I recently spotted some glucosamine HCl tablets that my grandfather takes every day, so I decided to utilize some of that. The ingredient list said
that it was pure glucosamine HCl.
2 Tablets were crushed to a powder. At the same time, some saturated sodium hydroxide solution is prepared. They were combined at room temperature.
After a day, the solution now looks oily, with the chunks of tablets going soft. Did I do something wrong? I am relatively new to working with organic
chemicals, so I might have broken a rule that I don't know about. Also, is free glucosamine soluble in water?Nicodem - 9-2-2012 at 14:24
The ingredient list said that it was pure glucosamine HCl.
That might just as well mean that the glucosamine hydrochloride is pure, but it does not necessarily mean that there are no binders and other
excipients in the tablets. Have you weighted the tablets to check the amount of additional material?
Quote:
After a day, the solution now looks oily, with the chunks of tablets going soft.
So you are saying the tablets did not entirely dissolve in water? Does not sound like pure glucosamine hydrochloride to me.weiming1998 - 10-2-2012 at 01:14
No, on the ingredient list it said: Each tablet contains 1500mg glucosamine HCl. The tablet looks about that weight, though I don't have an accurate
scale.
Anyway, Now I diluted, then filtered off the solution. It now looks an orangy-brown colour, like the colour you get when you dissolve meat in a sodium
hydroxide solution. I assume that the binder is some kind of fatty acid/protein, but I could be wrong. The binders in the tablets are going to be
designed to break down in an acidic environment, like your stomach, so I can try using a liquid acid, boil, filter, evaporate, then put in hydroxide.weiming1998 - 10-2-2012 at 06:29
When I tried to boil the tablets with dilute acetic acid, it took the binder off very effectively. I have then got a light orange solution of
glucosamine hydrochloride. I boiled the solution until crystals of glucosamine formed on the surface. Now, the solution was almost black. When I tried
to react it with NaOH, a strange thing happened. It reacted exothermically with the solution, but it was about as exothermic as trying to pour NaOH
into hydrochloric acid! Also, from the smell, the vapours are not water, they are ammonia! I do not think that the hydroxide ion was strong enough to
react with an amide to produce ammonia. So what might be the reason for ammonia evolution? weiming1998 - 13-2-2012 at 00:53
Oh, I get the ammonia evolution now. The NH2- ion inside glucosamine is so alkaline that it deprotonates water, forming NH3 and glucose. So the
reaction between NaOH/KOH and glucosamine HCl must be done in a water-free solvent. Do you have any idea what to use as a solvent that is easily
available? Alcohol wouldn't work (I think) because the NH2- will exchange the OH- in ethanol, forming ethyl amide and glucose.
For some reason, I cannot edit my previous posts. The button is gone.
