Formation and Mechanism of Alkali Metal Porphyrins and their Application to Analytical Chemistry

合成了一种水溶性卟啉（2，3.7，8，12，13，17，18-八溴-5，10，15，20-四（4-磺酸基苯基）卟啉; H<@D22@> D2 obtpps <@D14-@>D1 ; H2 P <@D14-@>D1），并将其用于水溶液中锂离子的测定和分离。八溴取代基通过吸电子作用降低卟啉的碱性，使卟啉在碱性水溶液中与锂离子反应形成锂配合物，其最大吸收峰沿着移动;锂卟啉的lmax（log λ/mol<@D1-1@>D1 dm <@D13@> D1cm <@D1-1@>D1）分别为490.5nm（5.31）和734 nm（4.36）。钠和钾离子不与卟啉反应。测定了Li<@D1+@>D1+HP<@D15-@>D1 [LiP]<@D15-@>D1+H<@D1+@>D1反应的平衡常数为10-8.81，[LiP]<@D15-@>D1在pH 13时的条件生成常数为10 <@D14.21@> D1。与四丁基铵离子（X<@D1+@>D1）形成对络合物，萃取的X<@D25@> D2 LiP解离成氯仿形式的X<@D24@> D2 LiP <@D1-@>D1和X<@D1+@>D1。[LiP<@D15@>D1-]<@D2a@>D2+5[X<@D1+@>D1]<@D20@>D2（]SY.dblharw. [)[X D_2LiP [D_1-D_1][D_20] D_2 +[X] D_1][D_20] D_2 =（8.4 ± 0.01）S_Y. [D112]= 0.7 × 10<@D112@>D1 mol<@D1-4@>D1 dm<@D112@>D1，其中下标a和o分别表示水相和有机相中的化学物质。本方法可用于血清、海水和温泉水中锂的测定，测定范围为0.07-0.7 mg dm<@D1-3@> D_1（1 × 10<@D1-5@> D_1 -1 × 10<@D1-4@> D_1 mol dm<@D1-3@> D_1）。当样品中含有镁离子时，N，N '-1，2-乙二基双-[N（羧甲基）甘氨酸]镁（Ⅱ）（[Mg（edta）]<@D12-@>D1或H<@D24@>D2 edta）对重金属离子有干扰。

A water-soluble porphyrin (2,3.7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin ; H<@D22@>D2obtpps<@D14-@>D1 ; H2P<@D14-@>D1) was synthesized and develped for the determination and separation of lithium ion in aqueous solution. Tne octabromo groups lower the basicity of the porphyrin by their eletron-withdrawing effect and enable the porphyrin to react with lithium ion in alkaline aqueous solution to form the lithium complex along with a shft of absorption maxima ; lmax (log epsilon/mol<@D1-1@>D1 dm<@D13@>D1 cm<@D1-1@>D1) of thg lithium porphyrin are 490.5 nm (5.31) and 734 nm (4.36). Sodium and potassium ions did not react with the porphyrin. The equilibrium constant for the reaction Li<@D1+@>D1+HP<@D15-@>D1 [LiP]<@D15-@>D1+H<@D1+@>D1 was found to be 10-8.81 and the condtional formation constant ofthe [LiP]<@D15-@>D1 at pH l3 is10<@D14.21@>D1.The [LiP]<@D15-@>D1 can be extracted into chloroform as an ion-pair complex with tetracuthylammonium ion (X<@D1+@>D1) and the extracted X<@D25@>D2LiP dissociates to X<@D24@>D2LiP<@D1-@>D1 and X<@D1+@>D1 in chlomform. The exttraction constant for the reaction of [LiP<@D15@>D1-]<@D2a@>D2+5[X<@D1+@>D1]<@D20@>D2(]SY.dblharw.[)[X<@D24@>D2LiP<@D1-@>D1]<@D20@>D2+[X<@D1-@>D1]<@D20@>D2 was found to be (8.4(]SY.+-。[)0.7) x 10<@D112@>D1 mol<@D1-4@>D1 dm<@D112@>D1, where subscripts of a and o denote chemical species in aqueous and organic phases, respectively. The above results were developed for the determination of lithium in serum, sea water and hot-spring water samples at a range of 0.07-0.7 mg dm<@D1-3@>D1 (1 x 10<@D1-5@>D1-1 x 10<@D1-4@>D1 mol dm<@D1-3@>D1). The interference of hevy metal ions was by N,N'-1,2-ethanediylbis-[N (carboxylmethyl)-glycinato] magnesium (II) ([Mg (edta)]<@D12-@>D1 or H<@D24@>D2 edta if sample contain magnesium (II) ion.