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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Can the Radical Anion of Alkyl-2-cyanoacrylates Initiate Anionic Polymerization of These Instant Adhesive Monomers?
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Can the Radical Anion of Alkyl-2-cyanoacrylates Initiate Anionic Polymerization of These Instant Adhesive Monomers?

机译：烷基-2-氰基丙烯酸酯的自由基阴离子可以引发这些即时粘合剂单体的阴离子聚合吗？

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摘要

Electron affinities of methyl-2-cyanoacrylate (MCA) and ethyl-2-cyanoacrylate (ECA) were predicted using four different density functional or hybrid Hartree-Fock/density functional methods. Equilibrium structures and harmonic vibrational frequencies were computed for the neutral and anionic species of each system. Because of structural similarities to cyanoethylene and 1,1-dicyanoethylene, the results for MCA and ECA are compared to previous work at the same levels of theory on these two cyano-substituted ethylenes. Spin densities and isotropic hyperfine splitting constants (hfs) were determined for the radical anions of these four systems as a gauge of the delocalization of the unpaired electron. An experimental EA exists for 1,1-dicyanoethylene, although collisional electron transfer experiments on short-lived anions are questionable. The EAs for the four systems studied here are predicted to be 0.06 (cyanoethylene), 1.36 (1,1-dicyanoethylene), and 1.08 eV (MCA and ECA). The computed spin densities and hfs constants for these radical anions indicate that the unpaired electron is primarily localized on the C atom of the CH_2 segment of each molecule. 1,1-dicyanoethylene, MCA, and ECA each have two electron withdrawing groups, which results in appreciable resonance stabilization and a bound radical anion. The radical anions of MCA and ECA are nucleophilic and can attack the neutral monomer to initiate polymerization by a newly proposed mechanism.
机译：使用四种不同的密度泛函或混合Hartree-Fock /密度泛函方法预测了2-氰基丙烯酸甲酯（MCA）和2-氰基丙烯酸乙酯（ECA）的电子亲和力。计算每个系统的中性和阴离子物种的平衡结构和谐波振动频率。由于与氰基乙烯和1,1-二氰基乙烯的结构相似，因此将MCA和ECA的结果与以前在这两种氰基取代的乙烯的理论水平相同的研究结果中进行了比较。确定了这四个系统的自由基阴离子的自旋密度和各向同性超细分裂常数（hfs），作为未成对电子离域的量度。尽管对短寿命阴离子的碰撞电子转移实验值得怀疑，但存在针对1,1-二氰乙烯的实验性EA。此处研究的四个系统的EA预计为0.06（氰基乙烯），1.36（1,1-二氰基乙烯）和1.08 eV（MCA和ECA）。这些自由基阴离子的计算自旋密度和hfs常数表明，未配对的电子主要位于每个分子CH_2链段的C原子上。 1,1-二氰基乙烯，MCA和ECA分别具有两个吸电子基团，可导致明显的共振稳定和键合的自由基阴离子。 MCA和ECA的自由基阴离子是亲核性的，可以通过新提出的机理攻击中性单体以引发聚合反应。

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