Ethyl sulfate process in which ethylene is reacted with sulfuric acid to produce ethyl sulfate followed by hydrolysis, but this method has been mostly replaced by direct hydration of ethylene. Ethyl sulfate can be produced in a laboratory setting by reacting ethanol with sulfuric acid under a gentle boil, while keeping the reaction below 140 °C. The sulfuric acid must be added dropwise or the reaction must be actively cooled because the reaction itself is highly exothermic. If the temperature exceeds 140 °C, the ethyl sulfate product tends to react with residual ethanol starting material, producing diethyl ether. If the temperature exceeds
Ethyl cyanohydroxyiminoacetate product can even be obtained in virtually quantitative yield. The compound can be purified by recrystallization from ethanol or ethyl acetate. Compared with the benzotriazole derivatives 1-hydroxybenzotriazole (HOBt) and 1-hydroxy-7-azabenzotriazole (HOAt) (which are widely used as peptide-linking reagents but are explosive), ethyl cyanohydroxyiminoacetate exhibits a markedly slowed thermal decomposition on heating. Ethyl cyanohydroxyiminoacetate is a white solid which is soluble in many solvents common in the synthesis of peptides, such as dichloromethane or dimethylformamide (DMF). In crystalline form, the compound is present as an oxime, whereas it exists as a salt or in a strongly basic solution predominantly as a