January 26, 2015


1. How is benzoic acid prepared from
(i) Toluene / Methyl benzene (ii) Phenyl cyanide (iii) Carbon dioxide?
a) By oxidation: Toluene / Methyl benzene is oxidised by acidified KMnO4 or Potassium dichromate or alkaline KMnO4 gives Benzoic acid.
                 H+ / KMnO4
C6H5CH3                 C6H5COOH
b) Hydrolysis: Phenyl cyanide is hydrolysed with aqueous acid to give Benzoic acid.
                 H+                        H+
                H2O  Benzamide  H2O
c) From Grignard reagent: Carbonation of C6H5MgBr followed by hydrolysis gives Benzoic acid.
Or CO2 reacts with C6H5MgBr followed by hydrolysis gives Benzoic acid.

2. Explain the reduction of Nitrobenzene in alkaline medium.
In alkaline medium, Nitro benzene on reduction forms the intermediate products nitrosobenzene (C6H5NO) and phenyl hydroxylamine (C6H5NHOH). These undergo bimolecular condensation reaction. According to the appropriate reducing agent in alkaline medium different products are obtained.
3. An organic compound (A) of molecular formula C2H6O liberates hydrogen with metallic sodium. Compound (A) on heating with conc.H2SO4 at 440 K gives an alkene (B). Compound (B) when oxidised by Bayer's reagent gives compound (C) of molecular formula C2H6O2. Identify (A), (B) and (C) and explain the reactions.
Ethyl alcohol
Ethylene glycol
4. The metal (A) is extracted from its sulphide ore. On treatment with dil. nitric acid metal A gives a compound (B), which is also known as Lunar Caustics. (C) on heating at 723 K gives compound (C) and O2 Identify A, B and C and explain the reactions.
Silver nitrate (Lunar caustics)
Silver Nitrite
5. Write a note on  i) HVZ - reaction ii) Decarboxylation iii) Kolbe's electrolytic reaction
i) HVZ – reaction (Hell-Volhard Zelinsky reaction):
Halogenation of Carboxylic acid with Halogen and Phosphorous trihalide.
Or Conversion of Carboxylic acid to α - bromo acid with Br2 / PBr3
                     Br2/PBr3                                                               H2O
ii) Decarboxylation:
 When anhydrous sodium salts of carboxylic acids are heated with soda lime, carboxyl group is removed with the formation of hydrocarbon containing one carbon atom less.
                         NaOH / CaO
RCOONa                     RH + Na2CO3
                        NaOH / CaO
CH3COONa                      CH4 + Na2CO3
iii) Kolbe's electrolytic reaction:
Electrolysis of concentrated aqueous solution of Sodium salt of acids gives Hydrocarbon.
CH3 – COO – Na           CH3 
          +                                |      + 2CO2   +  2Na
CH3 – COO – Na               CH3                    Sodium
6. Starting from benzene diazonium chloride how will you obtain the following i) Phenol, ii) Anisole, iii) p-hydroxy azobenzene?
i) When the aqueous solution of C6H5 N2 Cl is boiled, Phenol is obtained.
C6H5 N2 Cl → C6H5OH + N2 + HCl
    HO ––– H
ii) When C6H5 N2 Cl is warmed with alcohol, Anisole is formed.
C6H5 N2 Cl → C6H5O CH3 + N2 + HCl
CH3O ––– H
iii) Phenol couples with Benzene diazonium chloride in alkaline medium to form p-hydroxy azobenzene.

7. An organic compound (A) of molecular formula C6H6O gives violet colour with neutral FeCl3. (A) reacting with CCl4 and NaOH gives two isomers (B) and (C). (A) oxidation with CrO2Cl2 gives (D) of molecular formula C6H4O2. Identify (A), (B), (C) and (D). Explain the reactions.
o-Hydroxy benzoic acid /
Salicylic acid
p-Hydroxy benzoic acid
p – Benzoquinone
8. An organic compound (A) of molecular formula C7H6O, is called as oil of  bitter almonds. (A) oxidation gives (B) of molecular formula C7H6O2 which gives brisk effervescence with NaHCO3 solution. When (A) is refluxed with aqueous alcoholic KCN compound (C) is formed. . Identify (A), (B), (C) and (D). Explain the reactions.
Benzoic acid
Benzoin (Dimer of benzaldehyde)
9. An organic compound (A) of molecular formula C3H8O3 is obtained as by-product in the manufacture of soap. Compound (A) on heating with P2O5 gives an unsaturated compound (B) of molecular formula C3H4O. Compound (A) with well cooled mixture of conc. H2SO4 and fuming HNO3 form compound (C) which is yellow in colour. Identify A, B, C and D. Explain the reaction.
Nitroglycerine or Glyceryl trinitrate
10. Compound ‘A’ is a powerful oxidizing agent and also it is a red orange crystal which melts at 396oC. ‘A’ reacts with chloride salt and Conc.H2SO4 to give ‘B’ which is reddish orange in colour. ‘A’ also reacts with KOH to give ‘C’ which is yellow in colour. Find out (A), (B) and (C). Explain the reactions.
Potassium dichromate
Potassium chromate
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