4.6 Amines Flashcards
Group attached to amines
NH2
Primary amine
N bonded to 1 C
Secondary amine
N bonded to 2 C
Tertiary amine
N bonded to 3 C
How to obtain an amine from halogenoalkane?
Heat halogenoalkane with excess of ammonia dissolved in ethanol inside a sealed tube
• nucleophillic substitution
• amine salt is usually produced so need to heat with aq sodium hydroxide will release amine
Why excess ammonia used to convert halogenoalkane to amine
To promote the formation of a primary amine
Why must halogenoalkane to amine be done in a sealed tube
As the ammonia is lost if heated
Nitrile to amine
Reducing agent LiAlH4 dissolved in ethoxyethane
Reduction
Nitrobenzene to phenylamine
Reduction
Reducing agent - tin metal and concentrated hydrochloric acid
Heat under reflux in boiling water bath - phenyl-ammonium ions produced
After cooling - add aq NaOH yo decompose salt to phenylamine
Why are amines basic
N atom has a lone pair of electrons can act as a base by forming a co-ordinate bond with a H+
Why is phenyl amine less basic than ammonia
Lone pair of electrons on N becomes part delocalised pi-electron system of the benzene ring which makes the N relatively less negative
Ethanoylation of primary amines
React with ethanoyl chloride
Nucleophilic substitution
How to make nitric (III) acid in situ
React Sodium nitrate (III) with HCl (dilute)
Primary amine and nitric (III) acid at room temperature
Produce alcohol, water and nitrogen gas
Primary amines with cold nitric (III) acid
Form benzenediazonium salt
