L5 - Synthetic Routes

objectives

Understandings:

• The synthesis of an organic compound stems from a readily available starting material via a series of discrete steps.
• Functional group interconversions are the basis of such synthetic routes.
• Retro-synthesis of organic compounds.

Applications and skills:

• Deduction of multi-step synthetic routes given starting reagents and the product(s).

Guidance:

• Conversions with more than four stages will not be assessed in synthetic routes.
• Reaction types can cover any of the reactions covered in topic 10 and sub-topic 20.1.

I will now attempt to go through each reaction step labelled with a letter as a revision of the unit and to show reaction sequences

A - Free Radical Substitution

• Due to the lack of reactivity of alkanes you need a very reactive species to persuade them to react
• Free radicals need to be formed by homolytic fission of covalent bonds
• This is done by shining UV light on the mixture (heat could be used)
• Chlorine radicals are produced because the Cl-Cl bond is the weakest
• You only need one chlorine radical to start things off
• With excess chlorine you will get further substitution and a mixture of chlorinated products

B - Electrophillic Addition of HBr

C - Electrophilic Addition of Bromine

D - Direct Hydration of Alkenes

E - Hydrogenation of Alkenes

Addition Polymerisation

G - Nucleophillic Substitution of NaOH

H - Nucleophilic Substitution of Ammonia

N - Oxidation of Primary Alcohols