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Mechanisms of Methylenecyclobutane Hydrogenation over Supported Metal Catalysts Studied by Parahydrogen-Induced Polarization Technique
In this work the mechanism of methylenecyclobutane hydrogenation over titania-supported Rh, Pt and Pd catalysts was investigated using parahydrogen-induced polarization (PHIP) technique. It was found that methylenecyclobutane hydrogenation leads to formation of a mixture of reaction products including cyclic (1-methylcyclobutene, methylcyclobutane), linear (1-pentene, cis-2-pentene, trans-2-pentene, pentane) and branched (isoprene, 2-methyl-1-butene, 2-methyl-2-butene, isopentane) compounds. Generally, at lower temperatures (150–350 °C) the major reaction product was methylcyclobutane while higher temperature of 450 °C favors the formation of branched products isoprene, 2-methyl-1-butene and 2-methyl-2-butene. PHIP effects were detected for all reaction products except methylenecyclobutane isomers 1-methylcyclobutene and isoprene implying that the corresponding compounds can incorporate two atoms from the same parahydrogen molecule in a pairwise manner in the course of the reaction in particular positions. The mechanisms were proposed for the formation of these products based on PHIP results.
Salnikov, Oleg G.,Burueva, Dudari B.,Kovtunova, Larisa M.,Bukhtiyarov, Valerii I.,Kovtunov, Kirill V.,Koptyug, Igor V.
(2022/03/15)

A mild method for the replacement of a hydroxyl group by halogen: 3. the dichotomous behavior of α-haloenamines towards allylic and propargylic alcohols
A study of the deoxyhalogenation of allylic and propargylic alcohols with tetramethyl-α-halo-enamines is reported. Primary allylic and primary and secondary propargylic alcohols gave the corresponding halides in high yields. Secondary allylic and propargylic alcohols yielded the corresponding secondary halides but the reaction also produced some rearranged primary halides (I > Br > Cl). The reactions with tertiary allylic and tertiary propargylic alcohols gave several products and was therefore of little synthetic value. However, the addition of triethylamine to the reaction mixture or the use of lithium alkoxide instead of alcohol brought about a major change of the course of the reaction which led to amides carrying an allyl or an allenyl group at C2. This was shown to result from a Claisen-Eschenmoser rearrangement of an intermediate α-allyloxy- or propargyloxy-enamine.
Munyemana, Fran?ois,Patiny, Luc,Ghosez, Léon
(2021/06/07)

Study on heteropolyacid-based catalysts with high activity and reusability for isoprene synthesis from formaldehyde and isobutene
Silica-supported heteropolyacid catalysts with different pore structures were synthesizedviaimpregnation method using silicalite-1 with three-dimensional MFI structure, two-dimensional hexagonal SBA-15 and amorphous silica as supports. Moreover, these catalysts were employed for the gas phase one-step synthesis of isoprene from isobutene and formaldehyde. The result showed that the activity of silicotungstic acid supported on silicalite-1 (SiW/S-1) catalysts was significantly better than that on other supports, which indicates that the three-dimensional MFI structure and suitable pore size of silicalite-1 were more conducive to the production of isoprene. Furthermore, the formation rate of isoprene over 20% SiW/S-1 catalyst reached up to 8.5 times that on the bulk silicotungstic acid catalyst, which could be attributed to the highly dispersed silicotungstic acid and the suitable acidity produced by the strong interaction between silicotungstic acid and silicalite-1. In addition, the 20 wt% SiW/S-1 catalyst exhibited excellent reusability and was reused 10 times without obvious loss of activity.
Wang, Qingxue,Luo, Xu,Liu, Li,Tao, Shenghui,Xu, Shan
p. 5371 - 5381
(2021/04/06)

Method for preparing isoprene
The invention relates to a method for preparing isoprene by catalyzing isobutene and a formaldehyde solution through metal-doped cerium dioxide. Isobutene and a formaldehyde solution are used as reaction substrates, and under the action of a doped cerium dioxide catalyst, isoprene is prepared through Prins condensation, hydrolysis and dehydration. According to the method, isoprene can be obtained from isobutene and a formaldehyde solution in one step, and the catalyst is good in stability.
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Paragraph 0039-0111

(2021/04/14)

Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.
Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
p. 1996 - 2003
(2020/04/22)

Effects of steam on toluene hydrogenation over a Ni catalyst
The catalytic toluene hydrogenation over Ni/SiO2 was carried out using H2 or a H2/H2O mixture. The toluene conversion and MCH selectivity were evaluated under partial steam pressures 0?10 kPa, at H2/t
Atsumi, Ryosuke,Kobayashi, Keisuke,Xieli, Cui,Nanba, Tetsuya,Matsumoto, Hideyuki,Matsuda, Keigo,Tsujimura, Taku
(2019/12/23)

