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Preparation of α-terpineol and perillyl alcohol using zeolites beta
The preparation of α-terpineol by direct hydration of limonene catalyzed by zeolites beta was studied. The same catalyst was used to prepare perillyl alcohol by isomerization of β-pinene oxide in the presence of water. The aim was to optimize the reaction conditions to achieve high conversions of starting material and high selectivity to the desired products. In the case of limonene, it was found that the highest selectivity to α-terpineol was 88% with conversion of 36% under the conditions: 50?wt% of catalyst beta 25, 10% aqueous acetic acid (10?mL) (volume ratio limonene:H2O = 1:4.5), temperature 50?°C, after 24?h. In the case of β-pinene oxide, it was found that the highest selectivity to perillyl alcohol, which was 36% at total conversion, was obtained in the reaction under the following conditions: dimethyl?sulfoxide as solvent (volume ratio β-pinene oxide:DMSO = 1:5), catalyst beta 25 without calcination (15?wt%), demineralized water (molar ratio β-pinene oxide:H2O = 1:8), temperature 70?°C, 3?h. The present study shows that the studied reactions are suitable for the selective preparation of chosen compounds.
?erveny, Libor,Vysko?ilová, Eli?ka,Zítová, Kate?ina
p. 4297 - 4310
(2021/07/26)

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
supporting information
p. 6861 - 6865
(2021/09/14)

A Straightforward Synthesis of Trideuterated α-Terpinene for Mechanistic Studies
Regiospecifically trideuterated (2,6,6-2H3)-α-terpinene was prepared in six steps and with a deuterium incorporation of >99 % in 24 % yield from 1,4-cyclohexanedione monoethylene ketal. The synthetic procedure involved twofold cross-coupling reactions of alkylcuprates (lithium dimethylcuprate and chloromagnesium cyano(isopropyl)cuprate, respectively) with enol triflates to introduce the alkyl substituents on the 1,3-cyclohexadiene backbone. By changing the alkylcuprates, the synthetic approach could serve as a prototype for the synthesis of various 1,4-dialkyl-substituted 1,3-cyclohexadiene derivatives, which could be deuterium-labeled as well, for example for mechanistic studies.
Christoffers, Jens,Mitschke, Nico,Wilkes, Heinz
(2020/08/11)

Requirements for Terpene Cyclizations inside the Supramolecular Resorcinarene Capsule: Bound Water and Its Protonation Determine the Catalytic Activity
The elucidation of the requirements for efficient catalysis within supramolecular host systems is an important prerequisite for developing novel supramolecular catalysts. The resorcinarene hexamer has recently been shown to be the first supramolecular catalyst to promote the tail-to-head terpene cyclization in a biomimetic fashion. We herein present the synthesis of a number of resorcinarene-based macrocycles composed of different ratios of resorcinol and pyrogallol units capable of self-assembly and compare the corresponding assemblies regarding their catalytic activity in the cyclization of monoterpenes. The assemblies were investigated in detail with respect to a number of properties including the encapsulation of substrate and ion pairs, the structural incorporation of water, and the response to externally added acid (HCl). The results obtained strongly indicate that water incorporated into the hydrogen-bond network of the self-assembled structure plays an integral role for catalysis, effectively acting as a proton shuttle to activate the encapsulated substrate. These findings are also supported by molecular dynamics simulations, providing further insight into the protonation pathway and the relative energies of the intermediates involved.
Merget, Severin,Catti, Lorenzo,Piccini, Giovannimaria,Tiefenbacher, Konrad
supporting information
p. 4400 - 4410
(2020/03/04)

Sesquiterpene Cyclizations inside the Hexameric Resorcinarene Capsule: Total Synthesis of δ-Selinene and Mechanistic Studies
The synthesis of terpene natural products remains a challenging task due to the enormous structural diversity in this class of compounds. Synthetic catalysts are unable to reproduce the tail-to-head terpene cyclization of cyclase enzymes, which create this diversity from just a few simple linear terpene substrates. Recently, supramolecular structures have emerged as promising enzyme mimetics. In the present study, the hexameric resorcinarene capsule was utilized as an artificial cyclase to catalyze the cyclization of sesquiterpenes. With the cyclization reaction as the key step, the first total synthesis of the sesquiterpene natural product δ-selinene was achieved. This represents the first total synthesis of a sesquiterpene natural product that is based on the cyclization of a linear terpene precursor inside a supramolecular catalyst. To elucidate the reaction mechanism, detailed kinetic studies and kinetic isotope measurements were performed. Surprisingly, the obtained kinetic data indicated that a rate-limiting encapsulation step is operational in the cyclization of sesquiterpenes.
Zhang, Qi,Tiefenbacher, Konrad
supporting information
p. 12688 - 12695
(2019/08/12)

