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Haloalkanes and Haloarenes

Multiple Choice Questions

791.

Boiling water reacts with C₆H₅N $_{2}^{+}$ Cl^- to give

aniline
benzylamine
phenol
benzaldehyde

792.

When AgCl is treated with KCN

Ag is precipitated
a complex ion is formed
double decomposition takes place
no reaction takes place

793.
Which one of the following compounds is most reactive towards nucleophilic addition?

CH₃CHO

PhCOCH₃

PhCOPh

CH₃COCH₃

CH₃CHO

Carbonyl compounds undergoes nucleophilic addition reaction.

[X- shows negative inductive effect]

If group or atom attached with carbonyl carbon shows negative inductive effect, then it decreases electron density on carbonyl carbon and facilitate the attack of nucleophiles, hence reactivity of carbonyl compound increases.

[Y- shows negative inductive effect]

If group or atom attached with carbonyl carbon shows positive inductive effect, then it increases electron density on carbonyl carbon and supress the attack of nucleophiles, hence, reactivity of carbonyl compound decreases.

The aromatic aldehydes and ketones are less reactive than their aliphatic analogues. This is due to the +R effect of benzene ring.

On the basis of above informations, the increasing order of the nucleophilic addition reaction in the following compound will be CH3CHO > CH3COCH3 > PhCOCH3 > PhCOPh