- Production of renewable 1,3-pentadiene over LaPO4 via dehydration of 2,3-pentanediol derived from 2,3-pentanedione
-
1,3-Pentadiene plays an extremely important role in the production of polymers and fine chemicals. Herein, the LaPO4 catalyst exhibits excellent catalytic performance for the dehydration production of 1,3-pentadiene with 2,3-pentanediol, a C5 diol platform compound that can be easily obtained by hydrogenation of bio-based 2,3-pentanedione. The relationships of catalyst structure-acid/base properties-catalytic performance was established, and an acid-base synergy effect was disclosed for the on-purpose synthesis of 1,3-pentadiene. Thus, a balance between acid and base sites was required, and an optimized LaPO4 with acid/base ratio of 2.63 afforded a yield of 1,3-pentadiene as high as 61.5% at atmospheric pressure. Notably, the Br?nsted acid sites with weak or medium in LaPO4 catalyst can inhibit the occurrence of pinacol rearrangement, resulting in higher 1,3-pentadiene production. In addition, the investigation on reaction pathways demonstrated that the E2 mechanism was dominant in this dehydration reaction, accompanied by the assistance of E1 and E1cb.
- Bai, Chenxi,Cui, Long,Dai, Quanquan,Feng, Ruilin,Liu, Shijun,Qi, Yanlong
-
-
- Synthesis method of pentanediol, and synthesis method for preparing biomass-based pentadiene through conversion of levulinic acid and derivatives of levulinic acid
-
The invention provides a synthesis method of pentanediol, and the method comprises the following steps: carrying out conversion reaction on a mixed solution obtained by mixing levulinic acid and/or levulinic acid derivatives, a catalyst and an organic solvent in a hydrogen-containing atmosphere to obtain the pentanediol. According to the method, a large amount of cheap and easily available bio-based chemical levulinic acid or derivatives thereof can be utilized, pentanediol is obtained through catalytic conversion, and m-pentadiene is further obtained. The raw materials are derived from renewable resources, the m-pentadiene is prepared through hydrogenation and dehydration, and particularly, a green and sustainable process route for synthesizing the m-pentadiene is finally obtained through a dehydration reaction route and construction of a dehydration catalyst. The invention provides a method for green and sustainable synthesis of linear pentadiene based on bio-based chemical conversion, and the method has the advantages of simple operation, short flow, no need of harsh experimental conditions, easy preparation of raw materials and catalysts, and large-scale synthesis prospect.
- -
-
Paragraph 0157; 0161-0165; 0170; 0174-0177; 0178; 0182-0185
(2021/04/07)
-
- An In-Situ Self-regeneration Catalyst for the Production of Renewable Penta-1,3-diene
-
Catalyst deactivation is a problem of great concern for many heterogeneous reactions. Here, an urchin-like LaPO4 catalyst was easily developed for pentane-2,3-diol dehydration; it has an impressive ability to restore the activity in situ by itself during the reaction, accounting for its high stability. This facilitates the efficient production of renewable penta-1,3-diene from pentane-2,3-dione via a novel approach, where penta-2,3-diol was obtained as an intermediate in 95 % yield under mild conditions.
- Feng, Ruilin,Qi, Yanlong,Liu, Shijun,Cui, Long,Dai, Quanquan,Bai, Chenxi
-
supporting information
p. 9495 - 9498
(2021/05/27)
-
- Synthesis method of pentanediol and synthesis method for preparing biomass-based linear pentadiene based on lactic acid conversion
-
The invention provides a method for synthesizing pentanediol. The method comprises the following steps: carrying out hydrogenation reaction on a mixed solution obtained by mixing pentanedione, a hydrogenation catalyst and an organic solvent in a hydrogen-containing atmosphere to obtain the pentanediol. According to the invention, a large amount of cheap and easily available bio-based chemical lactic acid can be utilized to obtain pentanediol, and linear pentadiene is further obtained; the raw materials are from renewable resources, and linear pentadiene is obtained through the following steps: (1) condensing lactic acid to prepare pentanedione, (2) hydrogenating pentanedione to prepare pentanediol, and (3) dehydrating pentanediol to obtain linear pentadiene; linear pentadiene, especially 1, 3-pentadiene, is prepared from lactic acid through a process route of condensation, hydrogenation and dehydration; and a green and sustainable linear pentadiene synthesis method based on bio-based chemical conversion is provided, and is simple to operate, short in process, free of harsh experimental conditions, easy to prepare raw materials and catalysts, and has a large-scale synthesis prospect.
