Synthesis of Drugs

Define organic synthesis. the construction of organic molecules (which mainly contain C, O, N, and H), into other organic molecules, via organic reactions Give an example of organic synthesis. synthesis of paracetamol - the starting material, phenol, is cheap and readily available, this is then transformed into paracetamol via three steps/reactions. Why do organic reactions happen? - molecules react because they can move - in liquid or gas form, whole molecules move around continuously - if different molecules are mixed together, they continuously bump into each other - if collisions are favourably aligned (where their electrons orbitals overlap) and these collisions also have sufficient energy, a bond is formed to give a new molecule What can most organic reactions be categorised into? - addition reactions - elimination reactions - substitution reactions - oxidation and reduction reactions - rearrangement reactions What is functional group interconversion? where one functional group is transformed into another What is a conjugation reaction? where two molecules react to make a larger molecule, these involve functional group interconversion What are primary alcohols oxidised to? aldehydes What are aldehydes oxidised to? carboxylic acids What are secondary alcohols oxidised to? ketones by changing the 'OH' group to a 'Cl' group 1/3 How are carboxylic acids converted to acid chlorides? What are alkynes reduced to? alkenes What are alkenes reduced to? alkanes Define an electrophile. the molecule which accepts electrons to form a new bond (electron loving) Define a nucleophile. the molecule which donates electrons (nucleus loving) Describe the rules of drawing mechanisms. the start of the arrow is always at the electrons which are being used to form the new bond e.g., lone pair, negative charge, or bond the point of the arrow goes to the electropositive atom to which the new bond will be attached Define equilibrium law. when a system at equilibrium is disturbed, then the equilibrium readjusts itself to counteract the effect of the applied change and will work to establish a new equilibrium What does a reaction of an amine with an acid form? an amide and water esters are often used to mask the corresponding acid, which tend to have poor How is ester hydrolysis used in the conphysicochemical properties text of drug delivery? the ester is hydrolysed at the site of action liberating the active drug Describe ester hydrolysis. slow even in boiling water and requires accelerating this can be done through the use of acids, bases, or enzymes What is deprotonation? loss of hydrogen ions What is protonation? gain of hydrogen ions 2/3 What can happen if reactions don't stop the product goes on to react with some where we would like them to? more of the starting materials What is an example of the product reacting with some more of the starting materials? where an amine reacts with an organic halide the product is still nucleophilic and therefore will react further with the organohalide until the ammonium ion is produced How can you overcome the over alkylation of amine? reductive amination here the amine reacts with the electrophilic carbonyl to give an imine this is then formally reduced to give a mono-substituted/primary amine Define rearrangements. where the molecule is able to reorganise itself into a substitution pattern which is more stable or lower in energy How do you functionalise benzene? you need to use a good reactive electrophile as the delocalised electrons in benzene make it more stable (lower in energy) than an alkene, so it is less likely to react Define semi-synthesis. utilises compounds which have been isolated from natural sources (plants/bacteria/cell cultures) as starting materials chloramphenicol is considered to be a prototypical broad-spectrum antibiotic Describe the synthesis of chlorampheni- useful for the treatment of a number of col. bacterial infections it is cheap and easy to manufacture, frequently an antibiotic of choice 3/3