What are amines?
- Amines are organic compounds derived from NH3 where on or more of the hydrogen atoms in ammonia has been replaced by a carbon ring or chain
What is an aliphatic amine?
- the nitrogen atoms are attached to at least one straight or unbranched chains
What is an aromatic amine?
- The nitrogen atom is attached to an aromatic ring
How do you classify amines?
primary amine = attached to one carbon
secondary amine = attached to two carbons
tertiary amine = attached to three carbons
How do you name primary amines?
- when the NH2 is at the end of the chain you addthe suffix amine and the prefix is the alkyl group
- for example methylamine
- if the amine is on another carbon then you use the prefix (x - amino)
- for example 2 aminobutane
How do you name a secondary or tertiary amine?
kinda weird
- you use di or tri to indicate its position, for example dimethyl amine
- if there are multiple you use Number- alkylchain,amine
Why can amines react
- Amines behave as bases as they have a lone pair of electrons on the nitrogen which can accept a proton
- when the amine accepts a proton, a dative covalent bond is formed between the lone pair of electrons on the nitrogen atom and the proton
What forms when an amine reacts with an acid?
- the amine acts as a base and neutralises the acid, forming a salt
Show the reaction between propylamine and hydrochloric acid
What are the steps of preparing an aliphatic amine?
- formation of salt
- Amine formation
How do you form a salt (aliphatic amine prep)?
- ammonia has a lone pair of electrons and can therefore act as a nucleophile, donating a pair of electrons in a substitution reaction with a haloalkane
- This forms a salt
What is the reaction between 1 - chloropropane and ammonia?
- it forms propylammononium chloride
How do you form an amine from a salt (aliphatic prep)
- You react the ammonium salt with sodium hydroxide, forming an amine, Nacl and H20
What is the reaction between propylammonium chloride and sodium hydroxide?
- propylamine, Nacl and water
What are the essential conditions to form an aliphatic amine?
- ethanol as a solvent to prevent further substitution of the haloalkane by water to produce alcohols
- excess ammonia to prevent further substitution of the amine group to form a secondary and tertiary amine
How do you form a secondary amine and tertiary amine?
- primary amines still contain a lone pair of electrons on the nitrogen atom can further react with a haloalkane to form an ammonium salt
- the ammonium salt can then be reacted with NaOH which forms a secondary amine
- tertiary amines can be formed from further reacting a secondary amine
How do you form an aromatic amine?
- phenylamine can be formed by reducing nitrobenzene
- nitrobenzene can be heated under reflux with tin and HCL to form an ammonium salt
- the ammonium salt can then be reacted with excess NaOH, producing an aromatic amine
Draw the reduction of nitrobenzene.
- conc HCL/sn
- excess NAoh
- produces water
- 6(H)
