Szabó K, Nagypál I, Fábián I
Institute of Chemistry, Janus Pannonius University, H-7644 Pécs, Hungary.
Talanta. 1983 Oct;30(10):801-4. doi: 10.1016/0039-9140(83)80184-2.
The protonation constants of 2,2'-bipyridyl and ammonia have been determined by pH titration at 25 degrees , at ionic strengths of 0.1, 0.2, 0.5, 1.0, 1.5 and 2.0M obtained by using LiNO(3), NaNO(3), KNO(3), LiClO(4) and NaClO(4) as background electrolytes. The protonation constants generally change by about 0.3-0.4 log units for both ligands in nitrate media. A similar change in the protonation constant of ammonia was observed in perchlorate media. There is, however, a change of about 0.8-0.9 log units in the protonation constant of bipyridyl in the perchlorate media. This phenomenon is interpreted by postulating ion-pair formation between perchlorate and the protonated form of bipyridyl, HBp(+) + ClO(4)(-) rlharr2; HBp(+).ClO(4)(-) with formation constants of 0.54 in 2M lithium nitrate and 0.45 in 2M sodium nitrate.
通过在25摄氏度下进行pH滴定，使用硝酸锂、硝酸钠、硝酸钾、高氯酸锂和高氯酸钠作为背景电解质，分别在离子强度为0.1、0.2、0.5、1.0、1.5和2.0M的条件下测定了2,2'-联吡啶和氨的质子化常数。在硝酸盐介质中，两种配体的质子化常数通常变化约0.3 - 0.4个对数单位。在高氯酸盐介质中观察到氨的质子化常数有类似变化。然而，在高氯酸盐介质中，联吡啶的质子化常数变化约0.8 - 0.9个对数单位。这种现象被解释为通过假定高氯酸根与联吡啶的质子化形式之间形成离子对，即HBp(+) + ClO(4)(-)⇌HBp(+).ClO(4)(-)，在2M硝酸锂中的形成常数为0.54，在2M硝酸钠中的形成常数为0.45。
