- Generation of Br?nsted acid sites on Al2O 3-supported Ta2O5 calcined at high temperatures
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An alumina-supported tantalum oxide (Ta2O5/Al 2O3) calcined at 1223 K promoted both Friedel-Crafts alkylation of anisole with benzyl alcohol and isomerization of α-pinene, and exhibited Bronsted acidity despite the high temperature calcination. Among the Ta2O5/Al2O3 catalysts tested, 33 wt% Ta2O5/Al2O3 calcined at 1223 K showed the highest activity. A monolayer of tantalum acid-like compound, which has distorted octahedral symmetry, was stabilized over 33 wt% Ta 2O5/Al2O3 catalyst calcined at 1223 K. The two-dimensional Ta-O-Ta network of stabilized tantalum acid-like compound probably accounts for the generation of Bronsted acid.
- Kitano, Tomoyuki,Okazaki, Shota,Shishido, Tetsuya,Teramura, Kentaro,Tanaka, Tsunehiro
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- A comparative study on the gas-phase and liquid-phase thermal isomerization reaction of α-pinene
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In this paper, a method of preparation of ocimene is investigated, which is obtained from isomerization reaction of α-pinene. Two kinds of experimental apparatus are established for the investigation of the thermal isomerization reaction of α-pinene. The behavior of thermal isomerization reaction of α-pinene is respectively discussed in the gas phase and in the liquid phase. Under gas phase conditions, the conversion of α-pinene is 80% and the selectivity of ocimene is 30%-33%. Under liquid phase conditions, the conversion of α-pinene is 60% and the selectivity of ocimene is 50%-54%. According to the kinetic-molecular theory of ideal gases, two kinds of reaction models are proposed to visualize the reaction process. In addition, the mechanism and kinetics of thermal isomerization reaction of α-pinene are respectively discussed. The conclusion is that the gas phase reaction temperature is calculated to be 390-450 °C and the liquid phase reaction temperature is calculated to be 450-550°C. From a bond dissociation energy point of view, results support the hypothesis that the reaction involves biradical intermediates. Copyright
- He, Jindong,Gong, Yan,Zhao, Wentao,Tang, Xiangyang,Qi, Xin
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- Isomerization of α-Pinene over Immobilized AlCl3 Catalysts
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Immobilized AlCl3 catalysts supported on γ-Al2O3 and SiO2 were prepared by a two-step vapor method and their catalytic activities were evaluated by the liquid phase isomerization of α-pinene for the first time. The results showed that the immobilized AlCl3 catalyst gave excellent catalytic performance for the isomerization of α-pinene. The AlCl3/SiO2 catalyst gave 98.4% conversion of α-pinene and 93.7% selectivity for the main products such as camphene, limonene, and terpinolene at a reaction temperature of 40 °C. The AlCl3/γ-Al2O3 catalyst gave much higher activity, 95.5% conversion of α-pinene and 94.4% selectivity for the main products even at temperatures as low as 30 °C. The excellent catalytic performance of the immobilized AlCl3 catalysts is due to their strong acidity.
- Wu, Yihui,Tian, Fuping,He, Min,Cai, Tianxi
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- Mechanistic and kinetic insights into the thermally induced rearrangement of α-pinene
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(Chemical Equation Presented) The thermal rearrangement of α-pinene (1) is interesting from mechanistic as well as kinetic point of view. Carrier gas pyrolyses with 1 and its acyclic isomers ocimene (2) and alloocimene (3) were performed to investigate the thermal network of these hydrocarbons. Kinetic analysis of the major reaction steps allows for a deeper insight in the reaction mechanism. Thus it was possible to explain the racemization of 1, the formation of racemic limonene (4), and the absence of the primary pyrolysis product 2 in the reaction mixture resulting from thermal rearrangement of 1. Results supported the conclusion that the reactions starting with 1 involve biradical transition states.
- Stolle, Achim,Ondruschka, Bernd,Findeisen, Matthias
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- Superacidity in sulfated metal-organic framework-808
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Superacids, defined as acids with a Hammett acidity function H0 ≤ -12, are useful materials, but a need exists for new, designable solid state systems. Here, we report superacidity in a sulfated metal-organic framework (MOF) obtained by treating the microcrystalline form of MOF-808 [MOF-808-P: Zr6O5(OH)3- (BTC)2(HCOO)5(H2O)2, BTC = 1,3,5-benzenetricarboxylate] with aqueous sulfuric acid to generate its sulfated analogue, MOF-808-2.5SO4 [Zr6O5(OH)3(BTC)2- (SO4)2.5(H2O)2.5]. This material has a Hammett acidity function H0 ≤ -14.5 and is thus identified as a superacid, providing the first evidence for superacidity in MOFs. The superacidity is attributed to the presence of zirconiumbound sulfate groups structurally characterized using single-crystal X-ray diffraction analysis.
- Jiang, Juncong,Gándara, Felipe,Zhang, Yue-Biao,Na, Kyungsu,Yaghi, Omar M.,Klemperer, Walter G.
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- Fe(NO3)3-catalyzed monoterpene oxidation by hydrogen peroxide: An inexpensive and environmentally benign oxidative process
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Simple Fe(NO3)2·9H2O was demonstrated to be able to catalyze the oxidation of monoterpenes by hydrogen peroxide in methyl alcohol solution. Compared with the previous iron-catalyzed methods, the present procedure avoids the use of stabilizing ligands, additives, and corrosive peroxide organic oxidants. A novel, simple and highly efficient catalyst system was developed for oxidizing monoterpenes into a valuable derivates using hydrogen peroxide, an environmentally friendly oxidant. Graphical Abstract: Possible steps involved in the Fe(III)-catalyzed oxidation of β-pinene by hydrogen peroxide into myrtenol methyl ether in methyl alcohol[Figure not available: see fulltext.]
- Carari, Danieli Marcolan,Da Silva, Marcio Jose
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- ZrO2-SiO2 mixed oxides xerogel and aerogel as solid acid catalysts for solvent free isomerization of α-pinene and dehydration of 4-methyl-2-pentanol
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Sulfated and non-sulfated ZrO2-SiO2 mixed oxide xerogel and aerogel samples having varied Zr/Si molar ratio were evaluated as solid acid catalysts for the isomerization of α-pinene and dehydration of 4-methyl-2-pentanol. Sulfation resulted into enhancement in the catalytic activity of both xerogel and aerogel samples towards the studied reactions. For example, sulfated catalysts showed 86-98% conversion of α-pinene and 8-35% conversion of 4-methyl-2-pentanol. The selectivity data for camphene and limonene indicated the requirement of moderate acidity. The correlation with cyclohexanol dehydration showed that isomerization of α-pinene is a Bronsted acid catalyzed reaction. The relationship of 4-methyl-2-pentanol conversion with acid site density and sulfur per unit area was found to be linear.
- Sidhpuria, Kalpesh B.,Tyagi, Beena,Jasra, Raksh V.
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- Thermolysis of α-pinene in supercritical lower alcohols
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Thermal isomerization of α-pinene in supercritical solvents, viz., ethanol, methanol, and propan-1-ol, was carried out, and differences in the rate and selectivity of the process were revealed. In supercritical ethanol the reaction rate increases sharply and the selectivity remains unchanged with an increase in the temperature (from 290 to 390°C) or pressure (from 90 to 270 atm). The main reaction products are limonene, isomeric alloocimenes, and pyronenes. The selectivity for limonene in propan-1-ol is higher than in other alcohols when the conversion of α-pinene not higher than 50%. In supercritical ethanol (430°C, 120 atm, 140 s) limonene is more stable than α-pinene (conversion 8%).
- Chibiryaev,Anikeev,Yermakova,Mikenin,Kozhevnikov,Sal'nikova
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- A porous Br?nsted superacid as an efficient and durable solid catalyst
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The development of catalysts able to assist industrial chemical transformations is a topic of high importance. In view of the versatile catalytic capabilities of acid catalysts, extensive research efforts are being made to develop porous superacid materials with a high density of accessible active sites to replace molecular acid catalysts. Herein, we report the rational development of a porous Br?nsted superacid by combining important elements that target high strength acidity into one material, as demonstrated by grafting the sulfonic acid group onto a highly fluorinated porous framework, where the acid strength and stability are greatly enhanced by an electron-withdrawing environment provided by the polymer backbone, reminiscent of that seen in Nafion resin. In addition, the densely arranged acid groups that are confined in the three-dimensional nanospace facilitate the transfer of hydrons, thereby further increasing the acidity. By virtue of the pore structure and strong acidity, this system exhibits excellent performance for a wide range of reactions, far outperforming commercial acid resins under repeated batch and flow reaction conditions. Our findings demonstrate how this synthetic approach may instruct the future design of heterogeneous acid catalysts with advantageous reaction capabilities and stability.