Isoprene Synthesis from Formaldehyde and Isobutylene in the Presence of Aluminum- and Niobium-Containing BEA Catalysts
Abstract: A single-stage gas-phase synthesis of isoprene from formaldehyde and isobutylene in the presence of Al–BEA and Nb–BEA zeolite catalysts containing different amounts of aluminum and niobium has been studied. The physicochemical properties of the catalysts have been studied by low-temperature nitrogen adsorption, infrared spectroscopy of adsorbed CO, X-ray fluorescence analysis, and ammonia TPD methods. Catalytic tests have shown that, at similar formaldehyde conversion values, the isoprene selectivity is higher in the presence of the Al-containing BEA catalysts. It has been found that Al–BEA with Si/Al = 12 exhibits the highest activity in isoprene synthesis.
Chistov, D. L.,Drozhzhin, V. R.,Ivanova, I. I.,Kots, P. A.,Ponomareva, O. A.,Rodionova, L. I.
p. 942 - 949
(2020/09/02)

Highly efficient synthesis of isoprene from methyl tert-butyl ether and formaldehyde over activated carbon supported silicotungstic acid catalysts
In this contribution, we reported the liquid single-stage synthesis of isoprene from methyl tert-butyl ether (MTBE) and formaldehyde over activated carbon supported silicotungstic acid (STA/AC) catalysts. In comparison with the corresponding homogeneous STA catalysts, the STA/AC catalysts exhibited much higher activity of the prins condensation reaction under the same conditions. The results could be attributed to the highly dispersed STA, the relative weaker acidity resulting from the strong interaction between STA and AC and the structural collapse of STA. Additionally, the catalyst could be reused at least 3 times with only a slight decrease of activity. The physical and chemical properties of the STA/AC catalysts were characterized by means of DRIFT, HRTEM, HAADF-STEM, NH3-TPD, XRD, XPS and TG techniques. The excellent catalytic reactivity and easy recycling advantages make the STA/AC catalyst to be an attractive candidate of the prins reactions in the future.
Wang, SaiSai,Chen, Xingkun,Tan, Yuan,Zhao, Ziang,Yang, Wenshao,Huang, Chuanqi,Wang, Xuepeng,Chen, MiaoMiao,Du, Zhongnan,Ding, Yunjie
(2020/02/28)

Isoprene Synthesis from Formaldehyde and Isobutylene over Zeolite Catalysts
Abstract: Single-stage gas-phase synthesis of isoprene from formaldehyde and isobutylene in the presence of zeolite catalysts of the MFI, BEA, and FAU(Y) framework types and Al–BEA, Zr–BEA, Sn–BEA, and Nb–BEA catalysts synthesized by isomorphous substitution methods has been studied. Catalytic tests have shown that the isoprene yield increases in the following order: Zr–BEA Sn–BEA Nb–BEA Al–BEA, which is in agreement with the content of Br?nsted acid sites in the samples, whereas the formation of the major byproduct—carbon monoxide resulting from the decomposition of formaldehyde—increases with an increase in the number of Lewis acid sites. Comparison of the catalytic properties of zeolites of the different framework types has shown that the highest isoprene selectivity is exhibited by medium-pore MFI zeolites with a pore diameter of 5.5 ?.
Ponomareva,Chistov,Kots,Ivanova
p. 711 - 718
(2019/08/13)

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)

Accessing Frustrated Lewis Pair Chemistry through Robust Gold@N-Doped Carbon for Selective Hydrogenation of Alkynes
Pyrolysis of Au(OAc)3 in the presence of 1,10-phenanthroline over TiO2 furnishes a highly active and selective Au nanoparticle (NP) catalyst embedded in a nitrogen-doped carbon support, Au@N-doped carbon/TiO2 catalyst. Parameters such as pyrolysis temperature, type of support, and nitrogen ligands as well as Au/ligand molar ratios were systematically investigated. Highly selective hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustrated Lewis pairs interface formed by the combination of gold and nitrogen atoms of N-doped carbon that, according to density functional theory calculations, can serve as a basic site to promote the heterolytic activation of H2 under very mild conditions. This "fully heterogeneous" and recyclable gold catalyst makes the selective hydrogenation process environmentally and economically attractive.
Fiorio, Jhonatan Luiz,Gon?alves, Renato Vitalino,Teixeira-Neto, Erico,Ortu?o, Manuel A.,López, Núria,Rossi, Liane Marcia
p. 3516 - 3524
(2018/04/14)

METHOD FOR PRODUCING CONJUGATED DIENE
A method for producing a conjugated diene, including a step A of allowing an α-olefin and formaldehyde to react with each other to produce a γ,δ-unsaturated alcohol in the presence of an alcohol; and a step B of subjecting the γ,δ-unsaturated alcohol to a dehydration reaction at 135 to 210° C. in the presence of an aqueous solution of an acidic catalyst.
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Paragraph 0069-0074

(2018/10/30)

