Chapter 27: Amine, amino acid and polymers

Reactions of the carboxylic acid group in amino acids

The carboxylic acid group react with alkalis to form salts and with alcohol to form esters

What are the characteristics of addition polymerisation?

-Monomer contains C=C double bond. -Backbone of the polymer is a continuous chain of carbon atoms

What are the characteristics of condensation polymerisation?

-Two monomers, each with two functional groups -One monomer with two different functional groups -Polymer contain ester or amide linkages

Amides

Amides are the products of reactions of acyl chlorides with ammonia and amines. Amide groups are common in nature. For example, in proteins the amine and carboxylic acid groups of amino acids are bonded together to form amide groups.

Salt formation from an amine

Amines are bases and they neutralise acids to make a salt.

Amines and examples of there effects on the body

Amines occur commonly in nature with many being well know for their effects on the body. Seritonine acts as a neurotransmitter, responsible for the control of appetite, sleep, memory and learning, temperature regulation, muscle contraction and depression. Pseudoephedrine is an active ingredient in decongnistion medications such as in nose drops or in cold remedies. It works by shrinking nasal membranes and inhibiting nasal secretion

Amino acids

Amino acids are organic compounds contained both amine, NH2, and carboxylic acid, COOH, functional groups. The body has 20 common amino acids that can be built into proteins. These amino acids are all alpha-amino acids in which the amino group is attached to the alpha-carbon atom and the 2nd carbon, next to the carboxyl group. These 20 amino acids differ by the side chain, R, attached to the same alpha-carbon atom. There are also less common amino acids in which the main group is connected to the beta-carbon atoms (the 3rd carbon) and the gamma-carbon atom(the 4th carbon)

Polyamides made from 1 monomer containing 2 different functional groups

Amino acids containing both amine group and a carboxylic acid group. amino acids undergo condensation polymerisation to form polypeptides or proteins. A polypeptide or protein contains many different amino acids all linked together by amide bonds. When an amide bond is formed water is lost

Esterification of alcohols with amino acids

Amino acids, like carboxylic acids, are easily esterified by heating with an alcohol in the presence of concentrated H2SO4.

Formation of a primary amine

Ammonia has a lone pair of electrons on the nitrogen atom which allows ammonia to act as a nucleophile in a substitution reaction with a haloalkane. the product of this reaction is an ammonia salt. Aqueous alkali is then added to generate the amine from the salt For this reaction to occur there are some essential conditions -Ethanol is used as a solvent. This prevents any substitution of the haloalkane by water to produce an alcohol -Excess NH3 is used. this reduced further substitution of the amine group to form secondary and tertiary amines (both of which produce the salt) The alkali you use is usualy in the form of NaOH or KOH

Amino acids reaction with aqueous alkalis

An aiming acid reacts with an aqueous alkali, such as sodium or potassium hydroxide to form a salt and water

How can alkenes form polymers?

By addition polymerisation

Reactions of amines on an amino acids

The amine group is basic and reacts with acid to make salts. As such, amino acid will also react with acid to form salts

Chiral carbon atoms

Chiral carbon atoms exist widely in naturally occurring organic molecules. For example, all sugars, proteins, nucleic acid contain chiral carbon atoms. With the exception of glycine all alpha amino acids, RCH(NH2)COOH, contain a chiral carbon atoms with the alpha carbon atom bonded to 4 different atoms or groups. In the structure, the chiral carbon atom is shown labelled with an * Chiral is not just for carbon atoms it applies to any centre that holds attachment that can be exchanged as 2 non-superimposable mirror images

Formation of the polymer Nylon from 2 monomers each with 2 functional groups

Different types Nylon can be made by varying the carbon-carbon length.

Polyester made from 2 different monomers each containing 2 different functional groups

For this type of a polyester formation, 2 different monomers are involved, each with different functional groups. -1 monomer is a diol, with 2 hydroxyl groups -1 monomer is a dicarboxylic acid, with 2 carboxyl groups

Polyester made from 1 monomer each containing 2 different functional groups

For this type of polyester formation, only one monomer is involved, containing both different functional groups, a hydroxyl group, -OH and a carboxyl group, -COOH. Poly(glycolic acid) (PGA)is the simplest polyester of this type made by condensation polymerisation its monomer, glycolic acid, HOCH2COOH. Glycolic acid contains both a hydroxyl group and a carboxyl group

When is it hydrochloric acid and when is it hydrogen chloride?

Hydrochloric acid = aqueous solution Hydrogen chloride = gas (fume)

Aliphatic amines

In an aliphatic amine (e.g. CH3CH2NH2), the nitrogen atom is attached to at least one straight or branched carbon chain (alkyl group, R). Methylamine, CH3NH2, is the simplest aliphatic amine with one methyl group attached to the nitrogen atom

Aromatic amine

In an aromatic amine, the nitrogen atom is attached to an aromatic ring (aryl group, Ar). Phenylamine, C6H5NH2, is the simplest aromatic amine, with a phenyl C6H5 group attached to the nitrogen atom

What is poly(Trimethylene Terephthalate) (PTT)?

