The document describes several chemical tests used to distinguish between different organic compounds: 1. Lucas test distinguishes primary, secondary, and tertiary alcohols based on the speed at which turbidity appears when treated with Lucas reagent. 2. Iodoform test produces pale yellow iodoform when sodium hydroxide and iodine are added to compounds containing a CH3-CO or CH3-CH(OH) group, such as alcohols and methyl ketones. 3. Tollens' test, Fehling's test, and the azo dye test identify aldehydes and aromatic primary amines based on the products formed in reactions using specific reagents.

1. Class XII Chemistry Distinguish between organic pairs
Lucas test
 Used to distinguish primary, secondary and tertiary alcohols.
 Lucas reagent – equimolar mixture of conc. HCl and anhydrous ZnCl2
 Alcohol is treated with Lucas reagent, turbidity due to the formation of insoluble alkyl chloride is observed.
 If the turbidity appears immediately, the alcohol is tertiary.
 If the turbidity appears in about five minutes, the alcohol is secondary.
 A primary alcohol does not react with Lucas reagent at room temperature and hence no turbidity is formed.
Iodoform test
• Iodoform test is a test for the CH3-CO group and is characteristic for alcohols and methyl ketones
• Reagents- compounds containing CH3-CO or CH3-CH(OH) group, sodium hydroxide and iodine
• Product formed- iodoform,(CHI3) which is a pale yellow in colour
Tollens’ test
• Given by aldehydes and formic acid.
• Tollen’s reagent- ammoniacal silver nitrate solution
• The aldehydes are oxidised to corresponding carboxylate anion.The reaction occurs in alkaline medium.
• A bright silver mirror is produced due to the formation of silver metal.
• Also known as Silver mirror test.
Fehling’s test
• Fehling reagent comprises of two solutions,
• Fehling solution A and Fehling solution B
• Fehling solution A is aqueous copper sulphate
• Fehling solution B is alkaline sodium potassium tartarate (Rochelle salt).
• On heating an aldehyde with Fehling’s reagent, a reddish brown precipitate is obtained
Azo dye test
• It involves the reaction of any aromatic primary amine with nitrous acid followed by treatment with an
alkaline solution of 2-naphthol, when a brilliant yellow , orange or red coloured dye is obtained.
• Used to distinguish between aliphatic primary amine and aromatic primary amine.
Hinsberg’s test
• Used for distinguishing primary, secondary and tertiary amines.
• Hinsberg’s reagent- benzenesulphonyl chloride (C6H5SO2Cl)
• In this test amine is shaken with Hinsberg’s reagent in presence of excess of aqueous KOH solution.
• A primary amine gives a clear solution which on acidification gives an insoluble N-
alkylbenzenesulphonamide.10
• A secondary amine gives an insoluble N,N-dialkylbenzenesulphonamide which remains unaffected on
addition of acid.
• A tertiary amine does not react at all. Therefore, it remains insoluble in the alkaline solution but dissolves on
acidification to give a clear solution.
Differentiate
1. Phenol and benzoic acid
2. Butan-1-ol and 2-methylpropan-2ol
3. CH3CH2NH2 and(CH3)2NH
4. Ethyl amine and diethyl amine
5. Propan-1-ol and propan-2-ol
6. Methyl ethanoate and ethyl ethanoate
7. Aniline and N-ethyl aniline
8.
9. Aniline and benzylamine
10. Ethylamine and Aniline