Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: jhcoleman53 on November 08, 2013, 01:08:10 PM
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Not sure if this is the right forum dept. or not, but since it relates to some analyses we are doing, I figured I'd start here. I'm a biologist by nature and not a chemist, so please bear with me. We have been doing some method development for extraction of material from soil and one of the solvent systems we have been using is hydrochloric acid in acetonitrile, specifically 0.1M, 1M, 2M and 3M concentrations. We have noticed that after preparation of the solvents, after they sit for a couple days, there is a crystalline precipitate that forms, particularly in the 2M and 3M solutions....not so much in the 1M and nothing at all in the 0.1M. They will not redissolve with mixing, sonication, or mild heating. I'm guessing this is some kind of chloride salt, but I'm not sure. There is also a distinct odor of acetic acid to the mixture after it sits for a couple days. Is acetic acid being formed? Can anyone enlighten me on the reaction and products of a hydrochloric acid and acetonitrile mixture? Also, the precipitate does not form when we mix a 2M or 3M hydrochloric acid in methanol solution. Can you include some info on this mixture as well? Thanks much for the lesson!
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Acetonitrile hydrolyses to ammonia and acetic acid under strongly acidic conditions.
Type "nitrile hydrolysis" into any search engine and you will get a full explanation.