- -
-
Paragraph 0204; 0209-0210; 0211; 0216-0217; 0218; 0223-0224
(2021/05/19)
-
- Dehydra-decyclization of 2-methyltetrahydrofuran to pentadienes on boron-containing zeolites
-
1,3-Pentadiene (piperylene) is an important monomer in the manufacturing of adhesives, plastics, and resins. It can be derived from biomass by the tandem ring-opening and dehydration (dehydra-decyclization) of 2-methyltetrahydrofuran (2-MTHF), but competing reaction pathways and the formation of another isomer (1,4-pentadiene) have limited piperylene yields to MFI > BEA at a given temperature (523 K), indicating the non-identical nature of active sites in these weak solid acids. The diene distribution remained far from equilibrium and was tuned towards the desirable conjugated diene (1,3-pentadiene) by facile isomerization of 1,4-pentadiene. This tuning capability was facilitated by high bed residence times, as well as the smaller micropore sizes among the zeolite frameworks considered. The suppression of competing pathways, and promotion of 1,4-pentadiene isomerization events lead to a hitherto unreported ~86percent 1,3-pentadiene yield and an overall ~89percent combined linear C5 dienes' yield at near quantitative (~98percent) 2-MTHF conversion on the borosilicate B-MWW, without a significant reduction in diene selectivities for at least 80 hours time-on-stream under low space velocity (0.85 g reactant per g cat. per h) and high temperature (658 K) conditions. Finally, starting with iso-conversion levels (ca. 21-26percent) and using total turnover numbers (TONs) accrued over the entire catalyst lifetime as the stability criterion, borosilicates were demonstrated to be significantly more stable than aluminosilicates under reaction conditions (~3-6× higher TONs).
- Dauenhauer, Paul J.,Kumar, Gaurav,Liu, Dongxia,Ren, Limin,Tsapatsis, Michael,Xu, Dandan
-
supporting information
p. 4147 - 4160
(2020/07/14)
-
- Phosphonate-Modified UiO-66 Br?nsted Acid Catalyst and Its Use in Dehydra-Decyclization of 2-Methyltetrahydrofuran to Pentadienes
-
Phosphorus-modified all-silica zeolites exhibit activity and selectivity in certain Br?nsted acid catalyzed reactions for biomass conversion. In an effort to achieve similar performance with catalysts having well-defined sites, we report the incorporation of Br?nsted acidity to metal–organic frameworks with the UiO-66 topology, achieved by attaching phosphonic acid to the 1,4-benzenedicarboxylate ligand and using it to form UiO-66-PO3H2 by post-synthesis modification. Characterization reveals that UiO-66-PO3H2 retains stability similar to UiO-66, and exhibits weak Br?nsted acidity, as demonstrated by titrations, alcohol dehydration, and dehydra-decyclization of 2-methyltetrahydrofuran (2-MTHF). For the later reaction, the reported catalyst exhibits site-time yields and selectivity approaching that of phosphoric acid on all-silica zeolites. Using solid-state NMR and deprotonation energy calculations, the chemical environments of P and the corresponding acidities are determined.
- Caratzoulas, Stavros,Chen, Tso-Hsuan,Dauenhauer, Paul,Dorneles de Mello, Matheus,Han, Songi-I,Jain, Sheetal K.,Kumar, Gaurav,Li, Xinyu,Scott, Susannah L.,Tabassum, Tarnuma,Tsapatsis, Michael,Vlachos, Dionisios G.
-
supporting information
p. 13260 - 13266
(2020/06/08)
-
- Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
-
To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
- Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
-
p. 2389 - 2397
(2019/08/01)
-
- Method for synthesizing diene compounds based on aldehyde-ketone condensation reaction
-
The invention provides a method for synthesizing diene compounds based on an aldehyde-ketone condensation reaction. The method comprises the following steps: firstly, under the action of a condensation catalyst, performing a condensation reaction on ketone compounds and aldehyde compounds to obtain condensation products; then, under the action of a reduction catalyst, performing a reduction reaction on the condensation products obtained in the previous step to obtain reduction products; under the action of a catalyst, performing a dehydration reaction on the reduction products obtained in theprevious step to obtain the diene compounds. According to the method, ketone, aldehyde as well as homologues of ketone and aldehyde which are cheap and easy to obtain can be used as raw materials forsynthesizing the diene compounds such as butadiene, piperylene as well as homologues of butadiene and piperylene, experimental conditions are mild, the operation is simple, and a large-scale synthesisprospect is achieved.
