- Hydrogenolysis of tetrahydrofuran-2-carboxylic acid over tungsten-modified rhodium catalyst
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Catalysts for reduction of tetrahydrofuran-2-carboxylic acid (THFCA), which can be synthesized from furfural via oxidation and hydrogenation, were explored among the combinations of noble metal and reducible metal oxide supported on SiO2. Rh-WOx/SiO2 catalysts showed activity in C-O hydrogenolysis at 2-position of THFCA (to δ-valerolactone and 5-hydroxyvaleric acid) and higher yield ratio of these C-O hydrogenolysis products to carboxylic acid hydrogenation products than other bimetallic catalysts. The activity of Rh-WOx/SiO2 catalysts was highest at W/Rh = 0.25 mol/mol. XRD, TPR, CO adsorption and XAFS characterizations showed that the Rh-WOx/SiO2 (W/Rh = 0.25) catalyst contained Rh metal particles with surface modification with isolated W2+ oxide species. The mechanism that hydride-like species formed on Rh atom attacks the C atom at the α-position (2-position) of adsorbed carboxylate on W atom is proposed based on the similar kinetics and similar catalyst structure to Rh-MOx/SiO2 (M = Re, Mo) which is known to be active in THFA hydrogenolysis to 1,5-pentanediol.
- Asano, Takehiro,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
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- Alternative selective oxidation pathways for aldehyde oxidation and alkene epoxidation on a SiO2-supported Ru-monomer complex catalyst
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We have prepared a novel Ru-mononer complex supported on a SiO2 surface by using a Rumonomer complex precursor with a p-cymene ligand, which was found to be highly active for the selective oxidation of aldehydes and the epoxidation of alkenes using O2. The structure of the supported Ru catalyst was characterized by means of FT-IR, solid-state NMR, diffuse-reflectance UV/vis, XPS, Ru K-edge EXAFS, and DFT calculations, which demonstrated the formation of isolatedly located, unsaturated Ru centers behind a p-cymene ligand of the Ru-complex precursor. The site-isolated Ru-monomer complex on SiO2 achieved tremendous TONs (turnover numbers) for the selective oxidation of aldehydes and alkenes; e.g. TONs of 38,800,000 for selective isobutyraldehyde (IBA) oxidation and 2,100,000 for trans-stilbene epoxidation at ambient temperature, which are among the highest TONs in metal-complex catalyzes to our knowledge. We also found that the IBA sole oxidation with an activation energy of 48 kJ mol-1 much more facile than the trans-stilbene epoxidation with an activation energy of 99 kJ mol -1 was completely suppressed by the coexistence of trans-stilbene. The switchover of the selective oxidation pathways from the IBA oxidation to the trans-stilbene epoxidation was explained in terms of energy profiles for the alternative selective oxidation pathways, resulting in the preferential coordination of trans-stilbene to the Ru-complex at the surface. This aspect gives an insight into the origin of the efficient catalysis for selective epoxidation of alkenes with IBA/O2.
- Tada, Mizuki,Muratsugu, Satoshi,Kinoshita, Mutsuo,Sasaki, Takehiko,Iwasawa, Yasuhiro
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experimental part
p. 713 - 724
(2010/04/01)
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- METHOD FOR HYDROFORMYLATION
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The present invention relates to a process for the hydroformylation of compounds of the formula (I), where X is C, P(Rx), P(O—Rx) S or S(═O), where Rx is H, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl; A is a divalent bridging group having from 1 to 4 bridging atoms; and R1 is H, alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl; or salts thereof; in which the compound of the formula (I) is reacted with carbon monoxide and hydrogen in the presence of a catalyst comprising a complex of a metal of transition group VIII with a compound of the formula (II), where Pn is a pnicogen atom; W is a divalent bridging group having from 1 to 8 bridging atoms; R2 is a functional group capable of forming an intermolecular, noncovalent bond with the group —X(═O)OH; R3, R4 are each alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl; a, b, c are each 0 or 1; and Y1, Y2 and Y3 are each O, S, NRa or SiRbRc; and also compounds of the formula (II.a), where W′ is a divalent bridging group having from 1 to 5 bridging atoms between the flanking bonds, Z is O, S, S(═O), S(═O)2, N(RIX) or C(RIX)(RX); and RI to RX are each, independently of one another, H, halogen, nitro, cyano, amino, alkyl, etc.; or two radicals RI, RII, RIV, RVI, RVIII and RIX together represent the second part of a double bond.
