Journal of Molecular Catalysis Pub Date : 1994-10-13 DOI: 10.1016/0304-5102(94)00099-9

Cesar Ovalles , Carolina Fernández , Donald J. Darensbourg

{"title":"Homogeneous catalytic synthesis of formaldehyde using the tungsten carbonyl complex [(CO)5WCl]− in the presence of sodium methoxide","authors":"Cesar Ovalles , Carolina Fernández , Donald J. Darensbourg","doi":"10.1016/0304-5102(94)00099-9","DOIUrl":"10.1016/0304-5102(94)00099-9","url":null,"abstract":"<div>Formaldehyde can be synthesized (Turnover number=10) from sodium methoxide and carbon dioxide using the anionic tungsten carbonyl complex [(CO)5WCl]− as catalyst precursor and a molar ratio NaOMe/W lower than 8 at 125°C, 400 psi of CO2 for a 24-h period. The most probable mechanism involves the generation of the [(CO)5WOCH3]− species by the reaction of [(CO)5WCl]− with NaOMe. The methoxide complex can undergo β-hydrogen abstraction to yield formaldehyde and the terminal hydride [(CO)5WH]−, which in turn, decomposes under reaction conditions to provide the bridging hydride [(μ-H)W2(CO)10]−. Carbon dioxide insertion into the complex [(CO)5WH]−, followed by reaction of NaOMe regenerates the alkoxide compound [(CO)5WOCH3]− and sodium formate. A kinetic study of the reaction of [(CO)5WCl]− with NaOMe suggests that the mechanism involves nucleophilic attack of the base on the metal center, and proceeds by two different pathways depending on the molar ratio base/metal. For a ratio NaOMe/W < 8 the β-hydrogen reaction takes place with the formation of [(μ-H)W2(CO)10]− and formaldehyde. For higher base/metal ratio (>8) the formation of metal cluster is observed.</div>","PeriodicalId":16567,"journal":{"name":"Journal of Molecular Catalysis","volume":"93 2","pages":"Pages 125-136"},"PeriodicalIF":0.0,"publicationDate":"1994-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0304-5102(94)00099-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81064113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Lactose hydrolysis in milk by immobilized β-galactosidase 固定化β-半乳糖苷酶水解牛奶中的乳糖

Journal of Molecular Catalysis Pub Date : 1994-10-13 DOI: 10.1016/0304-5102(94)00092-1

J. Rogalski , A. Dawidowicz , A. Leonowicz

引用次数: 19

Physicochemical properties of TiO2SiO2 unmodified and modified with H2SO4 and activity for acid catalysis TiO2SiO2未经H2SO4修饰和经H2SO4修饰后的理化性质及酸催化活性

Journal of Molecular Catalysis Pub Date : 1994-10-13 DOI: 10.1016/0304-5102(94)00117-0

Jong Rack Sohn , Hyang Ja Jang , Man Young Park , Eun Hee Park , Sang Eun Park

{"title":"Physicochemical properties of TiO2SiO2 unmodified and modified with H2SO4 and activity for acid catalysis","authors":"Jong Rack Sohn , Hyang Ja Jang , Man Young Park , Eun Hee Park , Sang Eun Park","doi":"10.1016/0304-5102(94)00117-0","DOIUrl":"10.1016/0304-5102(94)00117-0","url":null,"abstract":"<div>A series of TiO2SiO2 catalysts were prepared by coprecipitation from the mixed solution of titanium tetrachloride and sodium silicate. Some of the sample were modified with 0.5 M H2SO4 and used as modified catalysts. The addition of TiO2 to SiO2 caused the increase of acidity and acid strength, and the shifts of OH and SiO stretching bands of silanol group to lower frequencies in proportion to the TiO2 content. Catalytic activities for 2-propanol dehydration and cumene dealkylation increased in relation to the increase of acidity and the band shifts to lower frequencies. The catalytic activities of modified catalysts were higher than those of unmodified catalysts, and the effect of modification on catalytic activity was higher for 2-propanol dehydration than for cumene dealkylation. The effect of modification on catalytic activity increased with increasing TiO2 content of the catalysts. Actually, 92-TiO2SiO2/SO2−4 had the highest increment in catalytic activity and 10-TiO2SiO2/SO2−4 had the lowest increment for the 2-propanol dehydration.</div>","PeriodicalId":16567,"journal":{"name":"Journal of Molecular Catalysis","volume":"93 2","pages":"Pages 149-167"},"PeriodicalIF":0.0,"publicationDate":"1994-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0304-5102(94)00117-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76471241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 25

