97-54-1Relevant academic research and scientific papers
Highly diastereoselective synthesis of new heterolignan-like 6,7-methylendioxy-tetrahydroquinolines using the clove bud essential oil as raw material
Merchan Arenas, Diego R.,Rojas Ruíz, Fernando A.,Kouznetsov, Vladimir V.
, p. 1388 - 1391 (2011)
The diastereoselective synthesis toward novel heterolignan-like 2-aryl-4-(4-hydroxy-3-methoxyphenyl)-6,7-methylendioxy-1,2,3, 4-tetrahydroquinolines using for the first time clove bud essential oil as a renewable material was carried out. The synthetic protocol consisted of the hydrodistillation of dried flower buds, the solid base-catalyzed isomerization of the obtained essential oil enriched with eugenol in order to give isoeugenol and its participation, as a chemical reagent (dienophile) in the BF 3·OEt2-catalyzed three component Povarov reaction, without previous purification. Final products were obtained as racemic mixtures of new trans-2,4-diaryl-r-3-Me-1,2,3,4-tetrahydroquinolines in moderate to good yields.
Is Isoeugenol a Prehapten? Characterization of a Thiol-Reactive Oxidative Byproduct of Isoeugenol and Potential Implications for Skin Sensitization
Ahn, Jongmin,Avonto, Cristina,Chittiboyina, Amar G.,Khan, Ikhlas A.
, p. 948 - 954 (2020)
Isoeugenol is widely used by the cosmetic and fragrance industries, but it also represents a known cause of skin sensitization adverse effects. Although devoid of a structural alert, isoeugenol has been classified as prehapten in virtue of the presence of a pre-Michael acceptor domain. Isoeugenol oxidation could theoretically lead to the generation of reactive toxic quinones, and photoinduced oxidative degradation of isoeugenol was reported to generate strongly thiol reactive byproducts. Nonetheless, the isoeugenol degradation product responsible for increased reactivity was found to be elusive. In the present study, an aged isoeugenol sample was subjected to reactivity-guided experiments to trap elusive thiol reactive species with a fluorescent nucleophile, viz. dansyl cysteamine (DCYA). The results herein presented demonstrate that photo-oxidation of isoeugenol led to the formation of a dimeric 7,4′-oxyneolignan with strong chemical reactivity, capable of nucleophilic substitution with thiols. The results were confirmed by isolation, structural characterization, and further NMR reactivity studies. Isoeugenol is already well-known as moderately reactive in thiol depletion assays, and was herein demonstrated to be capable of converting to more potent electrophilic species upon degradation, thus acting as a prehapten. The application of the reactivity-guided strategy described herein was shown to serve as an effective tool to investigate elusive skin sensitizers.
Controlled lignosulfonate depolymerization: Via solvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor
Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco
supporting information, p. 9894 - 9905 (2021/12/24)
Sodium lignosulfonate (LS) was valorized to low molecular weight (Mw) fractions by combining solvothermal (SF) and catalytic hydrogenolysis/hydrogenation fragmentation (SHF) in a continuous flow system. This was achieved in either alcohol/H2O (EtOH/H2O or MeOH/H2O) or H2O as a solvent and Ni on nitrogen-doped carbon as a catalyst. The tunability according to the temperature of both SF and catalytic SHF of LS has been separately investigated at 150 °C, 200 °C, and 250 °C. In SF, the minimal Mw was 2994 g mol-1 at 250 °C with a dispersity (?) of 5.3 using MeOH/H2O. In catalytic SHF using MeOH/H2O, extremely low Mw was found (433 mg gLS-1) with a ? of 1.2 combined with 34 mg gLS-1. The monomer yield was improved to 42 mg gLS-1 using dual catalytic beds. These results provide direct evidence that lignin is an unstable polymer at elevated temperatures and could be efficiently deconstructed under hydrothermal conditions with and without a catalyst. This journal is
One-pot hydroformylation/O-acylation of propenylbenzenes for the synthesis of polyfunctionalized fragrances
Delolo, Fábio G.,Vieira, Gabriel M.,Villarreal, Jesus A.A.,dos Santos, Eduardo N.,Gusevskaya, Elena V.
