Acceptorless dehydrogenative coupling of alcohols catalysed by ruthenium PNP complexes: Influence of catalyst structure and of hydrogen mass transfer

Abstract Base-free catalytic acceptorless dehydrogenative homo-coupling of alcohols to esters under neat conditions was investigated using a combined organometallic synthesis and kinetic modelling approach. The considered bifunctional ruthenium aliphatic PNP complexes are very active, affording TONs up to 15,000. Notably, gas mass transfer issues were identified, which allowed us to rationalize previous observations. Indeed, the reaction kinetics are limited by the rate of transfer from the liquid phase to the gas phase of the hydrogen co-produced in the reaction. Mechanistically speaking, this relates to the interconverting couple amido monohydride/amino bishydride. Overcoming this by switching into the chemical regime leads to an initial turnover frequency increase from about 2000 up to 6100 h−1. This has a significant impact when considering assessment of novel or reported catalytic systems in this type of reaction, as overlooking of these engineering aspects can be misleading.

[1]  Y. Shvo,et al.  Catalytically reactive (η4-tetracyclone)(CO)2(H)2Ru and related complexes in dehydrogenation of alcohols to esters , 1985 .

[2]  D. Spasyuk,et al.  From esters to alcohols and back with ruthenium and osmium catalysts. , 2012, Angewandte Chemie.

[3]  E. Bielinski,et al.  Well-Defined Iron Catalysts for the Acceptorless Reversible Dehydrogenation-Hydrogenation of Alcohols and Ketones , 2014 .

[4]  Sizhong Li,et al.  An efficient, green and scale-up synthesis of amides from esters and amines catalyzed by Ru-MACHO catalyst under mild conditions , 2015 .

[5]  E. Balaraman,et al.  Ruthenium Pincer‐Catalyzed Cross‐Dehydrogenative Coupling of Primary Alcohols with Secondary Alcohols under Neutral Conditions , 2012 .

[6]  T. Williams,et al.  Discovery, applications, and catalytic mechanisms of Shvo's catalyst. , 2010, Chemical reviews.

[7]  Joseph J. Bozell,et al.  Technology development for the production of biobased products from biorefinery carbohydrates—the US Department of Energy’s “Top 10” revisited , 2010 .

[8]  D. Milstein,et al.  Metal-ligand cooperation by aromatization-dearomatization: a new paradigm in bond activation and "green" catalysis. , 2011, Accounts of chemical research.

[9]  Andreas Martin,et al.  Syntheses of the fragrance hydroxyambran using hydrogenation methods , 2015 .

[10]  D. Spasyuk,et al.  Replacing phosphorus with sulfur for the efficient hydrogenation of esters. , 2013, Angewandte Chemie.

[11]  Pavel A. Dub,et al.  Practical selective hydrogenation of α-fluorinated esters with bifunctional pincer-type ruthenium(II) catalysts leading to fluorinated alcohols or fluoral hemiacetals. , 2013, Journal of the American Chemical Society.

[12]  Y. Maeda,et al.  Ruthenium-catalyzed oxidative transformation of alcohols and aldehydes to esters and lactones , 1987 .

[13]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[14]  M. Beller,et al.  Ruthenium-catalyzed hydrogen generation from glycerol and selective synthesis of lactic acid , 2015 .

[15]  S. Cohen,et al.  Ligand-metal cooperation in PCP pincer complexes: rational design and catalytic activity in acceptorless dehydrogenation of alcohols. , 2011, Angewandte Chemie.

[16]  A. Lough,et al.  Osmium and Ruthenium Catalysts for Dehydrogenation of Alcohols , 2011 .

[17]  M. Beller,et al.  Selective Catalytic Hydrogenation of Diethyl Oxalate and Related Esters , 2013 .

[18]  M. Beller,et al.  Selective hydrogen production from methanol with a defined iron pincer catalyst under mild conditions. , 2013, Angewandte Chemie.

[19]  D. Milstein,et al.  Metal-ligand cooperation. , 2015, Angewandte Chemie.

[20]  J. Bäckvall,et al.  Shvo’s Catalyst in Hydrogen Transfer Reactions , 2011 .

