- Thioderivatives of Resorcin[4]arene and Pyrogallol[4]arene: Are Thiols Tolerated in the Self-Assembly Process?
-
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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- 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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- 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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p. 11482 - 11492
(2017/08/30)
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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.
- -
-
Page/Page column 7
(2017/07/06)
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- Mechanisms into dehydroaromatization of bio-derived limonene to: P -cymene over Pd/HZSM-5 in the presence and absence of H2
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The mechanisms of dehydroaromatization of limonene to p-cymene are intrinsically investigated over Pd/HZSM-5 under different N2/H2 atmospheres using the mathematical tool of Matlab. It is found that the dehydroaromatization reaction network starts with the isomerization step, and is followed by the sequential dehydrogenation in the presence of N2 or H2 at the selected system. The addition of hydrogen in the atmosphere would not change this reaction pathway, but leads to lower selectivity of p-cymene due to the accelerated hydrogenation rates on the double bonds. Besides, the additional hydrogen speeds up the overall reaction by facilitating the isomerization step on limonene while impeding its reverse reaction, as isomerization of limonene is proved to be the determining step of the whole dehydroaromatization reaction. Furthermore, the presence of hydrogen dramatically decreases the apparent and true activity energy of the target dehydroaromatization reaction and reduces the impact of temperatures to such processes compared to that with a N2 gas carrier.
- Cui, Huimei,Zhang, Jingjing,Luo, Zhicheng,Zhao, Chen
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p. 66695 - 66704
(2016/08/02)
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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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- Fe(III)-catalyzed α-terpinyl derivatives synthesis from β-pinene via reactions with hydrogen peroxide in alcoholic solutions
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In this study, a novel and environmentally benign Fe(iii)-catalyzed terpinyl derivatives synthesis using hydrogen peroxide in alcohol solutions (i.e. methyl, ethyl, propyl, isopropyl and butyl alcohols) was investigated. The use of Bronsted acid catalysts was avoided and β-pinene was used as the starting reactant. High conversions (ca. 90%) and combined selectivities for the α-terpineol and terpinyl alkyl ethers (ca. 70-73%) were obtained when Fe(NO3)3 was used as the catalyst. The role of each component catalyst system was studied with special focus on the solvent. The use of a biodegradable and renewable origin solvent (ethyl alcohol), which was added to an inexpensive and mildly toxic catalyst and a green oxidant are the main positive features of this process.
- Da Silva,Carari,Manoel Da Silva, Adalberto
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p. 10529 - 10536
(2015/01/30)
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- Selective carvone hydrogenation to dihydrocarvone over titania supported gold catalyst
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Selective hydrogenation of natural carvone to industrially valuable dihydrocarvone was carried out at 100°C under hydrogen pressure over a 1.9wt.% Au/TiO2 catalyst. The gold catalyst has demonstrated high activity as well as stereo- and chemoselectivity in conjugated C=C double bond hydrogenation with predominant formation of trans-dihydrocarvone. The catalytic activity and trans-to cis-isomers ratio were shown to strongly depend on the solvent. In a range of C1 - C3 alcohol solvents both catalytic activity and trans-to cis-dihydrocarvone ratio increased following the order: 2-propanol a nearly complete carvone conversion (90%) after 13h in the case of methanol, with the trans-to cis-dihydrocarvone ratio being about 1.8. Based on the transition state theory a quantitative description of trans-to cis-dihydrocarvone ratio variations in different solvents was made.
- Demidova,Suslov,Simakova,Simakova,Volcho,Salakhutdinov,Murzin
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p. 189 - 194
(2015/03/14)
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- The selective conversion of D-limonene to p,α-dimethylstyrene
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Reaction conditions to facilitate the conversion of D-limonene selectively to p,α-dimethylstyrene (DMS) are described, in order to subsequently produce polymeric materials from biomass sourced from food waste. Limonene was dehydrogenated with several palladium catalysts and different solvents and bases, with copper chloride as oxidant at temperatures of 70-120 °C. Reaction conditions were identified using Pd(OAc)2 for the selective formation of only DMS from limonene in 2-5 hours, enabling the facile separation of DMS from unreacted starting material by vacuum distillation.
