amines, amino acids and polymers

Question 1

what are amines?

Answer 1

organic compounds derived from ammonia, NH3, in which one or more hydrogen atoms in ammonia have been replaced by an organic group (alkyl group)

Question 2

what are the different types of amine?

Answer 2

primary, secondary, tertiary and quaternary

Question 3

what is an aliphatic amine?

Answer 3

the nitrogen atom is attached to at least one straight or branched carbon chain

Question 4

what is an aromatic amine?

Answer 4

the nitrogen atom is attached to an aromatic ring

Question 5

Why are amine bases?

Answer 5

lone pair of electrons on nitrogen atom can accept a proton

Question 6

How do amines bond?

Answer 6

proton bonds to amine via a dative covalent (coordinate) bond. Both electrons in the bond originate from the lone pair on the nitrogen

Question 7

The strength of the amine base is dependent on what?

Answer 7

dependent on the availability of the lone pair of electrons on the nitrogen. The higher the electron density, the more readily available the electrons are.

Question 8

The electron density on nitrogen in an amine is dependent on what?

Answer 8

dependent on the type of group attached to the nitrogen

Question 9

How are aliphatic amines made?

Answer 9

-reacting a halogenoalkane with excess ammonia
-ammonia acts as a nucleophile in a substitution reaction with a haloalkane.
-ammonium salt is made and then aqueous alkali is added to generate the amine from the salt.

Question 10

what are the products formed during amine formation using NaOH?

Answer 10

amine + salt + water

Question 11

what are the essential conditions needed for the preparation of amines?

Answer 11

-ethanol is used as a solvent. This prevents any substitution of the haloalkane by water to produce alcohols
-excess ammonia is used. This reduces further substitution of the amine group to form secondary and tertiary amines.

Question 12

What is the disadvantage of making primary amines in this way?

Answer 12

as the product still contains a lone pair of electrons on the nitrogen, it can react further with the haloalkane to produce a secondary amine. Further substitution can occur producing tertiary and quaternary salts too - impure products

Question 13

how is the secondary amine obtained?

Answer 13

salt reacts with NaOH
products: secondary amine, salt and water

Question 14

what are the two ways in which aliphatic amines are made?

Answer 14

-by reacting a halogenoalkane with excess ammonia
-by reducing a nitrile

Question 15

what are the two ways in which aliphatic amines are made?

Answer 15

-by reacting a halogenoalkane with excess ammonia
-by reducing a nitrile

Question 16

How are aliphatic amines made by reducing a nitrile?

Answer 16

two amine are used

Question 17

How are aromatic amines made?

Answer 17

by reducing nitro compounds (e.g nitrobenzene).

Question 18

Why are aromatic amines useful?

Answer 18

used to make dye stuffs and pharmaceuticals

Question 19

What are the steps when producing aromatic amines?

Answer 19

step 1- heat (under reflux) nitrobenzene with concentrated HCl and Sn to form a salt such as C6H5NH3+Cl-
step 2- salt produced in step 1 is reacted with an alkali (NaOH) to produce an aromatic amine such as phenylamine.

Question 20

What are amides?

Answer 20

derivatives of carboxylic acids and have a functional group of -CONH2

Question 21

Describe the structure of a secondary amide?

Answer 21

one of the nitrogens attached to a hydrogen, in the amide group, is replaced by an alkyl group.

Question 22

Describe amino acids?

Answer 22

-amino acids have an amino group (-NH2) and a carboxyl group (-COOH)
-amino acids are amphoteric meaning they have acidic and basic properties
-general formula: RCH(NH2)COOH
-amino acids (except glycine) are chiral compounds

Question 23

What is the R-group of glycine?

Answer 23

hydrogen

Question 24

what are chiral molecules?

Answer 24

molecules where central carbon atom is attached to four different groups. They rotate plane polarised light.

Question 25

what are a-amino acids?

Answer 25

where both NH2 and COOH are attached to the same carbon. These are the most common amino acids.

Question 26

Amino acids react with acids and alkalis to form what?

Answer 26

salts

Question 27

Describe the reaction between amino acids and alkali?

Answer 27

alkalis react with the carboxylic acid group in amino acids to form a conjugate base- RCH(NH2)COO- which combines with a positive ion to form an amino salt and water

Question 28

Describe the reaction between amino acid and acid?

Answer 28

acids react with amino group (NH2) to form a conjugate acid

Question 29

Describe the reaction between amino acids and alcohols?

Answer 29

alcohol reacts with the carboxylic acid group in amino acids to form an ester. Sulphuric acid catalyst is used. amino acid + alcohol -> ester + water

Question 30

what is optical isomerism?

Answer 30

form of stereoisomerism, they have the same structural formula but different arrangement of atoms in space. Optical isomers are mirror images and have a chiral carbon atom.

Question 31

What are enantiomers?

Answer 31

mirror images of each other and are non-superimposable.

Question 32

amides are products of what reaction?

Answer 32

reaction between acyl chlorides with ammonia and amides

Question 33

How are optically active isomers detected?

Answer 33

standard light oscillates in all directions. When light is passed through a Polaroid filter it oscillates in one direction. Optically active isomers will rotate the plane polarised light- one enantiomer rotates clockwise and the other, anticlockwise.

Question 34

chiral carbon atom is labelled with what?

Answer 34

asterisk

Question 35

Describe addition polymers

Answer 35

-alkenes are monomers which join to form addition polymers -poly(alkenes) are saturated molecules, normally non-polar and hence unreactive

Question 36

What is condensation polymerisation?

Answer 36

2 different monomers with at least 2 functional groups react together. When they react, a link (amide or ester link) is made and water is eliminated (condensation)

Question 37

What are the two types of polymers which can be synthesised from condensation polymerisation?

Answer 37

polyamides- formed by reacting diamines with dicarboxylic acids polyesters- formed by reacting a diol(two hydroxyl groups) and carboxylic acid together

Question 38

Describe the hydrolysis of condensation polymers

Answer 38

-water can be used to produce the original monomers -alkali or acid can be used

Question 39

How can a condensation polymer contain amide and ester links?

Answer 39

molecules with amine and alcohol groups can react with dicarboxylic acids

Question 40

how can condensation polymers be formed from one type of monomer?

Answer 40

molecules with a carboxylic acid and either an alcohol or amine group can react with itself