[21]  G. Soloveichik,et al.  Reversible catalytic dehydrogenation of alcohols for energy storage , 2015, Proceedings of the National Academy of Sciences.

[22]  D. Spasyuk,et al.  Chemoselective hydrogenation of carbonyl compounds and acceptorless dehydrogenative coupling of alcohols. , 2015, Journal of the American Chemical Society.

[23]  Yehoshoa Ben‐David,et al.  Facile Conversion of Alcohols into Esters and Dihydrogen Catalyzed by New Ruthenium Complexes , 2005 .

[24]  K. K. Hii,et al.  Coordination Chemistry and Catalytic Activity of Ruthenium Complexes of Terdentate Phosphorus−Nitrogen−Phosphorus (PNP) and Bidentate Phosphorus−Nitrogen (PNH) Ligands , 2002 .

[25]  E. Balaraman,et al.  Electron-Rich PNP- and PNN-Type Ruthenium(II) Hydrido Borohydride Pincer Complexes. Synthesis, Structure, and Catalytic Dehydrogenation of Alcohols and Hydrogenation of Esters , 2011 .

[26]  D. Milstein,et al.  Applications of Acceptorless Dehydrogenation and Related Transformations in Chemical Synthesis , 2013, Science.

[27]  T. Marks,et al.  Covalent transition metal, lanthanide, and actinide tetrahydroborate complexes , 1977 .

[28]  S. Chakraborty,et al.  Iron-based catalysts for the hydrogenation of esters to alcohols. , 2014, Journal of the American Chemical Society.

[29]  M. Beller,et al.  Efficient and selective hydrogen generation from bioethanol using ruthenium pincer-type complexes. , 2014, ChemSusChem.

[30]  Yehoshoa Ben‐David,et al.  Ruthenium Pincer-Catalyzed Acylation of Alcohols Using Esters with Liberation of Hydrogen under Neutral Conditions , 2010 .

[31]  M. Beller,et al.  Pincer-Type Complexes for Catalytic (De)Hydrogenation and Transfer (De)Hydrogenation Reactions: Recent Progress. , 2015, Chemistry.

[32]  Zheng Wang,et al.  Catalytic hydrogenation of cyclic carbonates: a practical approach from CO2 and epoxides to methanol and diols. , 2012, Angewandte Chemie.

[33]  M. Beller,et al.  Low-temperature aqueous-phase methanol dehydrogenation to hydrogen and carbon dioxide , 2013, Nature.

[34]  D. Spasyuk,et al.  Acceptorless Dehydrogenative Coupling of Ethanol and Hydrogenation of Esters and Imines , 2012 .

[35]  M. Beller,et al.  Efficient hydrogen production from alcohols under mild reaction conditions. , 2011, Angewandte Chemie.

[36]  Nomaan M Rezayee,et al.  Tandem amine and ruthenium-catalyzed hydrogenation of CO2 to methanol. , 2015, Journal of the American Chemical Society.

[37]  J. Blum,et al.  Dehydrogenation of alcohols under ambient atmosphere by a recyclable sol–gel encaged iridium pincer catalyst , 2012 .

[38]  Bert F. Sels,et al.  Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization , 2015 .

[39]  D. Milstein,et al.  Bond activation and catalysis by ruthenium pincer complexes. , 2014, Chemical reviews.

[40]  Z. Guan,et al.  From Racemic Alcohols to Enantiopure Amines: Ru-Catalyzed Diastereoselective Amination , 2014, Journal of the American Chemical Society.

[41]  Franck Dumeignil,et al.  Catalytic Conversion of Alcohols into Carboxylic Acid Salts in Water: Scope, Recycling, and Mechanistic Insights. , 2016, ChemSusChem.

[42]  R. Ludwig,et al.  Base-free hydrogen generation from methanol using a bi-catalytic system. , 2014, Chemical communications.

[43]  Louis J. Farrugia,et al.  ORTEP-3 for Windows - a version of ORTEP-III with a Graphical User Interface (GUI) , 1997 .

[44]  A. Lough,et al.  PNP pincer osmium polyhydrides for catalytic dehydrogenation of primary alcohols. , 2011, Dalton transactions.

