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Karnataka Board PUCPUC Science 2nd PUC Class 12

What is meant by the following term? Give an example of the reaction in the following case. 2, 4-DNP-derivative

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Question

What is meant by the following term? Give an example of the reaction in the following case.

2, 4-DNP-derivative

Chemical Equations/Structures
One Line Answer
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Solution

When an aldehyde or ketone reacts with 2, 4-dinitrophenylhydrazine in a weak acidic medium, 2, 4-dinitrophenylhydrazone (2, 4-DNP derivative) is produced.

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Chapter 8: Aldehydes, Ketones and Carboxylic Acids - Exercises [Page 255]

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NCERT Chemistry Part 1 and 2 [English] Class 12
Chapter 8 Aldehydes, Ketones and Carboxylic Acids
Exercises | Q 8.1 (ix) | Page 255

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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, \[\begin{array}{cc}
\ce{(CH3)3C-C-CH3}\\
\phantom{....}||\\
\phantom{....}\ce{O}
\end{array}\],  \[\begin{array}{cc}
\ce{CH3-C-CH3}\\
||\\
\ce{O}
\end{array}\]

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