Method for synthesizing methyl heptenone from 2-methyl-3-buten-2-ol
The invention relates to a method for synthesizing methyl heptenone from 2-methyl-3-buten-2-ol. 2-methyl-3-butene-2-alcohol takes Saucy-Marbet reaction with 2-alkoxylpropylene in the near critical state to obtain methyl heptenone. The synthesis method has the advantages that the use of catalysts is not needed; the selectivity of the product of methyl heptenone can be improved.
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Paragraph 0037-0045; 0058-0068

(2020/09/20)

Gold-Ligand-Catalyzed Selective Hydrogenation of Alkynes into cis-Alkenes via H2 Heterolytic Activation by Frustrated Lewis Pairs
The selective hydrogenation of alkynes to alkenes is an important synthetic process in the chemical industry. It is commonly accomplished using palladium catalysts that contain surface modifiers, such as lead and silver. Here we report that the adsorption of nitrogen-containing bases on gold nanoparticles results in a frustrated Lewis pair interface that activates H2 heterolytically, allowing an unexpectedly high hydrogenation activity. The so-formed tight-ion pair can be selectively transferred to an alkyne, leading to a cis isomer; this behavior is controlled by electrostatic interactions. Activity correlates with H2 dissociation energy, which depends on the basicity of the ligand and its reorganization on activation of hydrogen. High surface occupation and strong Au atom-ligand interactions might affect the accessibility and stability of the active site, making the activity prediction a multiparameter function. The promotional effect found for nitrogen-containing bases with two heteroatoms was mechanistically described as a strategy to boost gold activity. (Graph Presented).
Fiorio, Jhonatan L.,López, Núria,Rossi, Liane M.
p. 2973 - 2980
(2017/05/31)

Production of isoprene
PROBLEM TO BE SOLVED: To provide a method for producing isoprene by subjecting isoamylene to a dehydrogenation reaction, which can produce isoprene in a high yield.SOLUTION: Provided is a method for producing isoprene by subjecting isoamylene to a dehydrogenation reaction, where the dehydration reaction is carried out using a supported type solid catalyst having a metal supported on a carrier comprising an oxide of zirconium.
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Paragraph 0061

(2017/12/15)

Structural and functional insights into asymmetric enzymatic dehydration of alkenols
The asymmetric dehydration of alcohols is an important process for the direct synthesis of alkenes. We report the structure and substrate specificity of the bifunctional linalool dehydratase isomerase (LinD) from the bacterium Castellaniella defragrans that catalyzes in nature the hydration of β-myrcene to linalool and the subsequent isomerization to geraniol. Enzymatic kinetic resolutions of truncated and elongated aromatic and aliphatic tertiary alcohols (C5-C15) that contain a specific signature motif demonstrate the broad substrate specificity of LinD. The three-dimensional structure of LinD from Castellaniella defragrans revealed a pentamer with active sites at the protomer interfaces. Furthermore, the structure of LinD in complex with the product geraniol provides initial mechanistic insights into this bifunctional enzyme. Site-directed mutagenesis confirmed active site amino acid residues essential for its dehydration and isomerization activity. These structural and mechanistic insights facilitate the development of hydrating catalysts, enriching the toolbox for novel bond-forming biocatalysis.
Nestl, Bettina M.,Geinitz, Christopher,Popa, Stephanie,Rizek, Sari,Haselbeck, Robert J.,Stephen, Rosary,Noble, Michael A.,Fischer, Max-Philipp,Ralph, Erik C.,Hau, Hoi Ting,Man, Henry,Omar, Muhiadin,Turkenburg, Johan P,Van Dien, Stephen,Culler, Stephanie J.,Grogan, Gideon,Hauer, Bernhard
p. 275 - 281
(2017/02/23)

Assembly line synthesis of isoprene from formaldehyde and isobutene over SiO2-supported MoP catalysts with active deposited carbon
Isoprene is a very important monomer for synthetic rubber. Its synthesis in the presence of MoP catalysts via the vapour phase reaction of isobutene with formaldehyde has been studied. The catalysis by various catalysts was characterized by TG analysis, the low-temperature adsorption of nitrogen, XRD, element analysis, TPD, the FT-IR of adsorbed pyridine, XPS and MAS NMR. A chemical process was proposed and confirmed. Isoprene was synthesized in an "assembly line" process through different active sites at the surface of the MoP catalysts, where the active sites were derived from P and Mo species and deposited carbonaceous species. In the induction period, carbon species are preferentially deposited on P species, leading to a decrease in the active Mo and P species (active sites 1), accompanied with a burst in active carbonaceous species (active sites 2). This soundly describes the burst in catalyst capacity in the induction period, which then decreases over time on stream at the expense of the active carbonaceous species. Accordingly, through the prior formulation of sites 1 with sites 2 in a catalyst, the time-consuming induction period can be nearly eliminated. We also observed that a good ratio of these two active sites can efficiently retard the catalyst deactivation. This study clarifies the roles of acid sites and active species in MoP catalysts in the synthesis of isoprene and shows that their optimal ratio can help reduce the length of the induction period and extend the lifetime of the catalysts.
Qi, Yanlong,Cui, Long,Dai, Quanquan,Li, Yunqi,Bai, Chenxi
p. 37392 - 37401
(2017/08/09)

