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CBSE Class 12 Chemistry 2022 Term 2 Delhi Set 3

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Question : 9 of 12
Marks: +1, -0
(a) What happens when
(i) Propanone is is treated with CH3MgBr{CH}_3 {MgBr} and then hydrolysed?
(ii) Ethanal is treated with excess ethanol and acid?
(iii) Methanal undergoes Cannizzaro reaction?
(b) Write the main product in the following reaction?
(i) 2CH3COCl+(CH3)2Cd────▸2 {CH}_3 {COCl}+ ( {CH}_3) _2 {Cd} {──── ▸}
(ii) CH3CH2CHO────────▸↖Zn(Hg)/  "ConcHCl"  {CH}_3 {CH}_2 {CHO} { {──────── ▸}}↖{ {Zn}( {Hg}) / \;\text " Conc HCl "\;}
Solution:  
(a) (i) When propanone reacts with ethyl magnesium bromide (Grignard's reagent) and hydrolysed, it forms aldehyde.
(CH3)2CO+H3CCH2MgBr   ────▸↙H2O( {CH}_3) _2 {CO}+ {H}_3 {CCH}_2 {MgBr} \;{  {──── ▸}}↙{ {H}_2 {O}} (CHCH2CH3∣3)2COH+Mg(OH)Br\underset{ \left( {CH}{\underset{\vert}{CH_2CH_3}}_3\right) _2 {COH}+ {Mg}( {OH}) {Br}}{}
(ii) When ethanal reacts with excess ethanol and acid gives acetal.
(iii) Methanal will undergo Cannizzaro reaction as it possesses α\alpha-hydrogen to form methanol.
OR
(b) (i) 2CH3COCl↙Propanone+(CH3)2Cd↙CadmiumChloride→2CH3COCH3{2 {CH}_3 {COCl}}↙{Propanone}+{ ( {CH}_3) _2 {Cd} }↙{Cadmium Chloride}\rightarrow2 {CH}_3 {COCH}_3 +CdCl2+ {CdCl}_2
(ii) CH3CH2CHO ↙Zn────▸−Hg  "Conc."  HClCH3CH2CH3↙Propane{CH}_3 {CH}_2 {CHO}   \overset{ {Zn}{──── ▸}- {Hg}} ↙{\;\text " Conc. "\; {HCl}} {{CH}_3 {CH}_2 {CH}_3 }↙{Propane}
(iii)
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