- Sanchez-Vazquez,Sheppard,Evans,Hailes
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p. 61652 - 61655
(2015/02/19)
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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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supporting information
p. 12844 - 12847
(2015/12/26)
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- Transcriptome profiling, and cloning and characterization of the main monoterpene synthases of Coriandrum sativum L.
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Terpenoids are a large and diverse class of specialized metabolites that are essential for the growth and development of plants, and have tremendous industrial applications. The mericarps of Coriandrum sativum L. (coriander) produce an essential oil (EO) rich in monoterpenes, volatile C10 terpenoids. To investigate EO metabolism, the transcriptome of coriander mericarps, at three developmental stages (early, mid, late) was sequenced via Illumina technology and a transcript library was produced. To validate the usability of the transcriptome sequences, two terpene synthase candidate genes, CsγTRPS and CsLINS, encoding 558 and 562 amino acid proteins were expressed in bacteria, and the recombinant proteins purified by Ni-NTA affinity chromatography. The 65.16 (CsγTRPS) and 65.91 (CsLINS) kDa recombinant proteins catalyzed the conversion of geranyl diphosphate, the precursor to monoterpenes, to γ-terpinene and (S)-linalool, respectively, with apparent Vmax and Km values of 2.24 ± 0.16 (CsγTRPS); 19.63 ± 1.05 (CsLINS) pkat/mg and 66.25 ± 13 (CsγTRPS); 2.5 ± 0.6 (CsLINS) μM, respectively. Together, CsγTRPS and CsLINS account for the majority of EO constituents in coriander mericarps. Investigation of the coriander transcriptome, and knowledge gained from these experiments will facilitate future studies concerning essential and fatty acid oil production in coriander. They also enable efforts to improve the coriander oils through metabolic engineering or plant breeding.
- Galata, Mariana,Sarker, Lukman S.,Mahmoud, Soheil S.
-
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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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p. 8196 - 8204
(2014/06/09)
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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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p. 39297 - 39300
(2014/11/08)
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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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p. 615 - 622
(2014/04/03)
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- A novel Fe(III) salt-catalyzed monoterpene aerobic oxidation in methyl alcohol
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The Fe(III)-catalyzed aerobic oxidation of monoterpenes in CH3OH has been developed, in which simple Fe(III) salts are used as catalysts in the absence of stabilizing ligands. Remarkably, Fe(NO3)3 catalyst efficiently promotes the oxidation of monoterpenes under air or dioxygen. The highest TON and TOF reached 476 and 162 h- 1, respectively. In general, reactions with 1.0-9.0 mol% of catalyst reached high conversions (ca. 90-99%) and high oxidation products selectivity (ca. 80%). Notably, α-pinene and β-pinene were selectively oxidized into only allylic product, myrtenol methyl ether. The significant breakthroughs of this simple oxidative process are the use of inexpensive Fe(III) salts as catalysts and environmentally-friendly oxidants (air or dioxygen).
- Ferreira De Paula, Fabiano Gomes,Berllini, Lilian,Da Silva, Márcio José
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p. 129 - 133
(2013/10/01)
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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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- 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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scheme or table
p. 98 - 105
(2012/07/14)
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- Microwave-assisted α-pinene acidic catalytic isomerisation
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A comparative study of microwave assisted α-pinene acidic catalytic isomerisation reactions with near-critical water procedure under microwave irradiation is presented. This study can be performed because in both cases the mechanism is similar, namely an acidiccatalyzed rearrangement. The non-critical method technique is milder using a lower temperature and pressure and a shorter reaction time than near-critical water conditions. The general aspect of the selectivity of the reaction products is changed, being higher for α-terpinolene and γ-terpinolene and lower for limonene and camphene compared to the non-critical conditions.
- Szuecs-Balazs, Jozsef Zsolt,Coros, Maria,Molnar, Diana,Vlassa, Mircea
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p. 209 - 213
(2013/03/13)
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- Microporous acidic cesium salt of 12-tungstosilicic acid Cs 3HSiW12O40 as a size-selective solid acid catalyst
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An acidic Cs salt of H4SiW12O4O 40 (Cs3HSiW12O40), which was prepared by titrating an aqueous solution of H4SiW12O 40 with an aqueous solution of Cs2CO3, possessed only micropores and exhibited size-selective catalysis for acid-catalyzed reactions in liquid phase.
