6D- amines, amides and polyamides

what are the functional groups where nitrogen atoms are found

amine, amide and nitrile

why do most amines have a higher boiling point than the comparable alkane (alkane with closest number of electrons)

amines can form hydrogen bonds

why is the boiling point of N,N-dimethylethylamine not significantly higher than that of pentane

doesn’t have N-H bonds so can’t form hydrogen bonds

what reagent is normally used to react an aldehyde or ketone to form a nitrile

NaCN in acid solution- H₂SO₄

which functional group will always be present in the product molecule from the formation of a nitrile from an aldehyde or ketone

alcohol

what is the mechanism for the reaction of an aldehyde or ketone to form a nitrile

nucleophilic addition

what is the reactant needed to convert a haloalkane to a nitrile

NaCN

why is ethanol the solvent used to convert a haloalkane to a nitrile

both haloalkane and the cyanide will dissolve in it

water would react with the haloalkane under alkaline conditions to make an alcohol and the reaction would not progress as planned

what solvent is used to convert a haloalkane into a nitrile

ethanol

what is the mechanism used to convert a haloalkane to a nitrile

nucleophilic substitution

what should a haloalkane be reacted with to produce an amine and what conditions should be used

heated with excess conc. ammonia in an ethanol solvent, product is made alkaline by the addition of sodium hydroxide solution

what needs to be controlled when making a primary amine

the haloalkane is not present in excess to prevent further substitution of the amine product to form a secondary or tertiary amine

how to name amines

primary amines:

• amine is on C1- suffix ‘amine’ used

• amine not on C1- prefix ‘amino’ used

secondary/tertiary amines:

• named as N-substituted derivative e.g. N-methylethylamine

how can amines be bases

weak bases- the lone pair on the nitrogen atom can accept a proton

what is a characteristic of amines

smelly

what causes amines to loose their smell

acid, will reappear if a stronger base is added

what impacts the base strength of amines

depends on how well N lone pair can accept H⁺

the higher the electron density of the N lone pair the stronger the base

how can amines be made from nitriles

150’C, nickel catalyst and hydrogen

what can amines be made from

nitriles, nitrobenzene, haloalkanes

how can an amine be made from benzene

benzene reacts with conc. HNO₃ and conc. H₂SO₄ catalyst to form nitrobenzene

nitrobenzene reacts with tin catalyst and conc. HCl- heat under reflux, then add aqueous alkali e.g. NaOH

write the equation for the reaction of nitrobenzene to form phenylamine

what type of reaction is that of nitrobenzene to form phenylamine

reduction

why can’t phenylamine be prepared by reacting chlorobenzene with ammonia

carbon atoms in the benzene ring can’t be attacked by nucleophiles such as NH₃, they are attacked by electrophiles instead

how to make a primary amine

reaction happens in two stages

reactants are ammonia and a primary haloalkane

1. in first stage a salt is formed as amines are bases

e.g. CH₃CH₂CH₂Br + NH₃ → CH₃CH₂CH₂NH₃⁺Br^-

2. a reversible reaction can then take place between this salt and excess ammonia in the mixture

e.g. CH₃CH₂CH₂NH₃⁺Br^- + NH₃ ←→ CH₃CH₂CH₂NH₂ + NH₄⁺Br^-

• the ammonia removes a hydrogen ion from the propylammonium ion to leave a primary amine

• the more ammonia there is in the mixture the more the forward reaction is favoured, therefore the reaction is often completed with a high excess of ammonia reagent in order to maximise yield of the product

how to make a secondary amine

reaction continues from making a primary amine

same two stages:

1. first stage forms a salt

2. reversible reaction between salt and excess ammonia in the mixture to form a secondary amine

how to make a tertiary amine

reaction continues from a secondary amine (which came from a primary amine)

same two steps:

1. first stage forms a salt

2. reversible reaction between salt and excess ammonia in the mixture to form a secondary amine

what is a molecule where a nitrogen has 4 alkyl chains attached

NOT an amine, uses the lone pair of electrons on nitrogen to bond to a fourth alkyl chain, creates a quaternary ammonium salt

how to make a quaternary ammonium salt

tertiary amine reactions with haloalkane

cannot be reacted further as no more hydrogens to lose and remains as a salt

what are the functional groups of amino acids

carboxylic acid and amine

what is the state of amino acids at RTP

solids- have much higher melting and boiling points than other structures with a similar Mr

how do amino acids nomally exist

as zwitterions

what is a chiral carbon

a carbon attached to 4 different groups of atoms (not functional groups just groups)

what type of isomerism uses chiral carbons

optical isomerism

what is the name for a carbon attached to 4 different groups of atoms

chiral carbon

what are optical isomers

non superimposable mirror image isomers- when placed on top of each other they are not the same shape e.g. your hands

how to draw optical isomers

1. draw chiral carbon and bonds emerging from it first in 3D

2. then draw mirror image

3. draw smallest group near the mirror

4. draw in all other groups using structural formula

5. then draw its mirror image

what happens if acid is added to an amino acid solution (pH is lower than isoelectric point- don’t need to know this term)

all the places where the H⁺ could go are occupied

what happens if an alkali is added to an amino acid solution (pH is higher than isoelectric point- don’t need to know this term)

all places where H⁺ could be lost are empty

what types of polyamine hydrolysis are there

• acid hydrolysis

• alkali hydrolysis

what are the reactants and products of acid hydrolysis of polyamides

using HCl_(aq)

forms protonated diamine and dicarboxylic acid

what are the reactants and products of alkaline hydrolysis of polyamides

using NaOH_(aq)

forms diamine and deprotonated dicarboxylic acid forming dicarboxylate salt

what are amides

contain a nitrogen adjacent to a carbonyl bond

what can amides be made from

• can be made from a single monomer containing a carboxylic acid or acyl chloride group and an amine group- half an amide forms at either end, 1 molecule of water made per condensation

• can be made from two monomers: a dicarboxylic acid or diacyl dichloride and a diamine- one amide forms in the middle and half at either end, 2 molecules of water made per condensation

(similar way to esters)

what type of polymerisation is used for polyamides

condensation polymerisation