Transition metal triflate catalyzed conversion of alcohols, ethers and esters to olefins
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
p. 15111 - 15118
(2018/05/04)

Elucidating the Importance of Hydrochloric Acid as a Cocatalyst for Resorcinarene-Capsule-Catalyzed Reactions
This survey of resorcinarene-capsule-catalyzed reactions demonstrates that HCl functions as a crucial cocatalyst by increasing the capsule's inherent Br?nsted acidity to enable or accelerate cationic reactions. The presence of HCl appears to be without consequences for other reactions.
K?ster, Jesper M.,Tiefenbacher, Konrad
p. 2941 - 2944
(2018/07/29)

Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies
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
supporting information
p. 11482 - 11492
(2017/08/30)

High density fuels from oxygenated terpenoids
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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(2017/07/06)

Hybrid catalysts based on platinum and palladium nanoparticles for the hydrogenation of terpenes under slurry conditions
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.
p. 1114 - 1122
(2017/02/15)

Mechanisms into dehydroaromatization of bio-derived limonene to: P -cymene over Pd/HZSM-5 in the presence and absence of H2
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
p. 66695 - 66704
(2016/08/02)

Fe(III)-catalyzed α-terpinyl derivatives synthesis from β-pinene via reactions with hydrogen peroxide in alcoholic solutions
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
p. 10529 - 10536
(2015/01/30)

Selective methoxylation of α-pinene to α-terpinyl methyl ether over Al3+ ion-exchanged clays
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
p. 171 - 179
(2015/05/05)

Terpene cyclization catalysed inside a self-assembled cavity
In nature, complex terpene natural products are formed by the so-called tail-to-head terpene (THT) cyclization. The cationic reaction cascade is promoted efficiently in complex enzyme pockets, in which cationic intermediates and transition states are stabilized. In solution, the reaction is hard to control and man-made catalysts able to perform selective THT cyclizations are lacking. We herein report the first example of a successful THT cyclization inside a supramolecular structure. The basic mode of operation in cyclase enzymes was mimicked successfully and a catalytic non-stop THT was achieved with geranyl acetate as the substrate. The results presented have implications for the postulated reaction mechanism in cyclase enzymes. Evidence indicates that the direct isomerization of a geranyl cation to the cisoid isomer, which so far was considered unlikely, is feasible.
Zhang, Q.,Tiefenbacher, K.
p. 197 - 202
(2015/04/21)

Selective carvone hydrogenation to dihydrocarvone over titania supported gold catalyst
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
p. 189 - 194
(2015/03/14)

Study of green epoxy resins derived from renewable cinnamic acid and dipentene: Synthesis, curing and properties
An epoxy based on cinnamic acid (Cin-epoxy) and an anhydride curing agent based on dipentene were prepared. Both products are liquids of low viscosity at room temperature. For the synthesis of the epoxy, cinnamic acid was first converted to a diacid by reacting with maleic anhydride via Friedel-Crafts reaction, followed by allylation of the carboxylic groups and subsequent epoxidation of the allyl double bonds. The curing agent was the Diels-Alder adduct of dipentene and maleic anhydride (DPMA). The chemical structures of Cin-epoxy and DPMA were confirmed by 1H NMR, 13C NMR, FT-IR and ESI-MS. Non-isothermal curing of Cin-epoxy was studied using differential scanning calorimetry (DSC). In addition to DPMA, two commercial anhydrides were also used to cure Cin-epoxy and the curing reactivity and properties of cured resins were compared. Thermal mechanical properties and thermal stability of the cured epoxy resins were studied using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Results showed that Cin-epoxy was slightly more reactive than the bisphenol A type epoxy DER 332 and displayed good dynamic mechanical properties and thermal stability. The Royal Society of Chemistry.
Xin, Junna,Zhang, Pei,Huang, Kun,Zhang, Jinwen
p. 8525 - 8532
(2014/03/21)

