I would like to prepare Tolmetin from Tolmetin sodium salt dihydrate (TSSD). TSSD is an commercial product, however I would like to work with Tolmetin only.
A good general procedure for generating free acids from their sodium salts is to simply partition a portion of the carboxylate salt between equal volumes of aqueous 1M HCl and Ethyl Acetate. Extract the water layer twice more with ethyl acetate, then combine your organic layers and wash with an aqueous sat. sodium chloride solution (brine). Finally, dry the organic layer with a suitable drying reagent such as sodium sulfate or magnesium sulfate to remove trace amounts of water, then filter off the drying agent and concentrate. This should yield the protonated carboxylic acid form of your compound, and it should be anhydrous. You may need to modify this general procedure to fit your needs, especially if you need this on a large scale, but this should be enough to get you started. Good luck!
Hi Md, do what William said and keep the hydrochloric acid layer( water) it contain a lot of your compound because your compound ( Tolmetin ) is amine and it can be as hydrochloride salt or Amine - acid salt which is soluble in water, adjust the PH of solution to neutral to get your compound, be car full.Good luck.
I think,the ion exchange chromatography is also a method to obtained the pure acid from its salts by exchange sodium cation to hydrogen ions by cation exchange resin.
Salim, the nitrogen present in tolmetin is part of an N-methylpyrrole system and is therefore nonbasic. It will not be protonated under the conditions I mentioned. It would be good practice to retain the water layer, but the majority of product should be extracted into the organic layer.
There's a very quick and easy conversion in the patent publication WO/2009/072139:
Tolmetin sodium (25 g) was dissolved in water (250 ml) at 20-25°C. The pH of the reaction mixture was adjusted to 1.5 to 4.0 at 20-25°C and the mixture was maintained for 60 minutes at 20-25°C. The solid obtained was filtered and washed with 2 x 50 ml water and dried under vacuum at 45°C for 10-12 hours to obtain 15-20 g crystalline tolmetin.
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