heroin synthesis (diacetylmorphine)

Where people go wrong in this synthesis is the conversion of morphine to diamorphine (heroin. The problem is they use acetic anhydride as acetylating agent but add no catalyst. The key is to use greater than stoichiometric amounts of acetic anhydride and then add a catalytic amount of pyridine or DMAP (dimethylaminopyridine). This agent will greatly increase yields as it assists acetylation. Heat may not be required and times are drastically reduced. DMAP is preferable. (Do you know why? The Methyl groups push electron density into the pyridine ring making the Nitrogen more basic and Nucleophilic)

If you are synthesising from codeine then you probably have pyridine on hand anyway, so add a few drops to the final step.

In short - and THEORETICALLY - if you wanted to learn the chemistry of this synthesis you would;
React codeine with a slight excess of boron tribromide (BBr3)or Pyridine.HCl (the former is far superior). Moprhine - the product - is insoluble in chloroform so you can easily perform an extraction to both remove and recover unreacted codeine.

Next take the morphine - which is tricky in the sense that the phenolic group is prone to deprotonation at high pH so ph 9 is recomended for extraction - and mix with acetic anhydride and DMAP or pyridine (only 10 mol% at most) to give heroin which IS chloroform soluble so it is easy to seperate from the morphine. There you have it. FOR EDUCATIONAL PURPOSES ONLY.