1. Alcohols , Phenols & Ethers
Chapter 11
Alcohols ,
Phenols &
Ethers
Mr. NIKAM R.K.

2. ALCOHOLS
Alcohols are the hydroxyl derivatives of hydrocarbons in which one or more hydrogen atoms are replaced by –OH group.
e.g. CH3OH (Methyl Alcohol)
C2H5OH (Ethyl Alcohol)

3. CLASSIFICATION OF ALCOHOLS
On basis of number of hydroxyl groups present in the molecule alcohols are classified as
A) Monohydric alcohols: Contain only one hydroxyl group in their molecule.
e.g. C2H5OH (Ethyl Alcohol)
CH3-CH2-CH2-OH( n-propyl alcohol)
B) Dihydric alcohols: Contain two hydroxyl groups in their molecule. They are also called diols or glycols.
e.g. HO-CH2-CH2-OH ethylene glycol (ethane-1,2-diol)
HO-CH2-CH2-CH2-OH (propane-1,3-diol)
C) Trihydric alcohols: Contain three hydroxyl groups in their molecule. They are also called triols or glycerols.
e.g HO-CH2-CH(OH)-CH2-OH glycerine/glycerol (propane1,2,3-triol).
D) Polyhydric alcohols: Contain more than three hydroxyl groups in their molecule situated on different carbon atoms.
e.g HO-CH2-CH(OH)-CH(OH)-CH(OH)-CH(OH)-CH2-OH sorbitol (hexahydric alcohols).

4. CLASSIFICATION OF MONOHYDRIC ALCOHOLS
Monohydric alcohols are classified according to the type of hybridization of carbon atoms to which the hydroxyl group is attached.
A) Alcohols containing Csp3-OH bond : In these alcohols hydroxyl group is attached to sp3 hybridized carbon atom of alkyl group.
They are represented as R-OH
The general formula of these alcohols is CnH2n+2O
or CnH2n+1OH. They are functional isomers of ethers.
These alcohols are further classified as primary(10), secondary(20), tertiary(30) alcohols in which –OH group is attached to primary,secondary and tertiary carbon atoms respectively.
e.g
R-CH2- OH CH3-CH2-OH ( ethyl alcohol)
R OH
CH-OH CH3-CH-CH3 (sec. propyl alcohol) R2

5. Classification Of Monohydric Alcohols
R CH3
R C-OH CH3 – C – OH (tert. Butyl alcohol)
R CH3
Allylic Alcohols- In these alcohols –OH group is attached to a sp3 hybridised carbon atom next to carbon-carbon double bond i.e. ALLYLIC CARBON.
Allylic alcohols may be primary, secondary or tertiary.
OH CH3
e.g.CH2=CH-CH2-OH CH2=CH-CH-OH CH2=CH-C-OH
Prop-2-en-1-ol But-3-en-2-ol CH3
2-methylbut-3-en-2-ol

6. CLASSIFICATION OF MONOHYDRIC ALCOHOL
Benzylic alcohols- In these alcohols –OH group is attached to sp3 hybridised carbon atom next to an aromatic ring. Benzylic alcohols can be primary, secondary or tertiary. Benzyl alcohol 1-phenyl ehtanol 2-phenylpropane-2-ol B) Alcohols containing CSP2 –OH bond- In these alcohols –OH group is attached to a sp2 hybridised carbon atom i. e. vinylic carbon. These alcohols are also called as VINYLIC ALCOHOLS. e.g. CH2=CH-OH (vinyl alcohol)

7. NOMENCLATURE OF ALCOHOLS
Alcohols are named according to common name system and IUPAC system. i) Common System- Common name of aliphatic monohydric alcohol is derived by entering name of alkyl group followed by word ‘alcohol’. Thus common name of alcohol is alkyl alcohol. ii) IUPAC System- (a) According to IUPAC System alcohols are named as ‘alkanols’, by replacing ending ‘e’ of parent alkanes by suffix ‘ol’. (b) Longest continous carbon chain containing –OH group is selected. (c) Carbon atoms are numbered from that end which is nearer to –OH group. (d) Position of other branches are indicated by proper numbers. (e) The locant indicating the position of –OH group is entered immediately before suffix ‘ol’. (f) The substituents are arranged in alphabetical order. (g) While naming polyhydric alcohols suffux ‘e’ from name of parent alkane is retained. (h) Prefixes like di, tri are added before suffix ‘ol’ & position of –OH groups are indicated by appropriate locants. (i) Cyclic alcohols are named by using prefix ‘cyclo’ and considering –OH group is attached to C-1.