- -
-
Paragraph 0172; 0178-0180; 0215; 0221-0223
(2019/05/08)
-
- Effect of Solvents on Acid-Catalyzed Claisen Amino Rearrangement in N-(1-Methyl-2-butenyl)aniline
-
Abstract: The effect solvents have on the processes of rearrangement and elimination in N-(1-methyl-2-butenyl)aniline (I) in the presence of HCl is studied. It is shown that the dependence of the rearrangement and elimination rate constants of (I) · HCl on the nature of solvents are described perfectly by the Koppel–Palm equation, which considers both nonspecific and specific solvation. The inhibitory effect of solvent nucleophilicity is explained by the complexation between (I) · HCl and solvent molecules. Analysis of the (I) · HCl conversion products obtained in a mixed solvent (m-toluidine + nitrobenzene) demonstrates the intermolecular transfer of the allyl moiety, confirming the formation of allyl cations in the Claisen amino rearrangement.
- Abdrakhmanov,Sharafutdinov,Mustafin,Zimin, Yu. S.,Daminev
-
-
- Terminal Alkenes from Acrylic Acid Derivatives via Non-Oxidative Enzymatic Decarboxylation by Ferulic Acid Decarboxylases
-
Fungal ferulic acid decarboxylases (FDCs) belong to the UbiD-family of enzymes and catalyse the reversible (de)carboxylation of cinnamic acid derivatives through the use of a prenylated flavin cofactor. The latter is synthesised by the flavin prenyltransferase UbiX. Herein, we demonstrate the applicability of FDC/UbiX expressing cells for both isolated enzyme and whole-cell biocatalysis. FDCs exhibit high activity with total turnover numbers (TTN) of up to 55000 and turnover frequency (TOF) of up to 370 min?1. Co-solvent compatibility studies revealed FDC's tolerance to some organic solvents up 20 % v/v. Using the in-vitro (de)carboxylase activity of holo-FDC as well as whole-cell biocatalysts, we performed a substrate profiling study of three FDCs, providing insights into structural determinants of activity. FDCs display broad substrate tolerance towards a wide range of acrylic acid derivatives bearing (hetero)cyclic or olefinic substituents at C3 affording conversions of up to >99 %. The synthetic utility of FDCs was demonstrated by a preparative-scale decarboxylation.
- Aleku, Godwin A.,Prause, Christoph,Bradshaw-Allen, Ruth T.,Plasch, Katharina,Glueck, Silvia M.,Bailey, Samuel S.,Payne, Karl A. P.,Parker, David A.,Faber, Kurt,Leys, David
-
p. 3736 - 3745
(2018/08/03)
-
- Tetrabutylphosphonium Bromide Catalyzed Dehydration of Diols to Dienes and Its Application in the Biobased Production of Butadiene
-
We report the use of the ionic liquid tetrabutylphosphonium bromide as a solvent and catalyst for dehydration of diols to conjugated dienes. This system combines stability, high reaction rates, and easy product separation. A reaction mechanism for the model compound 1,2-hexanediol is proposed and experimentally corroborated. This particular mechanism allows for the selective formation of conjugated dienes, in contrast with purely acidic catalysis. Next, the reaction is also performed on various other diols. As a first application, we assessed the biobased production of 1,3-butadiene. With 1,4-butanediol as the starting material, a 94% yield of butadiene was reached at 100% conversion.
- Stalpaert, Maxime,Cirujano, Francisco G.,De Vos, Dirk E.
-
p. 5802 - 5809
(2017/09/15)
-
- METHOD FOR PRODUCING CONJUGATED DIENE
-
The present invention relates to a manufacturing method of conjugated diene. According to the present invention, a manufacturing method of conjugated diene such as butadiene, or the like, through a contact oxidative dehydrogenation reaction of mono-olefin such as n-butene, or the like can effectively remove byproducts such as acrolein, butenone, benzaldehyde, and the like, during a dehydration process after a cooling process without using a desiccant. The manufacturing method comprises the following steps of: a) manufacturing a product gas including butadiene by oxidative dehydrogenation of a raw gas including n-butene; b) cooling the product gas, and manufacturing an organic solution by making the product gas absorb to an organic solvent; and c) obtaining crude butadiene by degassing and stripping the organic solution.COPYRIGHT KIPO 2016
- -
-
Paragraph 0071-0073
(2017/04/25)
-
- Production of aldehydes from 1,2-alkanediols over silica-supported WO3 catalyst
-
Vapor-phase dehydration of several 1,2-alkanediols, such as 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol and 1,2-pentanediol, to produce corresponding aldehydes was investigated over silica-supported WO3 catalyst, which was prepared by impregnation method and then calcined at 320?°C. Higher than 90% yield of aldehydes could be achieved over WO3/SiO2 catalyst at 250?°C with a feed of 20% aqueous 1,2-alkanediol solution. Both Br?nsted and Lewis acid sites exist on WO3/SiO2 catalyst, while Br?nsted acid sites are proposed to be the active species for the formation of aldehyde. High concentrations of H2O were effective for inhibiting the intermolecular reaction and improving the selectivity to aldehydes. The dehydration of different 1,2-alkanediols was compared under different reaction conditions. The reactivity of 1,2-ethanediol was low and the product distribution was several comparing with those of the other 1,2-alkanediols. Cyclic acetal, which was generated by the cyclodehydration of the produced aldehyde with another 1,2-alkanediol, was a main by-product, and the formation of acetal was affected by both the temperature and the carbon-chain length of the 1,2-alkanediols.
