DESIGN AND CHEMISTRY MATERIALS

BY: ITSDANICAPUTRY’S

DESIGNING NEW MEDICINAL DRUGS

The intermolecular bonds formed between the drug and its target molecule involved:Hydrogen bonding.Ionic attraction.Dipole-dipole force.Van der waals force.

Molecular modelling: has greatly speeded up the process of designing new medicines.

Molecular modelling on computer is used when designing medicine and other compounds (e.g. pesticides and polymers).Type of sesearch was used to make AIDS drugs in the late 1980s and 1990s.

Pharmaceutical industry: searching for new drugs.Most of the drugs contain at least one chiral centre.Using conventional organic reaction to make desire product will yield a 50:50 mixture of the two enantiomers ( 2 non-superimposable mirror images).

Benefits using pure enantiomers:Reduces the patient’s dossage by half.Protects drug companies from possible litigation.Three ways to prepare pure enantiomers:Optical resolution.Using optically active starting materials.Using a chiral catalyst.

CHIRALITY IN PHARMACEUTICAL SYNTHESIS

Optical resolution:Following a traditional shynthetic route to make the compound, resulting in a racemic mixture, then they separate the two enantiomers in a process.Using a chiral auxiliary that will react with one of the isomer in the mixture.Separated by physical, e.g. the solubility in a solven will differ, the unwanted enantiomer and the new product can be separated by fractional crystallisation.Large volume of organic solvents are used in the process.Chemistry are now using supercritical carbon dioxide as a solvent.

Using Optically Active Starting Materials:Uses starting materials that are themselves optically active and in the same orientation as the desired product.These are often naturally occuring compounds such as carbohydrates or L-amino acids.The synthetic route is desinged to keep any intermediates and the final product formed in the same enantiomeric form.

Chiral catalystEnsure only one specific enantiomer is formed in a reaction.The benefits:Only small quantities are needed.They can be used over and over again. Enzyme are often immobilized: allow the

reactants to be passed over without the need to separate the product from the enzyme after reaction.Use an enzyme process might take a longer develop than a conventional synthetic routeBut.....the benefits will be generally outweigh the disanvatages.

Pharmaceutical industry:make pure enantiomer from optical resolution and chiral synthesis.Use enzymes to promote stereoselectivity and produce single-enantiomer products.The specific shape and the nature of the molecular is interactions at the active site, only one enantiomer is formed.

DELIVERY OF DRUGSNano-cages of gold: using to deliver drugs to

target sites in the body.

The tiny gold particles can be selectivity absorbed by tumours. It heated up, and destroys the tumour without damaging healthy cells.

Coated by by a polyethylene glucol (PEG), this stops the immune system from attacking the gold particles and ejecting them from the blood stream.

Using liposomes:Liposomes: tiny membrane bubbles, usually made of phospholipid.Has water loving (hidrophilic) head.Water hating (hidrophobic) tail.Liposomes are using to the delivering drugs because a water-soluble drug can be carried in aqueous inside the liposome.A drug in the dissolves in fat can be transported in in the fatty layer of the wall made up of the tails of the molecules.Biodegradable and relatively non-toxic.Works in cancer treatment in a smiliar way with nano cages of gold.The liposomes are smiliar in size and can get throught the loosely packed walls of a tumour blood vessels, without throught the walls of the healthy blood vessels.Liposomes can fuse with cell membranes which have a smiliar structure and deliver contents inside the cell.Usage for skin treatment.

Designing polymers PEG is made from monomers of epoxyethane(is

a reactive cyclic molecule, CH2CH2O) reacted with 1,2-ethanodiol.

PEG often used as liquids or low melting point solids.

Solubility in water. Non-polar solvents.

The water in the timbers is replaced by PEG and the remains of the ship can then be slowy dried out without crumbling away.

Inspired by natural polymeric material: Neoprene was made from the polymerisation of the

monomer 2-chloro-1,3-butadiene in an addition reaction.

