Ruthenium triphos complexes Ru(X(CH2PPh2)3-κ3-P)(NCCH3)3](OTf)2; X = H3C-C, N) as catalysts for the conversion of furfuryl acetate to 1,4-pentanediol and cyclopentanol in aqueous medium

The ruthenium complexes [Ru(H3CC(CH2PPh2)(3)-kappa(3)-P)(NCCH3)(3)](OTf)(2) (1, (H3CC(CH2PPh2)(3) = triphos) and [Ru(N(CH2PPh2)(3)-kappa(3)-P)(NCCH3)(3)](OTf)(2) (2, N(CH2PPh2)(3) = N-triphos) have been evaluated as homogeneous ionic hydrogenation catalysts for the catalytic hydrodeoxygenation of furfuryl alcohol and furfuryl acetate to 1,4-pentanediol and cyclopentanol in aqueous media reaction mixtures. For furfuryl alcohol, only marginal yields of 1,4-pentanediol could be achieved with mass balance deficiencies due to humin formation ranging from 67% to 90%. Attempts to improve the catalytic activity of 2 by enhancing its water solubility by nitrogen protonation and (or) methylation failed. Employing the less self-reactive filthily, acetate as the substrate substantially diminishes humin formation, yielding up to 43% of 1,4-pentanediol and 19% of cyclopentanol (via Piancatelli rearrangement) with 1 and up to 33% of 1,4-pentanediol and 5% of cyclopentanol with 2. A design of experiments study was used to determine and compare the yield responses of the multiple parallel reaction channels with 1,4-pentanediol, cyclopentanol, and humins as a function of reaction temperature, time, catalyst load, and substrate concentration. This explores the correlations between these parameters and their impact on the reaction outcome and suggests an extremely complex overall reaction cascade of interdependent pathways of both acid-and metal-catalyzed steps with some significant differences emerging between the two catalysts.

钌配合物[Ru(H₃CC(CH₂PPh₂)₃ - κ³ - P)(NCCH₃)₃](OTf)₂（1，H₃CC(CH₂PPh₂)₃ = 三膦）和[Ru(N(CH₂PPh₂)₃ - κ³ - P)(NCCH₃)₃](OTf)₂（2，N(CH₂PPh₂)₃ = N - 三膦）已被评估为均相离子氢化催化剂，用于在水介质反应混合物中催化糠醇和乙酸糠酯加氢脱氧生成1,4 - 戊二醇和环戊醇。对于糠醇，由于形成胡敏素（产率损失在67% - 90%之间），只能获得少量的1,4 - 戊二醇，且物料平衡不足。通过氮质子化和（或）甲基化来提高2的水溶性以改善其催化活性的尝试失败了。使用反应活性较低的乙酸酯作为底物可大大减少胡敏素的形成，使用1时可得到高达43%的1,4 - 戊二醇和19%的环戊醇（通过皮安卡特利重排），使用2时可得到高达33%的1,4 - 戊二醇和5%的环戊醇。通过实验设计研究来确定和比较多个平行反应通道中1,4 - 戊二醇、环戊醇和胡敏素的产率响应随反应温度、时间、催化剂负载量和底物浓度的变化。这探究了这些参数之间的相关性及其对反应结果的影响，并表明存在一个极其复杂的整体反应级联，其中包含酸催化和金属催化步骤的相互依赖途径，且两种催化剂之间存在一些显著差异。