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化学学报
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化学学报 ›› 1990, Vol. 48 ›› Issue (10): 1000-1005. 上一篇    下一篇

研究论文

羰桥双共轭体系结构效应的研究 I. 羰桥两边支链的共轭竞争

蒋明谦;褚文华;戴萃辰   

  1. 中国科学院化学研究所
  • 发布日期:1990-10-15

A study of structural effect in carbonyl bridged Di-conjugative systems. I. Conjugative competition for carbonyl bridge

JIANG MINGQIAN;CHU WENHUA;DAI CUICHEN   

  • Published:1990-10-15

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548

为了定量地研究桥双共轭体系中的结构效应, 制备了TmBn、BmBn和TmTn系列共32个羰桥化合物, 测定了电子吸收光谱。发现: 电子光谱频率与由总双键数所构成的同系因子不成直线关系, 而是不规则的散布点, 表明分子中没有贯通的共轭基干, 羰基对整个分子的共轭极化有隔断作用。羰桥两边两个分支对羰桥的共轭作用是互相竞争的, 当共轭竞争的优势从一分支转移到另一分支时, 同系直线就分为斜率不同的两段, 其间出现转折点。随着两个共轭分支链长的改变, 拐点出现有规则的移动, 在羰桥化合物的同分异构体中, 两个分支的共轭竞争也很明显, 其电子吸收峰与一定的m+n值表现为V形曲线。

关键词: 羰基化合物, 共轭双键化合物, 结构效应, 桥环化合物, 电子吸收光谱

R(CH:CH)mCO(CH:CH)nR1 (R = thienyl, R1 = Ph, m = 0-3, n = 0-4, 6; R = R1 = Ph, m = 1-4, n = 0-2; R = R1 = thienyl, m = 1-4, n = 0-2) were prepared and their electronic absorption spectra in alcohol and cyclohexane determine A plot of scattered points was obtained in each case, indicating that there is no single conjugated system. Conjugative polarization on the mol. chain is blocked by the carbonyl bridge. The two branches on each side of the carbonyl bridge are in conjugative competition for the carbonyl group. When the wavelengths of absorption peaks for isomeric compounds are plotted against chain no. (m + n), a V-shaped curve with the lowest point at the middle was found.

Key words: CARBONYL COMPOUNDS, CONJUGATED DOUBLE BOND COMPOUNDS, STRUCTURAL EFFECT, BRIDGE COMPOUNDS

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