8. IUPAC NOMENCLATURE e.g. Common name IUPAC Name
CH3-OH Methyl alcohol Methanol
CH3-CH2-CH2-OH n-propyl alcohol propan-1-ol
CH3-CH-CH iso-propyl alcohol propan-2-ol OH
4) CH ) )
CH3-C-CH3
tert. Butyl alcohol
2 methyl-propan-2-ol
propane-1,2-diol cyclohexanol 7)
3-methyl cyclopentanol

9. PREPARATION OF ALCOHOLS
(i) From alkyl halides (hydrolysis) –
R-X + NaOH (aq) R-OH + NaX
alkyl halide alcohol
(ii) From alkenes (hydration)-
Addition of water molecule across the double bond in alkene is called hydration in alkene.
Hydration of alkene is carried out by passing an alkene through cold conc Sulphuric acid to give alkyl hydrogen sulphate, which on heating with water gives an alkene.
CH2=CH2 + H-OSO3H CH3-CH2O SO3H
ethene ethyl hydrogen sulphate
CH3-CH2O SO3H HOH/HEAT CH3-CH2-OH + H-OSO3H
ethanol

10. FROM ALKENES
This method is useful for preparation of sec. & tert. Alcohols
Only ethyl alcohol (primary alcohol) is prepared by this method.
As alkenes are easily available ,this method is used for industrial preparation of alcohols.
Mono or di substituted alkenes undergo acid catalysed hydration to give alcohol.
e.g.
CH H CH3
CH2-C=CH2 + HOH CH3-C-CH3 OH
iso butylene tert. Butyl alcohol

11. Mechanism of Hydration of alkenes
It consists following steps. Step I – Protonation of alkene H2O + H+ H3O+ H H C=C + H-O+-H -C-C+ + H2O Step II – Nucleophilic attack on carbocation H H H - C-C+ + H2O -C-C-O+-H Step III – Deprotonation to form alcohol. H H H -C-C-O+-H + H2O -C-C-OH + H3O+

12. Preparation of alcohols
(iii)From alkenes (hydroboration-oxidation) –
Diborane react with alkene to form trialkyl borane which on oxidation by hydrogen peroxide in presence of dil. NaOH gives alcohol.
6CH3 –CH= CH2 + B2H (CH3-CH2-CH2)3B
tripropyl borane
(CH3-CH2-CH2)3B + 3H2O OH CH3-CH2-CH2-OH + B(OH)3
propan-1-ol
Addition of borane to double bond takes place in such way that the boron atom gets attached to less substituted carbon(Anti-Markownikoff’s Rule)
More convinient hydroborating agent is borane-tetrahydrofurane
(BH3-THF)
(iv)From carbonyl compounds(Reduction) –
Aldehydes are reduced to primary alcohols while ketones are easily reduced to secondary alcohols.
Tertiary alcohols cannot be obtained by this method.

13. Preparation of alcohols
Hydrogenation is carried out in presence of catalyst like finely divided nickel,platinum or palladium. H
CH3-C=O + H Raney nickel / K CH3-CH2-OH
ethanal ethanol(pri. alcohol)
CH CH3
CH3-C=O + H2 Raney nickel / 413K CH3-CH-OH
propanone Propan-2-ol (sec. alcohol)
(b) Aldehydes and ketones may be reduced by nascent hydrogen supplied by sodium-amalgam and water.
CH3-C=O + 2H Na –Hg / H2O CH3-CH2-OH
ethanal ethanol (pri. Alcohol)
CH CH3
CH3-C=O + 2H Na –Hg / H2O CH3-CH-OH
Propanone propan-2-ol(sec. alcohol)

14. Preparation of alcohol(From carbonyl compound)
Catalytic hydrogenation has been replaced by reducing agents like sodium borohydride(NaBH4) & LiAlH4.
Sodium borohydride is safe and easy to handle,used in water or alcohol solutions.
LiAlH4 is expensive, react violently with water and alcohol therefore must be used in presence of dry ether or tetrahydrofurane.
When NaBH4 and LiAlH4 is used separate, hydrosis step is required because they function as hydride donor.
LiAlH4 does not reduce carbon-carbon double bond therefore it is used to prepare unsaturated alcohols from unsaturated aldehydes & ketones.
e.g.
CH3-CH=CH-CHO (i) LiAlH CH3CH=CH-CH2OH
but-2-en-1-al (ii) H3O but-2-en-1-ol
CH3-COOH (i) LiAlH CH3-CH2-OH
acetic acid (ii) H3O ethyl alcohol

15. Preparation of alcohol(From carbonyl compound)
(i) LiAlH4
CH3-CH2-COOC2H (ii)H3O CH3-CH2- CH2-OH + C2H5OH
Ethyl propanoate n-propyl alcohol
Acids are reduced to alcohols by first converting them to ester and then catalytic hydrogenation of ester is carried.
(v) From Grignard Reagent -
All three types of alcohols can be prepared by this method. Aldehydes or ketones undergo nucleophilic addition of Grignard reagent in presence of dry ether to form a complex which on acid hydrosis gives an alcohol
C=O + R∂--Mg ∂ +X R-C-O-Mg+-X HOH / H+ R-C-OH + MgX OH
Aldehyde or ketone complex alcohol

16. Preparation of alcohols ( From Grignard’s Reagent)
Methanal produces primary alcohol containing one more carbon atom than in Grignard’s Reagent.
Aldehydes( other than methanal ) produces secondary alcohol.
Ketone produces tertiary alcohol.
e.g.
Methanal gives ethanol.
Ethanal gives propan-2-ol (iso-propyl alcohol).
Propanone (acetone) gives 2-methylpropan-2-ol (tert. butyl alcohol).
Sec. & tert. Alcohols can be prepared by different combinations of aldehydes/ketones and Grignard’s Reagent.