- Sun, Daolai,Yamada, Yasuhiro,Sato, Satoshi,Suganuma, Satoshi,Katada, Naonobu
-
p. 164 - 171
(2016/09/09)
-
- Study of the Formation of the First Aromatic Rings in the Pyrolysis of Cyclopentene
-
The thermal decomposition of cyclopentene was studied in a jet-stirred reactor operated at constant pressure and temperature to provide new experimental information about the formation of the first aromatic rings from cyclic C5 species. Experim
- Herbinet, Olivier,Rodriguez, Anne,Husson, Benoit,Battin-Leclerc, Frédérique,Wang, Zhandong,Cheng, Zhanjun,Qi, Fei
-
p. 668 - 682
(2016/02/23)
-
- Solid-state molybdenum sulfide clusters with an octahedral metal framework as hydrogenation, dehydrogenation, and hydrogenolysis catalysts similar to the platinum group metals
-
Solid-state molybdenum sulfide clusters with a nonstoichiometric sulfur-deficient site, CuxMo6S8-δ (x = 2.94 and δ ? 0.3) and Mo6S8-δ (δ ? 0.4), catalyze the dehydrogenation of cyclohexene, the hydrogenation of alkyne, alkene, aldehyde, ketone, and nitrobenzene, and the hydrogenolysis of halogenobenzenes in a hydrogen stream above 300 °C. This catalytic behavior of the clusters is similar to that of the platinum group metals, which is attributable to the isoelectronicity of sulfur-coordinating molybdenum atom to the platinum group metals.
- Kamiguchi, Satoshi,Arai, Kanako,Okumura, Kazu,Iida, Hajime,Nagashima, Sayoko,Chihara, Teiji
-
p. 417 - 421
(2015/10/28)
-
- ALKANE DEHYDROGENATION PROCESS
-
Disclosed herein are processes for dehydrogenation of an alkane to an alkene using an iridium pincer complex. In the dehydrogenation reactions, hydrogen that is co-formed during the process must be removed for the chemical reaction to proceed and to prevent the excess hydrogen from poisoning the catalyst. In one embodiment the process comprises providing an alkane feedstock comprising at least one alkane and contacting the alkane with an iridium pincer complex in the presence of a hydrogen acceptor selected from the group consisting of ethylene, propene, or mixtures to form an alkene product. The processes disclosed herein can accomplish facile, low-temperature transfer dehydrogenation of alkanes with unprecedented selectivities and TONs at a reasonable rate of conversion.
- -
-
Paragraph 0074; 0084
(2015/09/28)
-
- METHOD OF FORMING C5 DI-OLEFINS
-
A process is disclosed that includes reacting a C1 source with n-butene to form a C-5 diolefin.
- -
-
Paragraph 0086; 0087
(2014/09/30)
-
- Preparation of functional styrenes from biosourced carboxylic acids by copper catalyzed decarboxylation in PEG
-
A general protocol for the copper-catalyzed decarboxylation of α,β-unsaturated carboxylic acids in PEG, particularly of biosourced cinnamic acid analogues, is reported. Moderate to high isolated yields (31-96%) towards the styrene derivatives were obtained. For the first time, decarboxylation of α-amino acids to the corresponding amines was successfully performed with good to high yields and extended to the decarboxylation of a few condensed heterocyclic compounds. Both the use of PEG as a green solvent and direct separation of the pure product of the reaction by distillation permitted the reuse of the solvent and the Cu-based catalytic system over several cycles without deactivation. This was extended to the synthesis of 4-vinylguaiacol on the laboratory scale in an average 92% yield. This journal is the Partner Organisations 2014.
