11O- Amines Flashcards
How to know if an amine is 1° 2° or 3°
1°- 1 alkyl group attached to N
2°- 2 alkyl groups attached to N
3°- 3 alkyl groups attached to N
How to name primary amines
R-NH2 general formula
Alkyl group, amine
eg propyl amine CH3CH2CH2NH2
How to name secondary amines
(R)(R)NH general formula R groups must be same
eg dimethylamine (CH3)2NH2
How to name tertiary amines
RRRN general formula R groups must be same
(C2H5)3N triethylamine
How to name animes with different sub groups
Write sub groups in alphabetical order and use priority list
CH3C2H5NH N-ethylmethylamine
NH2CH2COOH 2-aminoethanoic acid
What are two ways of producing primary aliphatic amines
Nucleophilic substitution of haloalkane with ammonia
Reduction of nitriles
1. Nucleophilic substitution of haloalkanes with CN-, forms a nitrile
2. Reduction of nitrile to primary amine by [H] or Ni catalyst
How can a primary amine to be formed from nucleophilic substitution
Use excess ammonia to prevent further substitution
How can a secondary, tertiary or quaternary ammonium salt be formed from nucleophillic substitution
Ammonia is in limit so once primary amine is formed it reacts with haloalkane forming secondary amine etc
- R-Cl + NH3 —> R-NH2 + Cl- + H+
- R-NH2 + R-Cl —> (R)2NH2 + Cl-
*Easiest to know what’s happening drawn out
Disads of preparing amines through nucleophilic substitution with NH3
Disad
Inefficient, mixture of 1°/2°/3°
Mixture needs to be separated by fractional distillation
How can primary amines be produced from reduction of nitriles
- Haloalkane reacts with CN- in a nucleophilic substitution reaction hot acid is needed, a nitrile is formed
- Reduction of CN bond using H2 and Ni catalyst, forming primary amine
*this method produces a molecule with a carbon length longer by one
Add of producing amines through reduction of nitriles
Only a 1° amine can be produced so purer product
How can aromatic amines be produced (phenylamine) give overall eq
1.Electrophilic substitution (nitration) of a benzene with conc H2SO4 and conc HNO3, produces nitrobenzene
- Nitrobenzene reduced to phenylamine using Sn and HCL as reducing agents
- Reaction happens in HCL, NaOH needed to liberate amine,
C6H5NH3+ + Cl- + NaOH—> C6H5NH2 + H2O + NaCl
Overall equation
C6H5NO2 + 6[H] —> C6H5NH2 + 2H2O
What are aromatic amines (phenylamine) used for
Manufacture of dyes
What type of base are amines
Weak bases
What does the strength of a base depend on
How easily it will accept a proton (H+), the easier it accepts a proton the stronger the base
Which of ammonia, primary aliphatic amines and primary aromatic amines is a stronger base (weakest to strongest)
Phenylamine (weakest)
Ammonia
Primary aliphatic amines (strongest)
Why are secondary amines stronger bases than primary amines
2° has a positive inducing effect from 2 alkyl groups, increases electron density, lone pair on N is more available, 1° has a positive inducing effect from 1 alkyl group
Why are tertiary amines LESS stronger bases than secondary amines
3° less soluble in water
Why are primary aromatic amines weak bases
Lone pair on N atom overlap with delocalised ring of electrons on benzene, this ring withdraws electrons from N atom, lone pair on N is less available
What are the uses of quaternary ammonium salts
Cationic surfactants like hair conditioner and fabric conditioner
Equation for production of an amine (reducing nitrile)
R-CN + 4[H] —> R-CH2-NH2
Equation for formation of aromatic amine (reduction of nitrile)
C6H5NO2 + 6[H] —> C6H5NH2 + 2H2O
Nucleophilic addition elimination reaction of ammonia/1° amine with acyl chlorides and acid anhydrides
Acyl chloride
R-COCl + 2CH3NH2 —> R-CONHCH3 + CH3NH3+ + Cl-
Acid anhydride
(RCO)2O +2CH3NH2 —> R-CONHCH3 + [CH3NH3]+ + [RCO2]-
2 mol of amine, 1st used for reaction, 2nd used to accept H+
Mechanism for
amines + acyl chlorides/ acid anhydrides—> N-Sub Amides
1.Lone pair from N onto C from carbonyl bond as C is s+ and Cl is s-, arrow from carbonyl bond onto O
2. -ve charge on O, arrow from lone pair into C-O bond
Arrow from C-Cl bond onto Cl
N is +ve, arrow from H onto N