Ionic liquid catalytic activated olefinic ketones condensation reaction synthetic isoprene method (by machine translation)
The invention relates to a kind of ionic liquid catalytic activated olefinic ketones condensation reaction synthetic isoprene method. Ionic liquid as catalyst, formaldehyde and isobutene reaction one-step synthesis of isoprene. The method of mild reaction conditions, high selectivity, catalyst the corrosiveness is low and can be used repeatedly; provides a simple, low cost isoprene synthesis method. (by machine translation)
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Paragraph 0039; 0040; 0053; 0054

(2017/09/05)

Activated olefinic ketones liquid phase preparation of isoprene in the technology
The invention relates to a method for manufacturing isoprene and belongs to the technical field of a chemical product manufacturing method. The method provided by the invention is characterized by comprising the following steps: in a unit for synthesizing 4,4-dimethyl-1,3-dioxane, a C4 fraction containing isobutene, formaldehyde and butyrolactam are countercurrent added, a reaction is fully carried out in a reaction kettle in the presence of a solid acid catalyst, and generated reaction products are rectified so as to obtain 4,4-dimethyl-1,3-dioxane; in a unit for synthesizing tert-butyl alcohol, the C4 fraction containing isobutene and water are added respectively through the top and the bottom of the reaction kettle, a reaction is fully carried out in the presence of cation exchange resin so as to generate tert-butyl alcohol, and due to tert-butyl alcohol extraction by water, yield of tert-butyl alcohol is raised; and in a unit for synthesizing isoprene, the generated 4,4-dimethyl-1,3-dioxane and the generated tert-butyl alcohol are added into the reaction kettle, and purity of generated isoprene can reach more than 99.5%. The technology provided by the invention has advantages of high yield of isoprene, few product impurity and simple post-treatment, and is a new energy-saving and resource-saving technology.
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Paragraph 0005; 0030-0035

(2017/08/25)

Sodium Diisopropylamide in Tetrahydrofuran: Selectivities, Rates, and Mechanisms of Alkene Isomerizations and Diene Metalations
Sodium diisopropylamide in tetrahydrofuran is an effective base for the metalation of 1,4-dienes and isomerization of alkenes. Dienes metalate via tetrasolvated sodium amide monomers, whereas 1-pentene is isomerized by trisolvated monomers. Facile, highly Z-selective isomerizations are observed for allyl ethers under conditions that compare favorably to those of existing protocols. The selectivity is independent of the substituents on the allyl ethers; rate and computational data show that the rates, mechanisms, and roles of sodium-oxygen contacts are substituent-dependent. The competing influences of substrate coordination and solvent coordination to sodium are discussed.
Algera, Russell F.,Ma, Yun,Collum, David B.
supporting information
p. 11544 - 11549
(2017/08/30)

METHOD OF PREPARING DIENE
The present invention relates to a producing method of diene and, more specifically, to a producing method of diene, comprising a step of carrying out a dehydration reaction by contacting a catalyst with aldehyde, wherein the catalyst has boron phosphate (BPO_4) which is supported in a phosphate-based carrier. The diene produced by the method according to the present invention has excellent selectivity and yield.COPYRIGHT KIPO 2016
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Paragraph 0055-0063

(2017/01/12)

METHOD FOR COLLECTING ISOPRENE CONTAINED IN FERMENTED GAS, AND METHOD FOR PRODUCING PURIFIED ISOPRENE
Methods include contacting a fermented gas including isoprene with a porous adsorbent and desorbing isoprene adsorbed on the porous adsorbent. The fermented gas may be obtained by culturing a microorganism having an ability to produce isoprene.
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Paragraph 0172; 0173; 0174

(2016/02/12)

PROCESSES FOR CONVERSION OF BIOLOGICALLY DERIVED MEVALONIC ACID
The invention relates to a process comprising reacting mevalonic acid, or a solution comprising mevalonic acid, to yield a first product or first product mixture, optionally in the presence of a solid catalyst and/or at elevated temperature and/or pressure. The invention further relates to a process comprising: (a) providing a microbial organism that expresses a biosynthetic mevalonic acid pathway; (b) growing the microbial organism in fermentation medium comprising suitable carbon substrates, whereby biobased mevalonic acid is produced; and (c) reacting said biobased mevalonic acid to yield a first product or first product mixture.
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Paragraph 0107-0111

(2016/06/13)

Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica
Gas phase Prins condensation of isobutene with formaldehyde has been studied over different Keggin-type heteropolyacids supported on amorphous silica. The catalysts were characterized by elemental analysis, X-ray diffraction, low temperature nitrogen adsorption, TPD of ammonia, FTIR of adsorbed pyridine and NMR spectroscopy. The activity of the supported heteropoly compounds was found to increase in the following order: H4SiMo12O40 3PMo12O40 4SiW12O40 ≈ H3PW12O40. The lower activity of the supported molybdenum heteropolyacids was attributed to their low thermal stability and partial decomposition during catalyst activation, which resulted in lower acidity. The variation of HPA content from 5 to 33 wt% was also shown to increase catalyst activity. Based on the relationship between the content of weak Br?nsted sites, the amount and type of carbonaceous deposits and the catalytic activity, it was concluded that the generation of working active sites over HPA catalysts involves the formation of unsaturated branched surface species over weak Br?nsted sites. These active carbonaceous species are responsible for selective isoprene synthesis. The best catalyst performance is observed over the catalyst with 20 wt% of H3PW12O40, which shows an isoprene yield of 48% with a selectivity of 63%.
Sushkevich,Ordomsky,Ivanova
p. 6354 - 6364
(2016/08/18)

Method for preparing isoprene from tert-butyl alcohol and formaldehyde
The invention discloses a method for preparing isoprene from tert-butyl alcohol and formaldehyde, belonging to the technical field of chemical synthesis. The method comprises the following steps: with an industrial formaldehyde solution and a tert-butyl alcohol solution as reactants, industrial phosphoric acid as a catalyst and metal salt as a reaction promoter, carrying out preheating, and carrying out reaction under a certain temperature and pressure so as to obtain isoprene. With the method provided by the invention, metal salt added into a reaction system is used as the reaction promoter, so the yield of isoprene can be effectively improved, and corrosion of liquid acid to equipment can be greatly mitigated; and a counterbalance valve is adopted as a reaction device to control pressure in a reactor, so good pressure control effect is realized, and the counterbalance valve exerts an emptying effect at the same time, wherein a receiving tank is internally divided into a lower layer water phase and an upper layer oil phase. The method provided by the invention has the following advantages: process conditions are easily controllable; pressure is stable; the catalyst and tert-butyl alcohol are reusable; and isoprene has high yield (relative to formaldehyde, isoprene has the highest yield of 74.21%).
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Paragraph 0020

(2017/06/27)

Mutant polypeptides and uses thereof
The present disclosure provides novel polypeptides with 3-buten-2-ol dehydratase activity, polypeptides with catalytic activity in the conversion of 3-methyl-3-buten-2-ol to isoprene, and crystal structure data for one of such polypeptides. Methods of making and using the polypeptides and their related crystal structure data are also provided.
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Page/Page column 53

(2016/01/25)

METHOD OF PRODUCING ISOPRENE
PROBLEM TO BE SOLVED: To provide a method which can produce isoprene in high yield when producing isoprene through dehydrogenation reaction of isoamylene. SOLUTION: This invention provides a method which produces isoprene through dehydrogenation reaction of isoamylene, wherein the dehydrogenation reaction is conducted using a solid catalyst comprising a zinc oxide as a main component under an inert gas atmosphere. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0033; 0037; 0040

(2018/02/14)

Pyrolysis of 3-carene: Experiment, Theory and Modeling
Thermal decomposition studies of 3-carene, a bio-fuel, have been carried out behind the reflected shock wave in a single pulse shock tube for temperature ranging from 920 K to 1220 K. The observed products in thermal decomposition of 3-carene are acetylene, allene, butadiene, isoprene, cyclopentadiene, hexatriene, benzene, toluene and p-xylene. The overall rate constant for 3-carene decomposition was found to be k / s-1 = 10(9.95 ± 0.54) exp (- 40.88 ± 2.71 kcal mol-1/RT). Ab-initio theoretical calculations were carried out to find the minimum energy pathway that could explain the formation of the observed products in the thermal decomposition experiments. These calculations were carried out at B3LYP/6-311 + G(d,p) and G3 level of theories. A kinetic mechanism explaining the observed products in the thermal decomposition experiments has been derived. It is concluded that the linear hydrocarbons are the primary products in the pyrolysis of 3-carene.
Sharath,Chakravarty,Reddy,Barhai,Arunan
p. 2119 - 2135
(2016/01/12)