It is a polyester used in the manufacturing of carpets and clothing fabrics

What is condensation polymerisation?

It is the joining of mongers with loss of a small molecule usually H2O (the condensation) or hydrogen chloride (HCl(g)). In this type of reaction 2 different functional groups are needed.

Amino acids have both an acidic COOH and an acid NH2 functional group, how does this affect the way it reacts?

It means that amino acids have similar reactions to both carboxylic acids and amines

Give an example of a compound which undergoes condensation polymerisation

Lactic acid, HOCH(CH3)COOH, to form poly(lactic acid) (PLA)​

Nomex

Nomex is a synthetic heat and fire-retardant polyamide, used in oven gloves and in the fire protective suits worn by formula 1 racing drivers and pit crew

Optical isomerism

Optical isomerism is found in molecules that contain a chiral center. In organic chemistry, the chiral centre is a carbon atom attached to 4 different atoms or groups of atoms. The presence of a chiral carbon atom in a molecule leads to the existence of 2 non-superimposable mirror image structures. These 2 molecules are known as optical isomers or enantiomers. For each chiral carbon atoms, there is always 1 pair of optical isomers

Preparation of aromatic amines

Phenylamine, C6H5NH2, is made by reduction of nitrobenzene, C6H5NO2. Nitrobenzene is heated under reflux with tin and HCl to form ammonia salt, phenylammonium chloride, which is then reacted with excess NaOH to produce the aromatic amine, phenylamine. Tin and HCl act as reducing agents

Polyamides

Polyamides are condensation polymers formed when monomers are joined tother by amide linkages in a long chain to form the polymer. As with polyesters, polyamides can be made from a monomer containing both a carboxylic acid (or acyl chloride) and an amine group, or from 2 monomers - one contained 2 carboxylic groups (or acyl chlorides) and the other containing 2 amine groups

Polyamide made from 2 monomers each containing 2 functional groups

Polyamides can be made by the reaction of a dicarboxylic acid (or acyl chloride) with a diamine. During the condensation reaction an amide bond from between the amine on 1 monomer and the carboxyl (ar acyl chloride group on the other monomer

Hydrolysing condensation polymers

Polyester and polyamides can be hydrolysed using hot aqueous alkali such as NaOH or by hot aqueous acid such as HCl

Stereoisomerism definition

Stereoisomerism are compounds with the same structural formula but a different arrangement of atoms. e.g. optical isomerism

Give an example of a polyester made from 2 monomers each containing 2 funcitonal groups

Terylene is a condensation polymer made from the reaction between the 2 monomers, benzene-1,4-carboxylic acid, HOOCC6H4COOH, and ethane-1,2-diol, HO(CH2)2OH.

Strength of amine bases

The strength of primary amine come from their availability of lone pair of electrons. The longer the chain the stronger the base. Benzene ring amines are not strong bases

What are polyesters and polyamide important for?

They are 2 important condensation polymers made on an industrial scale. Carboxylic acid and their derivates are common starting material for this preparation

What are amines?

They are organic compounds, derivates from ammonia, NH3 (usually include NH2), in which one or more hydrogen atoms in ammonia have been replaced by a carbon chain or ring. The are two types of amines aliphatic amines and aromatic amines

What are polyester used for?

They are used for electrical insulation

Making polyester

When making a polyester, monomers are joined together by ester linkage in a long chain to form the polymer. Polyesters can be made from a monomer containing both a carboxylic acid and an alcohol group, or from 2 monomers - one contained 2 carboxylic groups and the other containing 2 alcohol groups

What must you remember to do when drawing out the structure of an amine?

You must always show the lone pair of electron

Naming a primary amine

You name a primary amine, with the -NH2 groups on the end f the chain, by adding the suffix -amine to the end of the alkyl chain name. Where a primary amine contains an amine group on any other carbon but carbon-1, the amine is named using the prefix​ amino- and a number is added to indicate the position of the amine group along the chainAmi

Amines behave as ... in their chemical reactions as the.....

bases lone pair of electrons on the nitrogen atom can accept a proton. When an amine accepts a proton, a dative covalent bond is formed between the lone pair of electrons on the nitrogen atom and the proton. This forms an ion

Both PLA and PGA are ...

biodegradable polymers. Lactic acid is derived from maize, making its production more sustainable than polymers derived from fossil fuels

What is another way of saying optical isomer?

enantiomer

What are the reactions which amines undergo?

ion formation (when it acts as a base) and neutralisation (when a salt is formed)