Ni 和 Ni/Pd 催化木质素衍生芳烃的还原偶联以获得生物基增塑剂,ACS Central Science

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Ni 和 Ni/Pd 催化木质素衍生芳烃的还原偶联以获得生物基增塑剂
ACS Central Science ( IF 12.7 ) Pub Date : 2023-01-18 , DOI: 10.1021/acscentsci.2c01324
Zhi-Ming Su ₁ , Jack Twilton ₁ , Caroline B Hoyt ₂ , Fei Wang ₁ , Lisa Stanley ₂ , Heather B Mayes ₂ , Kai Kang ₁ , Daniel J Weix ₁ , Gregg T Beckham ₂ , Shannon S Stahl ₁

Affiliation

木质素衍生的芳香化学品提供了一种引人注目的石化原料替代品，新的应用是人们广泛关注的焦点。4-羟基苯甲酸 ( H )、香草酸 ( G ) 和丁香酸 ( S ) 很容易通过硬木木质素底物的氧化解聚获得。在这里，我们探索使用这些化合物来获得代表生物基、毒性较低的邻苯二甲酸酯增塑剂替代品的联芳基二羧酸酯。开发了化学和电化学方法用于H、G和S的磺酸盐衍生物的催化还原偶联，以获得所有可能的均偶联和交叉偶联产物。传统的 NiCl ₂/联吡啶催化剂能够获得H-H和G-G产物，但新的催化剂被发现可以提供更具挑战性的偶联产物，包括用于S-S 的NiCl ₂ /双膦催化剂和 NiCl ₂ /菲咯啉/PdCl _{2 /用于}H–G、H–S和G–S 的膦助催化剂体系. 使用化学还原剂（锌粉）的高通量实验方法被证明可为鉴定新催化剂提供有效的筛选平台，而电化学方法可以提高产量和/或促进更大规模的实施。增塑剂测试是用聚氯乙烯进行的，使用 4,4'-联芳基二羧酸产品的酯。与成熟的石油基邻苯二甲酸酯增塑剂相比，H-G和G-G衍生物尤其具有性能优势。

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Ni- and Ni/Pd-Catalyzed Reductive Coupling of Lignin-Derived Aromatics to Access Biobased Plasticizers

Lignin-derived aromatic chemicals offer a compelling alternative to petrochemical feedstocks, and new applications are the focus of extensive interest. 4-Hydroxybenzoic acid (H), vanillic acid (G), and syringic acid (S) are readily obtained via oxidative depolymerization of hardwood lignin substrates. Here, we explore the use of these compounds to access biaryl dicarboxylate esters that represent biobased, less toxic alternatives to phthalate plasticizers. Chemical and electrochemical methods are developed for catalytic reductive coupling of sulfonate derivatives of H, G, and S to access all possible homo- and cross-coupling products. A conventional NiCl₂/bipyridine catalyst is able to access the H–H and G–G products, but new catalysts are identified to afford the more challenging coupling products, including a NiCl₂/bisphosphine catalyst for S–S and a NiCl₂/phenanthroline/PdCl₂/phosphine cocatalyst system for H–G, H–S, and G–S. High-throughput experimentation methods with a chemical reductant (Zn powder) are shown to provide an efficient screening platform for identification of new catalysts, while electrochemical methods can access improved yields and/or facilitate implementation on larger scale. Plasticizer tests are performed with poly(vinyl chloride), using esters of the 4,4′-biaryl dicarboxylate products. The H–G and G–G derivatives, in particular, exhibit performance advantages relative to an established petroleum-based phthalate ester plasticizer.

更新日期：2023-01-18

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