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在1,2-聚丁二烯链分子中,导致仲碳(—CH_2—)谱峰分裂的原因是存在着两种gauche排列。在这样一个复杂体系中,由于主链仲碳与叔碳的gauche排列占有重要的位置,因此主链叔碳对化学位移的贡献对于仲碳谱有着决定性的影响。相比之下,乙烯基的贡献要小得多。两种贡献分别是γ_1=—6.37——6.41ppm与γ_2=0.0——1.56ppm。在不计入侧基的影响或同时考虑乙烯基的贡献这两种情况下,均方误差MSE分别是0.166×10~(-2)和0.364×10~(-2)ppm~2。本文同时讨论了模型链的种类、链长以及温度对键概率的影响。并指出有个别反常的情况发生。文中还对间同1,2-聚丁二烯的链结构进行了分析。
In the 1,2-polybutadiene chain molecule, the reason for the splitting of the secondary carbon (-CH 2 -) peak is the existence of two gauche arrangements. In such a complex system, the contribution of the main tertiary carbon to chemical shifts has a decisive effect on the secondary carbon spectrum because of the important position of the gauche arrangement of the secondary and tertiary carbons in the main chain. In contrast, the contribution of vinyl is much smaller. The two contributions are respectively γ_1 = -6.37 - 6.41 ppm and γ_2 = 0.0 - 1.56 ppm. The mean square error (MSE) was 0.166 × 10 -2 and 0.364 × 10 -2 ppm -2, respectively, regardless of the effect of pendant groups or the simultaneous contribution of vinyl groups. This article also discusses the type of the model chain, chain length and temperature on the key probability. And pointed out that there are some unusual circumstances. The paper also analyzes the chain structure of 1,2-polybutadiene.