From the lindlar catalyst to supported ligand-modified palladium nanoparticles: Selectivity patterns and accessibility constraints in the continuous-flow three-phase hydrogenation of acetylenic compounds
Site modification and isolation through selective poisoning comprise an effective strategy to enhance the selectivity of palladium catalysts in the partial hydrogenation of triple bonds in acetylenic compounds. The recent emergence of supported hybrid materials matching the stereo- and chemoselectivity of the classical Lindlar catalyst holds promise to revolutionize palladium-catalyzed hydrogenations, and will benefit from an in-depth understanding of these new materials. In this work, we compare the performance of bare, lead-poisoned, and ligand-modified palladium catalysts in the hydrogenation of diverse alkynes. Catalytic tests, conducted in a continuous-flow three-phase reactor, coupled with theoretical calculations and characterization methods, enable elucidation of the structural origins of the observed selectivity patterns. Distinctions in the catalytic performance are correlated with the relative accessibility of the active site to the organic substrate, and with the adsorption configuration and strength, depending on the ensemble size and surface potentials. This explains the role of the ligand in the colloidally prepared catalysts in promoting superior performance in the hydrogenation of terminal and internal alkynes, and short-chain alkynols. In contrast, the greater accessibility of the active surface of the Pd-Pb alloy and the absence of polar groups are shown to be favorable in the conversion of alkynes containing long aliphatic chains and/or ketone groups. These findings provide detailed insights for the advanced design of supported nanostructured catalysts. Hybrid nanocatalysts: The classical Lindlar and the newly developed NanoSelectTM catalysts are confronted in the semi-hydrogenation of alkynes (see figure). Systematic testing under continuous-flow three-phase conditions, coupled with detailed characterization analyses and molecular simulations, enable the understanding of the structure of the catalysts and the associated activity and selectivity patterns for a wide range of acetylenic compounds.
Vile, Gianvito,Almora-Barrios, Neyvis,Mitchell, Sharon,Lopez, Nuria,Perez-Ramirez, Javier
p. 5926 - 5937
(2014/05/20)

Phosphate-modified carbon nanotubes in the oxidative dehydrogenation of isopentanes
Ketonic/quinonic C=O groups on the surface of a carbon matrix are capable of abstracting hydrogen in C-H bonds from hydrocarbons and enable them to selectively convert into corresponding unsaturated hydrocarbons; this process is the oxidative dehydrogenation (ODH) reaction. However, a variety of inevitable defects or graphene edges and other oxygen-containing groups on the carbon matrix are detrimental to the selective production of alkenes due to their high activity towards overoxidation. Herein, we show that phosphate can not only impede the total oxidation but also cover the selective C=O groups, hence allowing its use as a modulator to defects and oxygen-containing functional groups on the multiwalled carbon nanotubes, regulating the distribution of active sites and related catalytic targets.
Huang, Rui,Liu, Hong Yang,Zhang, Bing Sen,Sun, Xiao Yan,Liang, Chang Hai,Su, Dang Sheng,Zong, Bao Ning,Rong, Jun Feng
p. 3476 - 3482
(2015/03/13)

Graphite oxide activated zeolite NaY: Applications in alcohol dehydration
A mixture of graphite oxide (GO) and the zeolite NaY (Si/Al = 5.1) was used to dehydrate various alcohols to their respective olefinic products. Using conditions optimized for 4-heptanol (15 wt% GO-NaY (1 : 1 wt/wt), 150°C, 30 min), a series of secondary and tertiary aliphatic alcohols were cleanly dehydrated in moderate to excellent conversions (27.5-97.2%). Several primary alcohols were also dehydrated, although higher catalyst loadings (200 wt% GO-NaY (1 : 1) and longer reaction times (3 h) were required. The enhanced dehydration activity was attributed to the ability of GO to convert NaY to an acidic form and without the need for ammonium cation exchange and/or high temperature calcination. The Royal Society of Chemistry 2013.
Todd, Alexander D.,Bielawski, Christopher W.
p. 135 - 139
(2013/03/29)

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.
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Paragraph 0037; 0046

(2013/03/28)

Compositions and methods of PGL for the increased production of isoprene
Provided herein are improved compositions and methods for the increased production of isoprene. Also provided herein are improved compositions and methods for the increased production of heterologous polypeptides capable of biological activity.
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Page/Page column

(2013/06/26)

Catalysis by coke deposits: Synthesis of isoprene over solid catalysts
A help rather than a hindrance: Carbonaceous deposits have been found to play a key role in the selective synthesis of isoprene from formaldehyde and isobutene over solid catalysts. They accumulate on the catalyst surface during the induction period and promote the interaction of the substrates at the steady state. The proposed mechanism (see scheme) shows the way forward for the design of efficient solid catalysts for the synthesis of isoprene. Copyright
Ivanova, Irina,Sushkevich, Vitaly L.,Kolyagin, Yury G.,Ordomsky, Vitaly V.
supporting information
p. 12961 - 12964
(2014/01/06)

Synthesis of isoprene from formaldehyde and isobutene over phosphate catalysts
Vapor phase Prins condensation of isobutene with formaldehyde has been studied over boron (BP), aluminum (AlP), titanium (TiP), zirconium (ZrP) and niobium (NbP) phosphates. The catalysts were characterized by elemental analysis, X-ray diffraction, low-te
Sushkevich,Ordomsky,Ivanova
p. 21 - 29
(2012/11/07)

FUEL COMPOSITIONS COMPRISING ISOPRENE DERIVATIVES
The invention provides for methods, compositions and systems using isoprene from a bioisoprene composition derived from renewable carbon for production of a variety of hydrocarbon fuels, fuel additives, and additives for fine chemistry and other uses.
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Page/Page column 66-67

(2012/01/06)

