Functional groups determine
What they do and physical properties and REACTIVITY
Molecular shape
- influence function???
What it reacts with???
What are coenzymes
Small molecules that help enzymes catalyse reactions
Structure of coenzyme A
Fun facts about alcohols
- low molecular weight alcohols are soluble in water due to hydrogen bonding
- undergo nucleophillic substitution reactions
- can be oxidised
- form esters with carboxylic acids
What are primary alcohols oxidised to
Aldhyde
Carboxllyic
(Still primary after oxidation)
What are secondary alcohols oxidised to
Ketone
What are tertiary alcohols oxidised to
The dont
Oxidation’s in lab can be carried out with…
H+/Cr2O72-
Reducxtuion in lab can be a carried out with…
LiAlH4
Silver mirror test
- selectively oxidises alhdyde to carbox
Oxidation/reduction in living system
Ethanol enzymatically oxidised to ethanal in liver
Oxidant = coenzyme, NAD+
Reductant = coenzyme, NADH
Enzyme = alcohol dehydrogenase
Ester vs ether
- ethers may be cleaved but are generally unreactive
- Esters are more easily cleaved by reaction with nucleophiles
Amine structure
Amide
Imine
Difference between amides and amines
Amines are very basic
AMIDES are not appreciatbly basic or nucleophillic
- amides have a c=o next to the nitrogen which competes for loan pair of electrons
- amides are acid derivatives - can react with nicleophilles such as water but are not very reactive and are quite resisitant to hydrolysis
Sulfur containing functional groups
Thiol and disulphide oxidation and reduction
- can be achieved with quite mild oxidants - O2
- reverse reaction can occur with mild reductants
- happens redily
Phosphorus containing functional groups
H3PO4 forms a series of phosphate esters where the OH groups are successively replaces by OR groups from alcohols
- the phosphates with “hydrogen” in them are strong acids and are generally ionised at physiological pH - thus usually represented in ionic form
Example of a phosphate di - ester
- some are esters of glycerol
Phosphate groups…
- help to solubilise compounds in water
- are quite resistance to hydrolysis
Example of diphsophate
Biological recognition
- shape of biological target (host) controlled by factors including:
- polar / non-polar attractions and repulsion’s
- steric effects - interaction between large groups are avoided geometric contaisnts inposed by rigid structure such as:
- rings
- planar blocks of atoms found in amides
- chiral it’s is also important