17. Structure of alcohols H O C-O bond length 142pm
C H O-H bond length 96pm
H C-O-H bond angle
H Oxygen atom sp3 hybridised
Structure of Methanol Carbon that bears –OH group is sp3 hybridised.
-OH group is attached to carbon by sigma bond formed by overlap of sp3 hybrid orbital of carbon and sp3 hybrid orbital of oxygen.
Oxygen atom carries two lone pairs of electrons hence due to repulsion between these lone pairs bond angle is slightly less than tetrahedral angle.
H-O bond in alcohol is polar covalent bond. Oxygen carries ∂- charge and hydrogen carries ∂+ charge.
Due to polar nature there is inter molecular hydrogen bonding in alcohols.

18. Physical properties of alcohols
Lower members are colourless liquids having distinctive smell. Higher members are colourless solids.
Alcohols have higher boiling points than corresponding alkanes, alkyl halides, aldehydes, ketones and ethers of nearly same molecular mass.
Higher boiling point of alcohol is due to association of alcohol molecules by intermolecular hydrogen bonding. More energy is required to break the association therefore alcohols have high B.P.
The boiling point of alcohols increases with increase in number of carbon atoms due to increase in van der waals forces.
The B.P. of alcohols decreases with increase in branching which decreases van der waals forces.
B.P. of alcohols increases with increase in number of –OH groups.
Lower members are highly soluble in water. The solubility is due to inter- molecular hydrogen bonding between water moleculs and alcohol molecules.

19. Hydrogen bonding Intermolecular hydrogen bonding in alcohols R R
O ∂ O ∂-
H ∂ H ∂ H ∂ H ∂+
O ∂ O ∂-
Hydrogen bonds
B) Intermolecular hydrogen bonding between alcohol and water molecules
R R
O∂ O ∂-
H ∂ H ∂ H ∂ H ∂+
H∂ H ∂+

20. Reactions of alcohols Reactions involving breaking of O-H bond
(i) Action of metals – Alcohols reacts with active metals like Na, K, Al to give corresponding alkoxide with evolution of hydrogen gas.
2C2H5-OH + 2Na C2H5-ONa + H2
6(CH3)3C-OH + 2Al [(CH3)3C-O]3Al + 3 H2
These reactions explain acidic nature of alcohols
Acidic character of alcohol is due to polar nature of O-H bond.
Alkyl groups are electron releasing groups and increases electron density on oxygen atom which results in decrease in polarity of O-H bond.
As number of alkyl group increases, acidic strength of alcohols decreases. Therefore order of acidic strength of alcohol is
primary secondary tertiary
Consider the reaction : R-O- + H-O-H R-O-H + OH-
Water is better proton donor than alcohol and alkoxide ion is better proton acceptor than hydroxide ion. Thus alcohols are weaker acids than water and alkoxide ions are stronger bases than hydroxide ion.

21. Reactions of alcohols
(ii) Esterification – Alcohols on reacting with carboxylic acids, acid chlorides and acid anhydrides gives esters. C2H5-OH + CH3COOH H+ CH3COO C2H5 +H2O C2H5-OH + (CH3CO)2O H+ CH3COO C2H5 + CH3COOH C2H5-OH + CH3COCl pyridine CH3COO C2H5 + HCl Pyridine neutrlizes HCl formed during reaction. B) Reactions involving breaking of C-O bond – (i) Reaction with hydrogen halides - Alcohols reacts with hydrogen halides to give alkyl halides. The order of reactivity of hydrogen halides is HI > HBR >HCl . The order of reactivity of alcohol is primary < secondary< tertiary . R-OH + HX R-X +H2O

22. Action of HCl
HCl is less reactive than HBr hence catalyst (Lewis acid) is required for primary and secondary alcohols.
Lucas reagent is mixture of conc. HCl and anhydrous ZnCl2.
Primary alcohol react with Lucas reagent very slowly on heating to give alkyl chlorides.
CH3-CH2-OH + HCl anhydrous ZnCl CH3-CH2-Cl + H2O
ethanol ethyl chloride
Sec. alcohol react with Lucas reagent much faster.
CH3-CH(CH3)-OH + HCl anhydrous ZnCl CH3-CH(CH3)-Cl + H2O
propan-2-ol chloropropane
Tert. alcohol react instantaneously with HCl at room temp.
(CH3)3-C-OH + HCl room temp (CH3)3-C-Cl + H2O
2-methylpropan-2-ol chloro-2-methylpropane
Alcohols are soluble in Lucas reagent but alkyl chlorides are immiscible.
Alkyl chloride produces turbidity in solution .
Therefore this reaction is used to distinguish 10,20 & 30 alcohols.
In tert. alcohol layer seperation takes place immediately.
In sec.alcohol layer seperation takes place after few minutes.
In case of pri.alcohols layer seperation takes place after long time with heating.

