Catalytically Hydrogenated Research Articles

Selective hydrogenation of vanillin over a graphene-encapsulated nitrogen-doped bimetallic magnetic Ni/Fe@NDC nano-catalyst.

One of the main obstacles to the development of sustainable biomass feedstocks today is the research of selective hydrogenation of biomass platform compounds for the synthesis of high-value chemicals. This work reports on the synthesis of a Ni/Fe bimetallic catalyst with nitrogen-doped carbon serving as the carrier, hydrogen serving as the primary donor, and isopropanol serving as the reaction medium and serving as a secondary donor. Vanillin was catalytically hydrogenated to produce 4-methylguaiacol, a complete hydrogenation product, under a reaction temperature of 200 °C for four hours. A single product with a good yield (95.26% conversion and selectivity up to 99%) was achieved by the moderate conditions, offering a potential route for the catalytic hydrogenation of biomass platform compounds.

Upgrading of Tall Fescue Grass Pyrolytic Bioliquid and Catalytic Valorization of The Biofurfural Obtained

AbstractThe production of added value products following catalytic hydrogenation reactions of bioliquids was studied. These bioliquids were obtained from the pyrolysis of raw and acid‐treated (H3PO4) Tall Fescue (Fescue arundinacea) waste. Before the pyrolytic test, the biomass samples were analyzed by a micro thermogravimetric analysis coupled with FTIR spectroscopy (TGA‐IR), which enables the chemical identification of functional groups of gaseous molecules originated by solid/gas transformations. From these results, the pyrolysis temperature was selected, and bench scale pyrolysis reactions were carried out. The pyrolysis bioliquids showed high furfural concentration, 46 and 70 % for fescue and acid washed fescue, respectively. The bioliquid with the highest furfural concentration was catalytically hydrogenated in aqueous phase. A batch reactor was employed, with Ru/C and Ru−Sn/C catalysts to produce high added value alcohols.

Pd/C catalyzed room-temperature, atmospheric pressure hydrogenation of furanic bio-oils from acidic ionic liquid catalyzed liquefaction of biomass in acetone

Furanic bio-oils were produced from liquefaction of corn cobs and switchgrass using 1-(3-propylsulfonic)-3-methylimidazolium chloride catalyst in acetone at 120 °C, 5 h. The biomass conversions to bio-oils for corn cobs and switchgrass were 43.8 ± 1.9 and 40.2 ± 1.4% (w/w) respectively. The bio-oils were then catalytically hydrogenated in water: methanol 3:1 (v/v) at room-temperature and atmospheric pressure using 5% Pd-C catalyst to give hydrogenated bio-oils and analyzed using GC–MS to identify the products. GC–MS analysis revealed that majority of the products in hydrogenated bio-oils is C4-C17 alcohols, ethers and furans. A total of 64 products were observed in GC–MS and 61 were identified with the use of mass spectroscopy. These products are arising from the partial reduction as well as deoxygenation of biomass derived furan aldehyde - acetone cross aldol products and acetone self condensation products. In addition, NMR analysis was used to quantify the effect of catalytic hydrogenation. 1H NMR spectra peak integration for the alkene-furan region (6.0–8.0 ppm) showed reductions of 19.0 to 1.8% and 19.1 to 2.6% due to the catalytic hydrogenation of bio-oils from corn cobs and switchgrass, confirming the effect of Pd-C catalyzed, 1 Atm., room temperature hydrogenation.

A general method for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations. Part 2, via catalytic reduction of acetylene alcohol MαNP esters

A general method for synthesizing enantiopure (100% ee) aliphatic alcohols with established absolute configurations has been developed and applied to alcohols CH3(CH2)n–CH(OH)–(CH2)mCH3, the enantiomeric discrimination of which is the most difficult, if m=n+1 and n is large. Racemic saturated alcohols with short chains could be directly enantioresolved as (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid (MαNP acid) esters by HPLC on silica gel, and their absolute configurations were simultaneously determined by 1H NMR diamagnetic anisotropy. However, the application of this powerful MαNP ester method to alcohols with long chains was difficult, because of smaller values of the separation factor α. In such cases, the use of the corresponding acetylene alcohol MαNP esters was crucial. Acetylene alcohol MαNP esters were largely separated by HPLC on silica gel, and their absolute configurations were unambiguously determined by 1H NMR as reported in the Part 1 paper. The MαNP esters obtained with established absolute configurations were catalytically hydrogenated to yield saturated alcohol MαNP esters. It was evidenced that no racemization occurred at the stereogenic center of the alcohol moiety during catalytic hydrogenation, by the coinjection of MαNP esters in HPLC. From the MαNP esters obtained, enantiopure (100% ee) aliphatic chain alcohols with established absolute configurations were recovered. Although the [α]D values of these alcohols were too small for the identification of the enantiomers, it was clarified that the analytical HPLC of MαNP esters is useful for identification in most cases.

