98-55-5Relevant academic research and scientific papers
Hydration of alpha-Pinene to obtain alpha-terpineol, using an ionic liquid as solvent, which is synthesized from a tertiary amine and an inorganic acid
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Paragraph 0016-0020, (2021/06/11)
An ionic liquid as a solvent in the hydration reaction of α-pinene to α-terpineol. The ionic liquid is obtained from the reaction of an amine and an inorganic acid. The use of the ionic liquid as solvent favors the selectivity towards the formation of α-terpineol and once the reaction product has been brought to room temperature, the organic phase can be physically separated from the inorganic one by decantation. The inorganic phase contains the ionic liquid, water and reaction catalyst and can be directly reused for a new reaction batch.
Preparation of α-Terpineol from Biomass Resource Catalysed by Acid Treated Montmorillonite K10
Sekerová, Lada,?erná, Hana,Vysko?ilová, Eli?ka,Vrbková, Eva,?erveny, Libor
, p. 2673 - 2683 (2021/01/15)
Abstract: A new type of heterogeneous catalyst for hydration of α-pinene was prepared. Montmorillonite K10 was treated by various acids (H2SO4, HCl, HNO3, and ClCH2COOH) and successfully used for the mentioned reaction. The used characterization techniques showed that the acid treatment improved the properties of K10 important for the catalytic activity (SBET and acidity). On the other hand, the morphology and particle size distribution remained the same. Regarding the selectivity (side and consecutive reactions can proceed), the optimal reaction conditions were found (temperature, type of the catalyst, amount of the catalyst, molar ratio α-pinene:?water, type of water, solvent). Using the optimal reaction conditions, 60% conversion of α-pinene was achieved with 45% selectivity to α-terpineol (80?°C, 25 wt% of K10/HCl, or K10/H2SO4, nα-pinene:nwater 1:7.5, 1,4-dioxane as a solvent, 24?h). Higher conversions of α-pinene, as well as higher selectivity to α-terpineol, were achieved using all acid treated K10 in comparison to raw K10. Considering the heterogeneous form of prepared catalysts, its availability, low price and easy method of preparation, these catalysts dispose of a large potential for application as catalysts for hydration reactions. Graphic Abstract: [Figure not available: see fulltext.].
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.
Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization
Kathe, Prasad M.,Berkefeld, Andreas,Fleischer, Ivana
supporting information, p. 1629 - 1632 (2021/02/09)
This report discloses the deallylation of O - and N -allyl functional groups by using a combination of a Ni-H precatalyst and excess Bronsted acid. Key steps are the isomerization of the O - or N -allyl group through Ni-catalyzed double-bond migration followed by Bronsted acid induced O/N-C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.
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.
Coupling Reaction between Aldehydes and Non-Activated Hydrocarbons via the Reductive Radical-Polar Crossover Pathway
Yahata, Kenzo,Sakurai, Shu,Hori, Shuhei,Yoshioka, Shin,Kaneko, Yuki,Hasegawa, Kai,Akai, Shuji
supporting information, p. 1199 - 1203 (2020/02/04)
Herein, we describe the generation of an organochromium-type carbanion species from a non-activated C-H bond and its nucleophilic addition to aldehydes. The catalytic carbanion generation occurred through formal deprotonation of a non-activated C-H bond under mild conditions and did not need the prefunctionalization or anion stabilizing group. Carbon radical intermediates generated by decatungstate photocatalyst-mediated hydrogen abstraction were captured by a chromium salt with the reductive radical-polar crossover reaction to produce organochromium carbanions.
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.
Sulfoxide-Chelated Ruthenium Benzylidene Catalyst: a Synthetic Study on the Utility of Olefin Metathesis
?ukowska, Karolina,P?czek, ?ukasz,Grela, Karol
, p. 2817 - 2823 (2016/09/13)
We provide an experimental summary of selected advances in olefin metathesis methodology that were reported over the past decades. A stable and universal sulfoxide-chelated ruthenium olefin metathesis catalyst [RuCl2(SIMes)(=CH?C6H4?S(O)Ph)], SIMes=1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene, was introduced and its application profile was studied in detail. A range of model substrates of natural origin was developed and successfully metathesized with variants of the reaction, such as ene–yne, cross, or ring-closing metathesis. All reported reactions were performed in non-pretreated solvents and in air to demonstrate the user-friendliness of the system. Besides the great functional group tolerance exhibited by the reported complex, its compatibility with multiple solvents was determined along with its air and moisture stability. Additionally, an interesting effect increasing the reaction efficiency was observed, if reactions were performed at temperatures around the solvent boiling point.
Unravelling transition metal-catalyzed terpenic alcohol esterification: A straightforward process for the synthesis of fragrances
Da Silva,Ayala
, p. 3197 - 3207 (2016/05/24)
Iron nitrate is a simple and commercially available Lewis acid and is demonstrated to be able to catalyze β-citronellol esterification with acetic acid, achieving high conversion and ester selectivity (ca. 80 and 70%, respectively), within shorter reaction times than those reported in the literature. To the best of our knowledge, this is the first report of a terpenic alcohol esterification reaction catalyzed by Fe(NO3)3. This process is an attractive alternative to the slow and expensive enzymatic processes commonly used in terpenic alcohol esterification. Moreover, it avoids the undesirable steps of neutralizing the products, which are always required in mineral acid-catalyzed reactions. We have performed a study of the activity of different metal Lewis acid catalysts, and found that their efficiency is directly linked to the ability of the metal cation to generate H+ ions from acetic acid ionization. The measurement of pH as well as the conversions achieved in the reactions allowed us to obtain the following trend: Fe(NO3)3 > Al(NO3)3 > Cu(NO3)2 > Ni(NO3)2 > Zn(NO3)2 > Mn(NO3)2 > Co(NO3)2 > LiNO3. The first three are recognized as stronger Lewis acids and they generate more acidic solutions. When we carried out reactions with different iron salts, it was possible to conclude that the type of anion affects the solubility of the catalyst, as well as the conversion and selectivity of the process. Fe2(SO4)3 and FeSO4 were insoluble and less active. Conversely, though they were equally soluble, Fe(NO3)3 was more selective for the formation of β-citronellyl acetate than FeCl3. We assessed the effects of the main reaction variables such as reactant stoichiometry, temperature, and catalyst concentration. In addition to citronellol, we investigated the efficiency of the iron(iii) catalyst in the solvent free esterification of several terpenic alcohols (geraniol, nerol, linalool, α-terpineol) as well as other carboxylic acids.
