醇类在惰性溶剂中的缔合溶液热力学

用Kretschmer-Wiebe模型结合Hildebrand-Scatchard公式处理含醇体系的活度系γ_i,得到醇类的自身缔合平衡常数K_A和氢键生成焓h_A。在烷烃溶剂中,K_A与烷烃的碳原子数关系不显著。在同一溶剂中,K_A依下列顺序减小: 甲醇>乙醇>正丙醇>正丁醇; 正丙醇>异丙醇; 正丁醇>异丁醇>仲丁醇>叔丁醇。所测醇类的h_A的平均值为:k_A=-24.3±0.6kJmol~(-1),与醇类的碳原子数及异构关系不显著计算出醇类-角鲨烯体系偏离Hildebrand-Scatchard公式的相互作用常数l_(AB),l_(AB)均为负值,|l_(AB)|依下列顺序减小: 甲醇>乙醇>正丙醇>正丁醇; 正丙醇>异丙醇; 正丁醇>异丁醇>仲丁醇>叔丁醇

THERMODYNAMICS OF ASSOCIATED SOLUTIONS OF ALCOHOLS IN INERT SOLVENTS

Under the condition of infinite dilution, the activity coefficients previously obtained have been treated by Kretschmer-Wiebe association model combining with Hiidebrand-Scatchard formula. In the binary systems of alcohol and alkanes,no relationship between the self association equilibrium constant and the number of carbon atoms of alkane has been found. The equilibrium constants decrease in the order: methanol>ethanol>n-propanol>n-butanol; n-propanol>isopropanol; n-butanol>isobutanol>sec-butanol>tert-butanol.The carbon number and isomeric form of the alcohols have little effect on the calculated enthalpy of H-bonding formation, the average value of which is -24.2(+-)1.5 kJ.mol~(-1).In the systems of alcohol and squalene, the calculated cross interaction coefficients l_(AB), which reflects the degree deviated from Hildebrand-Scatchard formula are negative, the absolute values of which are less than 0.1, and decrease in the order:methanol>ethanol>n-propanol>n-butanol;p-propanol>isopropanol;n-butanol>isobutanol>sec-butanol>tert-butanol.