Temperature controlled three-stage catalytic dehydrogenation and cycle performance of perhydro-9-ethylcarbazole

Organic liquid heteroaromatic compounds, e.g. 9-ethylcarbazole, are potentially promising hydrogen storage materials because they can be catalytically hydrogenated and dehydrogenated at relatively moderate temperatures. In the present work, the cyclic hydrogenation of 9-ethylcarbazole and the temperature controlled stage-wise dehydrogenation of perhydro-9-ethylcarbazole were investigated. Full hydrogenation of 9-ethylcarbazole was realized over a 5 wt% Ru/Al2O3 catalyst at 180 °C and 80 bar, yielding a gravimetric density of 5.79 wt%. The catalytic dehydrogenation of perhydro-9-ethylcarbazole over a 5 wt% Pd/Al2O3 catalyst was found to undergo a three-stage process, i.e. perhydro-9-ethylcarbazole → octahydro-9-ethylcarbazole, octahydro-9-ethylcarbazole → tetrahydro-9-ethylcarbazole, and tetrahydro-9-ethylcarbazole → 9-ethylcarbazole with the initial reaction temperatures of 128 °C, 145 °C and 178 °C, respectively. Our results indicate that 9-ethylcarbazole displays an excellent cycle performance with very little capacity degradation after 10 cycles of catalytic hydrogenation and dehydrogenation. The hydrogen gas produced from the dehydrogenation possesses a high purity of over 99.99% with no carbon monoxide or other poisonous gases for fuel cells.

Inactivity of iridium–triphenylphosphine complexes for catalytic imine hydrogenation: formation of neutral, dihydrido-ortho-metallated species

Reactions of cis,trans,cis-[Ir(H)2(PPh3)2(MeOH)2]PF6 in MeOH with the imines Ph(R′)C=NR under 1 atm H2 precipitate the neutral, Ir(III)-dihydrido complexes [Ir(H)2{RN=C(R′)(o-C6H4)}(PPh3)2], where R = alkyl or benzyl, and R′ = Ph, H, or Me; the dihydrides are well characterized through elemental analysis, NMR and IR data and, in one case, with the imine Ph2C=NCH2Ph, an X-ray structure. These products are formed via intermediate ortho-metallated species, exemplified by [Ir(H){PhCH2N=CPh(o-C6H4)}(PPh3)2(MeOH)]PF6 in the case of the Ph2C=NCH2Ph reaction; the intermediate then reacts with H2 (via net heterolytic cleavage: H2 → H− + H+) to give the neutral dihydride and HPF6 as co-product. The ‘unique’ imine PhCH=NPh, under the same conditions, does not form a dihydride and instead is readily catalytically hydrogenated to PhCH2N(H)Ph; remarkably, we have shown previously that this imine is ‘unique’ within the corresponding Rh system in that no catalytic hydrogenation occurs because the amine product ‘poisons’ the Rh centre by coordination through the N-phenyl ring.

From renewable raw materials to high value-added fine chemicals—Catalytic hydrogenation and oxidation of d-lactose

Kinetics and reaction mechanism of catalytic hydrogenation and oxidation of d-lactose were studied in three-phase laboratory reactors. Catalyst screening results and influence of temperature, pressure, catalyst loading and pH are reported as d-lactose was either catalytically hydrogenated to lactitol or oxidized to lactobionic acid. The product yield was significantly influenced by reaction conditions and catalyst choice. Additionally, during oxidation and hydrogenation processes, catalyst deactivation was severe under non-optimized conditions. Temperature dependency of lactose mutarotation was determined by NMR analysis.

