How do you account for the following ? (a) Boilling points of aldehydes lie between parent alkanes (b) Aldehydes and ketones have high dipole moments (c) NaHSO_(3) is used for the purification aldehydes and ketones (d) Iodoforms is obtained byt he reactionof acetone with hypoiodite but not with iodide (e) Hydrazones of aldehydes and ketones are not prepared in highly acidic medium

How do you account for the following ? (a) Boilling points of aldehyd

1.	How do you account for the following ? (a) Boilling points of aldehydes lie between parent alkanes (b) Aldehydes and ketones have high dipole moments (c) NaHSO_(3) is used for the purification aldehydes and ketones (d) Iodoforms is obtained byt he reactionof acetone with hypoiodite but not with iodide (e) Hydrazones of aldehydes and ketones are not prepared in highly acidic medium
Answer» Solution :Alkanes have low boiling points as no hydrogen bonding and no dipole- dipole- attractive forces are present. Alcohols have high boiling points as intermolecular hydrogen bonding is present. In aldehydes, dipole-dipole FORECES are present due to polar nature of CARBONYL group. Thus, boiling points of aldehydes lie between alkanes and alcohols. (b) The dipole moment is due to the large contribution of the polar structure (REASONANCE) to the hybrid. (c) Aldehydes and ketones form insoluble crystalline compound with`NaHSO_(3)` which can be filtered. These on distillation with saturated solution of `Na_(2)CO_(3)` agian give rthe aldehyde or ketone. (d) The reaction is initiated by the replacement of methyl protons `(H^(+))` by `I^(+)` `CH_(3)COCH_(3)+3IO^(-)rarrCOCH_(3)+3OH^(-)` (e) In highly acidic medium, the protonationof hydrazine decreases its nucleophilic character.