Ethyl cyanohydroxyiminoacetate Ethyl cyanohydroxyiminoacetate Ethyl cyanohydroxyiminoacetate (oxyma) is the oxime of ethyl cyanoacetate and finds use as an additive for carbodiimides, such as dicyclohexylcarbodiimide (DCC) in peptide synthesis. It acts as a neutralizing reagent for the basicity or nucleophilicity of the DCC due to its pronounced acidity (pKa 4.60) and suppresses base catalyzed side reactions, in particular racemization. Ethyl cyanohydroxyiminoacetate is obtained in the reaction of ethyl cyanoacetate and nitrous acid (from sodium nitrite and acetic acid) in 87% yield. Because of the rapid hydrolysis of the ester, the reaction should be carried out at pH 4.5, in buffered phosphoric acid the
Ethyl iodide Ethyl iodide Ethyl iodide (also iodoethane) is a colorless, flammable chemical compound. It has the chemical formula CHI and is prepared by heating ethanol with iodine and phosphorus. On contact with air, especially on the effect of light, it decomposes and turns yellow or reddish from dissolved iodine. It may also be prepared by reaction between hydroiodic acid and ethanol distilling off the ethyl iodide. Ethyl iodide should be stored in copper powder to avoid fast decomposition, though even with this method samples don't last more than 1 year. Because iodide is a good leaving group, ethyl iodide is an