Amines, Amino Acids and Polymers

what are amines?

amines are organic compounds derived from ammonia in which one or more of the hydrogen atoms in ammonia have been replaced by a carbon chain or ring

What do amines behave as? And why?

Amines behave as bases as the lone pair of electrons on the nitrogen atom can accept a proton

How do you form a primary amine?

The lone pair of electrons on the nitrogen means that ammonia can act as a nucleophile in a substitution reaction with a haloalkane. This produces an ammonium salt. The salt can then be reacted with an aqueous alkali forming the amine

What are the conditions when forming a primary amine?

1. An alcohol must be used as the solvent to prevent any substitution of the haloalkane by water to produce an alcohol

2. Excess ammonia is used to prevent further substitution of the amine group to form secondary or tertiary amines

How do you form seconday or tertiay amines?

An unpure pimary amine is formed from the previous reaction, therefore a lone pair of electrong still remains on the nitrogen in the product. By further reacting the primary amine with a haloalkane, another ammonium salt will form e.g. dipopylammonium chloride. This is then reacted with an aqueous alkali e.g. NaOH to form the seconday amine. e.g. dipropylamine.

For form a tertiary amine, continue reacting the secondary amine.

How do you form phenylamine?

It is made by the reduction of nitrobenzene. Nitrobenzene is heated under refluxed with tin and hydrochloric acid to produce the ammonium salt, phenylammonium chloride. It is then reacted with excess sodium hydroxide to form the aromatic amine, phenylamine

What are amino acids?

They are oganic compounds containing both amines, -NH2 and carboxylic acids, -COOH, functional groups

How do amino acids react?

Due to the amine group being basic, they can react with acids to form salts. The carboxylic acid group will also mean that they can react with aqueous alkali to also form salts or react with alcohol to form esters.

What must the amino acid be reacted with to form esters?

An alcohol and concentrated sulfuric acid

What is a zwitterion?

When an ion contains both a positive and negative charge. E.g. within an amino acid, the amine group can accept a proton from the carboxylic acid group

What is the charge on a zwitterion?

There is no overall charge as the positive and negative charges cancel out

What is the isoeletric point?

The pH at which the zwitterion is formed

What happens if the pH is above the isoeletric point?

Then the amino acid acts as an acid and looses a proton to form a negative ion

What happens if the pH is lower than the isoeletric point?

The amino acid acts as a base and gains a proton to form a positive ion

What are amides?

The products of reactions of acyl chlorides with ammonia and amines

What is stereoisomerism?

Compounds with the same structural formula but different arrangement of atoms

What is a chiral centre?

When a carbon atoms is attached to four different atoms or group of atoms

What is condensation polymerisation?

the joining of two monomers with loss of a small molecule like water or hydrogen chloride in which two different functional groups are needed

What two functional groups are needed to make a polyester?

A carboxylic acid or an alcohol

What are polyamides?

polyamides are condensation polymers formed when monomers are joined together by amide linkages in a long chain to form the polymer

What two functional groups are needed to make a polyamide?

A carboxylic acid (or acyl chloride) and an amine group

How do you hydrolyse condensation polymers?

By using hot aqueous alkali such as NaOH or by hot aqueous acid like HCl

Which is preferable to hydrolyse a condensation polymer with: acid or alkali?

hydrolysing with a base is preferable because it is not a reversible reaction like hydrolysis with an acid

What are amino acids general formula?

RCH(NH2)COOH

How may enantiomers be distinguished from one another?

By using a plane polarized light. The enantiomers rotate the plane in opposite directions