- Sun, Qi,Hu, Kewei,Leng, Kunyue,Yi, Xianfeng,Aguila, Briana,Sun, Yinyong,Zheng, Anmin,Meng, Xiangju,Ma, Shengqian,Xiao, Feng-Shou
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- Biochemistry and molecular genetics of the biosynthesis of the earthy odorant methylisoborneol in Streptomyces coelicolor
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Methylisoborneol (2) is a volatile organic compound produced by a wide variety of Actinomycete soil organisms, myxobacteria, and cyanobacteria. It has an unusually low odor threshold and, together with geosmin, is responsible for the characteristic smell of moist soil as well as unpleasant taste and odor episodes associated with public water supplies and contamination of various foodstuffs, including fish, wine, and beer. Despite considerable interest in detection and remediation of methylisoborneol, the biosynthesis of this methylated monoterpene has been obscure. In Streptomyces coelicolor, the sco7700 and sco7701 genes are shown to correspond to a two-gene operon responsible for methylisoborneol biosynthesis. Both genes have been amplified by PCR and the resulting DNA has been cloned and expressed in Escherichia coli. Incubation of recombinant SCO7701 protein, annotated as a possible C-methyltransferase, with geranyl diphosphate (1) and S-adenosylmethionine gave the previously unknown compound, (E)-2-methylgeranyl diphosphate (3). Incubation of 3 in the presence of Mg2+ with recombinant SCO7700, previously annotated only as a possible metal-binding protein or terpenoid synthase, resulted in the formation of 2-methylisoborneol (2). The steady-state kinetic parameters for both biochemical reactions have been determined. Incubation of geranyl diphosphate and S-adenosylmethionine with a mixture of both SCO7700 and SCO7701 resulted in formation of methylisoborneol (2). Cyclization of 2-methylgeranyl diphosphate (3) to methylisoborneol (2) likely involves the intermediacy of 2-methyllinalyl diphosphate. Copyright
- Wang, Chieh-Mei,Cane, David E.
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- α-Pinene isomerisation over heteropoly acid catalysts in the gas-phase
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The isomerisation of α-pinene was studied in the gas phase over solid heteropoly acid (HPA) catalysts in a fixed-bed continuous flow reactor at 200 °C and ambient pressure. The catalysts included bulk and SiO 2-supported H3PW12O40 and bulk Cs2.5H0.5PW12O40 possessing strong Br?nsted acid sites, as well as composites prepared by supporting 15 wt% H3PW12O40 on Nb2O5, ZrO2 and TiO2 possessing both Br?nsted and Lewis acid sites of moderate strength. The reaction yielded camphene as the main product in a mixture with monoterpene by-products such as limonene, terpinolenes, terpinenes, β-pinene, p-cymene and others. The HPA catalysts with strong Br?nsted acid sites exhibited high initial activities, but suffered from catalyst deactivation, resulting in low camphene yields. Conversely, the HPA catalysts supported on Nb2O5, ZrO 2 and TiO2, although weaker acids, showed more stable performance in α-pinene isomerisation. The HPA catalyst supported on TiO2 gave a camphene yield of 51% and a total camphene and limonene yield of 58%.
- Alsalme, Ali,Kozhevnikova, Elena F.,Kozhevnikov, Ivan V.
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- Monoterpenes etherification reactions with alkyl alcohols over cesium partially exchanged Keggin heteropoly salts: effects of catalyst composition
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In this work, cesium partially exchanged Keggin heteropolyacid (HPA) salts were prepared, characterized, and evaluated as solid catalysts in monoterpenes etherification reactions with alkyl alcohols. A comparison of the activity of soluble HPAs and their insoluble cesium salts showed that among three different Keggin anions the phosphotungstate was the most efficient catalyst. Assessments on the effects of the level of the protons exchange by cesium cations demonstrated that Cs2.5H0.5PW12O40 solid salt was the most active and selective phosphotungstate catalyst, converting β-pinene to α-terpinyl methyl ether. The influences of the main reaction parameters such as reaction temperature, time, catalyst load, substrate nature (i.e., alcohols and monoterpenes) were investigated. We have demonstrated that the simultaneous presence of the cesium ions and protons in the catalyst plays an essential role, being the 2.5–0.5 the optimum molar ratio. The Cs2.5H0.5PW12O40 salt was efficiently recovered and reused without loss of catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
- da Silva, Márcio José,Lopes, Neide Paloma Goncalves,Ferreira, Sukarno Olavo,da Silva, Rene Chagas,Natalino, Ricardo,Chaves, Diego Morais,Texeira, Milena Galdino
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- Hydration of α-pinene in a triphasic system consisting of α-pinene, water, and Cs2.5H0.5PW12O 40-SiO2 composite
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Cs2.5H0.5PW12O40-SiO 2 composite combined with (3-aminopropyl)triethoxysilane exhibited greater activity and selectivity for hydration of α-pinene at 333 K in a triphasic system (α-pinene/water/solid acid) compared to previously reported water-tolerant catalysts such as zeolites, polymer-resins (Amberlyst 15 and Nafion-H), oxides, and liquid acids such as H3PW 12O40 and H2SO4. The selectivity toward alcohols, including mono- and dialcohols, was approximately 80% over Cs2.5H0.5PW12O40-SiO2 composite. Copyright
- Horita, Naoto,Kamiya, Yuichi,Okuhara, Toshio
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- Catalytic Transformation of camphene over Aluminophosphate-based Molecular Sieves
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The catalytic transformation of camphene over AlPO4-11, SAPO-5, SAPO-11, VAPO-5, VAPO-11, CoAPO-5, CoAPO-11, NAPO-5, NAPO-11, ZAPO-5 and ZAPO-11 in the vapour phase has been studied.The products formed are tricyclene, bornylene and monocyclic terpenes.The
- Elangovan, S. P.,Arabindoo, Banumathi,Krishnasamy, V.,Murugesan, V.
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- Selective vapour-phase α-pinene isomerization to camphene over gold-on-alumina catalyst
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The vapour-phase isomerization of α-pinene for the first time was studied over a supported Au catalyst. α-pinene was isomerized to camphene over the 2.2% Au/γ-Al2O3 catalyst at 463-483 K using a solution of the reagent in n-octane as the initial reaction mixture and H2 or N2 as a carrier gas. Under these conditions, the selectivity to camphene reaches 60-80% at 99.9% conversion of α-pinene. The reaction is found to be first-order with respect to α-pinene, the apparent activation energy being similar to that observed with the conventional TiO2 catalyst. The prominent catalyst deactivation has been observed at increased α-pinene concentrations in the inlet reaction mixture (≥4 vol% in n-octane solution). According to HRTEM and TPO results, the deactivated catalyst contains the carbonaceous deposits that may block the catalyst surface. Almost complete regeneration was done in flowing O2 at temperature up to 923 K required to totally eliminate the coke deposits.
- Simakova,Solkina, Yu.S.,Moroz,Simakova,Reshetnikov,Prosvirin,Bukhtiyarov,Parmon,Murzin, D.Yu.
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- Catalytic and physicochemical properties of modified natural clinoptilolite
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A natural specimen from the deposit at Ku?in (Slovakia), rich in clinoptilolite type zeolite, was dealuminated using HCl solutions of increasing concentration (0.05-11.5 M). The samples were characterized by XRD, sorption of nitrogen, TPD of ammonia, FT IR and NMR spectroscopies. The preparations modified under mild conditions (acid concentration, temperature of dealumination) retained largely their crystallinity and acidity, and were active in the liquid phase isomerization of α-pinene. Upon more severe treatments, the samples became partially amorphous and lost their catalytic activity. The kinetics of α-pinene isomerization was studied over the most active catalysts. The reaction rate constants and apparent energies of activation were obtained. Initial reaction rates over the clinoptilolite type catalysts were compared with other acidic catalysts, including ferrierite-type zeolites.
- Dziedzicka, Anna,Sulikowski, Bogdan,Ruggiero-Miko?ajczyk, Ma?gorzata
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- Synthesis of mesoporous Beta and Sn-Beta zeolites and their catalytic performances
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Mesoporous Beta zeolite has been successfully prepared through hydrothermal synthesis in the presence of cationic ammonium-modified chitosan as the meso-template. Through a subsequent solid-gas reaction between highly dealuminated mesoporous Beta zeolite and SnCl4 steam at an elevated temperature, mesoporous Sn-Beta has been facilely obtained. It was revealed that the addition of cationic chitosan induced the nanocrystal aggregation to particle sizes of ～300 nm, giving rise to the intercrystalline/interparticle mesoporosity. In the Sn-implanting procedure, Sn species were demonstrated to be doped into the framework of the resulting mesoporous Beta zeolite in a tetrahedral environment without structural collapse. Due to the micro/mesoporous structures, both mesoporous Beta and Sn-Beta exhibited superior performances in α-pinene isomerization, Baeyer-Villiger oxidation of 2-adamantanone by hydrogen peroxide and the isomerization of glucose in water, respectively. the Partner Organisations 2014.
