Equilibrium constants for 1:1 hydrogen bond complexation between 3,5-dichlorophenol (DCP) and 17 ketones and 12 ethers in cyclohexane solution have been obtained by an FTIR method that takes into account both dimerization of the acid and formation of 2:1 complexes. Enthalpies of complexation for the same ketones and ethers have been determined by a calorimetric method, leading to values of log K, ÎG°, ÎH° and ÎS° for 1:1 complexation in the 29 systems, as well as log K2 for the 2:1 complexation between 2 mol of acid and 1 mol of base. For the ketone systems there is very little variation in the three thermodynamic parameters with alkyl substitution, but for the ethers there are systematic variations depending on the alkyl substituent or if the ethers are cyclic.Values of the OH stretching frequency in the DCP complexes with the ketones and ethers in cyclohexane have been obtained. The band shapes for the DCPâketone complexes are very asymmetric, possibly due to the presence of stereoisomeric complexes, but the νOH band for DCPâether complexes is symmetric and very suitable for the evaluation of any relationship between νOH and ÎH°. It is found that for the complexation of DCP with the 12 aliphatic ethers in cyclohexane, there is almost no connection between the calorimetrically determined ÎH° values and values of ÎνOH.
在
环己烷溶液中,通过FTIR方法获得了
3,5-二氯苯酚(DCP)与17种酮及12种醚之间1:1氢键复合的平衡常数,该方法考虑了酸的二聚化和2:1复合物的形成。对于相同的酮和醚,通过热量测定法确定了复合的焓变,得出了29个体系中1:1复合的log K、ΔG°、ΔH°和ΔS°值,以及2:1复合(2
摩尔酸与1摩尔碱之间)的log K2值。对于酮体系,三种热力学参数随烷基取代几乎没有变化,但对醚而言,参数则随着烷基取代基的不同或醚的环状与否而呈现系统性的变化。已获得
环己烷中DCP与酮和醚复合物的OH伸缩频率值。DCP–酮复合物的谱带形状非常不对称,可能是由于立体异构复合物的存在,而DCP–醚复合物的νOH谱带则对称,十分适合评估νOH与ΔH°之间的关系。研究发现,在
环己烷中,DCP与12种脂肪醚的复合几乎没有热量测定的ΔH°值与ΔνOH值之间的关联。