3.3.11- amines
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An amine is derived from _____ and all contain a ______ atom where hydrogens are replaced with an organic group (eg alkyl group)
An amine is derived from ammonia and all contain a nitrogen atom where hydrogens are replaced with an organic group (eg alkyl group)
5 types of amines
Primary amine - 1 organic group Secondary amine - 2 organic groups Tertiary amines - 3 organic groups quaternary ion - 4 organic groups Phenyl amine - (aromatic amines still primary)
Name of quaternary ion
tetramethylamine ion
Non aromatic amines are also known as …
Aliphatic Amines
Quaternary ammonium salts are used to make…
Cleaning products - detergents
Quaternary ammonium salts are used to make…
Cleaning products - shampoo - laundry detergents - washing up liquids
Quaternary ammonium salts with long hydrocarbon tails are called …
Cationic surfactants
How do cationic surfucahts work
Their non polar tails are attracted to oil/grease Polar head attracted to water Allows water and oil to mix removing grease from clothes, skin and dishes
How do cationic surfactants work in hair condionger and softener
They have a positive ammonium ion which is attracted to negatively charged fibres and hair This removes static so can be used in hair conditioner
A base is a …
Proton acceptor
How are amines able to act as bases
Amines have a lone pair of electrons that allows them to accept a proton and hence act as a base A proton bonds to amine via a dative covalent bond Both electrons in the bond come from LP on nitrogen
Strength of base dep on …
Availability of LP on nitrogen ⬆️ e- density comes = e- ⬆️ readily available = ⬆️ alkyl groups = ⬆️ inductive effect
Order of base strength from strongest to weakest from ammonia , Primary aliphatic amines and aromatic amines
Weakest base; 1) Aromatic amines 2) ammonia 3) primary aliphatic amines (Strongest)
Why are aromatic amines the weakest base
Benzene is a electron withdrawing group Lone pair on N is delocalised into the benzene ring (pulls e- away) Decreased e- density on nitrogen LP less available
Primary aliphatic amines is a strong base bc
Alkyl groups are electron pushing groups so push electrons toward N Increased inductive effect LP on nitrogen more available
Amines act as bases and …
Nucleophiles
2 ways to make aliphatic amines
1) Reacting it with a halogeno alkane with excess ammonia 2) reducing a nitrile
Products of nucleophillic substitution with amine
A primary amine Ammonium chloride salt
Why is it important to mention excess amine in nuc sub
2 mol of NH3 are needed in mechanism
Downside of using nuc sub when reacting halogenoalkane with excess ammonia
Reaction produces primary secondary tertiary amines and quaternary salts So thus product is impure
Why is are multiple types of Amines produced in nuc sub of Amines (halogenoalkane and excess ammonia)
This occurs bc prismry amines still have a LP of electrons so also acts as a nucleophile The amine can react with any remaining halogenoalkanes to produce secondary Amiens a—> then tertiary and quaternary salts
Reagent and conditions for reducing nitriles
Hydrogen gas Nickel or platinum catalyst High pressure and temp
Reducing amines also known as …
Catalytic hydrogenation
Adv of red nitriles over nuc sub
Only produces primary Amines (pur prod) Cheaper