- Jin, Junjiang,Ye, Xinxin,Li, Yongsheng,Wang, Yanqin,Li, Liang,Gu, Jinlou,Zhao, Wenru,Shi, Jianlin
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- Synthesis of terpinyl acetate using octadecylamine ethoxylate ionic liquids as catalysts
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Terpinyl acetate, an important natural flavor, can be synthesized by esterification of α-pinene with acetic acid under acidic conditions. In this work, seven acidic ionic liquids were first synthesized, using octadecylamine ethoxylates (AC 1810, AC 1815, AC 1820, and AC 1830) as the cations, and characterized by FT-IR, 1H NMR, and 13C NMR spectroscopy. The ionic liquids were then used as catalysts in the synthesis of terpinyl acetate. The effect of preparation conditions on catalyst performance was examined. It was found that the acidic ionic liquid 1-(3-sulfonic acid)propyl-3-poly(ethylene glycol) octadecylamine polyoxyethylene ether tetrafluoroborate ([PAC1815]+[BF4]-) was an excellent catalyst for synthesis of terpinyl acetate. The effects of the conditions used for preparation of terpinyl acetate were examined in detail, and the optimum preparation conditions were obtained. Under the optimum conditions, the yield of terpinyl acetate reached 35.70 %. When the catalyst was reused for the 5th time, the yield of terpinyl acetate was still 32.00 %. The results showed that effective separation and recycling of catalyst could contribute to developing a new strategy for synthesis of terpinyl acetate.
- Li, Lu,Liu, Shiwei,Shi, Yanjing,Yu, Shitao,Xie, Congxia,Qi, Chunjie
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- Structure-reactivity correlations in sulphated-zirconia catalysts for the isomerisation of α-pinene
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A range of mesoporous sulphated zirconias with tuneable structural and catalytic properties have been prepared by direct impregnation. The surface sulphate coverage can be readily varied, achieving a maximum value of ～0.2 monolayers. High-temperature calcination induces the crystallisation of tetragonal zirconia while suppressing the monoclinic phase and enhances surface acidity. Superacid sites only appear above a critical threshold SO4 coverage of 0.08 mL (corresponding to 0.44 wt% total S). Sulphated zirconias show good activity towards α-pinene isomerisation of under mild conditions. Conversion correlates with the number Bronsted acid sites, while the selectivity towards mono- versus polycyclic products depends on the corresponding acid site strength; superacidity promotes limonene formation over camphene.
- Ecormier, Muriel A.,Wilson, Karen,Lee, Adam F.
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- The kinetics, stereochemistry, and deuterium isotope effects in the α-pinene pyrolysis. Evidence for incursion of multiple conformations of a diradical
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Pyrolysis of optically active α-pinene gave 95% racemic limonene (dipentene), alloocimine, racemic α-pinene, α-pyronene. Activation parameters are reported. Pyrolysis of (S) syn-6-trideuteriomethyl α-pinene at 256.7°C for 2400s gave dipentene with twice as much deuterium as hydrogen transfer with kH/kD=1.49 and alloocimine with a Z and E trideuteriomethyl ratio of ca. 5 with kH/kD=0.89. The isotope effect on loss of starting material was 1.16. Separation of the enantiomers of α-pinene from 3600s pyrolyses at 256.7°C followed by NMR analysis revealed that the ratio of the R-syn to R-anti to S-anti isomers is 4.6:3.7:1 at roughly two half-lives. Kinetic analysis reveals that the previously proposed mechanism for all conversions involving slow interconversion of two diradicals with Cs symmetry is not consistent with the distribution of the ??-pinene isomers, particularly the formation of more suprafacial-retention product (R-anti) than bond-rotated isomer (S-anti). Inclusion of another Cs species (ignoring the deuteriums) that would be intermediate between the originally proposed Cs species, appears more consistent with the observations.
- Gajewski, Joseph J,Kuchuk, Ilya,Hawkins, Christopher,Stine, Robert
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- Hydrothermal synthesis of single-crystalline mesoporous beta zeolite assisted by N-methyl-2-pyrrolidone
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Highly crystalline beta zeolite with large intracrystalline mesopores has been facilely synthesized via the introduction of low-cost N-methyl-2- pyrrolidone (NMP) into common TEAOH-based zeolite synthesis mixtures, which exhibited remarkably higher catalytic activity contrast than conventional porous catalysts (ZSM-5, beta and Al-MCM-41) in acid-catalyzed reactions involving large molecules.
- Liu, Lijia,Wang, Hongbin,Wang, Runwei,Zeng, Shangjing,Ni, Ling,Zhang, Daliang,Zhu, Liangkui,Zou, Houbing,Qiu, Shilun,Zhang, Zongtao
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- The thermal isomerization of terpene compounds in supercritical alcohols
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The experimental data obtained were used to construct a kinetic model of the isomerization of α-pinene in supercritical ethanol. The model took into account the influence of both temperature and pressure on the rate and selectivity of the reaction. Nauka/Interperiodica 2007.
- Anikeev,Ermakova,Chibiryaev,Kozhevnikov,Mikenin
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- Isomerization of α-pinene over dealuminated ferrierite-type zeolites
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Isomerization of α-pinene was performed on a series of dealuminated ferrierite (FER)-type zeolites in liquid phase at 363 K using a batch reactor. The course of zeolite dealumination was followed in detail using 29Si, 27Al, 1H MAS NMR, XRD, FTIR, and sorption of nitrogen. The ammonium form of FER was dealuminated with aqueous solutions of HCl. While retaining the crystallinity of the zeolite particles, the treatments removed up to 53% of the tetrahedrally coordinated aluminum atoms from the FER framework. According to 29Si MAS NMR studies, the framework aluminum atoms located at the 10-membered rings in the main channels of FER (TB sites) were depleted preferentially from their positions. Even relatively mild dealumination of FER led to an active catalyst containing both Bronsted and Lewis centers, yielding up to 97% conversion of α-pinene at 363 K, in contrast to the 72% observed for the parent hydrogen form. Such catalytic behavior was discussed in terms of the conversion of a reactant inside micropores of the zeolite catalyst, on Bronsted acid centers with enhanced strength located probably in the vicinity of Lewis sites. The selectivity toward camphene and limonene changed smoothly with the dealumination level; thus, a higher selectivity toward limonene was observed at the expense of camphene formation with increasing the nSi / nAl ratio of the catalysts. The selectivity toward camphene and limonene was close to 85% for all of the materials studied. The initial rates of α-pinene transformations over FER-type materials exceeded those observed for other catalytic systems, heteropoly acid/SiO2 and H2SO4/ZrO2. This study demonstrates the successful application of a medium-pore zeolite for the catalytic transformation of α-pinene in liquid phase.
- Rachwalik, Rafal,Olejniczak, Zbigniew,Jiao, Jian,Huang, Jun,Hunger, Michael,Sulikowski, Bogdan
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- Isomerization of α-pinene to camphene
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The catalytic isomerization reaction of α-pinene to camphene over a clinoptilolite catalyst was investigated in a batch reactor open to the atmosphere between 130 and 155°C. The catalyst was selective to the isomerization of α-pinene to camphene. The effects of several variables, such as reaction temperature, amount of catalyst, stirring speed and catalyst particle size, on the conversion of α-pinene and selectivity to camphene were determined. The reaction fits a first-order parallel reaction with rate constants of k1 = 3.020·10-2 e-33381.6/RT for the production of camphene and of k2 = 1.576·10-2 e-31096.53/RT for the production of limonene.
- Findik,Guenduez
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- A cDNA clone for β-caryophyllene synthase from Artemisia annua
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An homology-based cloning strategy yielded a full-length cDNA from Artemisia annua that encoded a protein of 60.3 kDa which resembled a sesquiterpene synthase in sequence. Heterologous expression of the gene in Escherichia coli provided a soluble recombinant enzyme capable of catalyzing the divalent metal ion-dependent conversion of farnesyl diphosphate to β-caryophyllene, a sesquiterpene olefin found in the essential oil of A. annua. In reaction parameters and kinetic properties, β-caryophyllene synthase resembles other sesquiterpene synthases of angiosperms. The β-caryophyllene synthase gene is expressed in most plant tissues during early development, and is induced in mature tissue in response to fungal elicitor thus suggesting a role for β-caryophyllene in plant defense.
