In a systematic study of the extraction of gold(III) in acidic chloride solutions by a number of aliphatic esters with the focus on dibasic esters, it was found that di- or tribasic esters are more effective extractants than monobasic esters. The equilibrium for the extraction of gold(III) by a series of dibasic esters C₂H₅OCO(CH₂)_nCOOC₂H₅ (n = 0 to 8) has been studied. Diethyladipate (n = 4) was found to be the most reactive. The extraction of gold by diethyl adipate increases with increasing proton and with increasing chloride ion concentrations. The latter is due to the effect of chloride ions on the activity coefficient of the proton in concentrated HCl solutions. Gold is extracted more effectively by the use of diluents with a high dielectric constant. Gold is extracted as the tetrachloro-complex ion. Slope analysis has shown that the extracted gold complex contains three molecules of the ester and one hydrated proton. The Donor number obtained by calorimetric measurements increases with increasing number of methylene groups and is constant for greater than 3 methylene groups. The distribution coefficient correlates with the Donor number up to 4 methylene groups with steric effects resulting in a decrease in extraction for the higher chain length esters. It is proposed that gold is extracted as an ion-pair in the organic phase with a hydrated proton solvated by the esters.

在以脂肪族酯为重点的二元酯对酸性氯化物溶液中金（III）的系统研究中，发现二元或三元酯比一元酯更有效。一系列二元酯C ₂ H ₅ OCO（CH ₂）_n COOC ₂ H ₅萃取金（III）的平衡（n = 0至8）已被研究。发现己二酸二乙酯（n = 4）具有最高的反应性。己二酸二乙酯对金的提取随着质子的增加和氯离子浓度的增加而增加。后者是由于氯离子对浓HCl溶液中质子活度系数的影响。使用具有高介电常数的稀释剂可以更有效地提取金。金被提取为四氯配合物离子。斜率分析表明，提取的金络合物包含三个酯分子和一个水合质子。通过量热法测量获得的供体数随着亚甲基数的增加而增加，并且对于大于3个亚甲基而言是恒定的。分配系数与多达4个亚甲基的供体数相关，具有空间效应，导致较高链长的酯的提取减少。有人提出，金是与有机酯中的水合质子一起在有机相中以离子对的形式提取的。