Chapter 27.1 Flashcards
What are amines?
organic compounds where one or more H atoms in ammonia have been replaced by a carbon chain or ring.
formula for ammonia
NH3
What is an aliphatic amine?
an alkyl group - straight or branched carbon chain with a nitrogen atom attached.
What is an aromatic amine?
an aryl group - an aromatic ring with a nitrogen atom attached.
How can amines be classified? How is this determined
primary, secondary or tertiary - by the number of alkyl or aryl groups attached to the nitrogen atom.
define primary, secondary, tertiary
nitrogen attached to 1, 2 or 3 carbon atoms
What are amines used for?
Occur commonly in nature - amino acids, serotonin
How do we name amines with the -NH2 group at the end of the chain? What amines are these?
primary amines - use ‘amine’ at the end of the name [end of chain, end of name], carbon chains become methyl, ethyl, propyl
How do we name amines with the -NH2 group on middle carbons? What amines are these?
primary amines - [number]-amino is used in front of the normal name for that chain.
How do we name amines with the -NH2 group between 2 or 3 of the same chains? What amines are these?
secondary / tertiary amines - we use ‘amine’ at the end of the name and then name the sides of the chains as methyl, ethyl, propyl etc. As the side chains are of the same length/type, we use the prefixes di- or tri-.
How do we name amines with the -NH2 group between 2 or 3 different chains? What amines are these?
The smaller group is named as N-[smaller group]. This shows that the smaller group is attached to the nitrogen atom, not the larger group.
How do amines react?
As bases, as the lone pair of electrons on the nitrogen can accept a proton. A dative covalent bond is formed between the lone pair on the nitrogen atom and the proton. This proton (H+) makes the amine an ion as well, due to the addition of a positive charge.
How are salts formed from amines?
The base (amine) reacts with an acid to make a salt, as part of neutralisation. The name changes from ‘amine’ to ‘ammonium’ and the salt name from the anion is added to the end, e.g. chloride.
How are primary amines formed in the first part of the process (salt formation)?
Ammonia (NH3) has the lone pair of electrons. This means can accept protons - it is a base and a nucleophile. This means that it can react with a haloalkane in a substitution reaction. An ammonium salt is then formed.
What are the conditions required to form a primary amine in the salt formation part of the process?
Ethanol must be used as the solvent since this prevents any substitution of the haloalkane by water (H+ and OH-) to produce an alcohol. Excess ammonia is also used since this reduces further substitution of the amine group to form secondary and tertiary amines.