- Kamiya, Yuichi,Sano, Shogo,Miura, Yu-Ki,Uchida, Yohei,Ogawa, Yuki,Iwase, Yukari,Okuhara, Toshio,Degnan Jr.
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supporting information; scheme or table
p. 881 - 883
(2011/01/08)
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- Sustainable p-cymene and hydrogen from limonene
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A fine chemical intermediate in a wide range of chemical processes, p-cymene, has been obtained from Limonene, solids based on a natural clay (sepiolite) modified with sodium, nickel, iron or manganese oxides and programmable focalised microwaves. The process has the added bonus of one mol of hydrogen being produced per mol of limonene converted to p-cymene.
- Martin-Luengo,Yates,Rojo, E. Saez,Huerta Arribas,Aguilar,Ruiz Hitzky
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scheme or table
p. 141 - 146
(2011/06/19)
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- Reaction of sabinene with aldehydes in the presence of montmorillonite K10 clay
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Transformations of sabinene catalyzed by montmorillonite K10 clay were studied. The main reaction paths were found to be oligomerization and isomerization. The reaction of sabinene with crotonaldehyde gave rise to several polyfunctional heterocyclic compo
- Il'Ina,Korchagina,Volcho,Salakhutdinov,Tolstikov
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experimental part
p. 1002 - 1005
(2010/10/21)
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- Fate of monoterpenes in near-critical water and supercritical alcohols assisted by microwave irradiation
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The rearrangement of α- and β-pinene was studied under microwave irradiation in near-critical water and supercritical lower aliphatic alcohols, with the aim of identifying the pathway of α- and β-pinene isomerization. Generally, two pathways occur, pyroly
- Szuppa, Tony,Stolle, Achim,Ondruschka, Bernd
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experimental part
p. 1560 - 1567
(2010/07/04)
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- Biotransformation of one monoterpene by sporulated surface cultures of Aspergillus niger and Penicillium sp.
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In this study, biotransformation of menthol by sporulated surface culture of Aspergillus niger and Penicillium sp. was studied. The main bioconversion product obtained from menthol of A. niger was cis-p-menthan-7-ol and the main products obtained by surfa
- Esmaeili, Akbar,Sharafian, Shirin,Safaiyan, Shila,Rezazadeh, Shamsali,Rustaivan, Abdolhossein
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experimental part
p. 1058 - 1061
(2010/08/19)
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- On the isolation of neat allylic fluorides
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Neat cinnamyl fluoride, geranyl fluoride, 5-carbomethoxy-3-fluorocyclohexene and parent 3-fluorocyclohexene undergo spontaneous decomposition on contact with borosilicate glass or catalytic quantities of moderately strong acids that consists in polycondensation with elimination of HF initiated by electrophilic abstraction of F-. Acid sensitivity of these allylic fluorides correlates with stability of respective allylic cations, exceeds that of parent benzyl fluoride, yet can be mitigated by the use of Teflon and PFA containers that permit their isolation and handling in the neat state.
- Lee, Eunsung,Yandulov, Dmitry V.
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experimental part
p. 474 - 483
(2009/12/06)
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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.
-
supporting information; experimental part
p. 8908 - 8909
(2009/02/03)
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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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p. 161 - 170
(2008/09/17)
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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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p. 2893 - 2902
(2008/02/08)
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- Thermal transformation of monoterpenes within thionin-supported zeolite Na-Y. Acid-catalyzed or electron transfer-induced?
