Amines, Amino Acids And Polymers Flashcards
What are amines
Amines are organic compounds, derived from ammonia, NH3 in which 1 or more H atoms in ammonia have been replaced by C chain or ring
How are amines classified
Amines are classified as Primary, secondary or tertiary by the number of alkyl or Aryl groups are attached to N atoms
Draw a primary amine
CH3CH2CH2NH2
Nitrogen atom only has one carbon group attached, a lone pair and 2 H
Draw a secondary amine
(C2H5)2NH
Nitrogen is attached to 2 alkyl groups and one H and a lone pair
Draw a tertiary amine
(CH3)3N
Nitrogen attached to 3 carbon chains and 1 lone pair
Why do amines act as bases
Amines behave as bases due to lone pair of electrons on the nitrogen atom acts to accept a proton.
When it accepts a proton, a dative covalent bond is formed.
Amines act as bases so outline the reaction with an acid use propylamine and hydrochloric acid
+ Ethylamine reacting with Sulfuric acid
Propylamine reacts with hydrochloric acid react to from the salt propylammonium chloride
CH3CH2CH2NH2 + HCl —> CH3CH2CH2NH3+Cl-
Ethylamine reacts with sulphuric acids to from ethylammonium sulphate
2 CH3CH2NH2 + H2SO4 —> (CH3CH2NH3+)2SO4^2-
How can amines be prepared
1) reagents
2) conditions
3) nucleophile
4) equation
reagents
- excess alcoholic ammonia
conditions
- reflux under pressure
nucleophile
- ammonia (NH3)
equation
- C2H5Br + :NH3(acl) —> C2H5NH2 + HBr (or C2H5NH3+Br-)
Why is excess ammonia needed in the preparation of amines
Ammonia attacks halogenoalkanes because of lone pair. Amine produced also have a lone pair C2H5:NH2 so can also attack halogenalkane = substituted amines. Using excess ensure halogenoalkane react with ammonia before being able to react with any amine products.
Properties of amines
Amines are bronsted-Lowry bases as can be proton acceptors
They act as nucleophiles as lone pair attack electron deficient centre
Boiling point = higher due to H bonds
Solubility = low mass = more soluble also they form H bonds with other amines
Amines basicity effected by what groups and how
Benzene
* e- withdrawing so e- density on N and lone pair is less effective
So decreases the strength of base
Alkyl groups
* e- releasing so e- density on N increasing so lone pair is more effective
So increasing the strength of base
Reaction of amine with water
Amines + water —> weak alkaline solution
CH3NH2(g) + H2O(l) <—> CH3NH3+(aq) + OH-(aq)
Reaction of amines with acid
Amine + acid —> salt
C6H5NH3+Cl-(aq) + NaOH(aq) —> C6H5NH3+Cl-(aq)
Addition of NaOh(aq) - free base from its salt
C6H5NH3+Cl-(aq) + NaOH(aq) —> C6H5NH2(l) + NaCl(aq) + H2O(l)
Nucleophilic substitution of amines
…
Between methylamine & diethylamine which is the stronger base
Diethylamine is the stronger base as extra inductive effect of two alkyl groups compared to one. Diethylamine has greater electron density on N lone pair. Diethylamine therefore has greater ability to accept H+
Between phenylamine and propylamine which is the stronger base
Propylamine is the stronger base as the lone pair on phenylamine’s N id partially delocalised into e- ring (benzene). Propylamine has greater e- density on N lone pair so propylamine has greater ability to accept H+
Draw the structure of amino acid
+ what is its general formula
See notes
- amino acid is when the 2 functional groups amino and carboxylic acid are joined to the same carbon
General formula = RCH(NH2)COOH
Reactions of amino acids
with acids
With alkali
with acids
The amine group acts as a base to produce salt
(COOH)CHR(NH2) + HCl —> (COOH)CHE(N+H3) + Cl-
with bases
Carboxylic acid group acts to react to from salt and water
(NH2)CHR(COOH) + NaOH —> (NH3)CHR(COO-Na+) + H2O
Esterification reaction with amino acid and ethanol structural equation
(NH2)CHR(COOH) + (OH)CH2CH3 —> (N+H3)CHRC=OOCH2CH3 +H2O
Types of amino acid isomers
Can be L or R isomers- when produced these 2 steroidisomers form.
Chiral molecules are non-superimposable
*= chiral centre- carbons that are surrounded by 4 different group
Draw the chiral molecules of amino acids
Reaction of halogenoalkane with ammonia
(CH3CH2Cl)
CH3CH2Cl +NH3 —> CH3CH2NH3+Cl-
Chloroethane + ammonia —> ethylammonium chloride
What is condensation polymerisation?
When monomers join up with expulsion of small molecules (often H2O or HCl) to form a polymer
2 molecules that react to produce a large molecule and a small molecule
Which species from these function groups work to form smaller molecules during condensation polymerisation?
1- amines
2- carboxylic acids
3- alcohols
1- the H group on the amine
2- the OH group on the carboxylic acid
3- the OH group on the alcohol
Can also be a halogen group which reacts to form HX
