The hydration of acetaldehyde in aqueous solution
The hydration of acetaldehyde in aqueous solution
复制标题
乙醛在水溶液中的水合
DOI：
10.1039/tf9524800439
复制
发表时间：
1952
影响因子：
--
通讯作者：
J. Clunie
中科院分区：
文献类型：
--
作者：
R. Bell;J. Clunie
本文用量热法和分光光度法测定了乙醛在稀水溶液中的溶解热、水合热及其在0 ~ 54 ℃温度范围内的水合度。溶解热为0 ℃时Δ H =-1.96千卡/摩尔，25 ℃时Δ H =-1-63千卡/摩尔。水化热的平均值为Δ Hh =-5.103 ~0.05kcal/mole，水化度在实验误差范围内可用公式~ o~（[CH~ CH（OH）;？]/ [CH~ CHO]}=-3.657 +5100/4 * 576 T。有相当多的证据表明乙醛在水溶液中部分水合为分子CH 3CH（OH）2，并且当乙醛溶解在水中时，平衡不是瞬时建立的。Bell和Higginsonl以及Bell和Darwent 2总结了这一证据，并报道了可逆水合过程的动力学测量结果。然而，文献中关于水合的平衡程度以及溶解热和水合热存在混淆。因此，Schou 3报道了在稀溶液中通过测量紫外吸收得到的26%水合，而赫罗尔德和Wolf 4用同样的方法得到了60%水合。在这两种情况下都没有说明温度。
Calorimetric and spectrophotometric methods are used to determine the heat of solution and hydration of acetaldehyde in dilute aqueous solution, and its degree of hydration in the temperature range 0"-54" C. The heat of solution is AHs=-1.96 kcal/mole at O" C, and-1-63 kcal/mole at 25 C. The mean value of the heat of hydration is AHh=-5.10 3~ 0.05 kcal/mole, and the degree of hydration is given to within experimental error by the expression~ o~~~([CH~ CH (OH);?]/[CH~ CHO]}=-3.657+ 5100/4* 576T.There is a considerable amount of evidence that acetaldehyde is partly hydrated in aqueous solution to the molecule CH3CH (OH) 2, and that the equilibrium is not established instantaneously when acetaldehyde is dissolved in water. Bell and Higginsonl and Bell and Darwent2 have summarized this evidence, and reported kinetic measurements on the reversible hydration process. There is, however, confusion in the literature as to the equilibrium extent of hydration, and the heats of solution and hydration. Thus Schou 3 reported 26% hydration in dilute solutions from measurements of ultra-violet absorption, and Herold and Wolf 4 60% by the same method. In neither case is the temperature stated.