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Several monoterpenes (monocyclic, bicyclic or acyclic) isomerize and finally transform to p-cymene in the dark upon loading within thionin-supported zeolite Na-Y. The same reactions occur in Na-Y dried under the same conditions as thionin/Na-Y. It is postulated that the thermal treatment of Na-Y generates 'electron holes' (probably acidic sites). The transformation of monoterpenes occurs more likely via an electron transfer-induced reaction subordinated to the occurrence of the acidic sites. The radical cation of the more thermodynamically stable monoterpene, α-terpinene, eventually dehydrogenates to p-cymene. For comparison, the same reactions were performed within methyl viologen-supported Na-Y. Copyright
- Stratakis, Manolis,Stavroulakis, Manolis,Sofikiti, Nikoletta
-
-
- A cDNA clone for β-caryophyllene synthase from Artemisia annua
-
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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p. 523 - 529
(2007/10/03)
-
- Reaction of α-pinene with haloacetic acids
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The reactions of α-pinene with chloro-, bromo-, and trichloroacetic acids, accompanied by isomerization of α-pinene, were studied.
- Radbil',Zolin,Shkapova,Radbil'
-
p. 310 - 314
(2007/10/03)
-
- Polyethylene glycol as a non-ionic liquid solvent for polyoxometalate catalyzed aerobic oxidation
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The H5PV2Mo10O40 polyoxometalate in a polyethylene glycol solvent was effective for a series of aerobic oxidation reactions including oxydehydrogenation of alcohols and cyclic dienes, oxidation of sulfides and the Wacker reaction; the solvent-catalyst phase can be recovered and recycled.
- Haimov, Adina,Neumann, Ronny
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p. 876 - 877
(2007/10/03)
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- Reactions of some terpenes and their derivatives with acylating agents in the presence of aluminosilicate catalysts
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Reactions of camphene, α-fenchene, limonene, caryophyllene, α- and β-pinenes, verbenol, walterol, and verbenone with acylating agents in the presence of clay K-10 and wide-porous β-zeolite were studied. Presumable schemes and rules of the occurring proces
- Volcho,Tatarova,Suslov,Korchagina,Salakhutdinov,Barkhash
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p. 1418 - 1429
(2007/10/03)
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- Electron transfer-induced dehydrogenation reactions within methyl viologen-supported zeolite Na-Y under non-irradiative conditions
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Methyl viologen-supported zeolite Na-Y is a unique and very efficient medium for carrying out electron transfer-induced reactions in the absence of an irradiation source (spontaneously). Several monoterpenes loaded within the supported zeolite are dehydrogenated to p-cymene. The reaction occurs even in the open air with formation of minor amounts of ascaridole depending on the substrate. It is proposed that the radical cations of the monoterpenes are formed by single electron transfer to Na-Y, with methyl viologen acting as a promoter.
- Stratakis, Manolis,Stavroulakis, Manolis
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p. 6409 - 6411
(2007/10/03)
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- Triphenylpyrylium tetrafluoroborate-sensitized photochemistry of the terpenes sabinene, α-phellandrene, and α- and γ-terpinene
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The triphenypyrylium tetrafluoroborate (TPT)-sensitized reactions of several terpene donor molecules, including sabinene (1), α-phellandrene (4), α-terpinene (5) and γ-terpinene (6) give rise to significantly different products than reactions induced by other electron-transfer sensitizers, such as 1,4-dicyanobenzene (DCB). The divergent reactions require decidedly different key intermediates; the products obtained with TPT can be explained by dissociative recombination of the intermediate radical-radical cation pair in the triplet state, generating donor-derived biradicals.
- Climent, Maria-Jose,Miranda, Miguel Angel,Roth, Heinz Dieter
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p. 1563 - 1567
(2007/10/03)
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- Generation of acid sites on silica-supported rare earth oxide catalysts: Structural characterization and catalysis for α-pinene isomerization
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Silica-supported rare earth oxide catalysts (Ln/SiO2; Ln = La, Ce, Pr, Sm, Eu, Tb, Yb and Y), loading amounts of which were 3.4 mmol g (support)- 1, were characterized by α-pinene isomerization, temperature-programmed desorption (TPD), Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), thermogravimetric-differential thermal analysis (TG-DTA) and Raman spectroscopy. In the lanthanoid series, the catalytic activity increased with atomic number from 57La to 70Yb, except for Ce. All the Ln/SiO2 catalysts, except for Ce, were amorphous. On the surface of the catalyst, Ln-O-Si and Ln-O-Ln linkages formed, the ratio of which varied with the loaded element. The ratio of Ln-O-Si linkage increases with stronger affinity among LnO(n) units and SiO4 tetrahedra, and the affinity depends on the size of Ln3+. With increasing ratio of Ln-O-Si to Ln-O-Ln linkage, the catalytic activity increases. Silica-supported yttrium oxide catalyst, the trivalent ion radius of which is quite similar to that of ytterbium, exhibited the same activity as that of Yb/SiO2. Raman spectroscopic characterization revealed that excess loading of Yb atoms on SiO2-support block Yb-O-Si linkage to form Yb2O3 fine particles. When Yb/SiO2 was pretreated at 1273 K, fine ytterbium silicate crystallites formed. Ln-O-Si linkage without a long-ranged ordering structure was the active site for α-pinene isomerization.
