Hydrogenation of CO₂‐Derived Carbonates and Polycarbonates to Methanol and Diols by Metal–Ligand Cooperative Manganese Catalysis

Abstract

The first base-metal-catalysed hydrogenation of CO -derived carbonates to alcohols is presented. The reaction proceeds under mild conditions in the presence of a well-defined manganese complex with a loading as low as 0.25 mol %. The non-precious-metal homogenous catalytic system provides an indirect route for the conversion of CO into methanol with the co-production of value-added (vicinal) diols in yields of up to 99 %. Experimental and computational studies indicate a metal-ligand cooperative catalysis mechanism.

Phosphine Ligand‐Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions

“…Among various homogeneous transition metal catalysts, Ru-complexes are the most efficient reported to date. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][60][61][62][63] Metal-ligand cooperative catalysis [64][65][66][67] can dramatically improve catalytic performance of ADC reactions using pincer ligands bearing NH, OH or CH 2 functionality. [40][41][42][43][44][68][69][70][71][72][73][74][75][76][77][78][79][80][81] Milstein, [40] Sun, [41] Yu, [42] Kundu [43] and Chen [44] have independently developed bifunctional Ru(II) catalysts for the synthesis of pyridine and quinoline derivatives (Scheme 1), b...…”

Ru(II)‐PBTNNXN complex bearing functional 2‐(pyridin‐2‐yl)benzo[d]thiazole ligand catalyzed α‐alkylation of nitriles with alcohols

“…On the basis of the above experimental results and previous reports, [13,15,26] a possible mechanism has been proposed, as shown in Scheme 4. Through metal-ligand cooperation, [27][28][29][30][31][32] the dearomatization/rearomatization process can be achieved via deprotonation/reprotonation of the NH linker. Since 2a containing the NH linker is acidic, deprotonation occurs in the presence of base, which leads to dearomatization of the pyridine ring.…”

“…[13] Kundu and co-workers demonstrated that Ru complexes bearing N6,N6 0 -dimethyl-2,2'-bipyridine-6,6'diamine ligand efficiently catalyzed α-alkylation of arylacetonitriles with alcohols. [14] Recently, Ru catalyst based on tridentate bipyridyl imidazoline catalyzed analogous reaction was reported by Song et al [15] Metal-ligand cooperation (MLC) [27][28][29][30][31][32] plays an important role in catalysis. It can dramatically promote the catalytic activity applied in borrowing hydrogen catalysis using ligands containing functional groups such as NH [33][34][35][36][37] and OH [38][39][40] .…”

Indirect CO2 Methanation: Hydrogenolysis of Cyclic Carbonates Catalyzed by Ru‐Modified Zeolite Produces Methane and Diols

“…[23][24][25] Very recently,three examples of homogeneous catalysts based on an on-noble metal center (manganese) have been reported that transform organic carbonates into diols and methanol in high yields (Supporting Information, Table S1). [26][27][28] Alimitation of the aforementioned approaches is that the methanol and glycol-products must be separated prior to further utilization, which is an energy intensive step.H ence, we decided to develop acatalytic process that converts cyclic carbonates directly into methane and diols,producing valueadded gaseous-and liquid-phases that do not require further separation. To achieve this goal, we relied on aw ell-established type of heterogeneous catalyst (Ru nanoclusters stabilized by zeolites).…”

“…Presumably,t he acidic site present in the Ru-FAU catalyst is also able to promote reductive dehydration, rationalizing the formation of propane and the absence of MeOH, in sharp contrast with previous reports that produce MeOH selectively. [26,36] Thei nfluence of hydrogen pressure was studied with the conversion of PC ranging from 84 %a t4 0bar to 98 %a t 80 bar. Hydrogen pressure strongly impacts on the selectivity of gaseous products,with less CO 2 formed at higher hydrogen pressures (Supporting Information, Table S3, entries [5][6][7][8].…”