Amines and polymers (27) Flashcards
What is an amine?
It’s a compound derived from ammonia
What is the functional group of amine?
-NH2
What is an aliphatic amine?
A nitrogen atom attached to a straight or branched carbon chain
What is an aromatic amine?
A nitrogen atom attached to an aromatic ring
What is a primary amine?
A nitrogen attached to 2 hydrogens and an R group
What is a secondary amine?
A nitrogen attached to one hydrogen and 2 R groups
What is a tertiary amine?
A nitrogen attached to 3 R groups
Give two examples of amines and what they are used for
- Seratonin which is a neurotransmitter that controls depression, sleep, memory etc
- Pseudoephedrine which is an ingredient in decongestion medications for colds
How do you name primary amines?
When it is on the end of the carbon chain, you found the carbons and then add -amine on the end e.g ethylamine. If it not on the end of the carbon chain, you add the prefix amino-
How do you name secondary and tertiary amines?
These will have an N- at the beginning and you always count the groups attached to the N first and then add amine on the end
Why and how do amines act as bases?
Nitrogen has a lone pair of electrons on it so can accept a proton which makes it a base, and they form a dative covalent bond, making a positive ion
What reactions can amines undergo because they are bases?
Neutralisations to form a salt
How do you prepare a primary amine?
Ammonia has a lone pair of electrons on the nitrogen so can act as a nucleophile and take part in a substitution with a haloalkane to form an ammonium salt. The ammonium salt can then have an aqueous alkali added to it to make a primary amine.
What are the conditions of the preparation of a primary amine?
- Ethanol must be used as a solvent so that the haloalkane doesn’t undergo a nucleophilic substitution with water to form an alcohol
- Excess ammonia has to be used to make sure there isn’t further substitution of the amine group to make a secondary or tertiary amine
How do you make a secondary and tertiary amine?
After a primary amine is formed, the nitrogen still has a lone pair which means it can undergo further reactions with the alkali and this will result in secondary and even further will make tertiary
How do you make phenylamine?
You reduce nitrobenzene by reacting it with tin and HCl to form an ammonium salt. You then react it with excess NaOH to produce phenylamine.
What are the reducing agents used to make phenylamine?
Tin and HCl
What is an amino acid?
It contains both an amine and a carboxylic acid functional group.
Why are they a-amino acids
They are alpha-amino acids because the amine group is attached to the a carbon atom which is the second carbon atom. The carboxyl and amine group are attached to the same carbon
Why are there 20 different types of amino acid?
They all have a different R-group attached to their a-carbon
What is the general formula of an amino acid?
RCH(NH2)COOH
What are the reactions of an amine group an amino acid?
The amine is a base so will react with acids to make salts
What are the reactions of the carboxyl groups in an amino acid?
They react with aqueous alkalis to form a salt and water.
They can also react with alcohols to make an ester and water in the presence of H2SO4
How do you name amides?
- Primary amides have one carbon bonded to the N and they don’t have a prefix. Add -amide to the end
- Secondary amides have 2 carbons bonded to the N and they have a prefix of N-
- Tertiary amides have 3 carbons bonded to the N and they have a prefix of N,N-
What is an optical isomer?
Optical isomers are two non-superimposable mirror-image structures of each other
What is a chiral carbon?
A carbon with 4 atoms or a group of atoms attached
How do you draw optical isomers?
Draw one of them in its 3D tetrahedral arrangement and then draw the other one as an exact mirror image
What is condensation polymerisation?
The joining of monomers by losing a small molecule like water of HCl
What is the starting material of a condensation polymer?
Carboxylic acid
Name two examples of condensation polymers
Polyesters and polyamides
How do you make polyester?
You join together an alcohol and a carboxylic acid and remove water.
Give an example of a polyester made from a monomer containing two different functional groups
Lactic acid is made into polylactic acid. Lactic acid is derived from maize and is more sustainable than those derived by fossil fuels
Give an example of a polyester made from two monomers containing two functional groups
Terylene (PET) is made when benzene-1,4-carboxylic acid and ethane-1,2-diol. It forms an ester linkage and it is used for plastic bottles and clothing
How do you make a polyamide?
You join together a carboxylic acid and an amine group
Give an example of a polyamide made from a monomer containing two different functional groups
Amino acids can undergo condensation polymerisation to form polypeptides
Give an example of a polyamide made from two monomers containing two functional groups
Nylon can be made by combining a dicarboxylic acid and a diamine
How do you hydrolyse condensation polymers?
Add a hot aqueous alkali or hot aqueous acid
What happens if you do a base hydrolysis?
You will form a COO- and an Na+ and a diol
What happens if you do an acid hydrolysis?
You will form a dicarboxylic acid and diol
What is the trend in boiling points for amines?
Amines have a higher boiling point than alkanes because they can form hydrogen bonds between the partially negative nitrogen atom and the partially positive hydrogen on another amine
What is the trend in solubility for amines?
The lower mass compounds are soluble in water due to the fact they are polar and can form hydrogen bonds, but solubility decreases as molecules get heavier because NH2 has less effect