- Cadot, Stephane,Rameau, Nelly,Mangematin, Stephane,Pinel, Catherine,Djakovitch, Laurent
-
supporting information
p. 3089 - 3097
(2014/06/10)
-
- CATALYTIC DEHYDRATION OF ALCOHOLS AND ETHERS OVER A TERNARY MIXED OXIDE
-
A ternary V—Ti—P mixed oxide is shown to catalytically dehydrate 2-methyl-tetrahydrofuran in high conversion to give piperylene, in good yield. Volatile products collected from this reaction contain piperylene in concentrations as high as 80 percent by weight. Dehydration of glycerol to acrolein in high conversion and moderate selectivity is also demonstrated. The catalyst is also shown to dehydrate other alcohols and ether substrates. The catalyst is resistant to deactivation and maintains activity between runs.
- -
-
Paragraph 0040; 0046
(2013/03/28)
-
- RENEWABLE ACRYLIC ACID PRODUCTION AND PRODUCTS MADE THEREFROM
-
Processes and methods for making biobased acrylic acid products including acrylic acid, acrylic acid oligomers, acrylic acid esters, acrylic acid polymers and articles from renewable carbon resources are described herein.
- -
-
Paragraph 00140; 00141; 00142; 00143
(2014/01/08)
-
- Synthesis of piperylene and toluene via transfer dehydrogenation of pentane and pentene
-
The highly thermally stable anthraphos-based iridium pincer complex ( iPr4Anthraphos)Ir(C2H4) 3, was shown to catalyze transfer dehydrogenation of pentene and pentane using various olefins as acceptors in the temperature range of 160-250 C. Using pentene itself as an acceptor, disproportionation of pentene to pentane and pentadiene was observed, but yields of (E)- and (Z)-1,3-pentadienes (piperylenes) were limited to ~25% as a result of a self-Diels-Alder reaction of the 1,3-dienes to produce isomeric mixtures of the C10 dimers. Using propylene as the acceptor, higher yields of piperylenes were obtained (~40%), but self-Diels-Alder adducts were again observed along with low fractions of propylene/pentadiene Diels-Alder adducts. Using ethylene as the acceptor, the pentadienes produced via hydrogen transfer undergo an in situ Diels-Alder reaction with ethylene to produce 3-methylcyclohexene (along with toluene from further dehydrogenation) in good yields (65%). 3-Methylcylohexene was quantitatively dehydrogenated to toluene over a heterogeneous Pd/C catalyst.
- Kundu, Sabuj,Lyons, Thomas W.,Brookhart, Maurice
-
p. 1768 - 1773
(2013/09/02)
-
- PRODUCTION OF 2,4-HEXADIENOIC ACID AND 1,3-PENTADIENE FROM 6-METHYL-5,6-DIHYDRO-2-PYRONE
-
Described is a method of making sorbic acid, pentadiene, or 3-penten-2-one. The method includes partially hydrogenating 4-hydroxy-6-methyl-2-pyrone (HMP) to yield 5,6-dihydro-4-hydroxy-6-methyl-2H-pyran-2-one (4-DHMMP). Then, if 3-penten-2-one is desired, thermally decomposing the 4-DHMMP to yield 3-penten-2-one. If sorbic acid or pentadiene are desired, the 4-DHMMP is hydrogenated to yield 4-hydroxy-6-methyltetrahydro-2-pyrone (4-HMTHP). The 4-HMTHP is then dehydrated by contacting it with a solid acid catalyst to yield parasorbic acid (PSA). The PSA can then be ring-opened by contacting it with a solid acid catalyst. The reaction conditions of the ring-opening reaction can be controlled to yield sorbic acid and/or pentadiene.
