Consider the following carbonyl compounds: HCHO, CH3CHO, Cl3C-CHO, (CF3)2C=O (hexafluoroacetone), (C6H5)2C=O, (CH3)3C-CO-C(CH3)3 and CH3-CO-CH3. Counting acetone itself as NOT more reactive than itself, how many of these compounds are more reactive than acetone towards hydration (addition of water to give a gem-diol)?

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JEE Main levelNumerical answerDifficulty 2 of 3o1086

Consider the following carbonyl compounds: $HCHO$ , $CH X_{3} CHO$ , $Cl X_{3} C - CHO$ , $(CF X_{3}) X_{2} C = O$ (hexafluoroacetone), $(C X_{6} H X_{5}) X_{2} C = O$ , $(CH X_{3}) X_{3} C - CO - C (CH X_{3}) X_{3}$ and $CH X_{3} - CO - CH X_{3}$ . Counting acetone itself as NOT more reactive than itself, how many of these compounds are more reactive than acetone towards hydration (addition of water to give a gem-diol)?

Numerical answer type, tolerance 0.5.

Answer: 4

Electron-withdrawing groups (CCl3, CF3) and absence of alkyl groups raise reactivity. More reactive than acetone:

HCHO

CH X_{3} CHO

Cl X_{3} C - CHO

and hexafluoroacetone, i.e. 4. Benzophenone (conjugation and bulk) and di-tert-butyl ketone (severe hindrance) are less reactive, and acetone is the reference.

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Answer: 4

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