27 - Amines, amino acids and polymers

Question 1

aliphatic amine?

Answer 1

nitrogen attached to at least one straight or branched carbon chain

Question 2

aromatic

Answer 2

nitrogen atom is attached to an aromatic ring

Question 3

how to name amine with a NH2 group on carbon 1

Answer 3

alkyl chain - amine

Question 4

how to name an amine with NH2 not on carbon 1

Answer 4

use prefix amino

Question 5

how to name secondary or tertiary amines containing the same alkyl group on the nitrogen

Answer 5

di of tri indicates number of alkyl groups

Question 6

how to name secondary or tertiary amines with different alkyl groups attached to the nitrogen atom
CH3NHCH2CH2CH3
CH3N(CH2CH3)CH2CH2CH3

Answer 6

N-substituted derivative
CH3NHCH2CH2CH3 N-methylpropylamine
CH3N(CH2CH3)CH2CH2CH3 N-ethyl-Nmethylpropylamine

Question 7

Explain how amines act as bases?

Answer 7

• they have a lone pair on their nitrogen atom and it can accept a proton
• this forms a dative covalent bond between nitrogen and hydrogen

Question 8

Amine + Salt
CH3CH2CH2NH2 + HCl

Answer 8

-> acids
CH3CH2CH2NH+CL-
neutralisation

Question 9

CH3CH2NH2 + H2SO4

Answer 9

(CH3CH2NH3+)2SO4 2-

Question 10

forming a primary amine

Answer 10

ammonia reacts with a haloalkane, forming an ammonium salt

ammonium salt is mixed with aqueous alkali to generate the amine from the salt

Question 11

how to form propylamine + sodium chloride

Answer 11

salt formation
1-chloropropane + HN3 -> propylammonium chloride (salt)

amine formation
propylammonium + NaOH -> propylamine

Question 12

what are the conditions to form a primary amine?

Answer 12

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

Question 13

forming a secondary/tertiary amine

Answer 13

ammonia and a haloalkane react to form a primary amine- however this reaction isn’t pure as the primary amine can react further with a haloalkane to form a secondary amine.

-> you still need to react with NaOH to generate the mine from its salt

Question 14

How to form Dipropylamine and NaCl-

Answer 14

CH3CH2CH2Cl + CH3CH2CH2NH2 -> (CH3CH2CH2)2NH2+Cl-
Propylamine -> Dipropylammonium chloride

(CH3CH2CH2)2NH2+Cl- + NaOH -> (CH3CH2CH2)2NH + NaCl + H2O

Question 15

How to form Tipropylamine and NaCl-

Answer 15

CH3CH2CH2Cl +(CH3CH2CH2)2NH -> (CH3CH2CH2)2NH+Cl-
Propylamine -> Dipropylammonium chloride

((CH3CH2CH2)2NH+Cl- + NaOH -> (CH3CH2CH2)2N + NaCl + H2O

Question 16

how to prepare an aromatic amine

Answer 16

reduction of nitrobenzene
heat under reflux with tin and HCl (reducing agent)
-> it forms the ammonium salt (phenylammonium)
react with excess NaOH
-> forms phenylamine

Question 17

what is an amino acid?

Answer 17

organic compund containing both amine NH2 and carboxylic acid COOH functional groups
-> body has 20
R is a variable side chain

Question 18

what is an alpha amino acid
give its general formula

Answer 18

the amine group is attached to the alpha carbon - the second carbon atom, next to the carboxylic group
RCH(NH2)COOH

Question 19

what is a beta amino acid

Answer 19

where the amino acid is attached to the third carbon

Question 20

amino acids with aqueous alkalis

Answer 20

amino acid react with an aqueous alkali to form a salt and water

Question 21

how do you esterify a amine acid

Answer 21

heat with alcohol in the presence of concentrated sulfuric acid

Question 22

what is an amide

Answer 22

the products of reactions of acyl chlorides with ammonia and amines

Question 23

primary amide

Answer 23

one carbon bonded to nitrogen

Question 24

what is an optical isomer

Answer 24

it is found in molecules that contain a chiral centre (carbon attached to 4 different atoms)

this means there are two molecules that are non-superimosable mirror image structures (enantiomers)

Question 25

what are two important condensation polymers? give some starting materials

Answer 25

- polyesters and polyamides - carboxylic acids and their derivatives are common starting materials

Question 26

what is condensation polymerisation

Answer 26

the joining of monomers with loss of a small molecule, usually water or HCl.