23. Action of HBr Action of HI CH3-CH(CH3)-OH + HI CH3-CH(CH3)-I + H2O
Alcohols whrn heated with HBr gives alkyl bromides.
HBr is prepared in situ by adding NaBr to HCl or sulphuric acid.
HBr is stronger than HCl therefore ZnCl2 catylyst is not required.
CH3-CH2-OH + HBr CH3-CH2-Br + H2O
ethanol ethyl bromide
CH3-CH(CH3)-OH + HBr CH3-CH(CH3)-Br + H2O
propan-2-ol bromopropane
(CH3)3-C-OH + HBr (CH3)3-C-Br + H2O
2-methylpropan-2-ol bromo-2-methylpropane
Alcohols on heating with hydroiodic acid give alkyl iodide.
ZnCl2 is not required, no acceptable yield.
CH3-CH(CH3)-OH + HI CH3-CH(CH3)-I + H2O
propan-2-ol idopropane
Action of HI

24. Mechanism of Convertion of sec. alcohol to tert
Mechanism of Convertion of sec. alcohol to tert. Alkyl halide by action of HI
CH3 CH3 CH3-CH-CH-CH3 + HI CH3-C-CH2-CH3 + H2O OH I STEP I – The alcohol is protonated by acid. CH3 CH3 CH3-CH-CH-CH3 + H+ CH3-CH-CH-CH3 OH O+ H H STEP II – It involves formation of carbocation. CH3 CH3 CH3-CH-CH-CH3 CH3-CH-C+H-CH3 + H2O O+

25. CONTINUE….
STEP III – Secondary carbocation rearrange to more stable tert. carbocation by a hydride ion shift. Nucleophile I- ion attacks tert. carbocation to give tert. alkyl iodide. CH3 CH3 CH3 CH3-C- C+H-CH3 CH3-+C-CH2-CH3 CH3-C-CH2-CH3 H I

26. (ii) Reaction with phosphorous halides & thionyl chloride
Alcohol react with phosphorous halides and thionyl chloride gives alkyl halide.
e.g. 3C2H5OH + PCl C2H5Cl + H3PO3
3C2H5OH + PBr P + Br C2H5Br + H3PO3
3C2H5OH + PI P + I C2H5I + H3PO3
C2H5OH + PCl C2H5Cl + HCl + POCl3
In general
3R-OH + PX R-X + H3PO3
R-OH + PX R-X + HCl + POCl3
R-OH + SOCl Reflux / Pyridine R-Cl + HCl + SO2
∝ β

27. (iii) Dehydration {formation of alkenes}
Removal of water molecule from an alcohol molecule is called dehydration
of alcohols.
When an alcohol containing ∝ & β-hydrogen is heated with dehydrating
agents like conc. H2SO4 or P2O5 orAl2O3 orH3PO4 gives alkene with loss of
water molecule.
Alkene distills out from mixture as it has lower boiling point than alcohol,
The ease of dehydration of alcohol is 30 > 20> 10.
A primary alcohol is dehydrated by heating with 95% . H2SO4 at 443K.
e.g H H H H
H-βC – ∝C – H 95% H2SO4 , 413K H-C=C-H + H2O
H OH
ethanol ethene

28. Dehydration continued…..
e.g. H H H H – βC – ∝C – βC – H 60% H2SO4 , 373K CH3-CH=CH2 + H2O H OH H propan-2-ol propene Saytzeff’s Rule – In dehydration or in dehydrohalogenation alkene formed by elimination has greater number of alkyl groups attached to the doubaly bonded carbon atom. e.g. - Butan-2-ol on dehydration gives two different products. OH CH3-CH=CH-CH3 + H2O βCH3 – ∝CH – βCH2 – CH3 but-2-ene ( major ) CH3-CH2 -CH=CH2 + H2O butan-2-ol CH3 but-1-ene ( minor ) (CH3)3C-OH 20% H2SO4 , 363K CH3-CH=CH2 + H2O tert. butyl alcohol 2-methylpropene
60% H2SO4 , 373K

29. Mechanism of Intramolecular dehydration of alcohol
STEP I – Fromation of protonated alcohol . H H H H H H-βC – ∝C – O-H + H+ H-βC – ∝C – O+ -H H H H H STEP II – Fromation of carbocation. It is slow step and rate determining step H H H H H H-βC – ∝C – O+ -H slow H – C – C+ + H2O H H H H STEP III – Fromation of ethene by elimination of proton H H H – C – C+ CH2=CH2 + H+ H H Tert. Carbocation is more stable therefore 30 alcohols are easily dehydrated.

