Amines - Nitrogen Compounds Flashcards
What is an acid?
Releases H+
What is base?
A compound that neutralises an acid, by accepting H+, to form a salt
What is a salt?
Product of a reaction in which H+ from the acid is replaced by a metal or ammonium ion
What does a compound have to have to be a base?
Has to have a lone pair or negative charge
What are examples of bases?
Metal oxide
Metal carbonate
Metal hydroxide
Ammonia - accepts H+ to form NH4+
Can amines behave as bases?
YES
Why can ammonia behave as a base?
Lone pair on the N
So can accept H+ to form NH4+
What do you form when you add H+ to ethylamine?
Ethylammonium ion
What product is formed from CH3CH2NH2 + HCl?
CH3CH2NH3+Cl-
Ethylammonium chloride
What product is formed from CH3CH2CH2NH2 + H2SO4?
(CH3CH2CH2NH3)2SO4
Dipropylammonium sulphate
What product is formed from CH3CH2CH2NH2 + H3PO4?
(CH3CH2CH2NH3)3PO4
Tripropylammonium phosphate
What does the strength of a base depend on?
How available the nitrogen’s lone pairs are
What does it mean if a lone pair is more available?
Electron density = higher = stronger the base
Order ammonia, amine and phenylamine from weakest to strongest base
Phenylamine
Ammonia
Amine
Why is phenylamine the weakest base?
Benzene ring pulls electrons towards delocalised ring
Electron density increases at ring
So L.P less available
Why is ammonia the middle base?
Doesn’t have an aromatic ring to pull L.P away
Doesn’t have an alkyl group to pull L.P towards
Why is amine the strongest base?
Alky group pushes electrons towards N
Electron density increases at N
So L.P more available
What is the first step of forming a primary aliphatic amine?
Haloalkane + NH3 —-> ammonium salt
What is formed when 1-chloroethane + NH3?
CH3CH2NH3Cl
Ethylammonium chloride
What is the second step of forming a primary aliphatic amine?
Ammonium salt + aqueous alkali —-> primary amine + NaCl + H2O
What is formed when Ethylammonium chloride + NaOH?
CH3CH2NH2 + NaCl + H2O
Ethylamine
What are the conditions needed for forming a primary aliphatic amine?
Excess NH3
Ethanol as a solvent
Why do you need excess NH3 when forming a primary aliphatic amine?
Don’t want further substitution
Why do you need ethanol when forming a primary aliphatic amine?
To prevent substitution of haloalkane by water to make an alcohol
How is ethanol used when forming a primary aliphatic amine?
NH3 dissolved in ethanol
Ethanolic ammonia
What is the first step of forming a secondary aliphatic amine?
Primary amine + haloalkane —-> ammonium salt
What is formed when ethylamine + 1-chloroethane?
(CH3CH2)2NH2+Cl-
Diethylammonium chloride
What is the second step of forming a secondary aliphatic amine?
Ammonium salt + NaOH —-> secondary amine + NaCl + H2O
What is formed when diethylammonium chloride + NaOH?
(CH3CH2)2NH + NaCl + H2O
N,N diethylamine
What is the first step of forming a tertiary aliphatic amine?
Secondary amine + haloalkane —-> ammonium salt
What is formed when N,N diethylamine +
1-chloroethane?
(CH3CH2)3NH+Cl-
Triethylammonium chloride
What is the second step of forming a tertiary aliphatic amine?
Ammonium salt + NaOH —-> tertiary amine + NaCl + H2O
What is formed when triethylammonium chloride + NaOH?
(CH3CH2)3N + NaCl + H2O
Triethylamine
What is the first step of forming aromatic amines?
Nitrobenzene + 7[H] —-> Phenylammonium chloride
+ 2H2O
What is the second step when forming aromatic amines?
Phenylammonium chloride + NaOH —-> Phenylamine + H2O
What conditions are needed for the first step of forming an aromatic amine?
Conc HCl
Sn
REFLUX
What conditions are needed for the second step of forming an aromatic amine?
NaOH in excess
What is the overall equation for forming an aromatic amine?
Nitrobenzene + 6[H] —-> Phenylamine + 2H2O
