Hi,
I have done a bit of research into your problem and maybe can help.
Rifampicin is a is a pretty specialised antibiotic that is used to treat menegitis and i would worry as to why it was in the house in the first place. There is a possibility that you should wear extra ppe when dealing with this client as its likely that they have something rather nasty if they need to take this medcine.
here is some data on the structure :
http://www.bmb.leeds.ac.uk/mbiology/ug/ugteach/icu8/antibiotics/antimycobacterials.htmlHaving worked in big pharma, i can tell you that most drugs are not coloured but its the dyes that they add to the drugs to make them look better. Eg, I worked a Pfizer and they spent weeks (8 man team of some of the most intelligent people to grace this earth) removing a coloured impurity from a slimming pill. The best bit about it is, the pills were for dogs.... yeah they care about the colour of their tablets... o yeah and in addition to this... they were going to sugar coat the drug anyways. hahaha, idiots.
Alas, looking at the structure of the drug it may be
soluble in acid: try vinegar (piperidine moiety in the bottom right as drawn)
soluble in alkali: try sodium bicarbonate (numerous phenolic residues througout the structure)
Soluble in solvent: try dry cleaning solvent (tetrachloro ethylene)
try acetone (nail varnish remover)
However, Looking at the structure i would be a little concearned as to what it might do in the presence of strong alkali or acid. It is set up to do sigmatropic rearrangements in the top right ring as drawn and it contains an acetal which will open in the presence of acid.
Regardless of my ramblings, it should be soluble in solvent or mild alkali.
Let me know how you get on,
Hope this helps
Graeme Thurston
Access Cleaning Solutions