Lipase mediated resolution of 1,3-butanediol derivatives: chiral building blocks for pheromone enantiosynthesis. Part 3

( R,S)-1,3-Butanediol 5 was kinetically resolved by enzymatic acetylation with vinyl acetate under the presence of Chirazyme™ L-2, c–f, yielding ( S)-1- O-acetyl-1,3-hydroxybutane 6 and ( R)-1,3-di- O-acetyl-1,3-butanediol 7 with enantiomeric excesses of 91% ( E=67.3). Compounds 6 and 7 were easily transformed into the corresponding ( S)-3- O-(2-methoxyethoxymethyl)-3-hydroxybutanal 10 and ( R)-3-benzyloxybutanal 19, through a protection–deprotection and functional group interchange methodology. Subsequent reaction of 10 and 19 with 3-(methoxycarbonylpropionylmethylene)triphenylphosphorane afforded methyl ( E, S)-8- O-(2-methoxyethoxymethyl)-4-oxo-5-nonenoate 12 and ( E, R)-8-benzyloxy-4-oxo-5-nonenoate 20. The alkenes 19 and 20 were then catalytically hydrogenated to the corresponding saturated esters 13 and 21. Treatment of 13 and 21 with 1,2-ethanedithiol/F 3B·OEt 2 afforded dithioketals 14 and 22, which were respectively reduced to ( S)-1,8-dihydroxy-4-nonanone ethylidenedithioketal 15 and ( R)-8- O-benzyl-1,8-dihydroxy-4-nonanone ethylidenedithioketal 23. Finally, deprotection of 15 by catalytic hydrogenation under acidic conditions gave the expected (5 S,7 S)-(−)-7-methyl-1,6-dioxaspiro[4.5]decane 1. The (5 R,7 R)-(+)- 1 enantiomer was analogously prepared from 23. Both compounds were formed by this procedure with an e.e. of 91%.

Catalytic Hydrogenation of Fullerenes in the Presence of Metal Catalysts in Toluene Solution

Abstract The catalytic hydrogenation of fullerenes was studied in the presence of various metal catalysts in toluene solution under several conditions. Fullerenes were found to be catalytically hydrogenated in toluene solution in the presence of the Ru/carbon, Pdharbon, NiDiatomaceous Earth or Ptharbon as the catalysts. The reactivity of catalytic hydrogenation of the Ru/C was the highest for the among the used metal catalysts.

The catalytic hydrogenation of ethene on the surface of liquid caesium

The self-hydrogenation of 3 mol of C 2H 4 at 20 kN m −2 from 363 to 489 K on the surface of a jet of liquid caesium produces 2 mol of C 2H 6. The reaction is first order with activation energy 15.8 kJ mol −1. With an equal volume of HZ, the alkene is 100% catalytically hydrogenated to C 2H 6 by a first-order process with activation energy 45.5 kJ mol −1. Increasing the proportion of H 2 increases the rate of catalysis. A mechanism is suggested for each process.

Effect of low temperature catalytic hydrogenation on pyrolysis and hydropyrolysis of a bituminous coal

The effect of coal pre-hydrogenation under relatively mild conditions (400 °C, 7 M Pa hydrogen pressure) using a dispersed sulphided molybdenum catalyst on fluidized bed (flash) pyrolysis at atmospheric pressure and fixed-bed hydropyrolysis was investigated for a UK bituminous coal (82% dmmfC). In pyrolysis at 600 °C, the catalytic pre-treatment raised the overall conversion and tar yield by ≈ 20 wt% daf coal giving nearly 50 wt% tar with little extra gas. The effect of the pre-treatment in fixed-bed hydropyrolysis at 500 °C and 15 M Pa pressure is even more pronounced with the overall conversion increasing from approximately 40 to 80 wt% daf coal, which included less than a 5 wt% rise in gas yield. The same level of conversion was achieved in hydropyrolysis using the catalyst impregnated coal without pre-hydrogenation, indicating that the chemical transformations occurring in catalytic hydrogenation and in the early stages of hydropyrolysis are broadly similar. However, the fact that the conversion in hydropyrolysis is significantly higher than that in flash pyrolysis for the catalytically hydrogenated coal indicates that further hydrogenation occurs during hydropyrolysis.

