Question

36. Write chemical equations to illustrate the following name bearing reactions
A. (i) Cannizaro's reaction (ii) Aldol condensation
B. Give chemical tests to distinguish between the following pairs of compounds
Propanal and propone (ii) Actophenone and Benzophenone (iii)Phenol and Benzoic acid​

Answer 1

Answer:

a.(i) Cannizzaro's reaction : aldehyde which do not have an a- hydrogen atom undergoes self oxidation and reduction on treatment with concentrated alkali.

(ii) Hell - volhard - zelinsky reaction : carboxylic acid having an a- hydrogen are halogenated at the a- position on treatment with chlorine or bromine in the presence of small amount of red phosphorus to give a- halocarboxylic acids.

b.(I) proponal and propanone fehling's test

$ch_{3} ch_{3} cho + 2 {cu}^{2 + } + 5 {oh}^{ - } - > ch_{3} ch_{3} {coo}^{ - } + \: cu_{2}o + 3 h_{2}o$

propanone being a ketone will not give this test

(ii) Acetophenone and benzophenone

lodoform test

$c_{6} h_{5}co ch_{3} \: - > \: c_{6} h_{5}coona + chi_{3}$

yellow ppt.

benzophenone does not give this test

(iii) phenol and benzoic and Fecl3 test

$c_{6} h_{5}oh + fec l_{3} - > c_{6} h_{5} {o}^{ - } {6} \: {fe}^{3 - } + 3hcl \\ blue \: violet \:colour$

benzoic acid doesn't give this test