- Yamamoto, Takashi,Matsuyama, Takahiro,Tanaka, Tsunehiro,Funabiki, Takuzo,Yoshida, Satohiro
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p. 2841 - 2849
(2007/10/03)
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- Liquid-phase isomerization of α-pinene on a natural clinoptilolite
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The liquid-phase isomerization of α-pinene on a suspended powder (50-100 μm) of a natural clinoptilolite is studied. It is found that thermoevacuation at 500°C decreases the catalyst's activity and selectivity. The surface acidity decreases, whereas the surface concentration of Fe2+ ions increases. The reaction mechanism is proposed.
- Allakhverdiev,Sokolova,Gunduz,Kul'kova
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p. 1647 - 1650
(2007/10/03)
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- Acidic property of FSM-16
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Siliceous FSM-16 possesses acid sites to catalyze but-1-ene isomerization to produce but-2-ene (cis/trans = 1.4-1.7) at 323 K and 2,6,6- trimethylbicyclo[3.1.1]hept-2-ene (α-pinene) isomerization at 303 K. Catalytic activity was dependent upon heat treatment and reached a maximum at 673 K. The maximum acid strength was invariably H0 = -3.0 independent of the pretreatment temperatures. The acidity was much reduced by calcination at higher temperatures, but restored by water treatment at 353 K as long as the FSM-16 retained its structure.
- Yamamoto, Takashi,Tanaka, Tsunehiro,Funabiki, Takuzo,Yoshida, Satohiro
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p. 5830 - 5839
(2007/10/03)
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- Convenient one-pot synthesis of 4,8-dimethyl-bicyclo[3.3.1)non-7-en-2-ol via platinum/tin catalyzed hydroformylation/cyclization of limonene
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Limonene (1) was converted in one step into two diastereoisomers of 4,8-dimethyl-bicyclo[3.3.1]non-7-en-2-ol (2), useful as perfumes, employing PtCl2(PPh3)2/PPh3/SnCl2 and PtCl2(diphosphine)/PPh3/SnCl2 systems as bifunctional catalysts whose diphosphines were 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane (dppb). In the presence of the PtCl2(dppb)/PPh3/SnCl2 system, which was found to be the most promising combination, the selectivity for 2 reached the value of 82% at 95% conversion of 1.
- Dias, Adelson de O.,Augusti, Rodinei,Dos Santos, Eduardo N.,Gusevskaya, Elena V.
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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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p. 4471 - 4476
(2007/10/03)
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- Carbon monoxide as a building block in organic synthesis. Part V. Involvement of palladium-hydride species in carbonylation reactions of monoterpenes. X-ray crystal structure of 4
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A palladium precursor and SnCl2 as cocatalyst were used under 4 MPa of carbon monoxide for the catalytic alkoxycarbonylation of several monoterpenes into C11 esters.The active catalyst involves a palladium-hydride species whose formation was investigated.In the case of the model substrate 3-phenylpropene, the source of the hydrido ligand was determined to be the alkene itself.Allylic hydrogen abstraction seems to be a general way to produce the active hydridopalladium species since monoterpenes having labile allylic hydrogens were converted under exceptional mild conditions.An X-ray crystal structure analysis was carried out on . Key words: Palladium; X-ray structure; Terpenes; Carbonylation; Hydroesterification
- Naigre, Ruth,Chenal, Thomas,Cipres, Isabelle,Kalck, Philippe,Daran, Jean-Claude,Vaissermann, Jacqueline
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- Catalytic transformation of camphene over alumina, silica-alumina and zeolite catalysts
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Isomerisation of camphene in the vapour phase over alumina prepared from aluminium foil, aluminium isopropoxide, aluminium sulphate and aluminium nitrate, silica-alumina in different ratios (0.88, 1.86, 3.16) and zeolites such as H-5A, H-ZSM-5, H-Y has been studied.The products formed are tricyclene, bornylene and monocyclic terpenes.The product distribution is influenced by the acidic strength of the catalysts.Maximum amount of tricyclene is formed over lower acidic strength while maximum amounts of monocyclics like dipentene, terpinolene, α-and τ-terpinenes, p-menthene and p-cymene are formed over higher acidic strength.The concentration of bornylene in the product increases with acidity.The effects of temperature, contact time and partial pressure of pyridine on the conversion and product distribution have also been investigated.