30. Dehydration continued….
Alcohols can be dehydrated by passing vapours of alcohols over heated
alumina(Al2O3).
CH3-CH2-OH Al2O3 , 623K CH2= CH2+ H2O
ethanol ethene
CH3-CH-CH Al2O3 523K CH3-CH=CH2+ H2O OH
propan-2-ol propene
CH CH3
CH3-C-OH CH3-C=CH2
CH3
2-methylpropan-2-ol methylprop-2-en
Al2O3 423K

31. iv) Oxidation (formation of aldehydes and ketones)
Alcohols on oxidation give aldehydes and ketones which on further oxidation give carboxylic acids. The different oxidising agents used for oxidation are acidified potassium dichromate,acidified or alkaline potassium permanganate,dilute nitric acid or chromium trioxide. K2C r2O7 + 4H2SO4 K2SO4 + Cr2(SO4)3 + 4H2O + 3[O] 2KMnO4 + 3H2SO4 K2SO4 +2MnSO4 + 3H2O + 5[O] 2KMnO4 +2KOH 2 K2MnO4 + H2O + [O] 2HNO3 H2O+ 2NO + 3[O] 2CrO3 C r2O3 + 3[O] KMnO4 + H2O 2KOH + 2MnO2 +3[O] The nascent oxygen atom is used for oxidation. The OH group of primary and secondary alcohol forms carbonyl group by removal of two hydrogen atoms .Therefore the reaction is also known as dehydrogenation.

32. (a) Oxidation of primary alcohols
Primary alcohols on oxidation by acidified potassium dichromate gives aldehydes which on further oxidation gives carboxylic acids.
Both aldehydes and carboxylic acid contain same number of carbon atoms as in alcohol.
CH3CH2OH + (O) K 2Cr2O7 / dil. H2SO CH3-CHO + H2O
ethanol ethanal
CH3-CHO + (O) K 2Cr2O7 / dil. H2SO CH3-COOH
ethanoic acid
The best reagent for obtaining aldehyde from pri. alcohol is pyridinium chlorochromate (PCC) or pyridinium dichromate (PDC).
PCC is a complex obtained by mixing chromium trioxide with pyridine and HCl in dichloromethane.
PCC (C5H5NH+CrO3Cl) is mild oxidising agent which oxidises primary alcohol to aldehyde and further oxidation does not take place.
CH3-CH2-CH2-OH + (O) PCC CH3-CH2-CHO + H2O
propan-1-ol propanal

33. (b) Oxidation of secondary alcohols
A sec. alcohol on oxidation by potassium dichromate and dil. Sulphuric acid gives a ketone. The ketone resist further oxidation as it involves breaking of C-C bond. The oxidation of ketone requires severe conditions and gives mixture of products.
Ketone contain same number of C-atoms as in alcohol.
Sec alcohols can be oxidised to ketone by PCC.
CH CH3
CH3-CH-OH + (O) K 2Cr2O7 / dil. H2SO4 CH3-C=O + H2O
Propan-2-ol propanone

34. (c) Oxidation of tertiary alcohols
Tert alcohol resist oxidation as there is no alpha-hydrogen atom. Tert alcohols can be oxidised by using strong oxidising agents like acidic KMnO4 OR CrO3. CH3 CH3 CH3-C-OH CrO3 CH3-C=CH2 + H2O CH3 2-methylpropan-2-ol 2-methylpropene (o) CH3-C=O + CO2 + H2O Propanone

35. Oxidation of alcohols by hot copper at 573K
When vapours of primary or sec alcohols are passed over heated copper at 573K dehydrogenation takes place with formation of aldehydes and ketone resp.
Tert alcohol undergo dehydration under same condition with copper forming alkene.
CH3-CH2-OH Cu K CH3-CHO + H2
ethanol ethanal
CH CH3
CH3-CH-OH CH3-C=O + H2
propan-2-ol propanone
CH CH3
CH3-C-OH CH3-C=CH2 + H2O
CH3
2-methylpropan-2-ol methylpropene
Cu K
Cu K

36. Uses of alcohols Uses of methyl alcohol
As an industrial solvent for oils,fats,gums,celluloid etc.
For dry cleaning and preparation of perfumes and vanishes.
As an anti-fridge agent for automobile radiator in cold countries.
Used as starting material for preparation of methyl chloride,dimethyl sulphate and formaldhyde.
It is used to denature ethanol (to make ethyl alcohol unfit for drinking).
Uses of ethyl alcohol
As a solvent for dyes,oils,perfumes,cosmetics and drugs.
A mixture of 10-20% ethyl alcohol with pertolis used as motor fuel.
Used to prepare solid fuel which is dispersion of ethyl alcohol in calcium acetate.
As ethyl alcohol has low freezing point,it is used in thermometers.
It is main constituent of beverages.
It is an effective topical antiseptic and used as an ingredient in many mouth washes.
As a starting material for preparation of idoform,chloroform,acetic acid ethers etc.
Used as a fuel.