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Page/Page column 12
(2010/10/03)
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- An Industrial Process for Adipic Acid Production by the Liquid-Phase Oxidation of Cyclohexanone with Molecular Oxygen
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The liquid-phase O2 oxidation (auto-oxidation) of cyclohexanone by the use of acetic acid as a solvent and Mn and Co salts as catalysts at 1 atm of pure O2 at 70°C was presented. The selectivity of adipic acid was 77% and the combined selectivity of carboxylic acids, which consisted of adipic acid, glutaric acid, and succinic acid, was 93% for the 100% conversion of cyclohexanone. The combination of a Mn(OAc)2 catalyst and a Co(OAc)2 catalyst was effective for improving adipic acid selectivity in the liquid-phase oxidation of cyclohexanone with O2. Adipic acid was probably generated via 2-hydrocyclohexanone and 6-oxohexanoic acid, and glutaric acid was probably generated via 5-oxopentanoic acid. Water concentration did not show significant effect on the reaction. Use of a acid, e.g., p-toluenesulfonic acid, accelerated the oxidation reaction. The oxidation reaction proceeded under high pressure, even if the O2 concentration was 10 vol %.
- Shimizu, Atsushi,Tanaka, Katsutoshi,Ogawa, Hiroo,Matsuoka, Yuji,Fujimori, Masami,Nagamori, Yukito,Hamachi, Hidefumi,Kimura, Kazuyoshi
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p. 1993 - 2001
(2007/10/03)
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- Process for intermediates to 1-carbapenems and 1-carbacephems
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A stereoselective process for chiral intermediates to 1-carbapenum and 1-carbacephalosporins is provided comprising the use of an N-acyl-(4R)-substituted-1,3-thiazolidine-2-thione as a chiral auxiliary in boron enolate mediated aldol condensation with a protected-β-keto ester aldehyde. E.g., benzyl 3,3-(ethylenedioxy)-4-formylbutyrate is condensed with the boron enolate formed with n-butyryl (4R)-methoxycarbonyl-1,3-thiazolidine-2-thione to provide benzyl 3,3-ethylenedioxy-(5R)-hydroxy-6-[(4R)-methoxycarbonyl-1,3-thiazolidine-2-thione-3-ylcarbonyl]octanoate. Displacement of the thiazolidine-2-thione chiral auxiliary moiety with an O-alkyl, O-acyl or O-aralkyl hydroxyamine provides the corresponding chiral intermediate as the hydroxamate.
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- DYE-SENSITIZED PHOTO-OXYGENATION OF 1,2-CYCLOHEXANEDIONES
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The dye-sensitized photo-oxygenation of the enols of 1,2-cyclohexanedione (1) has been carried out in various solvents at -70 - 40 deg C.Singlet oxygen is involved in the reaction as evidenced by quenching and rate enhancement observed in deuterated methanol.The reaction proceeds by an ene reaction with singlet oxygen to afford the hydroperoxide, 4, which closes to a five-membered endoperoxide, 5, as a major path or to dioxetane (6) as a minor one.The endoperoxide, 5, decomposed to 5-oxoalkanoic acid (2) with evolution of carbon monoxide or was trapped by the solvent (MeOH or EtOH) to give methyl or ethyl 5-carboxy-2-hydroxypentanoate (3).Competition between the enol of 3-methyl-1,2-cyclohexanedione (1a) and 2,3-dimethyl-2-butene (TME) has shown that the enol is as reactive as TME toward singlet oxygen.
- Utaka, Masanori,Nakatani, Manabu,Takeda, Akira
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p. 2163 - 2168
(2007/10/02)
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- CUPRIC ION-CATALYZED DIOXYGENATION OF 1,2-CYCLOHEXANEDIONES. A NONENZYMATIC ANALOG FOR QUERCETINASE DIOXYGENATION
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1,2-Cyclohexanediones were found to be dioxygenated by molecular oxygen with the aid of cupric ion to afford 1,5-keto acids and carbon monoxide.The reaction proceeds possibly via an endoperoxide intermediate.Methyl α-hydroxyadipates were also formed as byproducts.The mechanism of oxygenation is discussed.
- Utaka, Masanori,Hojo, Makoto,Fujii, Yasuyuki,Takeda, Akira
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p. 635 - 638
(2007/10/02)
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- PHOTOSENSITIZED OXYGENATION OF THE ENOL FORMS OF 1,2-CYCLOHEXANEDIONES
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The enols of 1,2-cyclohexanediones have been found to undergo a photosensitized oxygenation in methanol to afford 5-oxoalkanoic acids and methyl 5-carboxy-2-hydroxypentanoates with liberation of carbon monoxide with a remarkable temperature dependency of the product distribution, which is best accounted for in terms of trapping of a five-membered endoperoxide intermediate by methanol.
- Utaka, Masanori,Nakatani, Manabu,Takeda, Akira
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p. 803 - 806
(2007/10/02)
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