- Cai, Yu,Jia, Jun-Wei,Crock, John,Lin, Zhi-Xin,Chen, Xiao-Ya,Croteau, Rodney
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- Photocatalytic removal of monoterpenes in the gas phase. Activity and regeneration
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We show the photocatalytic removal of various monoterpenes such as β-pinene, α-pinene, camphene and limonene in the gas phase as a function of the reaction temperature, from room temperature to 80°C, taking also into account the thermal catalytic isomeriz
- Salem, Ibtissam,Keller, Nicolas,Keller, Valerie
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- The influence of water on the isomerization of α-pinene in a supercritical aqueous-alcoholic solvent
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The influence of water as a cosolvent and catalyst of the isomerization of α-pinene in a supercritical aqueous-alcoholic (ethanol) solvent was studied experimentally. At T = 657 K and p = 230 atm, an increase in the concentration of water in the reaction mixture was found to increase the rate of the reaction and its selectivity with respect to the desired product, limonene. Water exhibited the properties of an acid catalyst because of its ionization. Mathematical experimental data processing was performed to evaluate and separate the contributions of the radical and ionic paths to the total rate of the reactions that occurred during the thermal isomerization of α-pinene.
- Ermakova,Chibiryaev,Mikenin,Sal'nikova,Anikeev
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- Isomerization of α-pinene over clinoptilolite
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The kinetics of the liquid-phase isomerization of α-pinene over a natural zeolite-clinoptilolite has been studied at 100-180°C and nitrogen pressures at 1-20 bar. Up to 80-85 wt% of conversion selectivity toward reaction products was constant with camphene and limonene as the main products. Only at relatively high conversions were other monocyclic and tricyclic products formed. The consumption rate of α-pinene followed first-order kinetics. Temperature dependence of the first-order kinetic constant obeyed Arrhenius dependence with the activation energy equal to 80.9 kJ/mol. Selectivities at particular conversions were seen to be independent of temperature and pressure. A reaction network and mechanism are advanced and the corresponding kinetic equations are derived. The kinetic model gave a good correlation between the theoretical and the experimental data.
- Allahverdiev, Ayaz I.,Irandoust, Said,Murzin, Dmitry Yu.
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- Transformations of monoterpene hydrocarbons on ferrierite type zeolites
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Transformations of α-pinene and limonene over hydrogen forms of commercial ferrierite type zeolites of different origin (Tosoh Corp. and Zeolyst Intern.) have been studied in the liquid phase at 313-363 K. The catalysts were characterized by XRD, sorption
- Rachwalik,Hunger,Sulikowski
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- Production of p-cymene and hydrogen from a bio-renewable feedstock-1,8-cineole (eucalyptus oil)
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The catalytic transformation of pure 1,8-cineole was performed in a custom-built down-flow fixed bed pyrolysis rig over various metal-doped alumina pellets controlled at temperatures between 523 K (250 °C) and 873 K (500 °C). Varying amounts of oxygen were added to the feed. Hydrophilic, hydrophobic and gaseous products were analysed separately. The hydrophilic phase was predominantly water, while the composition of the hydrophobic phase varied with catalyst type and contained mainly mixtures of both aromatic and non-aromatic C10 hydrocarbons. The main gases produced were hydrogen, carbon monoxide and carbon dioxide. As the reaction temperature increased, yields of gas phase components increased for all catalysts. The palladium-doped γ-Al2O3 catalyst at ～250 °C showed excellent yields and selectivity for the continuous production of p-cymene together with hydrogen gas. For the best catalysts and reaction conditions, the process is very atom and carbon efficient, with all ten carbon atoms from the cineole molecule being used in the p-cymene product in an oxygen-free environment. The process uses no solvents and the high yields achieved ensure there is no waste clean-up required.
- Leita, Benjamin A.,Warden, Andrew C.,Burke, Nick,O'Shea, Mike S.,Trimm, David
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- Discovering Monoterpene Catalysis Inside Nanocapsules with Multiscale Modeling and Experiments
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Large-scale production of natural products, such as terpenes, presents a significant scientific and technological challenge. One promising approach to tackle this problem is chemical synthesis inside nanocapsules, although enzyme-like control of such chemistry has not yet been achieved. In order to better understand the complex chemistry inside nanocapsules, we design a multiscale nanoreactor simulation approach. The nanoreactor simulation protocol consists of hybrid quantum mechanics-molecular mechanics-based high temperature Langevin molecular dynamics simulations. Using this approach we model the tail-to-head formation of monoterpenes inside a resorcin[4]arene-based capsule (capsule I). We provide a rationale for the experimentally observed kinetics of monoterpene product formation and product distribution using capsule I, and we explain why additional stable monoterpenes, like camphene, are not observed. On the basis of the in-capsule I simulations, and mechanistic insights, we propose that feeding the capsule with pinene can yield camphene, and this proposal is verified experimentally. This suggests that the capsule may direct the dynamic reaction cascades by virtue of π-cation interactions.
- Pahima, Efrat,Zhang, Qi,Tiefenbacher, Konrad,Major, Dan T.
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- Desilication of ZSM-5 and ZSM-12 zeolites: Impact on textural, acidic and catalytic properties
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Two zeolites of different topology: ZSM-5 and ZSM-12 were subjected to desilication in the NaOH solutions of increasing concentrations. Changes in the properties of modified zeolites were investigated by several methods ( 29Si and 27
- Gil, Barbara,Mokrzycki, ?ukasz,Sulikowski, Bogdan,Olejniczak, Zbigniew,Walas, Stanis?aw
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- Structural studies of high dispersion H3PW12O 40/SiO2 solid acid catalysts
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Highly dispersed H3PW12O40/SiO2 catalysts with loadings between 3.6 and 62.5 wt% have been synthesised and characterised. The formation of a chemically distinct interfacial HPW species is identified by XPS, attributed to pertubation of W atoms within the Keggin cage in direct contact with the SiO2 surface. EXAFS confirms the Keggin unit remains intact for all loadings, while NH3 adsorption calorimetery reveals the acid strength >0.14 monolayers of HPW is loading invariant with initial ΔHads = ～-164 kJ mol-1. Lower loading catalysts exhibit weaker acidity which is attributed to an inability of highly dispersed clusters to form crystalline water. For reactions involving non-polar hydrocarbons the interfacial species where the accessible tungstate is highest confer the greatest reactivity, while polar chemistry is favoured by higher loadings which can take advantage of the H3PW 12O40 pseudo-liquid phase available within supported multilayers. the Owner Societies 2006.
- Newman, Andrew D.,Brown, D. Robert,Siril, Prem,Lee, Adam F.,Wilson, Karen
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- Synthesis of Terpineol from Alpha-Pinene Catalyzed by α-Hydroxy Acids
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We report the use of five alpha-hydroxy acids (citric, tartaric, mandelic, lactic and glycolic acids) as catalysts in the synthesis of terpineol from alpha-pinene. The study found that the hydration rate of pinene was slow when only catalyzed by alpha-hydroxyl acids. Ternary composite catalysts, composed of AHAs, phosphoric acid, and acetic acid, had a good catalytic performance. The reaction step was hydrolysis of the intermediate terpinyl acetate, which yielded terpineol. The optimal reaction conditions were as follows: alpha-pinene, acetic acid, water, citric acid, and phosphoric acid, at a mass ratio of 1:2.5:1:(0.1–0.05):0.05, a reaction temperature of 70? C, and a reaction time of 12–15 h. The conversion of alpha-pinene was 96%, the content of alpha-terpineol was 46.9%, and the selectivity of alpha-terpineol was 48.1%. In addition, the catalytic performance of monolayer graphene oxide and its composite catalyst with citric acid was studied, with acetic acid used as an additive.
- Hu, Yi-Ming,Huang, Xiao-Rui,Meng, Zhong-Lei,Qin, Rong-Xiu,Wen, Ru-Si,Zhou, Yong-Hong
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- Method and Means for Releasing a Terpene Mixture to a Cannabis Flower During Storage
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A method and means for releasing a terpene mixture to a Cannabis flower during storage with may be from a cotton pulp card or a two-way humidity pack with an additional terpene blend for keeping a Cannabis flower fresh while naturally increasing the desired terpene levels. The product is a blend of humidity regulating agents infused with terpenes (plant derived) which allows for the product to be paired with herbal material to increase and maintain the relative humidity, while transferring the flavor/aroma/taste terpenes from the package into the herbal material. There are two embodiments, the first is a Terp Pack+Humidity (“Terp Pack+RH”) which contains a herban material to increase and maintain relative humidity, while releasing the infused terenes, and the second is more simply a Terp Pack (“Terp Pack”) which contains no humidity enhancing material and is only a carrier for releasing the terpene mixture.
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- Thioderivatives of Resorcin[4]arene and Pyrogallol[4]arene: Are Thiols Tolerated in the Self-Assembly Process?
