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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 25, Number 4
JKCSEZ 25(4)
August 20, 1981 

The Thermodynamics of the Formation of Pyridines-Iodine Charge Transfer Complexes

피리딘류와 요오드사이의 전하이동착물생성에 관한 열역학적 연구
Oh Cheun Kwun, Jin Burm Kyong, Myong Kyun Kim

권오천, 경진범, 김명균
피리딘, β-피코린 및 3,5-루티딘과 요오드사이에 형성되는 전하이동착물을 사염화탄소 용액에서 자외선분광광도법을 사용하여 연구한 결과 C5H5N·I2, β-C5H4(CH3)N·I2 및 3,5-C5H3(CH3)2N·I2 형의 1:1 분자착물이 형성됨을 알았다. 이들 착물생성에 대한 흡수최대는 온도가 상승함에 따라 blue shift되므로 이를 고려하여 각 온도에서의 평형상수를 구했다. 이 값으로부터 이들 착물생성에 대한 ΔH, ΔG 및 ΔS 이 열역학적 파라미터를 산출하였다. 이 결과 착물의 상대적 안정도가 다음 순서로 증가함을 알수가 있었다. Pyridine < β-Picoline < 3,5-Lutidine. 이러한 결과는 dipole moment, steric hindrance effect 및 positive inductive effect에 의한 electron density의 증가 때문인 것으로 설명할 수 있었다. 그리고 polymethylbenzene-iodine CT-complex와도 비교 검토하였다.

Ultraviolet spectrophotometric investigation were carried out on the systems of pyridine, β-picoline and 3,5-lutidine with iodine in carbon tetrachloride. The results reveal the formation of one to one molecular complexes of the type, C5H5N·I2, β-C5H4(CH3)N·I2 and 3,5-C5H3(CH3)2N·I2. The equrilibrium constants of complexes were obtained in consideration of that absorption maxima have the blue shift with the increasing temperatures according to the formation of the charge transfer complexes. The thermodynamic parameters, ΔH, ΔG and ΔS for the formation of the charge transfer complexes were calculated from these values. These results indicated that the relative stabilities of the pyridine, β-picoline and 3,5-lutidine complexes with iodine increase in the order, pyridine < β-picoline < 3,5-lutidine. These results were supposed to be the influence resulted from increase of electron density by the positive inductive effect and the dipole moment of the steric hindrance effect. And this results were compared and discussed with polymethylbenzene-iodine CT-complexes.

228 - 235
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