The lower
members are more soluble in water because they form hydrogen bonds with water The higher members, because of large size of hydrophobic chain of carbon atoms,
are insoluble in water but soluble in common organic solvents Aldehydes are
prepared by dehydrogenation or controlled oxidation of primary alcohols and
controlled or selective reduction of acyl halides Aromatic aldehydes may also be
prepared by oxidation of (i) methylbenzene with chromyl chloride or CrO3 in the
presence of acetic anhydride, (ii) formylation of arenes with carbon monoxide and
hydrochloric acid in the presence of anhydrous aluminium chloride, and (iii) cuprous
chloride or by hydrolysis of benzal chloride