CuII—diamine complex catalyzed hydrolysis of phosphate triesters adsorbed on strong-base ion exchange resins. 31P NMR relaxation measurements 崔二胺配合物催化强碱离子交换树脂吸附磷酸三酯的水解。31P核磁共振松弛测量

Journal of Molecular Catalysis Pub Date : 1994-10-13 DOI: 10.1016/0304-5102(94)00094-8

W.T. Beaudry, G.W. Wagner , J.R. Ward

{"title":"CuII—diamine complex catalyzed hydrolysis of phosphate triesters adsorbed on strong-base ion exchange resins. 31P NMR relaxation measurements","authors":"W.T. Beaudry, G.W. Wagner , J.R. Ward","doi":"10.1016/0304-5102(94)00094-8","DOIUrl":"10.1016/0304-5102(94)00094-8","url":null,"abstract":"<div>The CuII—diamine complexes, (bipy)CuSO4 and (tmen)CuSO4, catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate (PNDP) adsorbed on a strong-base ion exchange resin. Turnover is observed. The major hydrolysis products are diphenyl phosphate, p-nitrophenyl phenyl phosphate, and the ethanolysis product ethyl diphenyl phosphate (EDPP) which are observed in similar amounts in both the presence and absence of the CuII—diamine catalysts. The apparent bimolecular rate constants found for the (bipy) CuSO4 and (tmen)CuSO4 catalysts are 0.023 and 0.024 M−1 s−1, respectively. CuSO4 is inactive as a catalyst. 31P MAS NMR relaxation measurements of the stable EDPP product reveal that the CuII—diamine complexes greatly enhance T1 relaxation, whereas CuSO4 has only minimal effect. These results are consistent with the complexation of neutral phosphorus esters by the CuII—diamine catalysts. 31P T1 measurements of hydrolytically-stable dimethyl methylphosphonate (DMMP) in water solutions of Cu2+, (tmen)Cu2+, and Mn2+ suggest that DMMP exchanges rapidly between inner-sphere and outer-sphere complexes in a nearly identical manner with each of these paramagnetic species.</div>","PeriodicalId":16567,"journal":{"name":"Journal of Molecular Catalysis","volume":"93 2","pages":"Pages 221-231"},"PeriodicalIF":0.0,"publicationDate":"1994-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0304-5102(94)00094-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78711018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Enantioface-differentiating hydrogenation of the CO double bond using a modified Raney nickel: Role of the carboxylic acid added to the reaction system 用改性的雷尼镍对CO双键进行对映面分化氢化:加入反应体系的羧酸的作用

Journal of Molecular Catalysis Pub Date : 1994-10-13 DOI: 10.1016/0304-5102(94)00090-5

Tadao Harada , Toshihiro Kawamura , Shiro Haikawa , Tsutomu Osawa

引用次数: 13

Photocatalytic reduction of coordinated dinitrogen to ammonia — mononuclear versus dinuclear ethylenediaminetetraacetato ruthenium complexes 光催化还原配位二氮制氨-单核与双核乙二胺四乙酸钌配合物

Journal of Molecular Catalysis Pub Date : 1994-09-27 DOI: 10.1016/0304-5102(94)00097-2

N.Nageswara Rao

引用次数: 5

Kinetic behaviour and reaction mechanism of the hydrolysis of p-nitrophenyl palmitate in mixed micelles with Triton X-100 catalyzed by lipase from Candida rugosa 假丝酵母脂肪酶催化Triton X-100混合胶束水解对硝基苯棕榈酸酯的动力学行为及反应机理

Journal of Molecular Catalysis Pub Date : 1994-09-27 DOI: 10.1016/0304-5102(94)00104-9