Hydrothermal synthesis of single-crystalline mesoporous beta zeolite assisted by N-methyl-2-pyrrolidone
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
p. 39297 - 39300
(2014/11/08)

The selective conversion of D-limonene to p,α-dimethylstyrene
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
p. 61652 - 61655
(2015/02/19)

Fe(NO3)3-catalyzed monoterpene oxidation by hydrogen peroxide: An inexpensive and environmentally benign oxidative process
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
p. 615 - 622
(2014/04/03)

Superacidity in sulfated metal-organic framework-808
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.
supporting information
p. 12844 - 12847
(2015/12/26)

Synthesis of mesoporous Beta and Sn-Beta zeolites and their catalytic performances
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
p. 8196 - 8204
(2014/06/09)

A novel Fe(III) salt-catalyzed monoterpene aerobic oxidation in methyl alcohol
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
p. 129 - 133
(2013/10/01)

Solvent-free dehydration of alcohols using LiCI-acidicalumina
Conjugated enynes, dienes and simple olefins have been cleanly and selectively synthesized, good-to-excellent yields, by dehydration of corresponding alcohols using focused microwave irradiation on the surface of LiCI-acidic alumina.
Bagheri Marandi,Pourjavadi,Hosseinzadeh
p. 1141 - 1145
(2013/02/25)

Cyclization of citronellal in a supercritical solvent in a flow reactor in the presence of Al2O3
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
p. 1917 - 1919
(2013/01/15)

Organic reactivity of alcohols in superheated aqueous salt solutions: An overview
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
scheme or table
p. 1568 - 1573
(2012/10/07)

Transformations of monoterpene hydrocarbons on ferrierite type zeolites
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
scheme or table
p. 98 - 105
(2012/07/14)

An efficient microwave technique for exo- to endo-double bond migration in natural products
A few sesquiterpene lactones and monoterpenes when subjected to microwave irradiation on solid surface undergo facile carbon-carbon double bond migration from from exo- to endo-position.
Kaur, Damandeep,Setia,Chahal,Chhabra
experimental part
p. 611 - 614
(2011/06/21)

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
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.
experimental part
p. 1164 - 1170
(2012/06/30)

Unusual reactions of (+)-Car-2-ene and (+)-Car-3-ene with aldehydes on K10 clay
The reactions of (+)-car-2-ene (1) and (+)-car-3-ene (2) with aldehydes in the presence of montmorillonite clay were studied for the first time (Schemes 3 and 5). The major products of these reactions are optically active, substituted hexahydroisobenzofurans, probably formed as a result of an attack of the protonated aldehyde at the cyclopropane ring. Quite unexpectedly, the products are cis-configured at the ring-fusion site; the fact was established by means of quantum-chemical calculations and NMR data. It appeared that the behavior of the 2 : 3 mixture 1/2 in reactions with aldehydes in the presence of K10 clay differed substantially from the reactivities of the corresponding individual monoterpenes. Copyright 2010 Verlag Helvetica Chimica Acta AG, Zuerich, Switzerland.
Il'Ina, Irina V.,Volcho, Konstantin P.,Korchagina, Dina V.,Salnikov, Georgi E.,Genaev, Alexander M.,Karpova, Elena V.,Salakhutdinov, Nariman F.
experimental part
p. 2135 - 2150
(2011/02/16)

α-Pinene isomerisation over heteropoly acid catalysts in the gas-phase
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.
experimental part
p. 219 - 224
(2011/12/15)

Microporous acidic cesium salt of 12-tungstosilicic acid Cs 3HSiW12O40 as a size-selective solid acid catalyst
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.
supporting information; scheme or table
p. 881 - 883
(2011/01/08)

Sustainable p-cymene and hydrogen from limonene
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
scheme or table
p. 141 - 146
(2011/06/19)

Desilication of ZSM-5 and ZSM-12 zeolites: Impact on textural, acidic and catalytic properties
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
experimental part
p. 24 - 32
(2010/10/19)

Fate of monoterpenes in near-critical water and supercritical alcohols assisted by microwave irradiation
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
experimental part
p. 1560 - 1567
(2010/07/04)

Biotransformation of one monoterpene by sporulated surface cultures of Aspergillus niger and Penicillium sp.
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
experimental part
p. 1058 - 1061
(2010/08/19)