- Elangovan, S. P.,Krishnasamy, V.
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p. 1041 - 1045
(2007/10/02)
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- Composition of Mixtures of Hydrocarbons after BIRCH-Reduction of Substituted Benzenes and Acid Catalyzed Addition of Alcohols to Alkylsubstituted Cyclohexenes and Carbohexa-1,4-dienes
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10 different benzene hydrocarbons 1, indane, tetraline, anisol and phenol are reduced by sodium in liquid ammonia in the presence of methanol to the BIRCH products 2.The product mixture compositions are determined through capillary GLC.On storage at +6 deg C some rearomatization of the 1,4-cyclohexadienes 2 occurs.Data of the 1H- and 13C-.n.m.r. spectra and also mass spectra of the BIRCH 1,4-dienes 2 are given.For comparison 4-alkoxycyclohexenes 4 and 1-alkoxy-1-methylcyclohexanes 8 are prepared and spectroscopically characterized.Acid-catalyzed addition of alcohols to the 1,4-cyclohexadienes systems is a slow process and gives the 4-alkoxy-4-alkylcyclohex-1-enes (4) only in moderate yields up to 30percent.Most of the products are dimers 5 and also oligomers 6 of the parent hydrocarbons 2.
- Beger, J.,Thomas, B.,Vogel, T.,Kirmse, K.,Lang, R.
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p. 481 - 488
(2007/10/02)
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- Aromatization of Hydrocarbons y Oxidative Dehydrogenation Catalyzed by the Mixed Addenda Heteropoly Acid H5PMo10V2O40
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The mixed addenda heteropoly acid H5PMo10V2O40 dissolved in 1,2-dichloroethane with tetraglyme, forming the (tetraglyme)3-H5PMo10V2O40 complex, catalyzes the aromatization of cyclic dienes at moderate temperatures in the presence of molecular oxygen.Dehydrogenations of exocyclic dienes such as limonene show that dehydrogenation is preceded by isomerization to their endocyclic isomers.Aromatization takes place by succesive one-electron transfers and proton abstractions from the organic substrate to the heteropoly acid, the latter being reoxidized by dioxygen coupled with the formation of water.
- Neumann, Ronny,Lissel, Manfred
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p. 4607 - 4610
(2007/10/02)
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- Thermodynamics of the Isomerisation of the p-Menthadienes and the Additivity of the Properties of Cyclic Hydrocarbons
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We have studied the equilibria and obtained the thermodynamic parameters for the isomerisation of nine p-menthadienes in the range 225-350 deg C.An approach has been proposed and shown to be effective for the additive calculation of the properties of aliphatic hydrocarbons: this is based on the introduction of additional effective characteristics for an atom which take into account its participation in the ring system of the molecule.
- Kabo, G. Ya.,Roganov, G. N.,Filippenko, Z. A.
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p. 1521 - 1522
(2007/10/02)
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- Gas-Phase Dehydration of p-Menthenols by Reaction Gas-Chromatography. - Correlation of the Elimination Products with Heats of Formation from Force-Field Calculations
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A series of p-menthenols was dehydrated with alumina in the injection port of a gas chromatograph.The p-menthadienes thus generated were analyzed gas chromatographically and mass spectroscopically, and the relative amounts of the elimination products were correlated with heats of formation derived from force-field calculations.