37. Phenols Introduction–
The aromatic hydroxyl compounds in which one or more hydroxyl groups are directly attached to aromatic nucleus (like benzene ring) are called phenols.
The class name ‘Phenols’ is adopted from the simplest member phenol (hydroxy benzene).
In Greek ‘phene’ means benzene and ‘ol’ means OH.
Classification and Nomenclature of Phenols-
Phenols are classified as monohydric,dihydric and trihydric phenols depending upon number of hydroxyl groups.
Nomenclature-
Systematic name of phenol is benzenol.
The prefixes used are ortho(o) for 1-2 disubstituted phenols.
meta(m) for 1-3 disubstituted phenols.
para (p) for 1-4 disubstituted phenols.
In IUPAC system the numbering of ring starts with –OH substituted carbon as 1.
Other subs. Carbon is indicated by lowest number.
Substituents are cited in alphabetical order.
The name phenol for hydroxy derivatives of benzene is accepted by IUPAC system.
Compounds having one substituent are named as derivatives of phenol.
When carboxyl group,carbonyl group or ester group is present along with –OH group then phenols are named as derivatives of these groups.
Phenol is also called carbolic acid because it neutralize common bases.

38. Nomenclature
Monohydric Phenols Phenol ∝-naphthol (1-naphthol) (2-methyl phenol) (3-methyl phenol ) (4-methyl phenol) CHO COOH COOC2H5 OH OH OH 4-hydroxy benzaldehyde 2-hydroxy benzoic acid 4-hydroxyethyl benzoate

39. Nomenclature
Dihydric Phenols Catecol resorcinol hydroquinone(quinol) (benzene-1,2-diol) (benzene-1,3-diol) (benzene-1,4-diol) Trihydric Phenols Phloroglucinol pyrogallol (benzene-1,2,4-diol) (benzene-1,3,5-triol) (benzene-1,2,3-triol)

40. Structure of functional group
sp3 hybridised

41. Preparation of phenol
1)From chlorobenzene – (a)Dow’s process (b)Rashing process 2)From benzene sulphonic acid 3)From cumene 4)From aniline(diazotisation)

42. Rasching process + H2O Ca3(PO4)2 698K + HCl phenol
Physical properties of phenol –
Pure phenol is colourless crystalline solid.
It has characteristic smell known as ‘phenolic’ or ‘carbolic’ odour.
Its melting point is 315K & boiling point is 455K. The high B.P. is due to intermolecular bonding.
Phenol is sparingly soluble in water but completely soluble in alcohol, ether etc.
Phenol is weak acid, weaker than even carbonic acid (H2CO3)
Phenol turns pink on exposure to air and light due to formation of quinones.

43. Reactions of phenol
1)Acidic nature: a. Phenol > H2O > Primary alcohol > Secondary alcohol > Tertiary alcohol
The acidic character of alcohols is due to the polar nature of O–H bond.
Alkyl group is an electron-releasing group (–CH3, –C2H5) or it has electron releasing inductive effect (+I effect).
Due to +I effect of alkyl groups, the electron density on oxygen increases.
This decreases the polarity of O-H bond.
And hence the acid strength decreases.
* Phenol is more acidic than alcohol because:
• In phenol, the hydroxyl group is directly attached to the sp2 hybridised carbon of benzene ring which acts as an electron withdrawing group. Whereas in alcohols, the hydroxyl group is attached to the alkyl group which have electron releasing inductive effect.

44. Reactions of phenol
In phenol, the hydroxyl group is directly attached to the sp2 hybridised carbon of benzene ring. Whereas in alcohols, the hydroxyl group is attached to the sp3 hybridised carbon of the alkyl group. The sp2 hybridised carbon has higher electronegativity than sp3 hybridised carbon. Thus, the polarity of O–H bond of phenols is higher than those of alcohols. Hence, the ionisation of phenols id higher than that of alcohols.
The ionisation of an alcohol and a phenol takes place as follows:

45. Acidity of phenol
In alkoxide ion, the negative charge is localised on oxygen while in phenoxide ion, the charge is delocalised.
The delocalisation of negative charge makes phenoxide ion more stable and favours the ionisation of phenol. Although there is also charge delocalisation in phenol, its resonance structures have charge separation due to which the phenol molecule is less stable than phenoxide ion.

