1. They are good solvents for a large number of organic compounds including vinyl polymers, cellulose esters, synthetic rubbers, oils, fats, waxes and dyes.
2. Used in organic synthesis
3. Nitromethane reacts with halogen in presence of alkali to form trihalogen derivative. (e.g,.) with chlorine it forms chloropicrin, CCl₃NO₂ which is used as soil sterilzing agent.
4. Nitroethane is also used as a fuel additive and a precursor to Rocket propellants.

Compound (A) is nitro benzene on reduction with Sn / HCl gives compound (B) is Aniline
\(\underset {(A)} {\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{NO}_{2}}+6[\mathrm{H}] \stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} \underset {(B)}{ \mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{NH}_{2}}+2 \mathrm{H}_{2} \mathrm{O}\)
Compound (B) is Aniline reacts with Benzoyl chloride in the presence of pyridine to give compound (C) is N - phenyl benzamide.
Schotten - Baumann reaction:

Hoffmann's degradation reaction
Compound (A) is Benzamide
\(\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CO}-\mathrm{NH}_{2} \stackrel{\mathrm{Br}_{2} / \mathrm{KOH}}{\longrightarrow} \mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{NH}_{2}+\mathrm{KBr}+\mathrm{K}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}\)
Compound B is Aniline (primary amine)
Diazotization reaction:

It is because when NH₃ coordinates to Cu²⁺ ions and it forms the complex [Cu(NH₃)₄]SO₄ copper ions are present in coordination sphere, therefore. they are non-ionisable whereas SO₄^2- ions are counter ions which are ionisable.

(i) Nitration of aniline is accompanied by oxidation. But a mixture of cone. HNO₃ and cone. H₂SO₄ gives m-nitroaniline also. Nitric acid is a strong acid. It protonates aniline forming anilinium ion C₆H₅NH₃⁺ because of positive charge on nitrogen it is meta directing.

p-nitro aniline is prepared in the following three stages

(ii) Aniline reacts with acetyl chloride and acetic anhydride to form corresponding amides called anilides.
\({ C }_{ 6 }H_{ 5 }{ NH }_{ 2 }+\underset { Acetylchloride }{ ClCO{ CH }_{ 3 } } \rightarrow \underset { Acetanilide }{ { C }_{ 6 }{ H }_{ 5 }NHCO{ CH }_{ 3 } } +HCl\)
\({ C }_{ 6 }H_{ 5 }{ NH }_{ 2 }+\underset { Aceticanhydride }{ { CH }_{ 3 }COOCO{ CH }_{ 3 } } \rightarrow \underset { Acetanilide }{ { C }_{ 6 }{ H }_{ 5 }NHCO{ CH }_{ 3 } } +{ CH }_{ 3 }COOH\)

(i) Carbylamine reaction: Primary amines
on heating with chloroform and alcoholic potash forms a foul smelling substance called carbylamine or alkyl isocyanide
\(\underset { Chloroform }{ CH_{ 3 }{ NH }_{ 2 }+{ CHCl }_{ 3 } } +3KOH\rightarrow \underset { Methyl \ isocyanide }{ { CH }_{ 3 }NC } +3KCl+{ 3H }_{ 2 }O\)
This reaction is characteristic of primary amines. Secondary and tertiary amines do not undergo this reaction.
(ii) Mustard oil reaction: This is also a reaction characteristic of primary amine. When primary amines are warmed with carbon disulphide and mercuric chloride, alkyl isothiocyanate, having a pungent Mustard like odour is obtained
\(CH_{ 3 }{ NH }_{ 2 }+\underset { Carbondisulphide }{ S=C=S } \rightarrow \underset { Methyl \ isothicyanate }{ { CH }_{ 3 }-N=C=S } +{ H }_{ 2 }S\)
(iii) Aniline reacts with acetyl chloride and acetic anhydride to form corresponding amides called anilide.
\({ C }_{ 6 }H_{ 5 }{ NH }_{ 2 }+\underset { Acetyl \ chloride }{ ClCO{ CH }_{ 3 } } \rightarrow \underset { N-phenyl \ acetamide }{ { C }_{ 6 }{ H }_{ 5 }NHCO{ CH }_{ 3 } } +HCl\)
\({ C }_{ 6 }H_{ 5 }{ NH }_{ 2 }+\underset { Acetic \ anhydride }{ { CH }_{ 3 }COOCO{ CH }_{ 3 } } \rightarrow \underset { Acetanilide }{ { C }_{ 6 }{ H }_{ 5 }NHCO{ CH }_{ 3 } } +{ CH }_{ 3 }COOH\)
(iv) Formation of Schiff's base: Primary amines condense with aromatic aldehydes forming Schiff's base
\({ C }_{ 6 }H_{ 5 }CHO+{ H }_{ 2 }{ NCH }_{ 3 }\rightarrow \underset { Schiff's \ base\\ (benzal-N-methyl \ amine) }{ { C }_{ 6 }{ H }_{ 5 }CH=NC{ H }_{ 3 } } \)
(v) Reaction with nitrous acid: A cold solution of sodium nitrite reacts with aniline dissolved in hydrochloric acid, a clear solution is obtained. This solution contains 'benzene diazonium chloride'. This reaction is known as 'diazotisation'.
\({ C }_{ 6 }{ H }_{ 5 }N\boxed { { H }_{ 2 }+O } =N-OH\underrightarrow { HCl } \underset { Bensene\quad diazonium\quad chloride }{ { C }_{ 6 }{ H }_{ 5 }-N=N-Cl } \)

