Cyanate as an Active Precursor of Ethyl Carbamate Formation in Sugar Cane Spirit

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• 作者：Carlos A. Galinaro ; Thiago H. K. Ohe ; Augusto C. H. da Silva ; Sebasti茫o C. da Silva ; Douglas W. Franco
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2015
• 出版时间：August 26, 2015
• 年：2015
• 卷：63
• 期：33
• 页码：7415-7420
• 全文大小：276K
• ISSN：1520-5118

文摘

The thermodynamic and kinetic aspects of ethyl carbamate (EC) formation through the reaction between cyanate and ethanol were investigated. The rate constant values for cyanate ion decay and EC formation are (8.0 卤 0.4) 脳 10^鈥? and (8.9 卤 0.4) 脳 10^鈥? s^鈥?, respectively, at 25 掳C in 48% aqueous ethanolic solution at pH 4.5. Under the investigated experimental conditions, the rate constants are independent of the ethanol and cyanate concentrations but increase as the temperature increases (螖H₁^{猝?/sup> = 19.4 卤 1 kcal/mol, 螖S₁猝?/sup> = 鈭?2.1 卤 1 cal/K, and 螖G₁猝?/sup> = 23.0 卤 1 kcal/mol) and decrease as the solution pH increases. According to molecular modeling (DFT) that was performed to analyze the reaction mechanism, the isocyanic acid (HNCO) is the active EC precursor. The calculated 螖G₁猝?/sup>, 螖H₁猝?/sup>, and 螖S₁猝?/sup> values are in very good agreement with the experimental ones.}