46. In substituted phenols, the presence of electron withdrawing groups such as nitro group enhances the acidic strength of phenol. On the other hand, electron releasing groups, such as alkyl groups, in general, decreases the acid strength.
It is because electron withdrawing groups lead to effective delocalisation of negative charge in phenoxide ion.
(ii) Electrophilic substitution reaction –
Halogenation – Bromination of phenol
Nitration of Phenol
Sulphonation of Phenol
(iii) Kolbe’s reaction
(iv) Reimer Tiemann reaction
(v) Reaction with zinc dust
(vi) Oxidation of Phenol

47. (ii) Electrophilic aromatic substitution reactions

48. Distinguishing test between Alcohol & Phenol
Alcohols are neutral and have no action on litmus paper.
Phenol is weakly acidic in nature and turns blue litmus paper to red.
When treated with aqueous neutral ferric chloride solution,
Phenol gives violet colour while alcohols do not give violet colour.
3C6H5OH + FeCl (C6H5O)3Fe + 3HCl
phenol ferric phenoxide (violet colour)
USES OF PHENOL – Phenol is used in prep. of
Phenol-formaldehyde polymer which is used in a plastic called Bakelite.
Phenolphthalein and certain dyes.
Dettol which is used as an antiseptic.
Drugs such as salicylic acid, salol, aspirin etc.
2,4-dichlorophenoxy acetic acid which is used as salective weed killer.
Picric acid which is used as explosive.

49. Ethers
Introduction –
Ethers are derivatives of hydrocarbonsin which a hydrogen atom is replaced by an alkoxy (-OR) or an aryloxy (-OAr).
Ethers are also considered as derivatives of alcohols or phenols obtained by replacing hydrogen atom of hydroxyl group by an alkyl or aryl group.
Ethers are also considered as dialkyl or diaryl derivatives of water.
Ethers are also considered as alkyl or aryl oxides, R2O or Ar2O.
The functional group of ether is –C-O-C-
The general formula of aliphatic ethers is CnH2n+2O , same as that of monohydric alcohols.
Thus ethers are functional isomers of monohydric alcohols.

50. Classification of ethers
Ethers are classified into two types.
Simple or Symmetric ethers – Two alkyl or aryl groups attached to oxygen atoms are same. e.g. (1) CH3-O-CH dimethyl ether
Mixed or Unsymmetrical ether – Two alkyl or aryl groups attached to oxygen atom are different. e.g. (1) CH3-O-C2H5 ethyl methyl ether
Nomenclature of Ethers –
Common name – Simple ethers are named as dialkyl ethers or diaryl ethers. In case of mixed ethers name of alkyl groups are entered as separate words in alphabetical order followed by the word ‘ether’.
IUPAC System – According to IUPAC system name of ether is derived as alkoxy alkane or aryloxy arene. In case of mixed ethers larger alkyl group is considered as parent alkane.
e.g. ) (1) CH3-O-CH methoxy methane (dimethyl ether)
(2) CH3-O-C2H methoxy ethane (ethyl methyl ether)
(3) C6H5-O-C2H5 ethoxy benzene (phenetol OR ethyl phenyl ether

51. Structure of functional group

52. Metamerism – Ethers having same molecular formula but different alkyl groups attached on either side of oxygen atom are called metamers of each other. This phenomenon is called metamerism.
Metamers are either chain isomers or position isomers with same functional group and having different alkyl groups attached to oxygen atom.
e.g. (1) CH3-CH2-O-CH2-CH diethyl ether
(2) CH3-O-CH2-CH2-CH methyl n-propyl ether
(3) CH3-O-CH-CH methyl iso-propyl ether
CH3
Ethers exhibit following two types of isomerism
Chain isomerism
Functional isomerism – Ethers and monohydric alcohols are functional isomers.

53. Methods of preparation
From alcohols (Intermolecular dehydration)
When excess of ethyl alcohol is distilled with conc. Sulphuric acid at 413K gives diethyl ether
2C2H5-OH conc. H2SO K C2H5-O- C2H5 + H2O
The experimental procedure is
C2H5 OH + H OSO3H C2H5 –O-SO3H + H2O
ethyl hydrogen sulphate
C2H5 –O-SO3H + H OSO3H K C2H5-O- C2H5 + H2SO4
Sulphuric acid regenerated is reused therefore the process is continued by adding ethyl alcohol therefore called continous etherification process.
Substitution is favoured at 413K, increase in temperature becomes more favourable for elimination (dehydration).
This method is useful for preparation of ethers from primary alcohols only.
Simple ethers are prepared. Mixture of alcohol gives 3 diff. ethers.

