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The document discusses the properties and reactivity of amines and aniline. Some key points include: 1) Amines are basic due to their lone pair on nitrogen and aliphatic amines are stronger bases than ammonia due to inductive effects. Secondary amines are the strongest bases in aqueous solution. 2) Aniline is more reactive than benzene towards electrophiles due to the activating effect of the -NH2 group. It undergoes halogenation, nitration, and sulfonation. 3) Aniline does not undergo Friedel-Craft reactions as it reacts with the Lewis acid catalyst instead of undergoing substitution. Acetanilide is a weaker base than an

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Soumya Ranjan Naik
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19 views7 pages

Adobe Scan Oct 03, 2023

The document discusses the properties and reactivity of amines and aniline. Some key points include: 1) Amines are basic due to their lone pair on nitrogen and aliphatic amines are stronger bases than ammonia due to inductive effects. Secondary amines are the strongest bases in aqueous solution. 2) Aniline is more reactive than benzene towards electrophiles due to the activating effect of the -NH2 group. It undergoes halogenation, nitration, and sulfonation. 3) Aniline does not undergo Friedel-Craft reactions as it reacts with the Lewis acid catalyst instead of undergoing substitution. Acetanilide is a weaker base than an

Uploaded by

Soumya Ranjan Naik
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© © All Rights Reserved
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intermolecular hydrogen bonding with water molecules, but the

solubility decreases with increase in size of alkyl group.


CH,NH, > C,H,NH, > CGH,NH, > CoH,NH,
(C,Hs),N <<C,H),NH<C,H,NH,
Antl:
molecular like alkanes but lower boiling point than alcohols or
carboxylic acids of comparable molecular masses. As in amines the
strength of H-bonding is weaker than that of alcohol and acid.
CzHe < CHsNH2 < CH5OH < CH,COOH.

i) B.P. increases with increase in size of alkylgroup:


CH,NH, < C,H,NH, < C,H,NH,

ii) Among isomeric amines, the B.P. follows the order 3° amine < 20
amine< 1° amine This is because in 1° amine the extent of hydrogen
bonding is highest as 3 H-atoms are attached to nitrogen.
Ex:(CH,),N <C,H,NHCH, <CGH,NH,
Amines are basic because they possess a pair of unshared electrons on N atom, which they
can share with other atoms .The greater the electron density, the more basic the molecule.

Aliphatic amines are stronger base than NH, due to +I effect of alkyl groups which
increases the electron density on N atom.
The order of basicity: 30>20>10>NH,

Ex :(CH,),N >(C,H),NH > (C,H)NH,>NH


But it is only in gaseous phase

In aqueous solution due to simultaneous effect of inductive effect,


solvation effect and steric effect, the secondary amine is the strongest
base. The order of basicity in aqueous solution: 20>30>10>NH,
(C,H,),NH>(C,H,),N >(C,H)NH,>NH,
But when the alkyl gr is CH, then 1° amine is stronger base than 30
amine due to higher extent of H-bonding as size is small. So the basic
strength is (CH),NH > CH,NH, >(CH),N >NH3
.Aniine Is a Weaker base than alipnatiC amines as Well as ammonla due TO
resonance and less stability of anilinium ion. +

NH, NH,
NH,
NH,

(I) (u) (IV) (V)

EX:(C,H,),NH>(C,H,),N > NH, >CeH,NH,


(C,H),NH(C,H,),N > (C,H,)NH,>NH,
N-Akylaniline is stronger base than aniline due to +leffect of alkyl group.
CçH,NH, <CH,NHCH, < NH, <C,H,NH,
Benzyl amine is a stronger base than NH, due to weaker +I effect of
benzyl g.
CH,NH, < NH, < CH,CH,NH, < C,H,NH,
. As -NH, is a strongly activating group due to its +R effect so anline is highly
reactive towards electrophiles than benzene. -NH, iso- and p-directing
substituent.
. a.Halogenation: aniline reacts with Br2 water to form 2,4,6-Tribromoaniline.
NH, NH,
Br Br
3Br,/ HO, +3HBr

Aniline
Br
2.4.6-Tribrormoaniline

. In order to get mono-bromo aniline it s 1st protected by acylation reaction


b.Nitration: Aniline on nitration gives a mixture of o-, p- and m-nitro aniline. The m-nitro
aniline is formed because some aniline molecule undergo protonation to form anilinium
ion where the -NH3+ gr is meta directing substituent.
NH, NH, NH, NH,
Con. HNO,
+
NO
Con. H,SO.
288 K NO,
Aniline NO,
p-Nitroaniline m-Nitroaniline o-Nitroaniline
(51 $) (47 %) (2 %)

Q. Convert: Aniline to paranitroaniline

NH, NHCOCH, NHCOCH, NH,


(CHOp, HNO, /HS0 Hydrolysis
Pyridine 288 K H or OH

Aniline Acetanilide NO, NO,


p-Nitro 4-Nitroaniline
acetanilide
Sulphonation of Aniline and Friedel Craft Reaction
Sulphonation: Aniline reacts with conc. H,SO, to form p-amino benzene sulphonic acid.
NH, `HJASO, NH,
H,SO,, 453-473 K.

ao,H so
(nke ion)

Friedel-Craft reaction: Aniline doesn't undergo Friedel-Craft reaction because


as it is basic in nature it reacts with AlCI, which is an Lewis acid and is the
catalyst of the reaction to form a salt where the substituent acts as a strong
deactivating substituent. NH NHAICH

AICh HCI
Q. Accounts: Aniline Salt

i) Aniline is highly reactive towards bromine water


ii) Acetanilide is a weaker base than aniline
Ans:
i)Due to +R effect, -NH, is a stronger activating group.
ii) Due to -R effect of -COCH,, the electron density on nitrogen atom decrea

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