呋喃多烯酸酯类三岔共轭体系结构和性能之间的定量关系——(Ⅰ)紫外光谱

本文合成及制备了下述六个系列的化合物并测定了它们的紫外光谱、质谱。结果表明: α-C_4H_3O-(CH=CH)nCHO (FA-n) n=2,3,4,5。 α-C_4H_3O-(CH=CH)nCN FN-n) n=1,2,3~*,4~*,5~*。 α-C_4H_3O-(CH=CH)nCO_2Et (FE-n) n=1,2,3~*,5~*。 α-C_4H_3O-(CH=CH)nCH=C(CN)CO_2H (FNA-n)n=0,1,3~*,4~*。 α-C_4H_3O-(CH=CH)nCH=C(CN)CO_2Et (FNE-n)n=0,1,3~*,4~*, α-C_4H_3O-(CH=CH)nCH=C(CO_2Et)_2·(FM-n) n=0,1,3~*,4~*,5~*。 (*:表示文献中未知的化合物) 在环己烷、乙醇,甲醇和四氯化碳溶剂中各组电子吸收峰的波数与同系因子相联系时,都各有一条而且只有一条良好的直线。同系线性规律的专一性表明了,在呋喃多烯三岔系列中,呋喃环的端基当量仍然是2。并不因为在烯链的另一端具有两个强吸电子的共轭分岔基团的存在而增大呋喃环的端基当量。在FM-n系列中,利用经验公式算得的Sj′以及利用相似三角形式算得的sj的平均值都在0.4左右。这就定量地表明了,在末端二个羧酸酯基中,只可能有一个是端基,而另一个是代基。λ′计-λ实的最大值小于80的事实表明,FM-n系列的紫外吸收频率与结构之间的定量关系可以用扩大同系方程来近似地表示。但在FNE-n系列中,由于氰基的存在,用扩大同系方程计算得到的λ值与实验值偏差较大,?

The Quantitative Relationship between Molecular Structure and Properties in Forked Conjugateve Furyl Polyenic Acid Derivatives(Ⅰ) Ultraviolet Spectra

In this paper, the following six homologous series have been prepared and synthesized. Their electronic absorption and mass spectra have been determined.(Compounds marked by * are unknown.)It has been found that just like the linear systems, the frequencies of U.V. spectra of these forked conjugate series in cyclo-hexane, ethanol, methanol, tetrachloromethane also correlate with homologous factor, (1/2)2/N, to give good linear homologous lines.Based on the uniqueness of the rule of homologous linearity, it has been demonstrated that the terminal equivalent of furyl group remains unchanged upon introducing a strong electron-attracting gtoup as a forked branch and that the oxygen atom in the furyl group does not come into full conjugation with other parts of the furyl ring. The mass spectra also support this conclusion. The substituent equivalents of the branching group in the FM-n series have been calculated by both the empirical equation and the method of similar triangle described previously. Their values range from 0.24 to 0.66 with an average of 0.4. This indicates quantitatively that in FM-n, only one of the two ethoxycarbonyl groups attached simultaneously to the same trunk of the system becomes a terminal group, while the other one plays the role of a substituent.group.The extended homologous equation has been used to calculatethe wavelengths of the absorption maximum of the forked systems. The deviation of the calculated wavelengths from the experimental ones is less than 80A.The two series of cyano-containing forked systems exhibit largerdeviation, an abnormal phenomenon usually found with cyano compounds.