Chapter 28, 29 and 30 - Amines, Polymerisation, DNA Flashcards
What are amines
They are compounds derived from ammonia
They have unpleasant ‘fishy’ odours
How are amines named
Suffix -amine
Prefix amino-
What are the 4 types of amines
Ammonia
Primary amine
secondary amine
tertiary amine
Quaternary salts - not amines
What is the structure of an aliphatic amine
It has an alkyl group attached to the N
What is the structure of an aromatic amine
It has the nitrogen attached directly to a benzene ring
What is a quaternary salt
It is a nitrogen with a positive charge attached to 4 molecules
What do amines act as
weak Bronsted-Lowry bases
What are Bronsted-Lowry bases
Proton acceptors
Why can amines act how they do
They have a lone pair on the nitrogen that can readily accept protons
What does the ability of an amine to act as a base depend on
How well the lone pair on the nitrogen can accept H+
What is the order of base strength from strongest to weakest
Tertiary
Secondary
Primary
NH3
aromatic amine
In aliphatic amines, what causes the ability of a nitrogen to accept H+ to increase
alkyl groups push electrons towards the nitrogen increasing the availability of the N lone pair
Increasing the ability to accept H+
inductive effect
In aromatic amines, what causes the ability of a nitrogen to accept H+ to decrease
The N lone pair is partially delocalised into the benzene ring, reducing the availability of the N lone pair so reducing its ability to accept H+
Reducing the base strength
What are aromatic amines used as
Used in the manufacture of dyes
How are aromatic amines made
Reduction of aromatic nitro compounds
Sn + HCl
How are primary aliphatic amines made
2 stages
From Haloalkane
What is the first stage of making primary aliphatic amines
Nucleophilic substitution
Add CN- in Aqueous Alcohol
Form nitrile
CH3Br + CN- -> CH3CN + KBr
What is the second stage of making primary aliphatic amines
Reduction
Ni catalyst
From nitrile to primary amine
CH3CN + 2H2 -> CH3CH2NH2
What is the other method to making primary aliphatic amines
Haloalkanes react with excess of concentrated ammonia
nucleophilic substitution
CH3Br + 2NH3 -> CH3NH2 + NH4Br
What is the mechanism for making a primary aliphatic amine the other method
Nucleophilic substitution
Lone pair on NH3 attacks carbon
Breaks bond between carbon and bromine towards bromine
Lone pair on NH3 attacks hydrogen
Bond between hydrogen and nitrogen breaks towards nitrogen
What are the advantages and disadvantages of making a primary aliphatic amine the second method
1 step
Doesn’t add another carbon to product
Reaction can repeat and form multiple products
What can happen in the second method after the intial reaction
The product can act as a nucleophile to another haloalkane
This causes further reactions forming a mixture of primary, secondary, tertiary amines and quaternary salts
This method can’t be used to make amines
In the second method what is the main product with excess NH3
primary amine
In the second method what is the main product with excess haloalkane
quaternary salt
What do amino acids contain
Amine group
Carboxylic acid
What are alpha amino acids
Amino acid with 1 carbon between the NH2 and COOH group
What do amino acids exist as in the solid state
zwitterions
Why do amino acids exist as zwitterions
Ionic
High melting point
Usually solids at room temperature
Soluble in water
What do zwitterions look like
Carboxylic acid is COO-
Amine is NH3+
When dissolved in water, what are amino acids sensitive to
pH
What do amino acids look like at a low pH
Amine is protonated - NH3+
Acid is undissociated - COOH
What do amino acids look like at a high pH
Amine unprotonated - NH2
Acid dissociated - COO-
What are the reactions of amino acids like
It involves either the amine or carboxylic acid group
What reactions does the amine group do
Protonated by acids (low pH)
Acylation with acyl chloride/acid anhydride
Nucleophilic substitution with haloalkanes
What reactions does the carboxylic acid in the amino acid do
Deprotonated by bases (high pH)
Acylation with esterification with alcohols (conc H2SO4 catalyst)
What product is made from reacting 2 amino acids
peptides + water
What is the peptide link
The bond between the 2 amino acids
CO -NH
COOH loses OH
NH2 loses H
What are addition polymers
They are long chain molecules formed from lots of small molecules (monomers) joined together to form 1 big molecule (polymer)
How are addition polymers formed
When alkenes undergo self addition
What is the monomer structure
The structure of the monomer by itself
What is the polymer structure
The monomer structure when in the polymer with brackets around outside bonds
What is the repeating unit
The monomer structure with bonds to other monomers
What are condensation polymers
Long chain molecules formed from lots of small molecules (monomers) join together to form 1 big molecule (polymer) with another small molecule formed as well
What are condensation polymers normally made from
2 different monomers each with 2 functional groups that can react together
What are polyesters formed from
Dicarboxylic acids with diols
What is the bond between polyesters
OH from COOH
