Amines, Amino acids and polymers Flashcards
What is an amine
derivative of ammonia NH3
classified as primary, secondary or tertiary
aliphatic amine consists of N atom attached to at least 1 straight or branched carbon chain
aromatic- N attached to aromatic ring
Classifying amines
Primary- R–N–H 1 alkyl group attached
H
secondary- R–N–R 2 alkyl group attached
H
tertiary- R–N–R 3 alkyl group attached
R
naming amines
suffix amine
find longest C chain with N attached and name
use N to show position of branched chains attached to amine group
if 2 of same group attached just use Di- prefix
How does an amine react as a base
Weak base - only partially dissociates
accept proton from an acid
N atom donates lone pair of electrons
forms dative covalent bond with a proton
amine=proton acceptor
amine base acid reaction
Amine + base –> ammonium salts
e.g.
C2H5NH2 +HCl —> C2H5NH3+Cl-
or
CH3CH2NH2 + H2SO4 –> (CH3CH2NH3+)2 SO42-
Name- amine first then acid suffix
preparation of an aliphatic amine A
from Haloalkane
Reagents- ammonia + haloalkane
conditions: excess ammonia dissolved in ethanol (H2O would produce aldehyde)
reaction type: nucleophilic sub
overall: CH3CH2CH2Cl + NH3 –> CH3CH2CH2NH2 + HCl
technically in 2 stages :
CH3CH2CH2Cl + NH3 -> CH3CH2CH2NH3+ Cl- (salt formation)
CH3CH2CH2NH3+ Cl- + NaOH –> CH3CH2CH2NH2 + NaCl + H2O (amine formation)
same mech as other nucleophilic sub - break c-cl bond then arrow from ammonia to C
then draw intermediate, arrow from N-H bond to N and arrow from Cl- to that H
Further substitution in aliphatic amine
primary amines can undergo further sub
where the H groups on the N are replaced another alkyl chain can happen once or twice ( form di or tri amines)
e.g. CH3CH2CH2Cl + CH3CH2CH2NH2 –> (CH3CH2CH2)2NH + HCl
technically in 2 stages :
CH3CH2CH2Cl + CH3CH2CH2NH2 -> (CH3CH2CH2)2NH2+ Cl- (salt formation)
(CH3CH2CH2)2NH2+ Cl- + NaOH –> (CH3CH2CH2)2NH + NaCl + H2O (amine formation)
disadvantages of Further substitution in aliphatic amines
low % yield of desired product/amine
sep by fractional distillation of desire amine from mixture is needed and costly
How doe you avoid Further substitution in aliphatic amines
Use excess ammonia
Preparation of an aliphatic amine B
from nitrile
Reagents: Nitrile and H2
Conditions: Nickel cat
Reaction type: reduction
overall equ: CH3CH2CN + 2H2 –> CH3CH2CH2NH2
OR reagent of NaCN / KCN dissolved in ethanol - nucleophilic sub
preparation of an aromatic amine
Reagents: Nitroarene, tin (Sn) and conc HCl
Conditions: Heat under reflux (till all tin dissolves)
Reaction: Reduction
Overall: C6H5NO2 + 6[H] –> C6H5NH2 + 2H2O
C6H5NH2 - phenylamine
Amide functional group
O
=
R-C-N–
l
Classifying amides
Primary- CO–N–H 1 carbon groups attached H
secondary- CO–N–C 2 carbon groups attached H
tertiary- CO–N–C 3 carbon groups attached C
naming amides
use suffix amide
then name longest chain
use N to signify branching off N - still use prefix from branching e.g. methyl
preparation of amides- acyl chlorides
Reagents: acyl chlorides with ammonia and amines
No conditions
overall reaction:
CH3COCl + 2NH3 –> CH3CONH2 + NH4Cl
this produces a primary amide but you can produce other types as well using e.g. CH3NH2 or (CH3)2NH
preparation of amides- carboxylic acid
Only seen in production of polyamides
Reagents: carboxylic acid, amine
No conditions
Overall:
CH3COOH + CH3NH2 –> CH3CONHCH3 +H20
Primary amine forms secondary amide
different types of hydrolysis of amides
Acid-catalysed hydrolysis
Base-catalysed hydrolysis
Acid-Catalysed hydrolysis of amides
Reagent: HCl (aq) - must be aq (can be any acid)
Conditions: Heat
produces a carboxylic acid and ammonium salt - breaks the C-N bond
overall:
CH3CONHCH3 + HCl (aq) –> CH3COOH + CH3NH3+Cl-
Base-Catalysed hydrolysis of amides
Reagent: NaOH (aq) - must be aq (can be any alkali)
conditions: heat
produces carboxylic acid and an amine- breaks the C-N bond
Overall:
CH3CONHCH3 + NaOH –> CH3COO-Na+ + CH3NH2
alpha Amino acid general formular
H H O
N C C
H OH
Amin acid def
definition:
Basic amine group - NH2
Acidic carboxyl group - COOH
attached to same C
How many naturally occurring amino acids are there
20
Amino acid reaction- amine group
NH2 is basic and accepts protons - reacts with acid
neutralisation- produces salt
Overall:
NH2C(CH3)HCOOH + HCl –> NH3C(CH3)HCOOH + Cl-
Amino acid reaction - carboxylic acid (neut)
COOH is acidic and donates proton - reacts with alkali