The intermolecular forces between natural rubber polymers are Van der Wall’s forces.

Vulcanisation process was invented to make rubber tyres more resilient and hard wearing.

Kevlar (founded in 1970): synthetic polyamide with strong intermolecular forces.

Use of kevlar:1. Bullet-proof vests.2. Racing leathers for motorbike

riders.3. Strength arises from the hydrogen

bond between its polymer chains.4. Linear polymer chains.The role of side chains:LDPE: low density poly(ethene), produced in 1930s, softened plastic at relatively low temperature.HDPE: high density poly(ethene), produced in 1950sCarl Zeigler discovered a catalyst that resulted in straight polymer chainsHDPE is stronger than LDPE.

Poly(lactic acid), PLA.

Is a polyester.Becoming increasingly popular because the starting material used to produce it comes from plant starch.Biodegrability.Reduces greenhouse gas emission by around 30-50% compared with the manufacture and use of traditional oil-based plastics.The lactic acid molecules can undergo esterification (a condensation reaction) forming water as well as the polymer.Lactic acid (2-hydroxypropanoic acid) molecule has an alcohol and carboxylic group within each molecule.

NANOTECHNOLOGY

Nanotechnology: design and creation of machines that are so small to measure them in nanometers. 1nm = 10-9 m

Aim: making machines that are less than 100nm in size.

Two approaches to making the molecular machine:1. Sculpt at material until left with the molecules or atoms on the surface.

Microelectronis at the molecular level uses this technique.2. Developments involve building machine up from individual atoms or

molecules, and do this by physically moving the molecules using atomic force microscopes.

Special polymers called conjugate polymers that expand and contract when involved in transferring electrons.

Buckyballs The discovery of a form of carbon

first triggered interest in nano-particles and the field of nanoscience. Sir Harry and 2 other scientist have discovered it, and get noble prize in 1996s.

Fullerenes: a close relative is the ball shaped molecule (C70).

Bucky tubes Bucky tubes have also been made

called nanotubes, consist of a single rolled up sheet of carbon atoms in the graphite structure an are incredibly strong.

Fibres of tube can reinforce materials, such as those used in bullet-proof vests.

The tubes have free electrons, can be use in electrical equipment.

Benefits: Lighting. Molecular electronic Hydrogen fuel in transportations.

FIGHTING POLLUTION

Problem: CFCs (chlorofluorocarbons)CFCs are unreactive ande non toxic compound in normal conditions.CFCs are reactive in the atmosphere.

The problems might appears if more UV light reaches:Increase risk of sunburn.Faster ageing of skin.More skin cancer.Damage eyes, such as cataracts.Reduced restitance to some diseases.Disruption of plant photosynthesis, and food chains.

In the stratosphere, the UV light from the sun breaks up their molecules, high reactive chlorine atom splits off. Forming a chlorine free radical.

Adding 2 propagation reaction together gives the overall reaction:Cl* acting as a catalyst because it is constantly regenerated by the reaction of the ClO* free radical with an oxygen atom formed when an O3 molecule is broken down bu absorbed UV light.

GREEN CHEMISTRY6 important principles of a greener chemical industry:1. design of processes to maximize the amount of

raw material that’s converted into product. E.g. synthesis of ibuprofen, this principle improved the atom economy to 77.4% making more efficient use of the raw materials and creating less waste.

2. The use of raw material or feed stock that are rewenable rather than finite. E.g. biofuels, such as biodiesel and ethanol.

3. The use of safe, enviromentally friendly solvents, or no solvents at all where possibles. The use of auxiliary substances (e.g. solvents , separation agents, etc.) should be made unnecessary wherever possible.

4. The substances used in a chemical process should be selected to minimise the potential risk of chemical accidents.

5. The design of energy-efficient processes, the energy requirements of chemical process should be minimised to reduce their impact on the enviroment and the costs.

6. The consideration of waste reduction in the production process and at the end of a product’s lifecycle, aiming not to create waste in the 1st place.