Structure of meprobamate (source: Wikipedia) |
Meprobamate is an amide derived from carbamic acid. More specifically, from a dicarbamate of a diol in this case.
Carbamic acid: NH2COOH. It does not exist on its own, it automatically splits into NH3 and CO2.
The two clear amide bonds are indicated with the red circles.
Full name of meprobamate is: 2-methyl-2-propyl-1,3-propanediolcarbamate.
Properties
It is a white crystalic powder or forms colourless crystals.
It tastes quite bitter, acrid even.
It is sparingly soluble in water at a temperature of 25 °C, a little but more soluble at a higher temperature of 50 °C and it's good soluble in alcohol.
How to identify meprobamate
- Specific melting point of 104-108 °C
- Can look at the IR (infrared) spectrum
- Adding acetic acid anhydride and sulfuric acid (H2SO4) will form a precipitate with a very characteristic melting point of 124-128 °C = N,N-diacetylderivate is formed out of the acid reaction.
- Adding an alcoholic KOH (Potassium hydroxide), while under a reflux setup, and adding acetic acid together with cobaltnitrate (Co(NO3)2) will form an intense blue colour.
Content
Cook the a solution with an excess of H2SO4 under reflux during about 3 hours straight.
After cooling down the solution, add an excess of NaOH, then, distil.
NH3 is formed and will be caught in a 40 g/L boric acid solution.
Titrate with a 0,1 M HCl on methyl red as indicator.
Basically: Ammoniumsulfate is formed (NH4)2SO4 - adding NaOH will form NH3 - which is caught in boric acid to keep NH3 in solution. Then a titration on this NH3 is done.
Moles of HCl = Moles of NH3, and this way the content can be determined.
Practical use of meprobamate
It's used as a weak tranquilizer, a sedativum, anxiolyticum and muscle relaxans.
Although, it has to be noted that habituation occurs, physical and psychological.
It also is an enzyme inducer, so special care with other in-take of medicines needs to be noted. Also toxic!
Its use dates back, now it sees almost no use anymore, and is replaced with the more modern benzodiazepines.
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