(i) Primary amine react with nitrous acid to form alcohols and nitrogen gas
\(\underset { primary \ amine }{ { CH }_{ 3 }NH_{ 2 } } \rightarrow \underset { unstable }{ { [{ CH } }_{ 3 }-N=N-OH] } \rightarrow { CH }_{ 3 }OH+{ N }_{ 2 }\)
Aliphatic diazonium compound is unstable because of absence of resonance stabilisation.
(ii) Secondary amines react with nitrous acid to form N-nitroso amines which are water insoluble yellow oils.
\(\underset { Secondary \ amine }{ { { (CH }_{ 3 } })_{ 2 }NH } +HO-N=O\rightarrow \underset { N-nitroso \ dimethy \ amine-yellow \ oil\\ (insolube \ in \ water) }{ { (CH }_{ 3 })_{ 2 }N-N=O } \)
(iii) Tertiary amine react with nitrous acid to form trialkyl ammonium nitrite salts which are soluble in water
\(\underset { Tertiary \ amine }{ { (CH }_{ 3 })_{ 2 }N } +HONO\rightarrow \underset { trimethyl \ ammonium \ nitrite\\ (salt \ soluble \ in \ water) }{ { { (CH }_{ 3 }) }_{ 3 }{ NH }^{ + }{ NO }_{ 2 }^{ - } } \)

i) Nitrobenzene ⇾ Nitrosobenzene
When nitrobenzene is treated with glucose and NaOH (alkaline medium) Nitrosobenzene is formed.
\({ C }_{ 6 }{ H }_{ 5 }N{ O }_{ 2 }\rightarrow \underset { Nitrosobenzene }{ { C }_{ 6 }{ H }_{ 5 }NO+{ H }_{ 2 }O } \)
ii) Nitrobenzene ⇾ Azoxybenzene
When nitrobenzene is subjected to reduction with glucose and NaOH forms the intermediate products nitrosobenzene and phenyl hydroxyl amine. These undergo bimolecular condensation reaction to give azoxy benzene.
\({ C }_{ 6 }{ H }_{ 5 }N{ O }_{ 2 }\underrightarrow { Glucose+NaOH } \underset { Nitrosobenzene }{ { C }_{ 6 }{ H }_{ 5 }NO+{ H }_{ 2 }O } \xrightarrow [ { H }_{ 2 }O ]{ \triangle } \underset { Azoxy\quad benzene }{ { C }_{ 6 }{ H }_{ 5 }-N=N{ C }_{ 6 }{ H }_{ 5 } } \)
iii) Nitrobenzene ⇾ Hydrazobenzene
When nitrobenzene is subjected to alkaline reduction in the presence of Zn+NaOH, hydrozo benzene is formed.
\({ C }_{ 6 }{ H }_{ 5 }N{ O }_{ 2 }\underrightarrow { Zn/NaOH } \underset { Nitrosobenzene }{ { C }_{ 6 }{ H }_{ 5 }NH+{ NHC }_{ 6 }{ H }_{ 5 }} \)

(i) Nitroethane exhibits tautomerism of nitro form and aci form. Aciform of nitroethane contains (α - Hydrogen) replaceable hydrogen atom. Hence it dissolves in sodium hydroxide solution forming salt like compounds.

(ii) CH₃CH₂NO₂ has two a-hydrogen and that reacts with HNO₂
(iii) 2-methyl - 2 - nitro propane neither soluble in alkali nor reacts with nitrous acid. Because it contains a tertiary nitro group where aciform is not possible and . it does not contain α - H atoms. So it has neither of the properties.

(i) CH₃CN (Methyl cyanide) on reduction gives CH₃CH₂NH₂ (ethylamine) because addition of hydrogen takes place at ≡ CN
\({ CH }_{ 2 }-C\equiv N\xrightarrow [ 4H ]{ { LiAH }_{ 4 } } { \underset { Ethylamine\\ (Primary\quad amine) }{ { CH }_{ 3 }-{ CH }_{ 2 }{ NH }_{ 2 } } }\)
Whereas CH₃NC (Methyl isocyanide) on reduction with LiAlH₄ gives secondary amine
\({ CH }_{ 3 }-\underset { \overset { | }{ H } }{ N } -{ CH }_{ 3 }\)

In methyl cyanide, -CN group is attached to alkyl group and by reduction it gives a primary amine wherease in methyl isocyanide -NC group is attached to alkyl group and by reduction it gives a secondary amine.
(ii) (CH₃)₂ NH (Secondary amine) requires 2 moles of CH₃I to give a quaternary salt (crystalline product) whereas (CH₃)₂N (tertiary amine) require only one mole of CH₃I to give the same quaternary salt. It is due to the number of alkyl groups present in amines.
\(\underset { Secondary \ anmine }{ { ( }{ CH }_{ 3 })_{ 2 }-NH+{ 2CH }_{ 3 }I } \rightarrow { { [(CH }_{ 3 })_{ 4 }N] }^{ + }\underset { Tetramethy\\ ammonium \ iodide }{ { I }^{ - } } \)
(iii) Nitration of aniline with cone. HNO₃ results in the formation of m-nitro aniline because nitric acid is a strong acid. It protonates aniline forming anilinium ion C₆H₅NH3+ because of positive charge on nitrogen, it is meta directive and -NO₂ group is substituted at meta position.

