diazonium salts, sandmeyer

further chem

generate using only aromatic amines

C1=CC=CC=C1N#N

from

C1=CC=CC=C1N

with

is highly electron withdrawing
resonance stabilises positive charge on group by spreading around the ring

reaction mechanism: formation of diazonium ions

attack is on nitrogen of nitrosonium ion since it is less electronegative (more positive thus electrophilic) even though formal charge is displayed on oxygen

reaction mechanism: formation of nitrosonium ion:

strong acid required

is a good leaving group favourable thermodynamically (high entropy, very stable)

• aryl diazonium salts stable because aryl cations are slow to form (highly unstable)