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Three novel thiol bearing resorcin[4]arene and pyrogallol[4]arene derivatives were synthesized. Their properties were studied with regards to self-assembly, disulfide chemistry, and Br?nsted acid catalysis. This work demonstrates that (1) one aromatic thiol on the resorcin[4]arene framework is tolerated in the self-assembly process to a hexameric hydrogen bond-based capsule, (2) thio-derivatized resorcin[4]arene analogs can be covalently linked through disulfides, and (3) the increased acidity of aromatic thio-substituent is not sufficient to replace HCl as cocatalyst for capsule catalyzed terpene cyclizations.
- Nemat, Suren J.,Tiefenbacher, Konrad
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supporting information
p. 6861 - 6865
(2021/09/14)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- Preparation method of myrcene
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The method uses geraniol and/or nerol and/or linalool as a raw material, uses a palladium source and an organic phosphine as a catalyst to prepare myrcene, and realizes chemical synthesis of myrcene. The method has the advantages of high catalytic efficiency and high product selectivity.
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Paragraph 0043-0044
(2021/11/19)
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- Synthesis of isobenzofuran derivatives from renewable 2-carene over halloysite nanotubes
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Condensation of a terpene 2-carene with 4-methoxybenzaldehyde over a range of acid aluminosilicates including halloysite nanotubes (HNT) was studied for as a model for preparation of isobenzofuran derivatives with a pharmaceutical potential. The catalysts were characterized by FTIR with pyridine, UV by adsorption of 2-phenylethylamine from the aqueous phase, SEM, TEM and N2 physisorption. The largest selectivity to the desired product (ca. 70%) over halloysite nanotubes is associated with weak acidity of these catalysts (45 μmol/g), allowing avoiding side isomerization and condensation reactions. Moreover, the highest yield on air-dry HNT clearly indicates that weak Br?nsted sites favored the reaction. On the contrary, over strong Br?nsted and Lewis acids (Amberlyst-15, scandium triflate), the yield of isobenzofurans did not exceed 16% with formation of mainly 2-carene isomerization products. DFT calculations showed that interactions of the aldehyde with cyclopropane moiety of 2-carene giving isobenzofurans are more beneficial than an alternative direct attack of a proton, leading to side reactions. A possibility to reuse of HNT catalyst was confirmed. Overall, halloysite is a highly effective catalyst for production of isobenzofuran compounds based on 2-carene.
- Agabekov, V. E.,Aho, A.,Il'ina, I. V.,Korchagina, D. V.,Kravtsova, A. V.,Li-Zhulanov, N. S.,M?ki-Arvela, P.,Murzin, D. Yu.,Salakhutdinov, N. F.,Sandberg, T.,Sidorenko, A. Yu.,Volcho, K. P.
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- Enantioselective Tail-to-Head Cyclizations Catalyzed by Dual-Hydrogen-Bond Donors
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Chiral urea derivatives are shown to catalyze enantioselective tail-to-head cyclization reactions of neryl chloride analogues. Experimental data are consistent with a mechanism in which ?-participation by the nucleophilic olefin facilitates chloride ionization and thereby circumvents simple elimination pathways. Kinetic and computational studies support a cooperative mode of catalysis wherein two molecules of the urea catalyst engage the substrate and induce enantioselectivity through selective transition state stabilization.
- Kutateladze, Dennis A.,Strassfeld, Daniel A.,Jacobsen, Eric N.
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p. 6951 - 6956
(2020/05/19)
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- Exploring the Keggin-Type Heteropolyacid-Catalyzed Reaction Pathways of the Β-Pinene with Alkyl Alcohols
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Abstract: In this work, we investigated the activity of Keggin heteropolyacid catalysts (i.e., H3PW12O40, H3PMo12O40 and H4SiW12O40) in β-pinene reactions with alkyl alcohols (i.e. methyl, ethyl, propyl, sec-propyl, butyl and sec-butyl alcohols), and exploring the different aspects that drive the selectivity of this process. We have found that carbon skeletal rearrangements and isomerization providing intermediate carbocations that controlling the reaction selectivity. β-pinene was preferentially converted to α-terpinyl ion which undergoes a nucleophilic attack of alcohol providing alkyl alcohol. Bornyl ion was converted to bornyl and fenchyl ethers. The other secondary products were β-pinene isomers obtained from bornyl and α-terpinyl carbocations. Phosphotungstic acid (i.e., H3PW12O40) was the most active catalyst and selective toward the main product (α-terpinyl alkyl ether); the highest conversion (ca. 96%) and ether selectivity (ca. 61%) was achieved in the reactions with β-pinene. Although having also been alkoxylate, α-pinene was less reactive (ca. 40%), while camphene and limonene remained unreactive under reaction conditions studied. An increase of temperature resulted in an improvement on conversion of β-pinene and selectivity toward α-terpinyl methyl ether. Similarly, the H3PW12O40 concentration played a crucial role on reaction selectivity. This work presents positive features such as a short reaction time, high atom economy, mild reaction conditions (i.e., low temperature and room pressure). Even though soluble the catalyst was easily recovered by liquid -liquid extraction and efficiently reused. Graphical Abstract: [Figure not available: see fulltext.].
- Polo, Henrique Priori,Lopes, Neide Paloma Goncalves,da Silva, Márcio José
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p. 2844 - 2853
(2019/05/28)
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- Layer-assembled 3D Bi2WO6 hierarchical architectures by Ti-doping for enhanced visible-light driven photocatalytic and photoelectrochemical performance
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Layer-assembled three-dimensional (3D) catalysis gain substantial attention and widespread application in the field of photocatalysis and solar energy conversion. The 3D hierarchical architecture possesses large surface area and plenty reactive sites which contribute highly in catalysis performance. In this work we report a tetrabutyl titanate (TBT) assisted simultaneous approach of layer-assembled single-unit-cell 3D Bi2WO6 hierarchical architecture by Ti-doping. The Ti-doping beside its morphological effect can also generate crystal defects in the crystal lattice of Bi2WO6, resulting in highly enhanced visible-light driven photocatalytic performance towards highly stable refractory pollutants and profound photoelectrochemical ability. Moreover, the crystal defects mediated by Ti-doping can generate abundant oxygen vacancies which remarkably improve the selective adsorption towards different charges pollutants. Furthermore, the Ti-doping beside its great influence on the electron dynamic and band structure can also introduce the redox couples (Ti3+/Ti4+), resulting in significance enhancement in reactive oxygen species during photocatalytic reaction. The present work provides a valid route for constructing simultaneous approach of layer-assembled 3D hierarchical architecture and Ti-substitution in the crystal structure of Bi2WO6 with great improvement in photocatalytic and photoelectrochemical performance.
- Arif, Muhammad,Zhang, Min,Yao, Jiacheng,Yin, Hongfei,Li, Pengfei,Hussain, Ijaz,Liu, Xiaoheng
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p. 878 - 893
(2019/04/17)
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- Method for producing limonene by taking acidic ionic liquid loaded zirconia microcapsules as catalyst
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The invention provides a method for producing limonene by taking acidic ionic liquid loaded zirconia microcapsules as a catalyst. The method comprises the following steps: adding zirconium oxynitrateinto water, carrying out thorough dissolving, dropwise adding ammonia water to adjust the aqueous solution to be alkaline, carrying out room-temperature standing aging, and carrying out filtration, washing and baking, so as to obtain zirconium hydroxide; grinding zirconium hydroxide, then, mixing the ground zirconium hydroxide with a pore former and a sizing agent, then, carrying out compression sizing, and carrying out calcining, so as to obtain a porous zirconia carrier; adding porous zirconia into the acidic ionic liquid for thorough dipping, carrying out filtrating, sprinkling a gelatin-containing mixed solution, and carrying out baking, so as to obtain the acidic ionic liquid loaded zirconia microcapsules; and subjecting alpha-pinene, which serves as a raw material, to a reaction in aliquid-solid multiphase stirred reactor or fixed-bed reactor under normal pressure in the presence of the acidic ionic liquid loaded zirconia microcapsules, thereby obtaining the limonene. The catalyst has high selectivity to alpha-pinene isomerized principal products, the yield of limonene is high, the reaction conditions are mild, the corrosiveness to equipment is low, and thus, the method is environmentally friendly and safe.
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Paragraph 0023; 0027; 0032; 0037; 0042; 0047; 0052
(2018/06/16)
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- SnCl2-catalyzed synthesis of carbamates from renewable origin alcohols
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Effects of structure and reactivity of renewable origin alcohols in the conversion and selectivity of the SnCl2-catalyzed reactions in the presence and absence of urea were assessed. Convenient simple and suitable method for the synthesis of carbamates from renewable origin alcohols and urea in one-step are provided. We have assessed the activity of SnCl2 catalyst, a commercially affordable Lewis acid, in reactions of urea alcoholysis with different natural origin alcohols (geranyl, neryl, bornyl, cinnamyl, α-terpinyl and benzyl alcohols), aiming to synthesize carbamates, which are biologically active compounds, building blocks in organic synthesis and raw material to synthesize polyurethanes. The low cost of urea, the water tolerant catalyst and phosgene free reaction are positive aspects of this carbamates synthesis process. The different reaction pathways were assessed. A mechanism was proposed based on FT-IR experiments and experimental data.