Question 27

what do you need for a condensation reaction

Answer 27

two functional groups

Question 28

what bond holds monomers in a polyesters

Answer 28

monomers are joined by ester linkages O ∥ C --- O

Question 29

two ways polyesters are made

Answer 29

- made from one monomer containing both a carboxylic acid and an alcohol group - made from two monomers here one contains a two carboxylic acid groups and the other containing two alcohol groups

Question 30

two examples of polyesters made from two monomers with two functional groups groups

Answer 30

- one monomer is a dial, with wo hydroxyl group - one monomer is a dicarboxylic acid with two carboxylic acid groups

Question 31

what is a polyamide

Answer 31

condensation polymers formed when monomers are joind by amide linkages in a long chain

Question 32

what is a amide linkage

Answer 32

O O ∥ -------- C --- N ------- | H

Question 33

how can polyamides be made

Answer 33

- from one monomer containg both a COOH (or acyl chloride) and an amine group - from two monomers one containing two COOH (or acyl chlorides) and the other containing two amine groups

Question 34

(CH3)3CCHBrCH3 has stereoisomers. Explain the term stereoisomers and name this type of stereoisomerism

Answer 34

Same structural formula AND Different arrangement (of atoms) in space OR different spatial arrangement (of atoms) optical

Question 35

bond angle of a primary amine

Answer 35

107- trigonal pyrmidal

Question 36

what is a amine group attached to benzene

Answer 36

phenylamine

Question 37

compare melting point of a primary amina and an alkane of a similar chain length

Answer 37

- relatively high due to hydrogen bonding between molecules :N-H therefore h bonding only true to primary, secondary and phenylamine

Question 38

Tm and Tb of primary amines compared to secondary

Answer 38

low due to no hydrogen bonds

Question 39

are amines soluble

Answer 39

yes

Question 40

producing amines from a haloalkane

Answer 40

nucleophilic substitution - where N is the nucleophile in excess to prevent further subs primary : R-X + NH3 -> R -NH2 + HX ethanol is needed secondary : R-X + R-NH2 -> R-NH-R tertiary: R-X + R-NH-R -> R-N(R)-R

Question 41

producing amines from nitriles

Answer 41

Reagents: LiAlH4 (ether) or H2 with Ni/Pt catalyst R-CN + 2[H] -> R-C-NH2 reduction

Question 42

producing amines from nitrobenzene

Answer 42

Reagents: Conc HCL and SN catalyst followed by NaOH Benzen-NO2 + 6[H] -> benzene-NH2 + 2H2O product is phenylamine HCl does the reducing- however it causes a salt forming as lone pair on N accepts NaOH prevents the salt from forming as it neutralises excess H+

Question 43

amine in water

Answer 43

R-NH2 + H2O <=> R-NH3+ + OH- forming an alkaline solution lone pair on N accepts H+

Question 44

primary amine and HCl

Answer 44

R-NH2 + HCl -> R-NH3+ + Cl- forms a salt _______ ammonium chloride

Question 45

ethylamine and nitric acid

Answer 45

C2H5NH2 + HNO3 -> C2H5NH3+ + NO3-

Question 46

why doe most amino acids have optical isomerism

Answer 46

central carbon atom has 4 different groups bonded to it (ie chiral)

Question 47

what is a zwitterion how does it affect properties

Answer 47

COOh of an amino acid donates H+ to the amine group. Lone pair on nitrogen accepts the H+. forming a positive and negative end - opositly charged poles so it is very soluble and a very high Tm (due to strong electrostatic attractions-like ionic substances) overall it is uncharged