EduRev RCOOR

 

6. Reaction with halogens :

When treated with chlorine or Br, ether undergoes substitution, the extent of which depends on the conditions.

CH3CH2OCH2CHEthers Class 12 Notes | EduRev CH3CHClOCH2CH3Ethers Class 12 Notes | EduRev CH3CHClOCHClCH

In presence of light,

(C2H5)2O Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev

Mech.

The reaction proceeds by a free-radical mechanism, and α-substitution occurs readily because of resonance stabilization of the intermediate radical.

Ethers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRevEthers Class 12 Notes | EduRev, etc.

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