at 140 °C with high yields and unprecedented turnovers. A maximum of 92% yield of the β-alkylated product at 18 400 TON was obtained in the reaction of benzyl alcohol with 1-(4-(trifluoromethyl)phenyl)ethane-1-ol in the presence of 0.005 mol % of (Ph2NNN)NiCl2(CH3CN) and 5 mol % of NaOtBu at 140 °C after 24 h. The reaction exhibits zero-order dependence of rate on catalyst concentration and first-order
我们在此报告了一系列类型为 ( R2 NNN)NiCl 2 (CH 3 CN) (R = i Pr、t Bu、Cy、Ph 和p -FC 6 H 4 )的 NNN 钳形镍配合物的合成和表征) 基于双(亚氨基)吡啶配体。在溶液中,这些配合物被发现是分别含有一个和两个钳状配体的平衡混合物。虽然我们最近报道了前者的晶体结构 R = i Pr,但我们在本研究中报告了后者的晶体结构 R = p -FC 6 H 4. 所考虑的 NNN 钳形镍配合物已成功用于在 140°C 下以高产率和前所未有的周转率完成几种仲醇与各种苄醇的催化 β-烷基化。在苯甲醇与 1-(4-(三氟甲基)苯基)乙烷-1-醇在 0.005 mol% ( Ph2 NNN)NiCl 2 (CH 3 CN) 和 5 mol % NaO tBu 在 140 °C 后 24 小时。该反应表现出速率对催化剂浓度的零级依赖性和对碱、苯甲醇和 1-苯
Phosphine-free pincer-ruthenium catalyzed biofuel production: high rates, yields and turnovers of solventless alcohol alkylation
ethanol with 3-methoxy benzyl alcohol. DFT studies were complementary to mechanisticstudies and indicate the β-hydride elimination step involving the extrusion of acetophenone to be the overall RDS. While the hydrogenation step is favored for the formation of α-alkylated ketone, the alcoholysis step is preferred for the formation of β-alkylated alcohol. The studies were extended for the upgradation of ethanol
合成了基于双(亚氨基)吡啶和2,6-双(苯并咪唑-2-基)吡啶配体的无膦钳式钌羰基配合物。在无溶剂条件下,在140°C下用苯甲醇将1-苯基乙醇与苄醇进行β-烷基化反应,(Cy2 NNN)RuCl 2(CO)(0.00025 mol%)与NaOH(2.5 mol%)的结合非常有效(约93%的产率,在12000 TO h -1时为37.2万吨。这是迄今为止基于钌的催化剂的最高报道值。轻松完成各种醇组合的β-烷基化反应,最终在19 000 TO h -1达到380000 TON1-苯基乙醇与3-甲氧基苄醇的β-烷基化反应。DFT研究是对机理研究的补充,并指出涉及苯乙酮挤出的β-氢化物消除步骤成为整个RDS。尽管有利于形成α-烷基化的酮的氢化步骤,但是对于形成β-烷基化的醇,醇解步骤是优选的。研究扩大了将乙醇升级为生物燃料的研究。在基于双(亚氨基)吡啶的钳-钌络合物中,(Cy2 NNN)RuCl 2(CO)提供了高生产率(在170
Ligand-free Guerbet-type reactions in air catalyzed by <i>in situ</i> formed complexes of base metal salt cobaltous chloride
benign cobaltouschloride efficiently accomplishes the catalytic β-alkylation of alcohols in air at 140 °C. At higher loadings of cobaltouschloride (1 mol%) in the presence of 2.5 mol% NaOtBu, there is a rapid formation of heterogeneous Co nanoparticles (NPs) which are apparently sensitive to air and result in poor yields (ca. 25%) of β-alkylated products. In contrast, performing the reaction in an
价格低廉、地球资源丰富且对环境无害的氯化钴可在 140 °C 的温度下有效地在空气中实现醇的催化 β-烷基化。在存在 2.5 mol% NaO t Bu 的情况下,在较高的氯化钴负载量 (1 mol%) 下,会快速形成对空气明显敏感的异质 Co 纳米颗粒 (NPs),导致产率低 ( ca. 25% ) 的 β-烷基化产物。相比之下,在其他相同条件下在氩气气氛中进行反应会导致更高的产率(约44%)。通过在 2.5 mol% NaO t存在下以较低 (0.01 mol%) CoCl 2负载运行可以延迟空气中的异质化和最终活性损失卜在 140 °C。在这些条件下,醇的催化 β-烷基化以高产率(高达 89%)和前所未有的周转率(约8900 年)进行。机理研究表明基于原位生成的醇分子 Co 配合物的催化剂的参与。标记研究为 C-H 活化参与氯化钴催化的 β-烷基化提供了关键证据,KIE 为 1.61
Pincer-Cobalt-Catalyzed Guerbet-Type β-Alkylation of Alcohols in Air under Microwave Conditions
Guerbet-type β-alkylation of secondary alcohols catalyzed by chromium chloride and its corresponding NNN pincer complex
作者:Himani Narjinari、Niharika Tanwar、Lakshay Kathuria、Raksh Vir Jasra、Akshai Kumar
DOI:10.1039/d2cy00759b
日期:——
β-alkylated product under similar conditions. EPR studies suggest the involvement of chromium(II) activespecies when either CrCl3 or its corresponding NNN pincer is used. HRMS analysis, hot-filtration and mercury-drop test provided conclusive evidence for the homogeneous and well-defined molecular nature of the reaction mixture. Apparently, insertion of the α-alkylated ketone into the Cr–H bond is