Catalytic Deoxygenation of 1,2‐Propanediol to Give n‐Propanol

Abstract

Deoxygenation of 1,2-propanediol (1.0 M in sulfolane) catalyzed by bis(dicarbonyl)(m-hydrido)(pentamethylcyclopentadiene)ruthenium trifluo-+ OTf À ) (0.5 mol%) at 110 8C under hydrogen (750 psi) in the presence of trifluoromethanesulfonic acid (HOTf) (60 mM) gives n-propanol as the major product, indicating high selectivity for deoxygenation of the internal hydroxy group over the terminal hydroxy group of the diol. The deoxygenation of 1,2-propanediol is strongly influenced by the concentration of acid, giving faster rates and proceeding to higher conversions as the concentration of HOTf is increased. Propionaldehyde was observed as an intermediate, beingformed through acid-catalyzed dehydration of 1,2-propanediol. This aldehyde is hydrogenated to npropanol through an ionic pathway involving protonation of the aldehyde, followed by hydride transfer from the neutral hydride, dicarbonyl(pentamethylcyclopentadiene)ruthenium hydride [Cp*Ru(CO) 2 H]. The proposed mechanism for the deoxygenation/hydrogenation reaction involves formation of a highly acidic dihydrogen complex [Cp*Ru(CO) 2

Hydrogenolysis of 1,2‐Propanediol for the Production of Biopropanols from Glycerol

“…In the previous report, the conversion of 1,2-PrD to 1-PrOH can proceed by the acid-catalyzed dehydration of 1,2-PrD to propionaldehyde and the subsequent hydrogenation of propionaldehyde to 1-PrOH. [19] In the previous case, HOTf was used as an acid catalyst. The acid catalyst promoted 1,2-PrD conversion, however, it also catalyzed ether formation such as di-n-propyl ether and propylene glycol propyl ether.…”

“…It should be noted that the homogeneous Ru catalyst with HOTf for the conversion of 1,2-PrD is not active for the deoxygenation of glycerol. [19] One-pot conversion of glycerol to propanols is a characteristic of the RhÀReO x /SiO 2 catalyst. Figure 8 shows X-ray diffraction (XRD) patterns of RhÀReO x / SiO 2 (Re/Rh = 0.5) and Rh/SiO 2 after the catalytic use.…”

“…It has been reported that the homogeneous Ru catalyst catalyzed the hydrogenolysis of 1,2-propanediol to 1-propanol at 383 K with a moderate yield of 54 %. [19] At the same time, the system demands an organic solvent such as sulfolane and uses a homogeneous catalyst that is difficult to separate and recycle. Herein, the development of heterogeneous catalysts for the hydrogenolysis of 1,2-propanediol without using organic solvents is reported.…”

From 5-Hydroxymethylfurfural (HMF) to Polymer Precursors: Catalyst Screening Studies on the Conversion of 1,2,6-hexanetriol to 1,6-hexanediol

“…There are also reports [46][47][48][49][50][51][52] on the use of homogeneous ruthenium catalysts in combination with triflic acid (HOTf) and sulfolane as the solvent for the selective hydrodeoxygenation of a secondary alcohol in the presence of a primary alcohol. For example, Schlaf et al [51] reported the production of 1-propanol from 6 using [{Cp*Ru(CO) 2 While preparing this manuscript, Dumesic et al [44] reported hydrodeoxygenation reactions of various diols and triols using bimetallic Rh-ReO x catalysts on carbon supports. When using 2 as the substrate, 1 was obtained in 99.9 % at 8 % conversion (120°C, 34 bar, 4 h).…”

Ruthenium (II) sulfoxides-catalyzed hydrogenolysis of glycols and epoxides

“…The use of biomass substantially reduces net carbon dioxide emissions because the latter is recycled in biomass production. Stoichiometric methods for the deoxydehydration of diols are abundant [10,11] but catalytic methods are limited [12][13][14][15][16]. Hydrogenolysis of polyols by various heterogeneous catalytic systems has been recently reported [17,18].…”