, p. 272 - 279 (2020/06/17)
A process involving the hydroformylation/O-acylation of propenylbenzenes with a phenolic group is described for eugenol, isoeugenol, chavicol, propenyl guaethol, 2-allylphenol, and 2-allyl-6-methylphenol. The reactions occur in parallel, under the same reaction conditions in anisole, a solvent with an impressive sustainability rank comparable to those of ethanol and water. The products contain formyl and acetoxy moieties, both established olfactory groups in flavor and fragrance industry, and present potential as new fragrance components with less allergenic properties. To the best of our knowledge, this is the first time that a one-pot process involving hydroformylation combined with further functionalization in a remote site is described.
Discovery, Biocatalytic Exploration and Structural Analysis of a 4-Ethylphenol Oxidase from Gulosibacter chungangensis
Alvigini, Laura,Fraaije, Marco W.,Gran-Scheuch, Alejandro,Guo, Yiming,Mattevi, Andrea,Saifuddin, Mohammad,Trajkovic, Milos
, p. 3225 - 3233 (2021/10/04)
The vanillyl-alcohol oxidase (VAO) family is a rich source of biocatalysts for the oxidative bioconversion of phenolic compounds. Through genome mining and sequence comparisons, we found that several family members lack a generally conserved catalytic aspartate. This finding led us to study a VAO-homolog featuring a glutamate residue in place of the common aspartate. This 4-ethylphenol oxidase from Gulosibacter chungangensis (Gc4EO) shares 42 % sequence identity with VAO from Penicillium simplicissimum, contains the same 8α-N3-histidyl-bound FAD and uses oxygen as electron acceptor. However, Gc4EO features a distinct substrate scope and product specificity as it is primarily effective in the dehydrogenation of para-substituted phenols with little generation of hydroxylated products. The three-dimensional structure shows that the characteristic glutamate side chain creates a closely packed environment that may limit water accessibility and thereby protect from hydroxylation. With its high thermal stability, well defined structural properties and high expression yields, Gc4EO may become a catalyst of choice for the specific dehydrogenation of phenolic compounds bearing small substituents.
Method for synthesizing vanillin from eugenol through ozone oxidation
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Paragraph 0053-0056; 0066-0069; 0078-0081, (2020/12/31)
The invention relates to the technical field of organic chemical synthesis, in particular to a method for synthesizing vanillin from eugenol through ozone oxidation. The method comprises the followingsteps: adding dichlorotris(triphenylphosphine)ruthenium serving as a catalyst into eugenol to perform isomerization reaction to obtain isoeugenol, performing esterification reaction to obtain isoeugenol acetate, performing ozonation, and performing reducing; and carrying out alcoholysis and refining on the acetyl vanillin to obtain a pure product. The method solves the problems of low productionyield, use of a metal oxidant and difficult treatment of wastewater in the eugenol method in the prior art, eugenol isomerization adopts dichlorotris(triphenylphosphine)ruthenium as a catalyst, no wastewater is generated in the process, isoeugenol acetate is oxidized by ozone, the use of a heavy metal oxidant is avoided, and the method conforms to the green development trend. The method has the advantages of environmental protection and high yield.
Alkali/alkaline earth ion-exchanged and palladium dispersed MCM-22 zeolite as a potential catalyst for eugenol isomerization and Heck coupling reactions
Augustin, A.,Haripriya, T. V.,Sahu, P.,Sakthivel, A.,Shanbhag, G. V.,Sreenavya, A.