- -
-
Page/Page column 8
(2012/05/20)
-
- Rate constants and the H atom branching ratio of the reactions of the methylidyne CH(X2Π) radical with C2H2, C2H4, C3H4 (methylacetylene and allene), C3H6 (
-
The reactions of the CH radical with several unsaturated hydrocarbons C2H2 (acetylene), C2H4 (ethylene), C3H4 (methyl-acetylene and allene), C3H 6 (propene) and C
- Loison, Jean-Christophe,Bergeat, Astrid
-
body text
p. 655 - 664
(2009/05/07)
-
- Thermodynamic parameters of the single-stage dehydrogenation of isopentane to isoprene
-
From the results of experiments with platinum-containing catalysts operating in the steady mode, adiabatic changes in temperature in the course of 2-metylbutane dehydrogenation to monoolefins and isoprene were calculated. Dehydrogenation of 2-methylbutane
- Romanova,Lamberov,Shaikhutdinova,Gil'Manov,Gil'Mullin
-
body text
p. 1583 - 1591
(2009/05/06)
-
- Flash vacuum pyrolysis over solid catalysts. 1. Pyrazoles over zeolitest
-
Flash vacuum pyrolysis (fvp) reactions of 1H-pyrazole (1), 3,5-dimethylpyrazole (2), and 3,5-diphenylpyrazole (3) were carried out over zeolites. Reactions were performed using ZCOY-7, NH4-Y, and Na-Y zeolites. Reaction temperatures of heterogeneous reactions were lower than the corresponding temperatures in the homogeneous system, showing a catalytic effect of the zeolites. Compounds 1-3 afforded nitrogen extrusion in homogeneous fvp reactions while in the heterogeneous ones different reactions were present. Compounds 1 and 2 also afforded nitrogen extrusion; products arising from ring fragmentation were found in reactions of 2 and 3 while an isomeric imidazole was isolated in reactions of 3. Isomerization of 3 is attributed to a transition-state selectivity by the catalyst due to the relation between the size of the molecule and the cavity of the zeolite. This isomerization reaction was present only when zeolites with active Broensted sites were used.
- Moyano,Yranzo
-
p. 2943 - 2947
(2007/10/03)
-
- Transformation of 1,3-, 1,4- and 1,5-diols over perfluorinated resinsulfonic acid (Nafion-H)
-
The transformations of 1,3-, 1,4- and 1,5-diols over perfluorinated resinsulfonic acids (Nafion-H) were studied and correlations were examined between the structure of the investigated diols, the possible transformation directions and the catalytic properties of Nafion-H. Comparisons were also made between the catalytic properties of Nafion-H and zeolites. The characteristic transformations of 1,3-diols depend on their structure. 1,3-Propanediol undergoes dehydration via 1,2-elimination and yields oligomers via intermolecular dehydration. 1,3-Diols with an alkyl substituent on the carbon between those bearing the OH groups undergo 1,2-elimination yielding unsaturated alcohols and dienes, and give carbonyl compounds via the loss of water and hydride shifts analogous to the pinacol rearrangement. The strong acidity of Nafion-H and the lack of strong basic sites are advantageous for the latter reaction. 1,3-Diols with two substituents at this position mainly yield fragmentation products. Stereoselective cyclodehydration to the corresponding oxacycloalkanes is the characteristic transformation of 1,4- and 1,5-diols over Nafion-H.
- Bucsi,Molnar,Bartok,Olah
-
p. 3319 - 3326
(2007/10/02)
-
- Kinetic Features and Lattice-oxygen Participation in Propene Oxidation over Bi-Mo Oxide and some Mo Oxide Catalysts
-
The rates of propene conversion in the absence of oxygen have been compared with those in the presence of oxygen at the same propene pressures.Over Bi-Mo oxides which are mainly composed of the β- or γ-phase, the rates for propenal formation were 3.5-4.5 times bigger in the presence of oxygen than in the absence of oxygen.In contrast, some Mo-containing oxide catalysts such as MoO3, Co-Mo(1/1), Co-Te-Mo (1/1/1) and other Bi-Mo oxides exhibit little or no difference in the rates of propenal formation in the presence or absence of oxygen.In the case of but-1-ene and (E)-but-2-ene oxidation, both rates were nearly the same even on β- and γ-phase Bi-Mo oxides.Such a sensitive effect of oxygenon propenal formation formatin over β- and γ-phase oxides seems to originate from an appreciable increase of active sites owing to a reoxidation step.Using 18O tracer studies in propene oxidation, the extents of lattice-oxygen participation were determined over various Mo oxide catalysts.The number of active sites for propene oxidation was found to be closely related to the extent of lattice-oxygen participation.A modified redox mechanism was proposed on the basis of a different active site model for the reduction and reoxidation steps.The kinetic features were discussed using this model.
- Ono, Takehiko,Nakajo, Takahiko,Hironaka, Tatsuo
-
p. 4077 - 4081
(2007/10/02)
-
- EFFECTS OF SUBSTITUENTS IN ACID-CATALYZED CLAISEN AMINO REARRANGEMENT
-
A series of 4-R2-N-R1-N-(1-methyl-2-butenyl)- and 4-R2-N-R1-2-(1-methyl-2-butenyl)-anilines was synthesized.The rate constants of rearrangement and elimination of the hydrochlorides of the 4-R2-N-R1-N-(1-methyl-2-butenyl)anilines in nitrobenzene were measured at 110 and 130 deg C.The correlation equations which describe the effect of the nature of the substituents on the reactivity of the substrate in these reactions and the selectivity of their occurence were established.A mechanism of the processes was proposed.