On the isolation of neat allylic fluorides
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.
experimental part
p. 474 - 483
(2009/12/06)

Isomerization of α-pinene over dealuminated ferrierite-type zeolites
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
p. 161 - 170
(2008/09/17)

Selective purification of mono-terpenes for removal of oxygen containing species
The present invention is a method for preparing mono terpenes as porogens for porous silicon oxide dielectric film depositions in electronic devices by separating oxygen-containing impurity compounds from mono terpenes, comprising; providing a neat mono terpene containing oxygen-containing impurity compounds; providing an activated silica gel preparative chromatographic column; contacting the neat mono terpene containing oxygen-containing impurity compounds with the column; retaining the oxygen-containing impurity compounds on the column; and recovering neat mono terpenes depleted of oxygen-containing impurity compounds from the column.
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(2008/06/13)

Thermal transformation of monoterpenes within thionin-supported zeolite Na-Y. Acid-catalyzed or electron transfer-induced?
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
p. 16 - 20
(2007/10/03)

Reaction of α-pinene with haloacetic acids
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)

Reactions of some terpenes and their derivatives with acylating agents in the presence of aluminosilicate catalysts
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
p. 1418 - 1429
(2007/10/03)

Asymmetric synthesis of (R)-limonene and (S)-cembrene-A by an intramolecular cyclization reaction using a chiral leaving group
A six-membered monocyclic terpene, (R)-limonene, and a 14-membered monocyclic diterpene, (S)-cembrene-A, have been synthesized, respectively, by new enantioselective intramolecular cyclization reactions of neryl ether and (all-E)-geranylgeranyl ether using an (R)- 1,1′-binaphthyl-2-benzoxy-2′-oxy auxiliary as a chiral leaving group in the presence of tin(IV) chloride.
Ishihara,Nakamura,Yamamoto
p. 1113 - 1116
(2007/10/03)

Triphenylpyrylium tetrafluoroborate-sensitized photochemistry of the terpenes sabinene, α-phellandrene, and α- and γ-terpinene
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
p. 1563 - 1567
(2007/10/03)

Generation of acid sites on silica-supported rare earth oxide catalysts: Structural characterization and catalysis for α-pinene isomerization
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
p. 2841 - 2849
(2007/10/03)

Acidic Property of FSM-16. 2. Generation of Lewis Acid Sites and Catalysis
Catalysis over Lewis acid sites on siliceous mesoporous FSM-16 was confirmed. Acidic property of FSM-16 was studied by pyridine TPD measurements, and catalyses of α-pinene isomerization and methylamine synthesis. FSM-16 possess both Br?nsted and Lewis acid sites, and another Lewis acid site formed on FSM-16 when a catalyst was pretreated above 873 K. α-Pinene isomerization was catalyzed over Br?nsted acid sites, the activity of which is the highest when FSM-16 is pretreated at 673 K. Lewis acid sites on FSM-16 catalyze methylamine synthesis, and the initial rates are enhanced with increasing pretreatment temperature up to 1273 K. The structure of FSM-16 was completely retained throughout a pretreatment at 1273 K and a reaction procedure for methylamine synthesis at 673 K.
Yamamoto, Takashi,Tanaka, Tsunehiro,Inagaki, Shinji,Funabiki, Takuzo,Yoshida, Satohiro
p. 6450 - 6456
(2007/10/03)

Acidic property of FSM-16
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
p. 5830 - 5839
(2007/10/03)

The reaction of cyclic allylic alcohols with aliphatic alcohols in the presence of cerium(III) chloride
Cyclic secondary and tertiary allylic alcohols react with primary aliphatic alcohols in the presence of cerium(III) chloride heptahydrate to give alkyl allylic ethers. When secondary or tertiary aliphatic alcohols are used 1,3-dienes are obtained from allylic alcohols heaving the 3-methyl-2-en-1-ol moiety (3-8, 13-15).
Uzarewicz,Dresler
p. 181 - 195
(2007/10/03)

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
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.
p. 41 - 44
(2007/10/03)

Catalytic Transformation of camphene over Aluminophosphate-based Molecular Sieves
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.
p. 4471 - 4476
(2007/10/03)

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
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
p. 91 - 102
(2007/10/02)