COMPOSITIONS AND METHODS FOR PRODUCING ISOPRENE FREE OF C5 HYDROCARBONS UNDER DECOUPLING CONDITIONS AND/OR SAFE OPERATING RANGES
The invention features methods for producing isoprene from cultured cells wherein the cells in the stationary phase. The invention also provides compositions that include these cultured cells and/or increased amount of isoprene. The invention also provides for systems that include a non-flammable concentration of isoprene in the gas phase. Additionally, the invention provides isoprene compositions, such as compositions with increased amount of isoprene or increased purity.
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(2010/03/31)

CONVERSION OF PRENYL DERIVATIVES TO ISOPRENE
The present invention provides methods for producing derivatives from cultured cells. In addition, the present invention provides methods for conversion of prenyl deerivatives, obtained from biological or petrochemical sources, to isoprene by employing chemical or biological catalysts. The present invention also provides compositions that include the cultured cells or isoprene or prenyl derivatives produced there from.
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(2010/05/13)

PLANT FOR THE LIQUID PHASE SYNTHESIS OF ISOPRENE FROM ISOBUTYLENE AND FORMALDEHYDE
The invention relates to a plant for the synthesis of isoprene in a liquid phase from isobutylene and formaldehyde or from the source substances thereof. The inventive plant consists of a dimethyl dioxane synthesis unit detached from two parallel operating trimethyl carbinol synthesis units, and the trimethyl carbinol and dimethyl dioxane produced therein are simultaneously supplied for common decomposition to an isoprene synthesis unit. Light by-products extracted in a unit for rectifying high-boiling by-products, which unit is located downstream of the dimethyl dioxane synthesis unit, are supplied either to sales or to decomposition together with by-products (methyl-dihydropyrane fraction) which are produced during end-products separation and isoprene monomer extraction, or to sales and to a decomposition unit for decomposition together with the above-mentioned by-products (methyl-dihydropyrane fraction), afterwards to the end-product separation and isoprene monomer extraction unit. The end-product separation and isoprene monomer extraction unit is directly connected to the soprene synthesis unit, the decomposition unit and to the dimethyl dioxane synthesis unit. Said plant makes it possible to reduce the accumulation of high-boiling by-products, to decrease the production costs and to improve the engineering-and-economical performances of the process.
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Page/Page column 3-4

(2010/10/19)

ISOPRENE PRODUCTION METHOD
This invention is applicable in the area of basic-type organic and petrochemical synthesis - specifically, to methods applicable to obtaining of isoprene out of isobutylene and formaldehyde - and can be used in manufacture of artificial resins. The proposed method is designed to obtain isoprene by way of liquid-phase interaction between trimethyl carbinol (or its water solutions) and formaldehyde (or its source substances) in the presence of acidic catalyzer water solution; this can be made in one or several contacting stages, with use (at the final contacting stage) of separation reactor containing a heat supply zone, a reaction zone and a separation zone, with reaction products and water taken, out of the separation zone, in the form of a vapor flow to be subsequently cooled down, condensed and separated and with liquid flow of the catalyzer water solution put out for extraction and, after this, put back into the heating zone. As it goes from the reaction zone into the separation zone, the reactive flow is throttled. In the reaction zone, temperature is maintained at the level of 140-180 °C, while pressure is 8-25 atmospheres; in the separation zone, pressure is 1.2-9.5 atmospheres. The separation reactor contains two or three separation zones. The balance quantity of water is put out of catalyzer water solution, which is circulating along the circuit, by way of its evaporation as the flow is throttled into the separation zone (zones) during regulation of the quantity of the circulating liquid phase in the interval of 0.2-6.0 parts of the total reaction zone area.
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Page/Page column 7

(2010/04/23)

MICROBIAL DERIVED ISOPRENE AND METHODS FOR MAKING THE SAME
A method for producing isoprene comprising an aqueous medium including genetically modified host cells capable of producing isoprene, where the resulting isoprene composition is processed through at least one separation and/or purification process to provide an isoprene enriched composition and a system for doing the same.
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Page/Page column 49

(2010/09/18)

Synthesis of isoprene from 1,3-dioxolane and isobutylene
Possibility of synthesizing isoprene from 1,3-dioxolane and isobutylene in a single stage under conditions of a homogeneous or heterogeneous catalysis was examined.
Vavilov,Akhmed'Yanova,Liakumovich,Levin, Ya. A.,Baryshnikova
scheme or table
p. 1598 - 1601
(2011/02/17)

PROCESS FOR PRODUCING HIGH PURITY EXO-ALKENYLNORBORNENE
Embodiments of the present invention are directed generally to methods for producing high purity exo-alkenylnorbornenes from a mixture of conformational isomers thereof.
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Page/Page column 17-20

(2009/07/02)

