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Amines are organic compounds, derived from ammonia, NH3 in which 1 or more H atoms in ammonia have been replaced by C chain or ring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
Draw the polymer made from reaction between amine and carboxylic acid
Amine + carboxylic acid
Polymerisation removes water from the H (amine) and OH (carboxylic acid)
R-N(H)-C(=O)-R
See notes
Examples of polymers
Polyamides (nylon)
Polyesters (terylene)
Peptides
Starch
Draw an ester linkage
O
||
–O— C —
With negative dipoles on the Oxygen groups
Positive dipole on the carbon group
Draw the amide linkage
Also called peptide link
O
||
— C — N —
|
H
Negative dipole on the Oxygen groups and Nitrogen group
Positive dipole on the carbon group
Draw the polymer produced from addition of propandiol + propandionic acid
See notes
What reacts to produce a polyester?
Made from DIOLS + DICARBOXYLIC ACIDS
Or
Made from monomers with 2 different function groups
Products of the acid hydrolysis of polyesters
Acid hydrolysis
Polyester + H+ —> dicarboxylic acid + diol
Product of base hydrolysis of polyesters
Base
Polyester + NaOH —> dicarboxylate salt + diol
( -give group on O with Na+ attached)
Products of Base hydrolysis of polyamines
Base hydrolysis
Polyamine + NaOH —> dicarboxylate salt + diamine
( negative charge on O attached to Na+)
Products of acid hydrolysis of polyamines
Acid hydrolysis
Polyamine + H+ —> diamine + dicarboxylic acid
Diamine is a carbon chain with amine groups on the end and the start
Dicarboxylic acid is a carbon chain with 2 carboxylic acid groups one one each end
Compare addition polymers and condesation polymers in terms of
The molecules that could be monomers
Addition
C=C bonds (alleles)
Condensation
Alcohols + acids
Amines + acids
Amino acids
Amines + acyl chlorides
Compare the addition and condensation polymers in terms of
Processes to form polymers
Addition
All the atoms in the original monomers end up in the polymer
Condensation
Monomers joined up with the expulsion of a small molecule (e.g water)
Compare the addition and condensation polymers in terms of
Bonding that occurs
Addition
Has alkane links
Condensation
Ester link (-COO-)
Amine (peptide) link (-CONH-)
Compare addition and condensation polymers in terms of
Reactivity of them
Addition
Unreactive due to no-polar
Resistant to hydrolysis
Condensation
Reactive due to polar bonds
Hydrolysis by acids and alkalis
Compare the addition and condensation polymers in terms of
Uses
Addition polymers
Packaging
Insulation
Condensation
Clothing
Ropes
Give some examples of addition polymers and condensation ones
Addition
- poly(ethene)
- poly(propene)
Condensation
- nylon 6,6
- terylene
- peptides