- da Silva, Márcio José,Chaves, Diego Morais
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p. 1169 - 1180
(2019/01/28)
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- Transition metal triflate catalyzed conversion of alcohols, ethers and esters to olefins
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Herein, we report an efficient transition metal triflate catalyzed approach to convert biomass-based compounds, such as monoterpene alcohols, sugar alcohols, octyl acetate and tea tree oil, to their corresponding olefins in high yields. The reaction proceeds through C-O bond cleavage under solvent-free conditions, where the catalytic activity is determined by the oxophilicity and the Lewis acidity of the metal catalyst. In addition, we demonstrate how the oxygen containing functionality affects the formation of the olefins. Furthermore, the robustness of the used metal triflate catalysts, Fe(OTf)3 and Hf(OTf)4, is highlighted by their ability to convert an over 2400-fold excess of 2-octanol to octenes in high isolated yields.
- Keskiv?li,Parviainen,Lagerblom,Repo
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p. 15111 - 15118
(2018/05/04)
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- High density fuels from oxygenated terpenoids
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A method for the efficient synthesis of useful deoxygenated terpenoids from an abundant renewable source, using catalytic conversion of oxygenated terpenoids. Oxygenated terpenoids such as 1,4-cineole and 1,8-cineole are, for example, major components of turpentine and essential oils. These oxygenated terpenoids can also be produced from sugars via a biosynthetic approach. Catalytic deoxygenation of these substrates can be used to efficiently generate commercially important chemicals and high density fuels for turbine or diesel propulsion.
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Page/Page column 7; 8
(2017/07/06)
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- Method for preparing limonene from 3-carene
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The invention discloses a method for preparing limonene from 3-carene. The method comprises the following steps: (1) preparing terpin from 3-carene in the presence of sulfuric acid, wherein the reaction temperature is kept at 15-35 DEG C; and (2) preparing limonene from the terpin in the presence of sulfuric acid, wherein the reaction temperature is kept at 0-10 DEG C. The invention aims at providing a method for preparing limonene from 3-carene, wherein in the method, limonene is prepared from cheap 3-carene, the conversion rate is high while the preparation flow is relatively simple, and the prepared limonene is separated from other byproducts relatively easily.
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Paragraph 0017; 0018; 0019; 0020; 0021; 0022
(2017/04/27)
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- Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies
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The tail-to-head terpene cyclization is arguably one of the most complex reactions found in nature. The hydrogen-bond-based resorcinarene capsule represents the first man-made enzyme-like catalyst that is capable of catalyzing this reaction. Based on noncovalent interactions between the capsule and the substrate, the product selectivity can be tuned by using different leaving groups. A detailed mechanistic investigation was performed to elucidate the reaction mechanism. For the cyclization of geranyl acetate, it was found that the cleavage of the leaving group is the rate-determining step. Furthermore, the studies revealed that trace amounts of acid are required as cocatalyst. A series of control experiments demonstrate that a synergistic interplay between the supramolecular capsule and the acid traces is required for catalytic activity.
- Zhang, Qi,Catti, Lorenzo,Pleiss, Jürgen,Tiefenbacher, Konrad
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supporting information
p. 11482 - 11492
(2017/08/30)
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- Bifunctional catalyst Pd-Al-MCM-41 for efficient dimerization-hydrogenation of β-pinene in one pot
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A new type of bimetallic palladium and aluminum incorporated mobile crystalline materials (Pd-Al-MCM-41) as bifunctional catalysts has been hydrothermally synthesized. Characterization shows that these molecular materials exhibit an ordered mesoporous structure, high surface area and a good dispersion of palladium in the frame. The catalytic activity of the Pd-Al-MCM-41 for the dimerization-hydrogenation reaction system of β-pinene in one pot has been systematically studied. Pd0.5-Al30-MCM-41 (SiO2/Al2O3 = 30, 0.5 wt% palladium content) was found to be the best catalyst which gave a dimer yield of up to 64.7%. It is worth noting that palladium shows a good synergic catalytic effect with aluminum in the dimerization reaction and enhances the dimerization yield. Furthermore, the bifunctional catalyst displayed a good activity over 4 runs.
- Zhang, Song,Xu, Chao,Zhai, Guoqing,Zhao, Mingliang,Xian, Mo,Jia, Yuxiang,Yu, Zongjiang,Liu, Fusheng,Jian, Fangfang,Sun, Weizhi
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p. 47539 - 47546
(2017/10/19)
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- Unravelling transition metal-catalyzed terpenic alcohol esterification: A straightforward process for the synthesis of fragrances
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Iron nitrate is a simple and commercially available Lewis acid and is demonstrated to be able to catalyze β-citronellol esterification with acetic acid, achieving high conversion and ester selectivity (ca. 80 and 70%, respectively), within shorter reaction times than those reported in the literature. To the best of our knowledge, this is the first report of a terpenic alcohol esterification reaction catalyzed by Fe(NO3)3. This process is an attractive alternative to the slow and expensive enzymatic processes commonly used in terpenic alcohol esterification. Moreover, it avoids the undesirable steps of neutralizing the products, which are always required in mineral acid-catalyzed reactions. We have performed a study of the activity of different metal Lewis acid catalysts, and found that their efficiency is directly linked to the ability of the metal cation to generate H+ ions from acetic acid ionization. The measurement of pH as well as the conversions achieved in the reactions allowed us to obtain the following trend: Fe(NO3)3 > Al(NO3)3 > Cu(NO3)2 > Ni(NO3)2 > Zn(NO3)2 > Mn(NO3)2 > Co(NO3)2 > LiNO3. The first three are recognized as stronger Lewis acids and they generate more acidic solutions. When we carried out reactions with different iron salts, it was possible to conclude that the type of anion affects the solubility of the catalyst, as well as the conversion and selectivity of the process. Fe2(SO4)3 and FeSO4 were insoluble and less active. Conversely, though they were equally soluble, Fe(NO3)3 was more selective for the formation of β-citronellyl acetate than FeCl3. We assessed the effects of the main reaction variables such as reactant stoichiometry, temperature, and catalyst concentration. In addition to citronellol, we investigated the efficiency of the iron(iii) catalyst in the solvent free esterification of several terpenic alcohols (geraniol, nerol, linalool, α-terpineol) as well as other carboxylic acids.
- Da Silva,Ayala
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p. 3197 - 3207
(2016/05/24)
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- PHOTOLABILE PRO-FRAGRANCES
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The present invention relates to a method for producing photocleavable scent precursors, to products containing the scent precursors, and to the use of the scent precursors for prolonging the scent impression in the product and on surfaces treated with the product.
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Paragraph 0122
(2016/04/09)
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- PHOTOLABILE PRO-FRAGRANCES
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The present invention relates to a method for producing photocleavable scent precursors, to products containing the scent precursors, and to the use of the scent precursors for prolonging the scent impression in the product and on surfaces treated with the product.
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Paragraph 0167-0169
(2017/01/12)
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- Hybrid catalysts based on platinum and palladium nanoparticles for the hydrogenation of terpenes under slurry conditions
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Catalysts based on platinum and palladium nanoparticles immobilized in mesoporous phenolformaldehyde polymers modified with sulfo groups have been used for the hydrogenation of a number of terpenes, such as (S)-(–)-limonene, α-terpinene, γ-terpinene, and terpinolene. It has been found that Pd-containing catalysts exhibit higher activity in the exhaustive hydrogenation of terpenes, whereas Pt-containing catalysts have high selectivity for p-menthene.
- Karakhanov,Boronoev,Subbotina,Zolotukhina,Maximov,Filippova, T. Yu.
