4.6 Amines Flashcards
what are the 2 methods to prepare amines?
From halogenoalkanes or from a nitrile
What is a Primary amine?
An NH2 group bonded to only 1 carbon
How are amines prepared from halogenoalkanes?
nucleophilic substitution of halogen group with NH2
What is the overall reaction to form amines from halogenoalkanes?
R-Cl + NH3 —> R-NH2 + HCl
What are the conditions to from primary amines from halogenoalkanes?
excess ammonia
Why is excess ammonia needed to form primary amines?
To prevent further substitution of halogenoalkanes/ uses up the halogenoalkanes before further substitution can occur
What is the naming rule for amines?
<C5 -amine
>C5 Amino-
What are the conditions for preparation of amines from nitriles?
LiAlH4 in dry ether
What is the reaction type when preparing amines from nitriles?
Reduction
Overall reaction to prepare amines from nitriles
R-C=_N —> R-C-NH2
Steps to prepare an aromatic amine
- Nitration of benzene
- reduction of side chain
2a. acidic salt forms
2b. basic amine forms
What is the catalyst in the nitration of benzene?
H2SO4
What is the overall reaction for the nitration of benzene?
Benzene + HNO3 —> Benzene-NO2 + H2O
What are the catalysts for the reduction of nitrobenzene?
Sn (Tin) and HCl followed by NaOH
What is formed when ethanoyl chloride reacts with an amine?
Amide
What are the characteristics of a nitrile?
An unstable weak acid
Formation of nitic (III) acid
NaNO2 + HCl —-> HNO2 + NaCl
What can be used to test for aliphatic amines?
Cold nitric acid, bubbles of nitrogen gas will appear
What can be used to test for aromatic amines?
Nitric acid above 10*C will give bubbles
What are the catalysts and reagents to form a diazonium ion?
HNO2 (less than 10*C)
HCl (acid)
What are the catalysts and reagents used to form an azodye? And what colour is it?
Phenol
NaOH (less than 10*C)
Orange
What is the name given to the part of a molecule that gives colour? And what is that part?
Chlorofore
N_=N
diazonium ion + Napthalene-2-ol —>
red precipitate
