They can undergo subtitution reactions easily to form halogenated products. Submitted by pharm ajar
The reason is that the aryl group is able to stabalize the diazonium salt through resonance, while the alkyl group may not be resonance stabalized.
the intermediate positively charged nitrogen is being supplied by large electron clouds coming from both sides, i.e., the intermediary triple bonds with the other N that is attached to a conjugate...
Diazonium salts are unstable compounds, aromatic diazonium compound on hydrolysis give phenol and Nitrogen gas.C6H5-N2+Cl- + NaOH(Aq.) = C6H5-OH + N2 + NaCl
Not sure either, but i would guess that it is to protonate the oxygens so that they can leave?