Xi:Irritant;470-82-6Relevant articles and documents
A simple, convenient and expeditious approach to cineol
Bugar?i?, Zorica M.,Dunki?, Jelena D.,Mojsilovi?, Biljana M.
, p. 468 - 470 (2004)
A convenient two-step protocol preparation of cineol (1-isopropyl-4-methyl- 7-oxabicyclo-[2,2,1]heptane) from α-terpineol (p-menth-1-en-8-ol) is reported. The phenylselenoetherification of α-terpineol with PhSeX (X = Cl, Br, I) as a key step is described. α-Terpineol reacts with PhSeX to form the corresponding phenylselenoether in short reaction time and in quantitative yield. A subsequent reduction with Bu3SnH to cineol proceeds in high yield (98%)
Thioderivatives of Resorcin[4]arene and Pyrogallol[4]arene: Are Thiols Tolerated in the Self-Assembly Process?
Nemat, Suren J.,Tiefenbacher, Konrad
supporting information, p. 6861 - 6865 (2021/09/14)
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.
Preparation of α-terpineol and perillyl alcohol using zeolites beta
?erveny, Libor,Vysko?ilová, Eli?ka,Zítová, Kate?ina
, p. 4297 - 4310 (2021/07/26)
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.
Requirements for Terpene Cyclizations inside the Supramolecular Resorcinarene Capsule: Bound Water and Its Protonation Determine the Catalytic Activity
Merget, Severin,Catti, Lorenzo,Piccini, Giovannimaria,Tiefenbacher, Konrad
supporting information, p. 4400 - 4410 (2020/03/04)
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.
Method for synthetizing 1,8-eudesmin from alpha-terpilenol
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Paragraph 0018-0046, (2019/06/08)
The invention relates to a method for synthetizing 1,8-eudesmin from alpha-terpilenol, and belongs to the field of a synthesis method of 1,8-eudesmin. Alpha-terpilenol and a solid acid catalyst are added into a high-pressure reaction kettle; then, carbon dioxide and an additive are added; the reaction temperature is controlled to be 20 to 200 DEG C; the reaction pressure is 8 to 25MPa; stirring reaction is performed; after the reaction is finished, reaction products of 1,8-eudesmin are collected from the high-pressure reaction kettle; the additive is selected from at least one of materials from cyclohexane, methylbenzene, normal heptane, benzene and carbon tetrachloride. Supercritical carbon dioxide and specific organic matters are combined as solvents; the polarity of a carbon dioxide-organic solvent-alpha-terpilenol system is reduced; the solid acid catalyst is better dispersed; the mass transfer rate is improved, so that the conversion rate of the alpha-terpilenol and the selectivity of the 1,8-eudesmin are improved.
Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies
Zhang, Qi,Catti, Lorenzo,Pleiss, Jürgen,Tiefenbacher, Konrad
supporting information, p. 11482 - 11492 (2017/08/30)
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.
Terpene cyclization catalysed inside a self-assembled cavity
Zhang, Q.,Tiefenbacher, K.
, p. 197 - 202 (2015/04/21)
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.
Solvent extraction process
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, (2008/06/13)
A process for extracting a compound or composition of matter from a raw material containing that compound or composition as a constituent part is described. The process comprises the steps of (1) contacting the raw material with an extraction solvent comprising a heptafluoropropane so as to extract the compound or composition from the raw material into the solvent, and (2) separating the solvent containing the extracted compound or composition from raw material. The process is particularly adapted for extracting flavours, fragrances and neutraceuticals from materials of plant origin.
Thermal degradation of terpenes: Camphene, Δ3-carene, limonene, and α-terpinene
Mcgraw, Gerald W.,Hemingway, Richard W.,Ingram Jr., Leonard L.,Canady, Catherine S.,Mcgraw, William B.
, p. 4029 - 4033 (2007/10/03)
Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC-MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified. Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC-MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified.
