Synthesis of 4 useful precursors such as Allylbenzene, Propenylbenzene, 1-Phenyl-2-propanol and 1-Phenyl-2-chloropropane can be synthesized from 3-Phenylpropylamine.
The 3-Phenylpropylamine can be synthesized by reductive amination of 3-Phenylpropanal.
3-Phenylpropanal is made from cinnamaldehyde (3-Phenyl-2-propenal).
3-Phenyl-2-propenal==>>3-Phenylpropanal==>>3-Phenylpropylamine
PhCH=CH-CHO=========>>PhCH2CH2-CHO =====>>PhCH2CH2-CNH2
The 3-Phenylpropylamine is a primary amine. Primary amines form highly unstable diazonium salts on reaction with nitrous acid (HONO). The diazonium salt quickly loses nitrogen gas, and a n-propanyl carbocation ion is formed.
This n-propanyl carbocation ion is highly unstable itself and quickly undergoes rearrangement to a more stable carbocation; the sec-propanyl carbocation ion results.
The carbocations can either eliminate a proton, thereby producing an alkene, Allylbenzene and Propenylbenzene, or it can combine with a nucleophile for neutralization producing 1-Phenyl-2-propanol and 1-Phenyl-2-chloropropane.