物理化学学报 >> 1987, Vol. 3 >> Issue (01): 67-73.doi: 10.3866/PKU.WHXB19870112

研究论文 上一篇    下一篇

N-取代苯氨基乙酸的紫外光谱研究

朱志昂; 张一宝; 王芳; 陈荣悌   

  1. 南开大学化学系
  • 收稿日期:1985-08-24 修回日期:1986-04-21 发布日期:1987-02-15

ULTRAVIOLET SPECTRA OF N-SUBSTITUTED PHENYLGLYCINES

Zhu Zhiang; Zhang Yibao; Wang Fang; Chen Yunti   

  1. Department of Chemist; Nankai University Tianjin; The People's Republic of China
  • Received:1985-08-24 Revised:1986-04-21 Published:1987-02-15

摘要: 本文测量了N~-取代苯氨基乙酸(RPhG,R=p-OCH_3,p-CH_3,m-CH_3,-H,m-OCH_3,p-Cl,m-Cl,m-NO_2,p-NO_2)在正己烷、正庚烷、二氧六环、四氯化碳、苯、甲苯、氯笨、乙酸乙酯、乙醇、乙腈、30%乙醇-水、不同比例的乙醇-正庚烧等溶剂中的紫外吸收光谱。实验结果显示:(1)与苯相比, RPhG在各溶剂中的紫外吸收峰均发生红移。(2)RPhG在各溶剂中的第一吸收谱带吸收频率ν与RPhG的碱性强度pK_2值、理论计算的电子跃迁能ΔE之间呈较好的直线关系。(3)在非极性溶剂中, RPhG的ν值与溶剂特性函数f(n~2)之间呈直线关系。在极性溶剂中, ν与溶剂特性函数f(ε)之间呈直线关系, [ν-(AL_0+B)f(n~2)]与溶剂特性函数φ(ε)-φ(n~2)之间也呈直线关系。(4)在不同溶剂中, 同一取代基RPhG的ν~R对未取代PhG的ν~H之间存在着线性关系。

Abstract: The ultraviolet spectra of N-substituted phenylglycines (RPhG, R= p-OCH_3, p-CH_3 m-CH_3,-H, m-OCH_3, p-Cl, m-Cl, m-NO_2, p-NO_2) have been studied in n-hexane, n-heptane, dioxane, carbon tetrachloride, benzene, mehtylbenzene, diethyl ether, chlorobenzene,ethyl acetate, ethanol,acetonitrile, 30% ethanol-water, in different ratios of ethanol-n-heptane mixtures by means of Beckman DU-8 Spectrophotometer. The experiment results showed that
1. To compare with the characterized absorption bands of benzene, the bath-ochromic shift of ultraviolet absorption spectra of RPhG in varous solvents was observed. The energy difference between ground state and first excited state of RPhG followed the order
p-OCH_3m-NO_2In 30% ethanol-water the order appeared to be p-NO_22. Linear relationships were found between v of PRhG in various solvents and their base strengths pK_2 and between the transference energy ΔE as well.
3. In non-polar solvents, the frequency v of PRhG varies linearly with the solvent charcterization function f(n~2). In polar solvents, linear relationships did exist between [v-AL_0+B)·f(n~2)] and the solvent characterization function φ(ε)-φ(n~2) and between v of PRhG and f(ε) of solvent as well.
4. In different solvents, linear relationships did exist between the v_R of the same substitutent group of RPhG and the v_H of unsubstituted PhG.