- Bestmann, Hans Juergen,Kobold, Uwe,Vostrowsky, Otto
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p. 234 - 241
(2007/10/02)
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- Etude des phenomenes physico-chimiques intervenant lors du procede d'hydrodistillation
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During the steam distillation of aromatic plants, some terpenic compounds undergo various chemical reactions (hydrolysis, elimination, cyclisation rearrangement) which depend on the acidity of the water in which the plant is soaked.In order to study the physical and chemical phenomena involved in this process and in particular the formation of artefacts, we have performed steam distillation experiments on lavender flowers in a buffered aqueous medium.The essential oils collected are rich in linalol and linalyl acetate, two monoterpenic compounds known for their propensity to undergo heat induced transformations.At pH 4 or 7, the chromatograms of the essential oils are similar whereas in a more acidic medium (pH = 2), the degradation of linalyl acetate gives rise to a number of terpenic products (α and γ terpinenes; 2,6,6-trimethyl 2-vinyl tetrahydropyran; 1,4-cineol, cis and trans ocimenols, myrcenol, terpin 1-en 4-ol, etc.).A study of the reactions involved during the thermal degradation of linalyl acetate in a model experiment (heating to reflux) as well as the determination of the kinetic parameters, show that some terpenes, present in lavender oil originate in part from the transformations of linalyl acetate during steam distillation.Furthermore, the decomposition of this ester is directly and quantitatively related to the concentration of acid in the medium (pseudo first order rate constant is 0.008 min-1 at pH 7 and 0.0147 min-1 at pH 2).It is therefore necessary to control and maintain the pH of the water during steam distillation to avoid the alteration of the essential oils by formation of artefacts and preserve the integrity of the oil originally present in the plant.The study of the various steam distillation fractions gives informaiton on the kinetics of the steam distillation of the various components which apparently do not depend only on the boiling point but also on their polarity (hydrodiffusion phenomenon).
- Morin, Ph.,Gunther, C.,Peyron, L.,Richard, H.
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p. 921 - 930
(2007/10/02)
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- ISOMERIZATION EQUILIBRIUM OF THE p-MENTHADIENES IN THE VAPOR PHASE
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The isomerization equilibrium between nine p-menthadienes has been studied in the vapor phase at 250 deg C and their equilibrium ratios have been determined.A method for the quantitative GLC analysis of mixtures of isomeric p-menthadienes has been developed.
- Filippenko, Z. A.,Baranov, O. M.,Roganov, G. N.,Kabo, G. Ya.
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- Liquid Crystalline Catalysis, 3, Monomolecular Rearrangements of Terpene Derivatives in Liquid Crystalline Solvents
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The ability of limonene and linalool to rearrange in mesomorphic media is apparently determined by the constraints exerted by the solvent structure on the translational diffusions of the reactant solute molecules.Selective conversions seem to be promoted by the different media.Alkylcyclohexyl- and alkylbicyclohexyl-carboxylic acids and their mixtures with toluic acid have been used as solvents.The B structure of their smectic phases has been demonstrated by X-ray diffraction studies.
- Melone, S.,Mosini, V.,Nicoletti, R.,Samori, B.,Torquati, G.
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p. 399 - 410
(2007/10/02)
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- Dehydrogenation of β-Pinene to p-Cymene over Platinum-Alumina Catalyst in the Presence of Nitrogen, Hydrogen and Pyridine
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Dehydrogenation of β-pinene has been carried out over platinum-alumina (0.6percent Pt) catalyst at 300 deg C in the presence of nitrogen, hydrogen and pyridine.Nitrogen acts as a diluent while hydrogen acts both as a diulent and as a promoter.Pyridine on the other hand functions as a diluent and as a poison.As a result, it affects the formation of different products to different extent.The optimum conditions such as platinum concentration, temperature and contact time for dehydrogenation, hydrogenation and disproportionation reactions were established using cyclohexane, p-cymene and cyclohexene, respectively before actually studying the d ehydrogenation of β-pinene.
- Krishnasamy, V.,Mathur, Pravin,Chandrasekharan, K.
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