Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: xyz133 on December 18, 2017, 05:55:04 AM
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I am trying to convert benzimidazole derivate (base) to citrate. The benzimidazole is practically insoluble in water however I noticed the formation of salt when I macerate the mixture of citric acid and benzimidazole. The mixture I used was 1:1 mass ratio which resulted in final product that was part salt and part citric acid. What would be the correct procedure to obtain benzimidazol citrate (no excess base or acid)? I guess I should use molar ratio instead. But then again – citric acid contains 3 COOH groups, is the salt formation possible on all three of them? How important are steric effects here? Thanks for all the answers.
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What about doing it in organic solvent ? Wikipedia says citric acid is actually soluble in a bunch of organic solvents (alcohols, ethyl acetate, ETHER?!). How about dissolving it 1:1 in ethyl acetate or ether and the salt you want may crash right out.
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To clarify, probably a 1:1 ratio by moles rather than by mass might be better.
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Good catch sjb. Yes, clearly do it by molar ratio, mass is a useless way to do a ratio when talking about any chemical reaction.
PS: I noticed also that citric acid has decent solubility in dioxane (34g/100 mL, so that is an option, and indicates THF probably works too.