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ⅵ)取代基的亲油性及厚度在冠醚环上适当引入亲油取代基(如烃基),可以提高络合物的稳定性和对离子的输送速率(如6、7),但取代基过多或过大(8、18、19)使冠醚环的厚度增大,空间阻碍作用也增强,因而稳定性也降低。因此冠醚环上的取代基及其厚度有一个适当范围才比较合适。 4)溶剂及阴离子的影响冠醚在盐(M~(n+)X~(n-))的溶液中,存在着M~(n+)—冠醚与M~(n+)—溶剂,M~(n+)—X~(n-)的竞争,也就是说冠醚与阳离子作用时,必须剥去其溶剂化层或离子对,才能形成新的络离子
Ⅵ) Lipophilicity and Thickness of Substituents Proper introduction of lipophilic substituents (such as hydrocarbyl groups) on the crown ether ring can increase the stability of the complex and the rate of delivery of ions (eg, 6,7), but substitution of the substituent Too much or too much (8, 18, 19) increases the thickness of the crown ether ring and also increases the steric hindrance and thus the stability. Therefore, the crown ether ring substituents and the thickness of a suitable range is more appropriate. 4) Effects of Solvents and Anions Crown ethers present M ~ (n +) - crown ethers and M ~ (n +) - solutes in a solution of salt (M ~ (n +) X ~ (n-) n +) - X ~ (n-) competition, that is to say, when the crown ether interacts with the cation, the solvating layer or the ion pair must be stripped to form a new complex ion