[header] How to synthesise organic compounds [title] Check if the starting chemical is a mixture. [step] If your starting chemical is something like crude oil, you'll need to use distillation or fractional distillation to separate it into parts. [title] See if the starting and target chemicals have any groups in common. 
[step] For example, they may contain an amine group or a carboxyl group, etc. [title] If the starting chemical is a mixture, look at which parts can be used.