(iv) p-Toluidine contains a methyl group which has +I effect (electron withdrawing group and due to this, p-toluidine is a stronger base than p-nitro aniline in which the nitro group is less reactive and it deactivate the benzene rin make it a less basic

(i) When ethylamines is treated with chloroform and an alkali, carbylamine reaction takes place and a foul smelling substance called carbylamlne (or) alkyl isocyanide is formed.
C₂H₅NH₂ + CHCl₃ + 3NaOH ➝ \(\underset { Ethyl \ isocyanide }{ { C }_{ 2 }{ H }_{ 5 }NC+3NaCl+3{ H }_{ 2 }O } \)
(ii) When ethylamine is warmed with CS₂ and mercuric chloride, alkyl isothiocyanate having a pungent mustard like odour is obtained. This reaction is called mustard oil reaction.
C₂H₂NH₂ + S = C-S \(\underrightarrow { Hg{ Cl }_{ 2 } } \) C₂H₅ - N = C = S + H₂S
(iii) When ethylamine condense with aromatic aldehyde (benzaldehyde) Schiff's base is formed.
C₆H₅CHO + H₂NC₂H₅ ➝ \(\underset { Schiffi's \ base \ Benzal-ethylamine }{ { C }_{ 6 }{ H }_{ 5 }CH=N{ C }_{ 2 }{ H }_{ 5 }+{ H }_{ 2 }O } \)

i) (CH₃)₂ NH is stronger base than NH₃:
(a) (CH₃)₂NH (Secondary amine) is a stronger base than NH₃ (ammonia).
(b) In dimethylamine, the methyl group with +1 effects tends to Increase the electron density on the nitrogen atom.
(c) As a result, the electron releasing tendency or basic strength of amine increases.
ii) CH₃CH₂NH₂ is more basic than CH₃CONH₂:
(a) Resonance and inductive effect possible in acetamide involving the non bonding pair of electrons on the nitrogen atom.
(b) Another important factor is that amides containing a powerful electron is not readily available for donation and it is less basic.
(c) Thus ethylamine is more basic than acetamide.
iii) Aniline is less basic than Ethyl amine:
(a) The lone pair of electrons on the nitrogen atom of aniline is involved in resonance and is not easily available for donation to protons.
(b) The positive charge on nitrogen makes protonation difficult. Thus aniline is less basic than ethylamine.
vi) When aniline is heated with fuming sulphuric acid, p-amino benzene sulphonic acid is formed.

Aniline does not give o-amino benzene sulphonic acid because it is sterically less favoured.

Classification of nitro compounds

(i) Strongly Acidic Medium: When reduced with tin and hydrochloric acid, aromatic nitro compounds are converted to aryl amines.
\({ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }+6[H]\xrightarrow [ or \ Fe/con.HCl ]{ Sn/con.HCl } \underset { Aniline }{ { C }_{ 6 }{ H }_{ 5 }{ NH }_{ 2 }+2 } { H }_{ 2 }Oor\)
(ii) Neutral Medium: When reduced with a neutral, reducing agents like zinc dust and aqueous ammonium chloride, aromatic nitro compounds form aryl hydroxylamines.
\({ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }+4[H]\xrightarrow [ ]{ Zn/{ NH }_{ 4 }Cl } \underset { Phenyl\quad hydroxylamine }{ { C }_{ 6 }{ H }_{ 5 }{ NH }OH+ } { H }_{ 2 }O\)
(iii) Alkaline Medium: In alkaline medium, Nitro benzene on reduction forms the intermediate products nitro so benzene (C₆H₅NO) and phenyl hydroxylamine (C₆H₅NHOH). These undergo bimolecular condensation reaction. According to the appropriate reducing agent in alkaline medium different products are obtained.

(iv) Catalytic Reduction: Lithium Aluminium hydride is a powerful hydride ion donor. So it reduces nitro benzene to Aniline. This reduction can also be carried out by H/Ni.
\({ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }\underrightarrow { LiAl{ H }_{ 4 } } { C }_{ 6 }{ H }_{ 5 }{ NH }_{ 2 }[Aniline]\)
\({ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }\frac { { N }_{ 2 }/Ni }{ Catalytic \ hydrognation } { C }_{ 6 }{ H }_{ 5 }{ NH }_{ 2 }\)
(v) Electrolytic Reduction: When nitro benzene is reduced electrolytically in presence of concentrated sulphuric acid, phenyl hydroxylamine is first produced which rearranges to give p-amino phenol.