Chapter 27 - Amines, Amino Acids and Polymers Flashcards
Amines, Amino acids, amides, and polymers, Condensation polymers.
What is an amine?
Compounds derived from ammonia where one or more Hs in NH3 are replaced by a carbon ring or chain.
What is the difference between an aliphatic amine and an aromatic amine?
Aliphatic - nitrogen is attached to at least one straight or branched carbon chain
Aromatic - nitrogen is attached to an aromatic ring
What does a primary secondary and tertiary amine look like?
How do you name Primary amines? Secondary and Tertiary amines?
PRIMARY
- when NH2 at end of chain, add the suffix -amine to the name of the alkyl chain
e.g ethylamine
- When -NH2 not at the end of the chain, prefix amino- is added.
e.g. 2-aminopropane
SECONDARY and TERTIARY
If alkyl group on the N are the same, add prefix ‘di-‘ or ‘tri-‘ .
e.g (CH3)2NH is dimethylamine.
When >=2 different groups are attached to the N, compound is named as a N-substituted derivate of a larger group.
e.g. N-ethyl-N-methyl propylamine (tertiary)
What do amines often behave as and why?
Amines often act as Bases due to their lone pair - readily accepting H+ by forming dative bonds.
Amines and Ammonia can also act as nucleophiles.
Amine + acids = ?
Neutralisation - forming a salt (no water).
For the formation of aliphatic primary amines, what is reacted together in the two steps?
Ammonia + alkyl halide = salt
NaOH neutralises salt to form an amine.
(in ethanol with excess ammonia)
What is the purpose of ethanol in the formation of aliphatic amines?
Ethanol is a solvent, used to prevent substitution of haloalkane by water to produce alcohols.
How are aromatic amines produced?
Reduction of nitrobenzene.
+ Tin (Sn) and conc HCl (reducing agents)
–> forms ammonium salt (phenylammonium chloride)
+ Excess NaOH(aq) - neutralises the salt to form phenylamine
What are the two steps of forming a secondary amine and tertiary amine from a primary amine?
Primary amine + Alkyl halide and ethanol as solvent
then
Salt product + NaOH forms secondary amine
What do tin and HCl act as in formation of phenylamine from nitrobenzene?
Tin and HCl act as a Reducing agents
What is the general structure of an alpha amino acid?
An a amino acid has the NH2 and COOH groups attached to the same a-carbon.
Different a-amino acids have different side chains, R, attached to the same a-carbon atom.
General formula = RCH(NH2)COOH
a-carbon = C attached to the COOH group
Amino acid + aqueous alkali = ?
Salt + Water
What do amino acids contain?
An Amino acid has both an Amine group (NH2) and a Carboxyl acid group (COOH) group. hence amino acid :)
Amino acids + acid = ?
Ammonium salt
Heating an Amino acid + alcohol (with conc H2SO4) = ?
Ester + H2O
What is a chiral carbon?
A chiral carbon is attached to four different atoms / groups of atoms
Amino acids are amphoteric, what does this mean?
Have acidic and basic properties
COOH acts as an acid
NH2 acts as a base
what are amides?
O=C-N
How are amides formed?
Reaction of acyl chloride with ammonia/amines
What are stereoisomers?
Compounds with the same structural formula but a different arrangement of atoms in space.
There are two types of stereoisomers: optical and E/Z isomerism.
What is optical isomerism?
Optical isomerism is found in molecules that contain a carbon atom with a chiral centre.
1) a chiral atom is attached to four different atoms or groups of atoms
2) the four groups attached to the chiral carbon are arranged in space as two non superimposable mirror images called optical isomers
3) each chiral carbon atom has one pair of optical isomers
What do optical isomers have in common?
Same physical properties
Do a-amino acids contain chiral centers?
Excluding glycine, all a-amino acids contain a chiral carbon
What are the bidentate ligands you need to know? How many lone pairs of electrons?
NOTE: N has 1 lone pair and O has 2 lone pairs of electrons.
How to draw optical isomers?
What are polyesters?
Monomers joined together by ester linkages
what does a polyester ester link look like?
What are the two monomer types that form polyesters?
Monomers with Diols (2 hydroxyl groups) or Dicarboxylic acids
How can polyesters be formed from one monomer?
Condensation polymerisation when polyesters are formed by monomers that have one end as an alcohol (OH) group and the other end as a carboxyl group (COOH )
An ester linkage forms between molecules, and water is produced.
What is condensation polymerisation?
Formation of long chain molecules from lots of small molecules joined together, with another small molecule (e.g. H2O or HCl) produced.
What are polyamides?
Where monomers are joined together with amide linkages (CONH) to form the polymer
Polyamides can be made from either:
1) one monomer containing both a carboxylic acid and amine group
2) two monomers one containing two carboxylic acid groups and the other containing two amine groups.
What does a polyamide amide linkage look like?
How can polyesters be formed from two monomers?
One monomer contains two hydroxyl (OH) groups- a diol
Another monomer contains two carboxylic acid groups
How can polyamides be formed from just one monomer?
Amino acids contain a carboxylic acid and amine group. They form water.
What is the common name for polyamides made from two monomers?
Nylon
How can polyamides be made from two monomers (2 ways)? What does an amide bond look like?
Polyamides can be made by the reaction of a dicarboxylic acid/ diacyl chloride with a diamine.
What is required for polyesters and polyamine’s to undergo hydrolysis? What are the products?
polyesters and polyamides can be broken down by hydrolysis using:
1) hot aqueous acid like HCl (acid hydrolysis) to form a carboxylic acid and an alcohol
2) hot aqueous alkali like NaOH to form a carboxylate salt and an alcohol
Show the base and acid hydrolysis of polyamides.
Show the base and acid hydrolysis of polyesters.
What is formed from polyester undergoing acid hydrolysis?
A Diol and a Dicarboxylic acid
What is required to undergo base hydrolysis?
Excess NaOH
What is formed from acid hydrolysis of polyamide?
Diammonium salt and Dicarboxylic acid
What is formed from polyester undergoing base hydrolysis?
A Diol and a Salt of dicarboxylic acid
How do you identify the type of polymerisation given the monomers and the monomers from the polymer chains?