ChemInform Abstract: Synthesis of Some Substituted Pyrroline‐1‐oxides by Catalytic Hydrogenation of Aliphatic γ‐Nitrocarbonyl Compounds.

AbstractThe γ‐nitrocarbonyl compounds (I) are catalytically hydrogenated to produce a mixture of the pyrrolidine‐N‐oxides (II) and the cyclic hydroxylamines (III).

Synthesis of four new diastereoisomers of dl-5-hydroxymethyl-1,2,3,4-cyclohexanetetrol

Four new diastereoisomers of the pseudo-sugar dl-5-hydroxymethyl-1,2,3,4-cyclohexanetetrol, having (1,2,3,4/5)- ( 2), (1,5/2,3,4)- ( 3), (1,2,3/4,5)- ( 4), and (1,2,4,5/3)-configurations ( 5), have been synthesised by unambiguous sequences from readily available pseudo-sugars. Acetonation of dl-(1,2,4/3,5)-5-hydroxymethyl-1,2,3,4-cyclohexanetetrol with 2,2-dimethoxypropane in N,N-dimethylformamide in the presence of toluene- p-sulfonic acid gave the 1,2:4,7-di- O-isopropylidene derivative ( 9) in good yield. Oxidation of HO-3 in 9 with ruthenium tetraoxide in chloroform gave the ketone 11, which was catalytically hydrogenated to give the 3-epimer ( 12) of 9. Deprotection of 12 gave the 1,2,3,4/5-isomer 2 in good yield. Likewise, compounds 3 and 4 were synthesised from (1,3,5/2,4)- and (1,2/3,4,5)-5-hydroxymethyl-1,2,3,4-cyclohexanetetrol, respectively. Compound 5 was obtained by catalytic hydrogenation of dl-(1,2,4/3)-5-hydroxymethyl-5-cyclohexene-1,2,3,4-tetrol.

A convenient method for the synthesis of 6-enaminopurine derivatives by catalytic hydrogenation of 6-cyanomethylenepurines

6-Cyanomethylenepurines have been catalytically hydrogenated to the corresponding α-(aminomethylene)purine-6-acetic acid derivatives in good yields using dimethylformamide-benzene as solvent over Pd-C under medium pressure.

ChemInform Abstract: STEREOSELECTIVE CATALYTIC HYDROGENATION OF α‐HYDROXY KETOXIMES

AbstractDas ausgehend von dem optisch aktiven Aminalkohol (Ia) erhaltene Oxim (Va) wird stereoselektiv katalytisch zu den Aminoalkoholen (I) hydriert (Überschuß des erythro‐ Isomeren); analog reagiert auch das isomere Z‐Racemat (Vb) zu den entsprechenden racemischen Aminoalkoholen (68‐7l% Ausbeute; erythro :threo ‐ 89 : ll).

Stereoselective Catalytic Hydrogenation of α-Hydroxy Ketoximes

Abstract Two isomers(E and Z) of benzoin oxime and 2-hydroxy-1-phenyl-1-propanone oxime were catalytically hydrogenated by using palladium on charcoal and erythro amino alcohols were obtained in about 80% diastereomeric excess. The syn-anti isomerization of these oximes in the presence of palladium on charcoal was also studied in connection with the stereoselectivity of the catalytic hydrogenation of the oximes.

New method for the preparation of ortho-phenylene-diamine

4-Chloro-2-nitro-aniline, advantageously obtainable from benzene, can be catalytically hydrogenated to ortho-phenylene-diamine. In this process the reduction of the nitro-group and the dehalogenation take place in competition. Results of our laboratory experiments, carried out to choose a catalyst, active for both reaction steps, as well as to limit the suitable operation conditions are presented in this paper. On the basis of our kinetic investigations, two new routes are proposed for manufacturing ortho-phenylene-diamine. One of them is a low pressure, batch-type catalytic hydrogenation of 4-Chloro-2-nitro-aniline, using Raney nickel catalyst and applying mechanical agitation. The other is a high pressure, continuous process with palladium catalyst supported on charcoal and mixing by the hydrogen gas.