[45]  N. J. Robertson,et al.  Synthesis of high molecular weight polyesters via in vacuo dehydrogenation polymerization of diols. , 2012, Macromolecular rapid communications.

[46]  M. Beller,et al.  Hydrogenation of Aliphatic and Aromatic Nitriles Using a Defined Ruthenium PNP Pincer Catalyst , 2015 .

[47]  Z. Lai,et al.  Enhanced Reactivities toward Amines by Introducing an Imine Arm to the Pincer Ligand: Direct Coupling of Two Amines To Form an Imine Without Oxidant , 2012 .

[48]  Jong-Ho Choi,et al.  Selective conversion of alcohols in water to carboxylic acids by in situ generated ruthenium trans dihydrido carbonyl PNP complexes. , 2014, Dalton transactions.

[49]  D. Wass,et al.  Catalytic Conversion of Ethanol to n-Butanol Using Ruthenium P-N Ligand Complexes , 2015 .

[50]  D. Gelman,et al.  Coordination Versatility of sp3-Hybridized Pincer Ligands toward Ligand–Metal Cooperative Catalysis , 2012 .

[51]  Matthias Beller,et al.  Towards a green process for bulk-scale synthesis of ethyl acetate: efficient acceptorless dehydrogenation of ethanol. , 2012, Angewandte Chemie.

[52]  M. C. Cassani,et al.  Homogeneous catalytic hydrogenation of perfluoro methyl esters , 2013 .

[53]  Robert B. May,et al.  Amine-free reversible hydrogen storage in formate salts catalyzed by ruthenium pincer complex without pH control or solvent change. , 2015, ChemSusChem.

[54]  M. Beller,et al.  Hydrogenation of esters to alcohols with a well-defined iron complex. , 2014, Angewandte Chemie.

[55]  Z. Guan,et al.  Catalytic acceptorless dehydrogenations: Ru-Macho catalyzed construction of amides and imines. , 2014, Tetrahedron.

[56]  M. Drees,et al.  Ruthenium complexes with cooperative PNP-pincer amine, amido, imine, and enamido ligands: facile ligand backbone functionalization processes. , 2010, Inorganic chemistry.

[57]  Takao Saito,et al.  Catalytic Hydrogenation of Esters. Development of an Efficient Catalyst and Processes for Synthesising (R)-1,2-Propanediol and 2-(l-Menthoxy)ethanol , 2012 .

[58]  N. Fairweather,et al.  Homogeneous Hydrogenation of Fatty Acid Methyl Esters and Natural Oils under Neat Conditions , 2015 .

[59]  Junming Sun,et al.  Recent Advances in Catalytic Conversion of Ethanol to Chemicals , 2014 .

[60]  J. Hartwig,et al.  Acceptorless, Neat, Ruthenium-Catalyzed Dehydrogenative Cyclization of Diols to Lactones , 2005 .

[61]  G. Sheldrick.  SHELXT – Integrated space-group and crystal-structure determination , 2015, Acta crystallographica. Section A, Foundations and advances.

[62]  A. Corma,et al.  Chemical routes for the transformation of biomass into chemicals. , 2007, Chemical reviews.

[63]  Jianliang Xiao,et al.  Chemoselective dehydrogenative esterification of aldehydes and alcohols with a dimeric rhodium(ii) catalyst , 2016, Chemical science.

[64]  R. Sheldon.  Green and sustainable manufacture of chemicals from biomass: state of the art , 2014 .

[65]  Miguel Peña‐López,et al.  Ruthenium pincer-catalyzed synthesis of substituted γ-butyrolactones using hydrogen autotransfer methodology. , 2015, Chemical communications.

[66]  Chunyu Song,et al.  Computational Mechanistic Study of Fe-Catalyzed Hydrogenation of Esters to Alcohols: Improving Catalysis by Accelerating Precatalyst Activation with a Lewis Base , 2014 .

[67]  M. Beller,et al.  Selective ruthenium-catalyzed methylation of 2-arylethanols using methanol as C1 feedstock. , 2014, Chemical communications.

[68]  Betina Jørgensen,et al.  Bioethanol: fuel or feedstock? , 2007 .