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Chemistry. Session. Organic Compounds with Functional Groups Containing Oxygen-II. Session Objectives. Preparation of methanol and its properties Preparation of ethanol and its properties Preparation of ethylene glycol and its properties Preparation of glycerol and its properties

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session
Session

Organic Compounds with Functional Groups Containing Oxygen-II

session objectives
Session Objectives
  • Preparation of methanol and its properties
  • Preparation of ethanol and its properties
  • Preparation of ethylene glycol and its properties
  • Preparation of glycerol and its properties
  • Preparation of phenol
methanol
Methanol

Preparation

1. From destructive distillation of wood

Pyroligneous acid obtained from destructive distillation of wood consists of 5% methyl alcohol

2. By catalytic hydrogenation of carbon monoxide.

3. From natural gas

properties of methanol
Properties of methanol

Colourless liquid.

Highly poisonous in nature; as little as 30 ml can cause death.

Uses

As a solvents in paints, varnishes.

Chiefly for making formaldehyde.

As an antifreeze for automobile radiators.

To denature ethyl alcohol.

20% mixture of methyl alcohol and gasoline makes a good motor fuel.

ethanol
Ethanol

Fermentation of sugar

Fermentation stops when alcohol formed is more than 14 percent due to the acidic nature of the alcohol.

Synthesis of alcohol

important reactions
Important reactions

Reaction with sulphuric acid:

(i) At room temperature

C2H5OH + H2SO4 C2H5OSO2OH + H2O

(ii) At 140oC

C2H5OH + H2SO4 C2H5OC2H5 + H2O

(iii) At 170oC

C2H5OH + H2SO4 C2H4 + H2O

Reaction with alumina:

specific reactions
Specific reactions

Reduction

oxidation

Formation of iodoform

uses of ethyl alcohol
Uses of ethyl alcohol

Manufacturing of alcoholic beverages.

As an industrial solvent.

Manufacturing drugs, flavouring extracts, and perfumes.

As an antiseptic in hospitals.

In manufacturing of synthetic rubber.

absolute alcohol
Absolute alcohol

100% pure ethyl alcohol

Commercial alcohol is 95% ethyl alcohol.

Because at this composition water and alcohol formed azeotropic mixture,it cannot separated by further distillation.

Method to obtain absolute alcohol

Laboratory method:

Quicklime is added to the commercial alcohol. The mixture is refluxed for 8 hours. It is then distilled to give absolute ethyl alcohol.

CH3CH2OH + H2O + CaO  CH3CH2OH + Ca(OH)2.

Industrial method:

Commercial alcohol is extracted with benzene. Distillation this gives absolute alcohol at 78oC.

denatured alcohol
Denatured alcohol

Mixture of commercial ethyl alcohol with small amount of very poisonous substances.

Heavy excise duty

Alcoholic beverages.

Denatured

For industrial purposes, it is duty free.

alcoholic beverages
Alcoholic beverages

Wine  12% ethyl alcohol.

Beers  4% ethyl alcohol.

Whiskey  40-50% ethyl alcohol.

Brandy  40-50% ethyl alcohol.

Content of ethyl alcohol in beverages is indicated by ‘Proof Spirit’

Proof is the double of volume of ethyl alcohol in beverages.

preparation of ethylene glycol
Preparation of ethylene glycol

1. By oxidation of ethylene with cold dilute potassium permanganate solution.

2. By hydrolysis of 1,2-dibromoethane with aqueous sodium carbonate solution.

preparation of glycol
Preparation of glycol

3. By hydrolysis of ethylene oxide with H2O at 200oC under pressure or with dilute H2SO4 at 60oC.

properties of glycol
Properties of glycol

It’s a colourless viscous liquid, b.p 197oC.

It has a sweet taste.

It is hygroscopic.

Soluble in ethanol and water.

Toxic as methyl alcohol when taken orally.

reactions with sodium
Reactions with sodium

It shows all the reactions of –OH group. Due to two –OH group it consumes more reactants. Sometimes more drastic conditions are require to react with second –OH group of ethylene glycol.

For example

It is used as coolent in automobiles and synhetic fibres like dacron, polyester used for making wrinkle free clothes.

oxidation of glycol
Oxidation of glycol

(i). Nitric acid yields a number of substances.

slide18

(ii) With acidic potassium permanganate or potessium dichromate gives formic acid.

(iii). Periodic Acid Cleavage of Glycols

dehydration of ethylene glycol

; 500oC

H2SO4; 

H2SO4; 

 ;ZnCl2

Dehydration of ethylene glycol

CH3CHO

propane 1 2 3 triol glycerol
Propane-1,2,3-triol(Glycerol)

Preparation

1. From fats and oils: by product of soap industry.

This reaction is called saponification.

properties
Properties

Colourless, odourless sweet tasting and syrup liquid, b.p. 290oC.

It is nontoxic.

Soluble in water and ethanol.

It is hygroscopic, i,.e., absorbs moisture from air.

reaction with nitric acid
Reaction with nitric acid

Gives nitroglycerine; pale yellow oily liquid;

a powerful explosive.

reaction with hydrogen iodide

-I2

-I2

Reaction with hydrogen iodide

With small amount of HI

With large amount of hydrogen iodide.

reaction with oxalic acid

-CO2

Reaction with oxalic acid

At 110oC, gives glyverol monoformate.

At 260oC, gives allyl alcohol.

oxidation
Oxidation

Two primary alcohol groups in glycerol are capable of being oxidized to the aldehydes and then the carboxyl group. The secondary alcohol group can be oxidized to the carbonyl group.

Variety of oxidation products obtained depending on the nature of the Oxidising agent.

  • With dilute HNO3 gives glyceric acid and tartonic acid.
  • With concentrated HNO3 gives mainly glyceric acid.
  • With bismuth nitrate gives mainly mesoxalic acid.
  • With bromine water, sodium hypobromite, or Fenton’s reagent (FeSO4+H2O2), gives a mixture of glyceraldehyde and dihydroxyacetone.
  • With periodic acid gives fornaldehyde and formic acid.
dehydration
Dehydration

When heated alone or with KHSO4 two molecules of water eliminates.

phenol
Phenol

Containing —OH group attached directly to an aromatic ring.

Compounds which contain an —OH group in a side chain attached to anb aromatic ring are not phenols. They are called aromatic alcohol. For example

preparation of phenol
Preparation of phenol

From aryl sulphonic acids

Aryl sulphonic acid gives corresponding phenol on heating with molten sodium hydroxide at 570-620 K.

preparation of phenol1
Preparation of phenol

Chlorobenzene is hydrolysed by treating it with NaOH at 623 K and 320 atm.

preparation of phenol2
Preparation of phenol

From hydrolysis of diazonium salt

Diazonium salts are prepared by treating an aromatic primary amine with nitrous acid (NaNO2 + HCl) at low temperature.

preparation methods
Preparation methods

Synthesis from cumene

By decarboxylation of salicylic acid with soda lime