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प्रश्न
What is meant by the following term? Give an example of the reaction in the following case.
Cyanohydrin
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उत्तर
Aldehydes and ketones react with hydrogen cyanide (HCN) to yield cyanohydrins. This reaction occurs very slowly with pure HCN. Therefore, it is catalysed by a base and the generated cyanide ion (CN−) being a stronger nucleophile readily adds to carbonyl compounds to yield corresponding cyanohydrin.
\[\ce{HCN + O\overset{-}{H} <=> {_{\bullet}^{\bullet}}\overset{-}{C}N + H2O}\]
APPEARS IN
संबंधित प्रश्न
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Predict the product of the following reaction:
\[\begin{array}{cc}
\phantom{..............}\ce{O}\\
\phantom{..............}||\\
\ce{R - CH = CH - CHO + NH2 - C - NH - NH2 ->[H+]}\end{array}\]
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| The carbon-oxygen double bond is polarised in aldehydes and ketones due to higher electronegativity of oxygen relative to carbon. Therefore, they undergo nucleophilic addition reactions with a number of nucleophiles such as HCN, NaHSO3, alcohols, ammonia derivatives and Grignard reagents. Aldehydes are easily oxidised by mild oxidising agents as compared to ketones. The carbonyl group of carboxylic acid does not give reactions of aldehydes and ketones. Carboxylic acids are considerably more acidic than alcohols and most of simple phenols. |
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(c) (i) Arrange the following compounds in increasing order of their reactivity towards CH3MgBr: (1)
CH3CHO, \[\begin{array}{cc}
\ce{(CH3)3C-C-CH3}\\
\phantom{....}||\\
\phantom{....}\ce{O}
\end{array}\], \[\begin{array}{cc}
\ce{CH3-C-CH3}\\
||\\
\ce{O}
\end{array}\]
(ii) Write a chemical test to distinguish between propanal and propanone. (1)
OR
(c) Write the main product in the following: (2)
| (i) |  |
| (ii) |  |
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