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
2-Ethyl-2-oxazoline ring-opening polymerization of 2-ethyl-2-oxazoline can be initiated by alkylation with e.g. methyl tosylate or triflates (in particular methyl triflate) and leads to the water-soluble poly(2-ethyl-2-oxazoline) which is a propionyl-substituted linear polyethylenimine and can also be seen as a pseudo-polypeptide. The polymerization of 2-ethyl-2-oxazoline can also be carried out as living cationic polymerization. Copolymers with other 2-alkyl-2-oxazolines and other monomers allow the preparation of random copolymers and block copolymers. The copolymers obtained can be used as biocompatible drug carriers, in coatings and adhesives, and in many other applications. The elimination of the propionyl group from poly (2-ethyl-2-oxazoline) yields linear polyethyleneimine. 2-Ethyl-2-oxazoline