12 Chemiasdsastry Notes Ch11 Alcohols Phenols and Ethers

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CBSE Class-12 Chemistry Quick Revision Notes

Chapter-11: Alcohols, henols an! Ethers

Structure o" alcohols:

reparation o" alcohols:

a) From alkeneAcid catalysed hydration

+ (H2 O,H )

Mark, Addition

Or Hydroboration - oxidation

H ,H O ! OH

2 "

2 2 Mark, addition

#rod$ct is anti mark

Alkene % Alcoholb) From esters

H2 catalyst

Esters % Alcoholc) From aldehydes and ketones

H2 !Pd

or

NaBH& Or

LiAlH&

Or Grignard 's reaent

Alcoho l Aldehydeand ketone

d) From carboxylic acids


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LiAlH& H2

l

O Alcoho Carboxylicacids

Structure o" phenols:

reparation o" phenols:a) From ben*ene

+ Oleum

% NaOH !H

%

#aterial !o$nloa!e! "rom http:%%myCBSE&ui!e'com an! http:%%onlineteachers'co'in

ortal "or CBSE Notes, (est apers, Sample apers, (ips an! (ricks


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b) From chloroben*eneaOH at "2,2. atm/0res

% H1l %

c) From c$mene+

H2O,H

% O2

%

d) From anilineaO ,H1l

H O,arm

2 % 2

%

hysical properties o" alcohols an! phenols:a) oilin 0oints

oilin 0oints o3 alcohols and 0henols are hiher in com0arison to other classes o3com0o$nds/ 4his is beca$se the 5OH ro$0 in alcohols and 0henols is in6ol6ed in intermolec$lar

hydroen bondin/

4he boilin 0oints o3 alcohols and 0henols increase ith increase in the n$mber o3 carbonatoms/ 4his is beca$se o3 increase in 6an der 7aals 3orces ith increase in s$r3ace area/

8n alcohols, the boilin 0oints decrease ith increase o3 branchin in carbon chain/


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4his is beca$se o3 decrease in 6an der 7aals 3orces ith decrease in s$r3ace area/

b) 9ol$bility



9ol$bility o3 alcohols and 0henols are sol$ble in ater d$e to their ability to 3orm

hydroen bonds ith ater molec$les/ 4he sol$bility o3 alcohols decreases ith increase in si*eo3 alkyl!aryl (hydro0hobic) ro$0s/

Chemical properties o" alcohols:8/

:eactions in6ol6in clea6ae o3 O5H bond; Alcohols react as n$cleo0hiles; a) :eactionith metals

2R O H + 2Na % 2R O Na+H2

odium alkoxide

b)


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conc/HCl +!nCl !Lucas reaent 2

ROH +H" %R" +H O

2

b) :eaction ith 0hos0hor$s trihalides

ROH +P" % R " +H PO (" = Cl,Br)

c) >ehydration reaction#r otic acids(conc/H2 &

O orHP &

O )

Or Catalysts ( anhyd /!nC 2

l or al$mina)

Alcohol % C = C +H O

2 d) Oxidation reaction

Acidi#ied 0otassi$m 0ermananat Alcohol % Carboxylicacid

C$ ,?@ k Or Cr

O

Or i)

#rimary

PCC Alcohol %Aldehyde

C$ ,?@ k Or

ii)

Cr

9econdaryO

Alcohol %%etone

C$ ,?@ k

Or

iii)%&n &

4ertiary

O

Alcohol


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%Alkene

1hemical 0ro0erties o3 0henols;8/

:eactions in6ol6in clea6ae o3 O5H bond; Alcohols react as n$cleo0hiles; a) :eaction

ith metals




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b)


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b) #henol is more acidic than alcohol;8n 0henol, the hydroxyl ro$0 is directly attached to thes'( hybridised carbon o3

ben*ene rin hich acts as an electron ithdrain ro$0 hereas in alcohols, the hydroxylro$0 is attached to the alkyl ro$0 hich ha6e electron releasin ind$cti6e e33ect/ 8n 0henol, the

hydroxyl ro$0 is directly attached to thes'( hybridised carbon o3 ben*ene rin hereas in

alcohols, the hydroxyl ro$0 is attached to thes')hybridised carbon o3 the alkyl ro$0/ 4hes'2 hybridised carbon has hiher

electroneati6ity thans') hybridised carbon/ 4h$s, the 0olarity o3 O5H bond o3 0henols is


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hiher than those o3 alcohols/ Hence, the ionisation o3 0henols is hiher than that o3 alcohols/

4he ionisation o3 an alcohol and a 0henol takes 0lace as 3ollos; 8n alkoxide ion, the

neati6e chare is localised on oxyen hile in 0henoxide ion, the chare is delocalised/

4he delocalisation o3 neati6e chare makes 0henoxide ion more stable and 3a6o$rs the

ionisation o3 0henol/ Altho$h there is also chare delocalisation in 0henol, its resonancestr$ct$res ha6e chare se0aration d$e to hich the 0henol molec$le is less stable than 0henoxide

ion/




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2

83 it is a 0rimary alcohol, no t$rbidity a00ears at room tem0erat$re/ 4$rbidity a00ears

only on heatin/ 83 it is a secondary alcohol, t$rbidity a00ears in ? min$tes/ 83 it is a tertiaryalcohol, t$rbidity a00ears immediately/

c) Methanol and ethanol

8odo3orm test;


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b) From alkyl halide and sodi$m alkoxide

.illiamson 's synthesis

Ethers Alkyl halide and sodi$m alkoxide Here, the alkyl halide sho$ld be0rimary and alkoxide sho$ld be tertiary/ 8n case o3 aromatic ether, the aromatic 0art sho$ld beith 0henoxide ion/

hysical properties o" ethers;

a) Miscibility;Miscibility o3 ethers ith ater resembles those o3 alcohols o3 the same molec$lar mass/

4his is d$e to the 3act that $st like alcohols, oxyen o3 ether can also 3orm hydroen

bonds ith ater molec$le/

b) oilin 0oints;


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Other con6ersion reactions;

a) #henol to salicyldehyde

b) #henol to ben*ene dia*oni$m chloride




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12 Chemiasdsastry Notes Ch11 Alcohols Phenols and Ethers

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