, (2020/11/13)
Abstract: Alkali and alkaline earth metal ions (Na+, K+, Cs+, Mg2+) exchanged MCM-22 zeolites were prepared and subsequently palladium (2 wt.%; Pd) was dispersed on above exchanged MCM-22 zeolite materials. All the MCM-22 materials were systematically characterized by FTIR, powder X-ray diffraction, N2 sorption analysis and temperature-programmed desorption (TPD) of CO2. The XRD pattern and FTIR data confirmed the existence of the MCM-22 framework structure even after exchanging bulky metal ions and palladium loading. TPD studies using CO2 supports that the cesium and magnesium incorporated MCM-22 possess a strong and large number of basic sites. The alkali and alkaline-earth metal ions exchanged MCM-22 catalysts were explored for industrially important eugenol isomerisation, whereas the palladium containing MCM-22 materials were utilised for Heck coupling reaction of styrene with iodobenzene. The Cs-MCM-22 showed the best activity for the eugenol isomerization with the isoeugenol yield of 76%. The Cs/Pd-MCM-22 was shown as promising heterogeneous catalyst for Heck coupling reaction of styrene with iodobenzene and yield 99% stilbene. For both isomerization and Heck coupling reaction, the catalysts retain their activities even after several runs. Graphic Abstract: Among different alkali and alkaline earth ion-exchanged MCM-22 materials, cesium containing MCM-22 was shown as a promising catalyst for isomerization of lignin-derived biomass model compound viz., eugenol. Subsequently, the palladium dispersed CsMCM-22 was found to be the potential catalyst for Heck coupling under ambient conditions.[Figure not available: see fulltext.].
Biphasic hydrogenation of eugenol with ruthenium and rhodium nanoparticles stabilized in ionic liquids
Baricelli, Pablo,Borusiak, Margarita,Castro, William,Crespo, Isis,Dominguez, Olgioly,Oma?a, Ofelia,Rosales, Merlin
, p. 4982 - 4987 (2020/12/28)
The purpose of this study was to evaluate on the catalytic activity nanostructured systems of ruthenium and rhodium stabilized in ionic liquids derived from imidazole: IL1= butylmethyllimidazole tetrafluoroborate [BMIM][BF4] and IL2= butylmethylimidazole hexafluorophosphate [BMIM][PF6] in the biphasic hydrogenation of eugenol under mild reaction conditions T= 80°C, P= 100psi during 4 hours. The metallic nanoparticles (NPs-M) were synthesized using the ligand hydrogenation displacement reaction for the ruthenium III tris(acetylacetonate), [Ru(acac)3], and bis-μ-cloro-di(1,5-ciclooctadieno) dirhodium(I), [Rh(COD)Cl]2, showing a mean particle size between (2.0±0.2) nm and (4.0±0.2) nm. The nanostructured systems Rh/IL2, Ru/IL2 and Ru/IL1 show similar activities and different from the Rh/IL1 system. On the other hand, the systems stabilized in the IL1 were more selective towards the formation of the 2-methoxy-4-propylphenol than the systems stabilized in the IL2. Nevertheless, in general, the catalysts were good for hydrogenating eugenol, resulting in Rh/IL1 nanoparticles less reactive than Rh/IL2, Ru/IL1 and Ru/IL2.
METHOD OF FORMING MONOMERS AND FURFURAL FROM LIGNOCELLULOSE
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Page/Page column 19; 21; 22, (2020/06/05)
The present disclosure relates to a method of producing monophenolicmonomers and furfural from lignocellulosic biomass beating the biomass in a solvent together with a zeolite based catalyst.
Chemodivergent hydrogenolysis of eucalyptus lignin with Ni@ZIF-8 catalyst
Liu, Xue,Li, Helong,Xiao, Ling-Ping,Sun, Run-Cang,Song, Guoyong
supporting information, p. 1498 - 1504 (2019/03/26)
Reductive catalytic fractionation (RCF) of lignocellulosic biomass, that is depolymerization of the native lignin component into well-defined monomeric phenols in the first step, offers an opportunity to utilize entire biomass components. Herein, we report that Ni@ZIF-8 can serve as a chemodivergent catalyst in RCF of eucalyptus sawdust, thus selectively producing phenolic compounds having either a propyl or propanol end-chain under different reaction conditions. In both cases, high yields of lignin monomers and a high degree of delignification were achieved, next to well-preserved carbohydrate pulp suitable for further processing. A mechanistic study using model compounds indicated that the dehydroxylation at the γ-position of the β-O-4 structure may be involved in the selectivity-controlling step.