H from OH react together to form water
Forms COO bond
What is an example of polyesters
Terylene
Made from benzene-1,4-dicarboxylic acid and ethane-1,2-diol
What are polyamides
Polymers formed from dicarboxylic acid and diamines
Form peptide link
What is an example of polyamides
nylon - 6,6
Kevlar
What are addition polymers known as
Plastics
What are polyalkenes
addition polymers
saturated
What are the properties of addition polymers
unreactive
chemically inert
What are the advantages of the properties of addition polymers
Safe
Durable
What are the disadvantages of the properties of addition polymers
Don’t biodegrade
Pollution hazard
Difficult to dispose of
How are Non-Biodegrable polymers disposed of
Landfill
Incineration
Recycling
What is Landfill
Polymers are buried in sites dedicated to waste
Land available is limited though
What is incineration
Polymers are burned
Releases lots of heat energy which can be used to generate electricity
Carbon Dioxide is released - global warming
Toxic gases can also be produced under certain conditions
What is recycling
Reusing polymers
Not always practical - expensive to separate
Protects the useful hydrocarbon resources
What does the amide and ester links in poly amides and polyesters do
They can react with acids and bases causing the polymer structure to break reforming the monomers
Called hydrolysis
What are the properties of condensation polymers
Biodegradable
What are molecules formed up to 50 amino acids joined together known as
Polypeptides
What are molecules with more than 50 amino acids joined together known as
Proteins
What are proteins
Polymers of amino acid monomers
What are the 3 structures of proteins
Primary
Secondary
Tertiary
What is the primary protein structure
Amino acids joined in a chain
What is the secondary protein structure
Amino acids form a beta-pleated sheet or a alpha helix
Folding of its polypeptide chain
What are the tertiary protein structures
A combination of the beta-pleaded sheets and alpha-helix’s
What causes secondary protein structures
Hydrogen bonding interactions between C=O and N-H groups from different sections of the chain
How do the hydrogen bonds form
Nitrogen and oxygen are electronegative so C=O and N-H bonds are polar
Lone pair on oxygen atom is attracted to delta positive hydrogen of N-H forming a hydrogen bond
What bonds are there in a tertiary structure
Van Der Waals forces
Hydrogen bonds
Ionic Bonds
Disulphide bridges (covalent bonds)
How can peptides be broken down
By hydrolysis
Produces individual amino acids that they were formed from
What are conditions for hydrolysis
HCl and boil for 24 hours
or
Enzyme
What are enzymes
They are protein molecules that act as biological catalysts
They have an active site where the reaction takes place
What do enzymes react with
Molecules called substrates
Why do enzymes only work with certain substrates
The active sites are very particular shapes
They are stereospecific
What are inhibitors
Molecules with similar shape to the active site can compete with the substrate molecules
They can block the active site so no substrate fits in
How do many drugs work
Using enzyme inhibition
e.g. aspirin, penicillin
What is DNA stand for
deoxyribonucleic acid
What is DNA
A polymer
Present in all living cells
Formed from nucleotides (monomers) join together
What is the structure of DNA
There are 2 polynucleotide chains (strands) spiralled together in a double helix structure
What is a nucleotide
Phosphate bonded to a deoxyribose sugar which is bonded to a base
What are the bases
Adenine
Guanine
Cytosine
Thymine
How is a nucleotide formed
Phosphate attaches to the 5th carbon in the sugar
N-H on Base attaches to the 1st carbon
How does the phosphate bond to the sugar
H from OH on phosphate and OH from sugar react
Bond between Oxygen and CH2
How does the phosphate from the other nucleotide bond onto the sugar
OH on phosphate reacts with H on the 3rd carbon on the sugar
Produces water
How are the 2 strands of DNA held together
Base pairing
How are the bases paired
Adenine - Thymine
Cytosine - Guanine
How do the bases bond together
AT - Bond between NH and O
Bond between N and NH
GC - Bond between O and NH
Bond between NH and N
Bond between NH and O
What are the 2 strands described as
complementary
What is cisplatin
A complex of platinum(ll) with 2 chlorides and 2 ammonia ligands
Successful anti-cancer drug
What causes cancer
When cells in the body divide and replicate uncontrollably forming tumours
How do cells divide
A cell replicates its DNA
The strands unwind so they can be copied
How does cisplantin work
It attaches to N atoms of nearby guanine bases in DNA
Ligand replacement reaction
This stops strands unwinding so the cell can’t replicate properly
What are the side effects of cisplantin
Hair loss
Nausea
Immunosuppresion
What are the solutions to the side effects of cisplantin
Use lowest therapeutic dose
Develop new drugs
Find ways of targeting the cancer cells directly
Why don’t addition polymers undergo hydrolysis
The c-c bonds are too strong
Or No polar groups/Non-polar
Depends on alkene
What are the uses of quaternary salts
Hair conditioner / disinfectant