- Abdrakhmanov, I. B.,Saraeva, Z. N.,Nigmatullin, N. G.,Komissarov, V. D.,Tolstikov, G. A.
-
p. 2117 - 2122
(2007/10/02)
-
- Selective Lanthanide-catalysed Reactions. Catalytic Properties of Sm and Yb Metal Vapour Deposition Products
-
The characteristics of lanthanide catalysts obtained when Sm and Yb were vaporized into a frozen organic (tetrahydrofuran, benzene and methylcyclohexane) matrix (77 K) were investigated.These low-valent, highly dispersed lanthanide particles (indicated as Sm/THF, Sm/benzene, Yb/THF, Yb/benzene etc.) were catalytically active and selective for hydrogenation and isomerization.Samarium usually showed a greater activity than ytterbium.Olefin hydrogenation obeyed the rate law v=kPH, suggesting that the reaction is controlled by catalytic activation of hydrogen.The molecular isotopic identity of hydrogen was conserved during the hydrogenation.Yb/THF and Yb/benzene were active for partial hydrogenation of benzene to cyclohexene.For the hydrogenation of olefins and acetylenes the substrate specificity was high; thus C-C double bonds were more readily reduced than triple bonds.The samarium and ytterbium catalysts discriminate between terminal and internal C-C triple bonds, only internal CC bonds (but-2-yne and pent-2-yne) being reduced very selectively in contrast to acetylene, methylacetylene and but-1-yne.Solid base character of the lanthanide provides a cause for these differences in catalytic properties.
- Imamura, Hayao,Kitajima, Keiji,Tsuchiya, Susumu
-
p. 1647 - 1654
(2007/10/02)
-
- Selective Hydrogenation of Internal and Terminal CC Bonds on Rare Earth Catalysts Formed by Metal Vapor Deposition
-
The rare earth catalysts obtained when Sm and Yb were vaporized into a frozen organic matrix exhibited selective hidrogenation of various acetylenic derivatives.Sm/THF and Yb/THF discriminated between internal and terminal triple bonds.
- Imamura, Hayao,Kitajima, Keiji,Tsuchiya, Susumu
-
p. 249 - 250
(2007/10/02)
-
- Reactions retrodieniques - XVIII. Synthese par thermolyse eclair et etude d'allenes fonctionnels reactifs
-
The flash thermolysis of anthracenic Diels-Alder adducts leads to the obtention and low temperature spectroscopic characterization (ir, 1H and 13C nmr) of allenes 1-11 (see table 1).Butadienal 1, the simplest α-allenic aldehyde, is thus obtained from its precursors 13, 14 or 17.Thermolysis of the intermediate allylic alcohol 15 gives buta-1,3-dien-2-ol 18, which tautomerizes to methylvinylketone even at -100 deg C.An attempted synthesis of a natural δ-allenic ester, methyl laballenate 19, was undertaken using this method; however, the thermolysis of ester 24 leads via 19 to methyl acrylate and (Z + E) pentadeca-1,3-diene 25, resulting formally from a retroene cleavage of 19.Thermolyses of related esters 26 and 27 give in the same way the corresponding 1,3-dienes.Allenes with gem electron attracting groups are very reactive compounds acting as ketene equivalents in nucleophilic additions and or dipolar cycloadditions.The thermolysis of adducts 28-32, obtained by Knoevenagel condensation of malonic derivatives with ketone 16, leads to the following allenes of this series: 1,1-dicyano-1-methoxycarbonyl propadiene 4, 1,1-bis-(ethoxycarbonyl) propadiene 5 and 1,1-bis-(methoxycarbonyl) propadiene 6.Yields and purity are lower in the case of 3 and 5, owing to the presence of the thermolabile ethoxycarbonyl groups.The possibility of performing nucleophilic additions to the most polymerizable of these allenes: 1,1-dicyanopropadiene 2, is demonstrated by its clean, good yield additions at -50 deg C with methanol, methyl lithium, aniline ir dimethylamine.Allenes O or N-substituted on the allenic carbon are often reactive substances and are known mainly in the case of alkyl ethers and tertiary amines.The flash thermolysis of allylic alcohol 38 gives in good yield propanediol 7 which tautomerizes into acrolein at -50 deg C.Trimethylsilyloxypropadiene 8, 1-trimethylsilyloxybuta-1,2-diene 9 and 3-trimethylsilyloxybuta-1,2-diene 10 could also be obtained from their precursors 40, 44-46.Thermolysis of amine 49 leads in the same way to propadienamine 11, a reactive enamine postulated as a cosmic species and tautomerizing at -65 deg C into 1-azabuta-1,3-diene 50.