Neutralisation- produces salt
Overall:
NH2C(CH3)HCOOH + NaOH –> NH2C(CH3)HCOO-Na+ + H2O
Amino acid reaction - carboxylic acid (esterification)
Overall:
NH2C(CH3)HCOOH + C2H5OH + H+ –> NH2C(CH3)HCOOC2H5 + H2O
Stereoisomer definiton
same structural formular but diff spatial arrangement of their atoms
Optical isomer definition
pair of non superimposable mirror images of 1 another
contain chiral centre
Chiral centre
carbon atom with 4 different groups attached
Drawing a pair of optical (Enantiomers)
drawn using tetrahedral shape (109.5) about the Chiral C
other isomer is drawn as the mirror image
so if the — line is on the left of 1 it will be on the right of the other with same group attached
equation for the number of optical isomers
2^n n= no of chiral centres
what is a racemic mixture
equal amounts of 2 optical isomers in a mixture
Addition polymerisation of alkenes
alkene monomers can join to form long saturates molecules called addition polymers
in addition polymerisation
reagent: alkene monomer
Conditions: high temp and pressure + catalyst
A D ( A D )
general equation: n C=C —>( –C-C– )
B E ( B E ) n
Alkene monomer —> alkane polymer
processing waste addition polymers, benefits
benifitits for sustaiabiltiy by:
combustion for energy for production
removal of toxic waste products e.g. HCl
use as an organic feedstock for production of plastics and other organic chemicals
sorted and recycled
how to minimise environmental damage when managing polymers
develop biodegradable polymers and can be broken down by microorganisms
e.g. PLA made from lactic acid
develop photodegradable polymers- oil based polyemers which bonds weaken by absorbing light
use alkaline scrubber to neutralise toxic gases e,g, HCl produced when burning
Problems with disposal of addition polymers
NON biodegradable- non polar C chain doesnt breakdown by hydrolysis very stable dont breakdown naturally
Burning produces toxic gas e.g. Cl2 or HCl
Condensation polymerisation
2 monomers with diff functional groups
or 1 with 2 functional groups
H2O or HCl (small molecule) is lost
forms: polyesters and polyamides- fibres in clothing
Polyesters formation (carboxylic acid)
reagents: dicarboxylic acid + diol
condensation polymerisation
loose H2O to form ester bond COO lose OH from acid and H from alcohol)
same equation as addition
Polyesters formation (Acyl chloride )
reagents: diacyl chloride + diol
condensation polymerisation
loose HCl to form ester bond COO lose Cl from acyl and H from alcohol)
same equation as addition
Polyesters formation (1 monomer)
reagent: monomer with Carboxylic acid and alcohol functional group
condensation polymerisation
loose H2O to form ester bond COO lose OH from acid and H from alcohol)
same equation as addition
Polyamides formation (carboxylic acid)
reagents: dicarboxylic acid + diamine
condensation polymerisation
loose H2O to form amide bond CONH (lose OH from acid and H from amine)
same equation as addition
e.g. kevlar
Polyamides formation (acyl chloride)
reagents: diacyl chloride + diamine
condensation polymerisation
loose HCl to form amide bond CONH lose Cl from acyl and H from amine)
same equation as addition
Polyamides formation (1 monomer)
reagent: monomer with Carboxylic acid and amine functional group
condensation polymerisation
loose H2O to form amide bond CONH lose OH from acid and H from amine)
same equation as addition
Hydrolysis of polymers- basics
add- cant be hydrolysed as non polar bonds C=C
con- can be hydrolysed due to polar bonds
COO or CONH
Acid or base
Acid cat hydrolysis of polyester
Reagent- HCl(aq) / any aq acid
conditions- heat
products- dicarboxylic acid + dialcohol
base cat hydrolysis of polyester
Reagent-NaOH(aq) / any aq base
conditions-heat
products-salt of dicarboxylic acid and dialcohol
Acid cat hydrolysis of polyamide
Reagent- HCl(aq) / any aq acid
conditions- heat
products- dicarboxylic acid and ammonium salt of diamine
base cat hydrolysis of polyamide
Reagent-NaOH(aq) / any aq base
conditions- heat
products- Salt of a dicarboxylic acid and a diamine
degradable polymer def
polymer that breaks down into smaller fragments when exposed to light, heat or moisture
undergo hydrolysis
biodegradable polymer def
polymer that breaks down completely into CO2 and H2O
undergo hydrolysis
e.g. PLA - derived from Corn starch
Photodegradable polymer
Condensation polymers contain C=O bonds are photodegradable
C=O absorbs light radiation - breaks
