question_answer

    (a) Write chemical equations to illustrate the following name bearing reactions. (i) Cannizzaro reaction                                   (ii) Hell-Volhard-Zelinsky reaction (b) Give chemical tests to distinguish between the following pairs of the compounds. (i) Propanal and propanone                        (ii) Acetophenone and benzophenone (iii) Phenol and benzoic acid                                                                                                                                                 [2+3] Or (a) How will you bring about the following conversions? (i) Ethanol to 3-hydroxy butanal                (ii) Benzaldehyde to benzophenone (b) An organic compound 'A' has the molecular formula It get hydrolyzed with dilute sulphuric acid and gives a carboxylic acid 'B' and an alcohol 'C' oxidation of 'C' with chromic acid also produced 'B'. 'C' on dehydration reaction gives but-1-ene. Write equations for the reactions involved.                                    [2 + 3]

Answer:

(a) Cannizzaro reaction Aldehydes without when treated with concentrated alkali solutions there is disproportionate of aldehyde forming alcohol (by reduction) and acid salt (by oxidation). This reaction is called Cannizzaro reaction. [1] (ii)Hell-Volhard Zelinsky reaction (HVZ) (b)(i)

Propanal	Propanone
Iodoform test ?ve	+ve Yellow ppt

[1] (ii)

(ii) Acetophenone	Benzophenone
Iodoform test +ve	-ve

[1] (iii)

Phenol	Benzoic acid
Neutral solution colour gives violet solution no reaction	Gives buff-coloured ppt. Gives brisk effervescence due to

Or (a)    (i)Ethanol to 3-hydroxy butanal [1] (ii) Benzaldehyde to benzophenone [1] (b) Thus, (C) is Thus, Ais        [1] B is                                 [1] C is