amines Flashcards
what are amines
compounds based on ammonia where one or more of the hydrogen atoms have been replaced by alkyl or aryl groups
what can amines be classified as
primary secondary or tertiary
Preparation of aromatic amines from nitrobenzenes: reagents and conditions
Conc hcl and tin catalyst
Preparation of aromatic amines from nitrobenzenes: equation
Benzene-NO2 + 6[H] > benzene-NH2 + 2H2O
Preparation of aromatic amines from nitrobenzenes: reaction type
Reduction
Preparation of aromatic amines from nitrobenzenes: uses of aromatic amines
Dyes and drugs
General formula aliphatic amines
CnH2n+3N
Preparation of primary aliphatic amines from halogenoalkanes: reagents and conditions
Excess ammonia in ethanol and warm
Preparation of primary aliphatic amines from halogenoalkanes: general equation
RBr + 2NH3 > RNH2 + NH4+Br-
Preparation of primary aliphatic amines from halogenoalkanes: mechanism
Nucleophilic substitution
Preparation of primary aliphatic amines from halogenoalkanes: why must excess ammonia be used
To prevent further substitution
Preparation of primary aliphatic amines from nitriles: reagents and conditions
H2 Ni catalyst
Preparation of primary aliphatic amines from nitriles: general equation
R-C(triple bond)N + 2H2 > RCH2NH2
Base
Substance that accepts H+ ions
Why are ammonia and amines weak bases
Lone pair of electrons on the nitrogen atom, which can accept a proton from an acid
What do amines dissolve in acids to give
The corresponding alkyl-ammonium salt
How can the amine be reformed from an alkylammonium salt
By adding an alkali
What is the ability of a substance to act as a base termed
Basicity
What is the order of basicity of amines
Primary amines>NH3>benzene NH2
Comparing primary aliphatic amines and ammonia: what does the alkyl group in primary amines release and why
Electron density towards the nitrogen atom due to positive inductive effect
Comparing primary aliphatic amines and ammonia: what does release of electron density towards nitrogen atom increase
Electron density on the nitrogen atom and the lone pair is more available to accept H+
Comparing primary aliphatic amines and ammonia: are aliphatic amines stronger bases than ammonia
Yes
Comparing primary aromatic amines and ammonia: where is the lone pair of electrons on the nitrogen atom of aromatic amines
Delocalised into the pi ring
Comparing primary aromatic amines and ammonia: what effect does the delocalisation of the lone pair have on the electron density of the nitrogen atom
Decreases it- lone pair less available to accept H+