Regioselective iron-catalyzed decarboxylative allylic etherification
[Chemical Equation Presented] An anionic iron complex catalyzes the decarboxylative allylation of phenols to form allylic ethers in high yield. The allylation is regioselective rather than regiospecific. This suggests that the allylation proceeds through π-allyl iron intermediates in contrast to related allylations of carbon nucleophiles that have been proposed to proceed via π-allyl complexes. Ultimately, iron catalysts have the potential to replace more expensive palladium catalysts that are typically utilized for decarboxylative couplings.
Trivedi, Rushi,Tunge, Jon A.
body text
p. 5650 - 5652
(2010/02/28)

Propylene and isoprene production
A process for producing propylene and isoprene from a feed stream comprising 1-butene and isobutene is disclosed. The feed stream is reacted in a catalytic distillation reactor containing an olefin isomerization catalyst to produce an overhead stream comprising 2-butene and isobutene and a bottoms stream comprising 2-butene. The overhead stream is reacted in the presence of a metathesis catalyst to produce propylene and isoamylenes. Isoprene is produced by dehydrogenation of isoamylenes.
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Page/Page column 3-4

(2009/03/07)

1,4,2-Diazaphospholidine-3,5-diones and related compounds: A lecture on unpredictability in catalysis
1,4,2-diazaphospholidine-3,5-diones and related compounds and unpredictability in catalysis was studied. The five-membered ring species 4 6, which are all readily accessible by the McCormack reaction, optionally with subsequent hydrogenation, were selected for this study. The use of saturated species of type 4 (1-organyl-phospholanes) as catalysts led to a complete reverse in the selectivity of the reaction, in favor of the formation of the isocyanate trimers. Owing to the high activity of the corresponding P-oxides in carbodiimidization reactions, it can be assumed that the findings can be attributed to partial air oxidation of the trivalent phosphorus species applied. The symmetrical species 6, in total contrast to the other two members of the series, do not exhibit any catalytic activity with respect to isocyanates and instead react cleanly with two equivalents of isocyanate to effect the extrusion of 1,3-diene.
Richter, Frank U.
supporting information; experimental part
p. 5200 - 5202
(2009/12/24)

Thermal ring opening of 1,1-dibromo and 1-bromo-2- chloromethylcyclopropanes: Observation of a formal debromochlorination
When the title compounds are thermolyzed in the gas phase under vacuum or in hot quinoline, several products are formed. A predominant product in all cases is a chlorine-free buta-1,3-diene which has been formed by formal debromochlorination, a reaction n
Sydnes, Leiv K.,Alnes, Karl F. S.,Pettersen, Anita,Brinker, Udo H.
experimental part
p. 479 - 483
(2010/06/16)

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)

Catalysis by hydrogen chloride in the gas-phase elimination kinetics of 2-phenyl-2-propanol and 3-methyl-1-buten-3-ol
A homogeneous, molecular, gas-phase elimination kinetics of 2-phenyl-2-propanol and 3-methyl-1-buten-3-ol catalyzed by hydrogen chloride in the temperature range 325-386 °C and pressure range 34-149 torr are described. The rate coefficients are given by the following Arrhenius equations: for 2-phenyl-2-propanol log k1 (s-1) = (11.01±0.31)-(109.5±2.8)kJ mol-1 (2.303 RT) -1 and for 3-methyl-l-buten-3-ol log k1, (s-1) = (11.50±0.18)-(116.5±1.4)kJmol-1 (2.303 RT) -1. Electron delocalization of the CH2=CH and C 6H5 appears to be an important effect in the rate enhancement of acid catalyzed tertiary alcohols in the gas phase, A concerted six-member cyclic transition state type of mechanism appears to be, as described before, a rational interpretation for the dehydration process of these substrates. Copyright
Rasse, Rafael J.,Dominguez, Rosa M.,Herize, Armando,Tosta, Maria,Brusco, Doris,Chuchani, Gabriel
p. 44 - 48
(2007/10/03)

The preparation of HCF2CdX and HCF2ZnX via direct insertion into the carbon halogen bond of CF2HY (Y = Br, I)
The difluoromethylcadmium and zinc reagents have been prepared in DMF via direct insertion of Cd0 into the carbon halogen bond of CF2HY (Y = Br, I). These reagents are stable at 65-75 °C and exhibit prolonged stability and activity at room temperature. Metathesis of the difluoromethylcadmium reagents with Cu(I)X (X = Br, Cl) at -55 °C rapidly produces difluoromethylcopper. The copper reagent is significantly less stable than the cadmium or zinc reagent and rapidly decomposes at room temperature. The difluoromethylcadmium and copper reagents exhibit good reactivity with allylic halides, propargylic derivatives and 1-iodoalkynes to provide good yields of the corresponding difluoromethylalkenes, difluoromethylallenes and difluoromethyl-2-alkynes. Alkylation is successful only with reactive alkyl halides. Generally, the difluoromethylcopper reagent is more reactive than the difluoromethylcadmium reagent and generally exhibits higher regioselectivity in reactions that can occur by either α- or γ-attack.
Burton, Donald J.,Hartgraves, Greg A.
p. 1198 - 1215
(2008/02/08)