OCR CHEMISTRY A2 module 2: polymers and synthesis

this is a set of notes made from the OCR A2 chemistry book, it has all the information in, just in a more concise bullet pointed format including all the pictures from the reactions that are in the book

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  • Created on: 17-10-11 19:20
Preview of OCR CHEMISTRY A2 module 2: polymers and synthesis

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Polymers and synthesis
Amino acids
Amino acids are the building blocks for two groups of biological molecules:
Peptides
Proteins
Proteins act as enzymes , hormones and antibodies, they transport substances such as oxygen, vitamins and minerals to cells in
the body.
Structural proteins such as collagen and keratin are responsible for bones, teeth, hair and skin.
The body has 20 different amino acids, each have a amine group, a carboxylic acid group and a variable `R' group.
HN = amine group
O=COH = carboxyl group
R= variable side chain
Zwitterions
The carboxyl group and the amine group can interact to form a internal salt known as a zwitterions.
A proton is transferred from the acid to the amine group (making NH3)
A zwitterions has no overall charge because the charges cancel out

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Proton is transferred from OH bond to the NH2 bond making NH3+ and COO
The isoelectric point is the PH where there is no net electrical charge. The zwitterions exists at this PH. Each amino acid has a
different isoelectric point
At a more acidic PH than the isoelectric point:
The amino acid acts as a base and accepts a proton from the acid and forms a positively charged ion.…read more

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Proteins are polypeptides with generally more than 50 amino acids.
Hydrolysis of polypeptides
Acid hydrolysis
Polypeptides and proteins can be
hydrolysed using aqueous acid, water is
added to break up the peptide bond
and make its constituent amino acids.
The amino acids are positively charged
due to the addition of the H+ ions.
The protein is usually heated under reflux with 6mol dm3 HCL for 24 hours.…read more

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Optical isomerism
Optical isomerism occurs when a carbon atom is attached to for different groups, this is know as a chiral carbon.
If a molecule has a chiral centre then a mirror Image is possible, they are non super imposable and are optical isomers (or enantimers)
Optical isomers are chemically identical just rotated differently.…read more

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Condensation polymerisation
bond forms between a amine group and a carboxyl group
amide link forms and waters released…read more

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Polyamides are used in clothing and protective equipment (Kevlar)
Addition polymerisation
addition polymers are made from one monomer only
there is only one product (the polymer)
Condensation polymers
the joining of monomers with the elimination of a small molecule (H2O or HCl)…read more

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NaOH or hot HCl (hot HCl is slower)
hydrolysis of polyamides
hydrolysed by hot NaOH
or hot HCl
degradeable polymers
biodegradable polymers have
chemical bonds that can undergo
hydrolysis for example:
poly(lactic acid) derived
from corn starch
poly(glycolic acid) isolated from sugar
cane and unripe grapes
these polymers are replacing oilbased products.
Photodegradable polymers
Photodegradable plastics are synthetic polymers that become weak when exposed to sunlight. The polymers are blended with
light sensitive additives that catalyse the breakdown of the polymer.…read more

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Alternatively C=O bonds can be incorporated into the backbone of the molecule, the double bond absorbs the light energy and
breaks the polymer chain.
Chriality in pharmaceuticals
A chiral carbon is a carbon atom that has 4 different groups attached to it. Each chiral carbon has 2 stereo isomers. So if there
is 2 chiral carbons there are 4 stereo isomers
in the 1950's a drug called thalidomide was made to prevent morning sickness in pregnant women.…read more

Comments

Anika

these notes are really good.

 

Thank you =)

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