54. Mechanism
Inter molecular dehydration of alcohol at 413K is bimolecular nucleophilic substitution (SN2) . It involves three steps. Step 1 – Formation of protonated alcohol. H CH3-CH2-O-H + H+ Fast CH3-CH2-O + - H Step 2 – Nucleophilic attack of alcohol molecule on protonated alcohol. H H CH3-CH2-O-H + CH3-CH2-O + - H slow CH3-CH2- O + - CH2CH3 + H2O Step 3 – Deprotonation to give ether CH3-CH2- O + - CH2CH3 Fast CH3-CH2- O - CH2CH3 + H+

55. Methods of preparation
(ii) From alkyl halides (Williamson synthesis) R-O-Na + X- R’ R-O-R’ + NaX Sodium alkoxide ether e.g. 1) CH3-O-Na + I- CH3 CH3-O-CH3 + NaI sodium methoxide dimethyl ether 2) OH O-Na+ O-CH3 + NaOH CH3I Phenol sodium phenoxide Anisole Limitations – (1) Best yield of unsymmetrical ether is obtained when alkyl halide is primary and alkoxide is tert. (2)Sec. & tert. Alkyl halide gives alkene instead of ether by β-elimination.

56. Methods of preparation
(iii) From diazomethane and alcohols –
This method is used to preparation of simple andmixed ethers.
Alcohols on reaction with diazomethane in presence of fluoroboric acid HBF4
or BF3 as catalyst give ethers.
R-OH + CH2N HBF R-O-CH3 +N2
e.g. CH3-OH + CH2N HBF CH3-O-CH3 + N2
Limitations – Only methyl ethers are obtained by this method.
Physical properties of Ethers –
B.P. of ethers are slightly higher than that of alkanes but lower than that of alcohols of comparable masses.
Ethers are soluble in water because they form hydrogen bond with water molecule.

57. Chemical properties of Ethers
Action of hydrogen halides –
Ethers are cleaved by strong acids HI or HBr but HCl does not cleave ethers.
Ethers when heated with conc. Hydrogen halide give alkyl halides.
In cold – Simple ethers gives one molecule of alkyl halide and one molecule of an alcohol.
R-O-R + HX cold R-X + R-OH
R-O-R + HI cold RI + R-OH
Mixed ethers gives lower alkyl iodide and higher alcohol.
R-O-R’ + H-X cold R-X + R’-OH
R-O-R’ + HI cold RI + R’-OH
If one of alkyl group is tert. then tert. alkyl halide and lower alcohol is formed

58. Action of hydrogen halide--- continued…..
b) In hot – Simple ethers gives two molecules of same alkyl halide. R-O-R + 2H-X 2HX + H2O R-O-R + 2HI 2HI + H2O Mixed ethers gives two molecules of diff. alkyl halides. R-O-R’ + 2H-X RX + R’X + H2O R-O-R’ + 2HI RI + R’I + H2O c)When alkyl aryl ethers are cleaved phenol and alkyl halide is formed. e.g. O-CH3 OH + HI + CH3-I

59. Mechanism
Step 1 – Ether is protonated to give dialkyl oxonium ion as oxygen of ether is basic. H R-O-R’ + H-X R-O+-R’ + X- Step 2 – Halide ion is good nucleophile attacks least substituted C-atom of dialkyl oxonium ion and displaces an alcohol. It is SN2 clevage . a) If primary or sec. alkyl groups are present lower alkyl groups form alkyl halide. X- + R-O+-R’ X-R + R’-OH b) If one of alkyl group is tert. then tert. alkly halide is formed. R-O+-R’ R+ + R’-OH

60. Mechanism continued…..
Step 3 – At higher temperature alcohol molecule react with excess of hydrogen halide gives alkyl halide. H R’-O-H + H-X R’-O+-H + X- X- + R’-O+-H R’-X + H2O

61. Chemical properties of Ethers
(2) Hydrolysis / Action of dil. sulphuric acid ( formation of alcohols ) – Simple ethers on heating with dil. sulphuric acid under pressure give two molecules of same alcohol. R-O-R + H2O dil. Sulphuric acid , pressure 2R-OH e.g. CH3-O-CH3 + H2O dil. Sulphuric acid , pressure 2CH3-OH Mixed ethers under similar condition gives mixture of two diff. alcohols. R-O-R’ + H2O dil. Sulphuric acid , pressure R-OH + R’-OH CH3-O-C2H5 + H2O dil. Sulphuric acid , pressure CH3OH + C2H5 OH

62. Chemical properties of ethers
(3) Electrophilic substitution – The alkoxy group (-OR) in aromatic ethers is ortho, para directing and activates athe aromatic ring towards electrophilic substitution.
Halogenation
Friedal-Crafts reaction
Nitration
Uses of diethyl ethers- 1) As industrial solvent for oils,fats,gums,resins etc.
2) As a solvent for Grignard reagent. 3) As a refrigerant. 4) A mixture of diethyl ether and ethyl alcohol, known as Natalite, is used as fuel (substitute of petrol)

63. Electrophilic substitution reactions

64. Crown Ethers
Discovered by - Charles J. Pederson Crown ethers are macro cyclic polyethers containing large rings of carbon & oxygen atoms. They are named as n-crown–m, where ‘n’ is the total number of carbon & oxygen atoms. ‘m’ is the number of oxygen atoms in the ring. The first ether synthesized was 18-crown-6 ether. - CH2 group o - Oxygen atom