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p. 1114 - 1122
(2017/02/15)
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- Selective methoxylation of α-pinene to α-terpinyl methyl ether over Al3+ ion-exchanged clays
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In this study, we report the use of clay-based catalysts in the methoxylation of α-pinene, for the selective synthesis of α-terpinyl methyl ether, TME. The main reaction products and intermediates were identified by GC-MS. The reaction conditions (stirring rate and catalyst load) that afford a kinetic regime were established. SAz-1 (Cheto, Arizona, USA) source clay and a montmorillonite (SD) from Porto Santo, Madeira Archipelago, Portugal, were modified by ion-exchange with Al3+ to produce catalysts with markedly different acidities and textural properties. The catalysts based on the high layer-charge SAz-1 montmorillonite proved to be the most active. Ion-exchange with Al3+, followed by thermal activation at 150°C, afforded the highest number of Br?nsted acid sites - a significant proportion of which were located in the clay gallery - and this coincided with the maximum catalytic activity. The influence of various reaction conditions, to maximize α-pinene conversion and selectivity, was studied over AlSAz-1. When the reaction was performed for 1 h at 60°C, the conversion reached 65% with 65% selectivity towards the mono-ether, TME. Similar conversions and selectivities required up to 50 h over zeolites and other solid acid catalysts. The kinetic dependencies of this reaction on temperature and reagent concentration, over the selected clays were also investigated. It was established that, in the temperature and reagent concentration regime studied, the reaction was first order with respect to α-pinene. The apparent activation energies over the two catalysts, calculated from Arrhenius plots, were almost identical at 72 kJ mol-1.
- Catrinescu,Fernandes,Castilho,Breen
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p. 171 - 179
(2015/05/05)
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- Sonocatalytic degradation of a textile dye over Gd-doped ZnO nanoparticles synthesized through sonochemical process
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The present study was performed to sonochemically synthesize GdxZn1-xO (x = 0-0.1) nanoparticles for sonocatalysis of Acid Orange 7 (AO7) in an aqueous medium. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM
- Khataee, Alireza,Soltani, Reza Darvishi Cheshmeh,Karimi, Atefeh,Joo, Sang Woo
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p. 219 - 230
(2015/02/19)
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- METHOD FOR PRODUCING ORGANIC COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of subjecting a compound having on one carbon atom a carbon atom constituting a carbon-carbon double bond and a functional group such as a hydroxyl group to a reductive reaction condition and producing an organic compound having the functional group substituted with a hydrogen atom. SOLUTION: There is provided a method for producing a compound represented by a formula (50) from a raw material compound represented by a formula (10). The method includes a step of irradiating a reaction system with light, the reaction system comprising the raw material compound, a hydrogen source compound, and a catalyst having a palladium component supported by a carrier containing titanium oxide. (R11 to R15 are a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms which may have a cyclic structure or a derivative group thereof, or a heteroatom-containing group having 1 to 20 carbon atoms which may have a cyclic structure or a derivative group thereof; and R16 is a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms or an acyl group having 1 to 20 carbon atoms which may have a cyclic structure, or -CH(CH2OH)2).) COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0084-0087; 0097; 0129; 0137; 0138
(2018/10/16)
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- Alkylation of 2,4-dimethylphenol with (+)-α- and (-)-β-pinenes in the presence of aluminum xylenolate
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Alkylation of 2,4-dimethylphenol with (+)-α- and (-)-β-pinenes in the presence of aluminum 2,4-dimethylphenoxide generated in situ led to the formation of mixtures of products, from which optically active compounds were isolated. The structure of 2-bornyl
- Chukicheva,Krylova,Buravlev,Suponitskii,Kutchin
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p. 589 - 595
(2014/06/10)
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- Effect of high-temperature calcination on the generation of Bronsted acid sites on WO3/Al2O3
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The acid properties of a series of alumina-supported tungsten oxide (WO3/Al2O3) catalysts with loadings of 5-50 wt% WO3 calcined at various temperatures were investigated by acid-catalyzed reactions (benzylation of anisole and isomerization of α-pinene) and FTIR spectroscopy. The relationships between acid properties, structures, and catalytic performances were evaluated. Both the catalytic activity and amount of Bronsted acid sites depend on the calcination temperature and WO3 loading. High-temperature calcination (1123 K) generated Bronsted acid properties, and 20 wt% WO 3/Al2O3 calcined at 1123 K exhibited the highest activity among the catalysts tested. The activities for the benzylation of anisole and α-pinene isomerization over WO3/Al 2O3 calcined at 1123 K were proportional to the Bronsted acidity, which indicates that these reactions occurred on the Bronsted acid sites. Tungsten oxide, which has distorted octahedral symmetry, was loaded as 2D monolayer domains below 20 wt%, and these domains covered most of the alumina surface at 20 wt%. If the WO3 loading was sufficient to form 2D tungsten oxide monolayer sheets (>20 wt%), some of the Bronsted acid sites on WO3/Al2O3 were obscured by monoclinic WO3 that has no Bronsted acid sites, which resulted in a decrease of the catalytic activity. This suggests that Bronsted acid sites are generated at the boundaries between tungsten oxide monolayer domains.
- Kitano, Tomoyuki,Hayashi, Tomohiro,Uesaka, Toshio,Shishido, Tetsuya,Teramura, Kentaro,Tanaka, Tsunehiro
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p. 2011 - 2020
(2014/08/05)
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- TRANSITION METAL CATALYSTS FOR C-O HYDROGENOLYSIS AND HYDRODEOXYGENATION
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Phosphoranimide-metal catalysts and their role in C—O bond hydrogenolysis and hydrodeoxygenation (HDO) are disclosed. The catalysts comprise of first row transition metals such as nickel, cobalt and iron. The catalysts have a metal to anionic phosphoranimide ratio of 1:1 and catalyze C—O bond hydrogenolyses of a range of oxygen-containing organic compounds under lower temperature and pressure conditions than those commonly used in industrial hydrodeoxygenation.
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Paragraph 0190
(2014/07/08)
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- Ring-Opening Reactions of α- And β-Pinenes in Pressurized Hot Water in the Absence of Any Additive
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Reactions of α- and β-pinenes in pressurized hot water were examined in a batch reactor made of a SS316 1/2-in. tube at temperatures of 250-400 C, pressures of 4-30 MPa, and reaction times of 1-30 min in the absence of any additive under an argon atmosphere. The maximum yields of limonene from α-pinene were ca. 70% in 20 min at 300 C or 1 min at 400 C. Limonene was obtained from β-pinene in ca. 16% yield for 30 min at 300 C and 1 min at 400 C. Reversible production of myrcene in 14% yield and formation of unidentified C20 dimer fractions were noted for 1 min at 370 C from β-pinene. The conversion of α-pinene to limonene took place under anhydrous conditions, albeit at slightly lower yield of 65% compared to processes conducted in the presence of water, where increased limonene yield of 70% was observed for 1 min at 400 C. The conversion of β-pinene to limonene under anhydrous conditions was limited to 6.1% in contrast to 11.9% in the presence of water for 7 min at 370 C. In the presence of oxygen, p-cymene was formed in 23% and 24% yield at the expense of limonene from α- and β-pinenes, respectively, for 30 min at 400 C.
- Kawahara, Tomomi,Henmi, Yui,Onda, Natsu,Sato, Toshiyuki,Kawai-Nakamura, Akiko,Sue, Kiwamu,Iwamura, Hiizu,Hiaki, Toshihiko
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supporting information
p. 1485 - 1491
(2014/01/06)
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- Thermal behavior of pinan-2-ol and linalool
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Linalool is an important intermediate for syntheses of isoprenoid fragrance compounds and vitamins A and E. One process option for its production is the thermal gas-phase isomerization of cis- and trans-pinan-2-ol. Investigations of this reaction were performed in a flow-type apparatus in a temperature range from 350-600 °C and a residence time range of 0.6-0.8 s. Rearrangement of the bicyclic alcohol led to linalool, plinols arising from consecutive reactions of linalool and other side products. Effects of residence time, temperature, surface-to-volume-ratio, carrier gas, and the presence of additives on yield and selectivity were studied. Furthermore, the effects of such parameters on ene-cyclization of linalool affording plinols were investigated. Results indicate that manipulation of the reaction in order to affect selectivity is difficult due to the large free path length to other molecules in the gas phase. However, conditions have been identified allowing one to increase the selectivity and the yield of linalool throughout pyrolysis of pinan-2-ol.
- Leiner, Janne,Stolle, Achim,Ondruschka, Bernd,Netscher, Thomas,Bonrath, Werner
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p. 8358 - 8375
(2013/08/23)
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- Mechanistic insights into the rhenium-catalyzed alcohol-to-olefin dehydration reaction
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Rhenium-based complexes are powerful catalysts for the dehydration of various alcohols to the corresponding olefins. Here, we report on both experimental and theoretical (DFT) studies into the mechanism of the rhenium-catalyzed dehydration of alcohols to olefins in general, and the methyltrioxorhenium-catalyzed dehydration of 1-phenylethanol to styrene in particular. The experimental and theoretical studies are in good agreement, both showing the involvement of several proton transfers, and of a carbenium ion intermediate in the catalytic cycle. Ionic or concerted? Rhenium-based complexes are powerful catalysts for the dehydration of various alcohols to the corresponding olefins. Experimental and DFT studies into the mechanism of the rhenium-catalyzed dehydration of alcohols to olefins are reported. The experimental and theoretical studies are in good agreement, both showing the involvement of a carbenium ion intermediate in the catalytic cycle (see figure). Copyright
- Korstanje, Ties J.,Jastrzebski, Johann T. B. H.,Kleingebbink, Robertus J. M.