- Hakiki, Abdelhak,Ripoll, Jean-Louis,Thuillier, Andre
-
p. 911 - 920
(2007/10/02)
-
- Nitrogen extrusion in the flash vacuum thermolysis (FVT) of 1-H-pyrazole and 3,5-dimethylpyrazole (1)
-
Flash vacuum thermolysis of 1 H-pyrazole (1) afforded propyne (2) and 3,5-dimethylpyrazole (3) afforded 1,3-pentadiene (4) with Ea = 71.3 Kcal/mole, log A = 15.44 and Ea 66.9 Kcal/mole, log A 15.08 respectively.Alternative mechanisms are discussed including one with tautomerism to 3-H-pyrazole.The possible intermediacy of vinyldiazomethanes is also examined.
- Perez, Jorge D.,Yranzo, Gloria I.
-
p. 473 - 476
(2007/10/02)
-
- The Selective Conversion of n-Pentane into Pent-1-ene via Trihydro(trans-penta-1,3-diene)bis(triarylphosphine)rhenium
-
Treatment of n-pentane with heptahydridobis(triarylphosphine)rhenium and 3,3-dimethylbutene gives trihydrido(trans-penta-1,3-diene)bis(triarylphosphine)rhenium; trimethyl phosphite converts this, with high selectivity, into pent-1-ene.
- Baudry, Denise,Ephritikhine, Michael,Felkin, Hugh,Zakrzewski, Janusz
-
p. 1235 - 1236
(2007/10/02)
-
- Evidence for a 1,4 Hydrogen Shift in 2 Deuterium-Labeled Vinyl Carbene Intermediate in the Formation of 1,3-Pentadiene from 3,5-Dimethylpyrazole
-
The formation of 1,3-pentadiene via a 1,4 hydrogen shift from a deuterium-labeled vinylcarbene intermediate is demonstrated in the thermolysis of 3,5-dimethylpyrazole.
- Perez, Jorge D.,Yranzo, Gloria L.
-
-
- Copper(I) Chemical Ionization-Mass Spectroscopic Analysis of Esters and Ketones
-
The present work lays the foundation for the understanding and evaluation of atomic metal ions as a new class of chemical ionization reagent ions.In particular, a thorough study of the gas phase ion chemistry of Cu(1+), generated by laser ionization from the pure metal, with a series of oxygenated compounds is reported.Definite patterns of reactivity for different classes of oxygenated compounds are observed which, together with an understanding of the reaction mechanisms, provide the basis for predicting the Cu(1+) chemical ionization mass spectra of new compounds with analogous functional groups.The chemistry of Cu(1+) is found to be dramatically different from that of Ti(1+) and Li(1+) reported earlier providing a significant indication of the flexibility and selectivity afforded by atomic metal reagent ions.
- Burnier, R. C.,Byrd, G. D.,Freiser, B. S.
-
p. 1641 - 1650
(2007/10/02)
-
- Thermal Decomposition of cis-2,4-Dimethyl-trans-3-vinyloxetan
-
The thermal decomposition of the title compound yields penta-1,3-diene and ethanal as major products when pyrolysed in the gas phase between 326 and 384 deg C.This fragmentation reaction is kinetically first order and probably occurs by a biradical mechanism.Arrhenius parameters have been determined for this decomposition: log k/S-1=13.42+/-0.60-(200.3+/-7.5kJ mol-1)/RTln10.As well as the major decomposition pathway there are several minor ones.A ring expansion reaction to yield 2,6 dimethyl-3,6-dihydro-2H-pyran and a trans-cis isomerization to trans-2,4-dimethyl-3-vinyloxetan both occur to the extent of from 2 to 3 percent of the fragmentation reaction.Both these compounds are themselves thermally unstable at the reaction temperatures.The results are compared with those reported for other oxetans and also for appropiately substituted cyclobutanes.
- Carless, Howard A. J.,Maitra, A. Kumar,Pottinger, Ruth,Frey, Henry M.
-
p. 1849 - 1856
(2007/10/02)
-