J.C. Martin, J.F. Bello, F.J. Burguillo, M.G. Roig

{"title":"Kinetic behaviour and reaction mechanism of the hydrolysis of p-nitrophenyl palmitate in mixed micelles with Triton X-100 catalyzed by lipase from Candida rugosa","authors":"J.C. Martin, J.F. Bello, F.J. Burguillo, M.G. Roig","doi":"10.1016/0304-5102(94)00104-9","DOIUrl":"10.1016/0304-5102(94)00104-9","url":null,"abstract":"<div>The physicochemical properties of lipase from Candida rugosa in the hydrolysis of micellized p-nitrophenyl palmitate, such as thermal stability, enzyme concentration and the effect of ionic strength on the rate of catalysis, have been characterized. As regards the specificity for a series of p-nitrophenyl esters (p-NPCn), n = 2, 4, 8, 12 and 16 being the number of carbon atoms of the hydrophobic tail, the lipase from Candida rugosa proved to be non-specific, although it did hydrolyze them at different rates, depending on n and the physicochemical nature of the substrate (mixed micelles with surfactant or simple solution). At Triton X-100 levels above the critical micelle concentration (c.m.c.), the kinetic behaviour of the hydrolysis of p-nitrophenyl palmitate in Triton X-100 mixed micelles catalyzed by Candida rugosa lipase was consistent with the Michaelis—Menten rate equation under three different experimental conditions: (i) the molar fraction of substrate held constant and the Triton X-100 concentration varied; (ii) the bulk substrate concentration held constant and the Triton X-100 concentration varied, and (iii) the Triton X-100 concentration held constant and the bulk substrate concentration varied. Kinetic analysis performed in the above conditions revealed that the simple model described by Verger et al. [J. Biol. Chem., 248 (1973), 4023] correctly interprets the kinetic behaviour of the commercial lipase from Candida rugosa used in the study and highlights the advantage that this classic mechanism may have in current lipase modelling in biocatalysis.</div>","PeriodicalId":16567,"journal":{"name":"Journal of Molecular Catalysis","volume":"93 1","pages":"Pages 37-52"},"PeriodicalIF":0.0,"publicationDate":"1994-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0304-5102(94)00104-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87440405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Role of surface chlorine species in the oxidative coupling of methane in the presence of tetrachloromethane on magnesium phosphate and sulphate 在四氯甲烷存在下，表面氯在甲烷与磷酸镁和硫酸盐氧化偶联中的作用

Journal of Molecular Catalysis Pub Date : 1994-09-27 DOI: 10.1016/0304-5102(94)00096-4

Shigeru Sugiyama , Kohji Satomi , Nozomi Kondo , Naoya Shigemoto , Hiromu Hayashi , John B. Moffat

{"title":"Role of surface chlorine species in the oxidative coupling of methane in the presence of tetrachloromethane on magnesium phosphate and sulphate","authors":"Shigeru Sugiyama , Kohji Satomi , Nozomi Kondo , Naoya Shigemoto , Hiromu Hayashi , John B. Moffat","doi":"10.1016/0304-5102(94)00096-4","DOIUrl":"10.1016/0304-5102(94)00096-4","url":null,"abstract":"<div>The oxidative coupling of methane was carried out over Mg3 (PO4)2 and MgSO4 in the presence of tetrachloromethane (TCM) in order to compare the catalytic activities, the interaction between TCM and each catalyst and the effect of the nature of the anion. The conversion of methane on the sulphate increased with increase in the partial pressure of TCM and of reaction temperature, while with the phosphate the presence of TCM had little effect under the same conditions as those on the sulphate. With both catalysts the addition of TCM increased the selectivities to ethylene. Relatively large quantities of chlorinated species were detected on the catalyst surface of the used phosphate by XPS, although none were detected by XRD analyses. In contrast, only small quantities of chlorinated species were formed on the sulphate catalyst and magnesia was detected by XRD in the bulk phase of the used sulphate. The interactions between TCM and the catalyst and, in particular, the effect of the nature of the anion are discussed.</div>","PeriodicalId":16567,"journal":{"name":"Journal of Molecular Catalysis","volume":"93 1","pages":"Pages 53-65"},"PeriodicalIF":0.0,"publicationDate":"1994-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0304-5102(94)00096-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89175367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 28

Catalytic activity of anchored vanadyl complexes 锚定钒基配合物的催化活性

Journal of Molecular Catalysis Pub Date : 1994-09-27 DOI: 10.1016/0304-5102(94)00086-7

Rajinder Kaur Bhatia , G.N. Rao

引用次数: 10

Recent contributions of carbonylation reaction to the synthesis of fluorinated pharmaceutical compounds 羰基化反应对合成含氟药物化合物的最新贡献

Journal of Molecular Catalysis Pub Date : 1994-09-27 DOI: 10.1016/0304-5102(94)00077-8

Carlo Botteghi , Gino Del Ponte , Mauro Marchetti , Stefano Paganelli

引用次数: 9

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