The synthesis, configuration, and conformation of cis‐ and trans‐3‐amino‐3,4‐dihydro‐1‐hydroxy‐4‐methylcarbostyrils and other configurationally related compounds

AbstractThe cis‐ and trans‐3‐amino‐3,4‐dihydro‐1‐hydroxy‐4‐methylcarbostyrils (Ia and Ib) were synthesized by catalytic hydrogenation of erythro‐ and threo‐α‐amino‐β‐(o‐nitrophenyl)butyric acid hydrochlorides, IIIa and IIIb, respectively, under acidic conditions. The free bases of IIIa and IIIb were catalytically hydrogenated under neutral conditions to yield the erythro‐ and threo‐α‐amino‐β‐(o‐aminophenyl)butyric acids (VIa and VIb), which were converted by acidification to their corresponding lactams, cis‐ and trans‐3‐amino‐3,4‐dihydro‐4‐methylcarbostyrils, IIa and IIb. The erythro and threo isomers of α‐amino‐β‐(o‐nitrophenyl)‐butyric acid were prepared and separated by liquid chromatography via a diastereomeric mixture of (V) of methyl α‐acetamido‐β‐(o‐nitrophenyl)butyrates. The configurations and conformational assignments of the cyclic hydroxamic acids Ia and Ib were first established by analysis of the proton nmr spectra. In turn, the configurations of the o‐nitroaromatic amino acids IIIa and IIIb were assigned as well as the other structurally related compounds (VIa, VIb, IIa and IIb) derived therefrom.

Synthesis of the 3‐methyl and 4‐methyl derivatives of 3‐amino‐3,4‐dihydro‐1‐hydroxycarbostyril and related compounds

AbstractThe 3‐methyl and 4‐methyl derivatives of 3‐amino‐3,4‐dihydro‐1‐hydroxycarbostyril were synthesized by the reductive cyclization of α‐methyl‐β‐(o‐nitrophenyl)alanine and α‐amino‐β‐(o‐nitrophenyl)butyric acid hydrohalides, respectively, under conditions of catalytic hydrogenation in acidic solution. The free bases of the latter two o‐nitroaromatic amino acids were also catalytically hydrogenated under neutral conditions to yield the respective α‐methyl‐β‐(o‐aminophenyl)alanine and α‐amino‐β‐(o‐aminophenyl)butyric acid which were converted to the corresponding lactams, 3‐methyl‐ and 4‐methyl‐3‐amino‐3,4‐dihydrocarbostyrils. α‐Methyl‐β‐(o‐nitrophenyl)alanine was obtained by acid hydrolysis of 5‐methy)‐5‐(o‐nitrobenzyl)hydantoin which was prepared by treatment of o‐nitrophenylacetone with potassium cyanide and ammonium carbonate. α‐Amino‐β‐(o‐nitrophenyl)butyric acid was synthesized by condensation of α‐bromo‐o‐nitroethylbenzene with diethyl acetamidomalonate, followed by acid hydrolysis of the condensation product. The 4‐methylated compounds were obtained as synthetic mixtures of two diasteromeric racemates in nearly the same amounts as shown by nmr spectral analysis. Unlike the demethylated parent compound, 3‐amino‐3,4‐dihydro‐1‐hydroxycarbostyril, neither the 3‐methyl nor 4‐methyl analog was found to possess any antibacterial activity.

Preparation and characterization of head‐to‐head polymers. VIII. Head‐to‐head poly(vinyl cyclohexane)

AbstractHead‐to‐head poly(vinyl cyclohexane) (H‐H PVCH) was prepared from 2,3‐diphenylbutadiene, which was polymerized by radical, 1,4 polymerization to poly(2,3‐diphenylbutadiene) and then catalytically hydrogenated to H‐H PVCH, H‐H PVCH was also prepared by catalytic hydrogenation of H‐H polystyrene (PS). The catalytic hydrogenations were carried out at an initial hydrogen pressure of 2000 psi and a temperature of 200°C. Some chemical, physical, and thermal properties of H‐H PVCH were investigated and compared with the properties of atactic and isotactic head‐to‐tail (H‐T) PVCH. The glass transition temperature of the H‐H polymer was found to be 50°C lower than that of the atactic H‐T polymer which indicates that the backbone chain has more flexibility. Both H‐H and H‐T PVCH showed comparable thermal stability. The temperature of the maximum rate of thermal degradation by differential thermogravimetric analysis was approximately 40°C higher than that of the corresponding polystyrenes.