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p. 13224 - 13234
(2013/10/01)
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- Kinetic and mechanistic study on the thermal isomerization of ocimene in the liquid phase
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The rate of thermal isomerization of ocimene in the liquid phase has been investigated in the range 90-150°C. The rate constant for the disappearance of ocimene may be expressed by k=1.3×1010e -11994.2/T(min-1), from which we can infer that the activation energy is 99.7kJmol-1 and the pre-exponential factor is 1.3×1010min-1. The half-life for the disappearance of ocimene may be expressed by t1/2=5.2×10-11e 11994.2/T(min). The conclusion has been supported by the study results that the ocimene is safe when temperature is below 100°C. A discussion of the mechanism concerning the conversion is included. Copyright
- He, Jindong,Xie, Meng,Tang, Xiangyang,Qi, Xin
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body text
p. 373 - 378
(2012/07/30)
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- Unique catalysis of gold nanoparticles in the chemoselective hydrogenolysis with H2: Cooperative effect between small gold nanoparticles and a basic support
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Gold nanoparticles on hydrotalcite act as a heterogeneous catalyst for the chemoselective hydrogenolysis of various allylic carbonates to the corresponding terminal alkenes using H2 as a clean reductant. The combination of gold nanoparticles and basic supports elicited significantly unique and selective catalysis in the hydrogenolysis.
- Noujima, Akifumi,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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p. 6723 - 6725
(2012/07/28)
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- Supported H4SiW12O40 catalysts for α-pinene isomerization
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The heterogeneous isomerization of α-pinene was studied at 100, 130 and 160°C using 10% supported H4SiW12O40 (SiW) on SiO2, TiO2 and HZSM-5. The effect of the reaction temperature and the concentratio
- Szuecs-Balazs, Jozsef-Zsolt,Coros, Maria,Woiczechowski-Pop, Adrian,Blanita, Gabriela,Vlassa, Mircea
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p. 1208 - 1217
(2012/11/13)
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- A 1,6-ring closure mechanism for (+)-δ-cadinene synthase?
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Recombinant (+)-δ-cadinene synthase (DCS) from Gossypium arboreum catalyzes the metal-dependent cyclization of (E,E)-farnesyl diphosphate (FDP) to the cadinane sesquiterpene δ-cadinene, the parent hydrocarbon of cotton phytoalexins such as gossypol. In contrast to some other sesquiterpene cyclases, DCS carries out this transformation with >98% fidelity but, as a consequence, leaves no mechanistic traces of its mode of action. The formation of (+)-δ-cadinene has been shown to occur via the enzyme-bound intermediate (3R)-nerolidyl diphosphate (NDP), which in turn has been postulated to be converted to cis-germacradienyl cation after a 1,10-cyclization. A subsequent 1,3-hydride shift would then relocate the carbocation within the transient macrocycle to expedite a second cyclization that yields the cadinenyl cation with the correct cis stereochemistry found in (+)-δ-cadinene. An elegant 1,10-mechanistic pathway that avoids the formation of (3R)-NDP has also been suggested. In this alternative scenario, the final cadinenyl cation is proposed to be formed through the intermediacy of trans, trans-germacradienyl cation and germacrene D. In addition, an alternative 1,6-ring closure mechanism via the bisabolyl cation has previously been envisioned. We report here a detailed investigation of the catalytic mechanism of DCS using a variety of mechanistic probes including, among others, deuterated and fluorinated FDPs. Farnesyl diphosphate analogues with fluorine at C2 and C10 acted as inhibitors of DCS, but intriguingly, after prolonged overnight incubations, they yielded 2F-germacrene(s) and a 10F-humulene, respectively. The observed 1,10-, and to a lesser extent, 1,11-cyclization activity of DCS with these fluorinated substrates is consistent with the postulated macrocyclization mechanism(s) en route to (+)-δ-cadinene. On the other hand, mechanistic results from incubations of DCS with 6F-FPP, (2Z,6E)-FDP, neryl diphosphate, 6,7-dihydro-FDP, and NDP seem to be in better agreement with the potential involvement of the alternative biosynthetic 1,6-ring closure pathway. In particular, the strong inhibition of DCS by 6F-FDP, coupled to the exclusive bisabolyl- and terpinyl-derived product profiles observed for the DCS-catalyzed turnover of (2Z,6E)-farnesyl and neryl diphosphates, suggested the intermediacy of α-bisabolyl cation. DCS incubations with enantiomerically pure [1- 2H1](1R)-FDP revealed that the putative bisabolyl-derived 1,6-pathway proceeds through (3R)-nerolidyl diphosphate (NDP), is consistent with previous deuterium-labeling studies, and accounts for the cis stereochemistry characteristic of cadinenyl-derived sesquiterpenes. While the results reported here do not unambiguously rule in favor of 1,6- or 1,10-cyclization, they demonstrate the mechanistic versatility inherent to DCS and highlight the possible existence of multiple mechanistic pathways.
- Faraldos, Juan A.,Miller, David J.,Gonzalez, Veronica,Yoosuf-Aly, Zulfa,Cascon, Oscar,Li, Amang,Allemann, Rudolf K.
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supporting information; experimental part
p. 5900 - 5908
(2012/05/07)
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- Amberlyst-15: A reusable heterogeneous catalyst for the dehydration of tertiary alcohols
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Tertiary alcohols react under mild conditions in the presence of Amberlyst-15 (dry) (solid-supported sulfonic acid) to give predominantly the most stable alkene in very good yield. The dehydration of tertiary alcohol functionality occurs without observation of rearrangement and polymerization products, and with outstanding substrate tolerance, which include the NHCBz, NHBoc, OSEM, OTBDMS, OBOM and ethylene ketal functional groups. Amberlyst-15 (dry) can be easily recovered from the reaction medium and reused for five cycles, maintaining the catalytic efficiency. In addition, the dehydration can occur under continuous operation.
- Frija, Luís M.T.,Afonso, Carlos A.M.
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scheme or table
p. 7414 - 7421
(2012/09/22)
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- Organic reactivity of alcohols in superheated aqueous salt solutions: An overview
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The low dielectric constant and high self-dissociation constant of water in a temperature range between 150 and 250 °C make it a very appealing solvent for synthesis. Surprisingly, while organic chemistry in water at low temperature or around its critical point has been investigated in detail, very little seems to be known about the behaviour of organic molecules under hydrothermal conditions. The present work thus aims at shading some light on this field. As a start, we decided to investigate the reactions in which alcohols can undergo in water in the above-mentioned temperature range. Knowing that very strong salt effects on organic reactions have already been observed in super critical water, the impact of salt on the outcome of our tests was also investigated in detail.
- Avola, Sabine,Goettmann, Frederic,Antonietti, Markus,Kunz, Werner
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scheme or table
p. 1568 - 1573
(2012/10/07)
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- Liquid phase acetoxylation of α-pinene over Amberlyst-70 ion-exchange resin
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Heterogeneously-catalyzed and solvent-catalyzed liquid phase acetoxylation of α-pinene with acetic acid acting as both a solvent and a reagent was studied. Both solvent-catalyzed and catalytic experiments were carried out and various reaction conditions were studied. The influence of temperature, pressure, solvent and gas milieu were taken into account. Bornyl, fenchyl, verbenyl as well as α-terpinyl acetates, limonene, camphene and γ-terpinene were found among reaction products. The addition of the catalyst allowed for maximization of the yield of bornyl acetate. The predominant products obtained were α-terpinyl, verbenyl and bornyl acetates. The reaction pathways were identified and evaluated. The aim of this work was to study the feasibility of batch acetoxylation of α-pinene. The analysis of the complex product distribution is not trivial and, consequently, resolving the reaction network was important. The optimized reaction conditions were searched for aiming at an efficient conversion of α-pinene to a mixture of valuable products.
- Golets,Ajaikumar,Blomberg,Grundberg,W?rn?,Salmi,Mikkola
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scheme or table
p. 43 - 50
(2012/10/18)
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- Cyclization of citronellal in a supercritical solvent in a flow reactor in the presence of Al2O3
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The reactivity of citronellal under supercritical solvent conditions in a flow reactor in the presence of Al2O3 is examined. It is shown that at 160°C, the main transformation product of citronellal is isopulegol, and when the temperature is increased to 190°C, they are monoterpenes with a para-menthane framework and myrcene. Pleiades Publishing, Ltd., 2012.
- Anikeev,Il'Ina,Volcho,Salakhutdinov
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p. 1917 - 1919
(2013/01/15)
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