- Highly diastereoselective synthesis of new heterolignan-like 6,7-methylendioxy-tetrahydroquinolines using the clove bud essential oil as raw material
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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.
- Merchan Arenas, Diego R.,Rojas Ruíz, Fernando A.,Kouznetsov, Vladimir V.
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Read Online
- Is Isoeugenol a Prehapten? Characterization of a Thiol-Reactive Oxidative Byproduct of Isoeugenol and Potential Implications for Skin Sensitization
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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.
- Ahn, Jongmin,Avonto, Cristina,Chittiboyina, Amar G.,Khan, Ikhlas A.
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Read Online
- Discovery, Biocatalytic Exploration and Structural Analysis of a 4-Ethylphenol Oxidase from Gulosibacter chungangensis
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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.
- Alvigini, Laura,Fraaije, Marco W.,Gran-Scheuch, Alejandro,Guo, Yiming,Mattevi, Andrea,Saifuddin, Mohammad,Trajkovic, Milos
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p. 3225 - 3233
(2021/10/04)
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- Controlled lignosulfonate depolymerization: Via solvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor
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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
- Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco
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supporting information
p. 9894 - 9905
(2021/12/24)
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- One-pot hydroformylation/O-acylation of propenylbenzenes for the synthesis of polyfunctionalized fragrances
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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.
- Delolo, Fábio G.,Vieira, Gabriel M.,Villarreal, Jesus A.A.,dos Santos, Eduardo N.,Gusevskaya, Elena V.
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p. 272 - 279
(2020/06/17)
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- Method for synthesizing vanillin from eugenol through ozone oxidation
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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.
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Paragraph 0053-0056; 0066-0069; 0078-0081
(2020/12/31)
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- Alkali/alkaline earth ion-exchanged and palladium dispersed MCM-22 zeolite as a potential catalyst for eugenol isomerization and Heck coupling reactions
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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.].
- Augustin, A.,Haripriya, T. V.,Sahu, P.,Sakthivel, A.,Shanbhag, G. V.,Sreenavya, A.
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- Biphasic hydrogenation of eugenol with ruthenium and rhodium nanoparticles stabilized in ionic liquids
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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.
- Baricelli, Pablo,Borusiak, Margarita,Castro, William,Crespo, Isis,Dominguez, Olgioly,Oma?a, Ofelia,Rosales, Merlin
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p. 4982 - 4987
(2020/12/28)
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- METHOD OF FORMING MONOMERS AND FURFURAL FROM LIGNOCELLULOSE
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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.
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Page/Page column 19; 21; 22
(2020/06/05)
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- Free Radical Scavenging Activity of Essential Oil of Eugenia caryophylata from Amboina Island and Derivatives of Eugenol
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Essential oil from Eugenia caryophylata was normally used to heal many different deseaces. Various chemical compositions of essential oil distilled and steamed of Moluccas Eugenia caryophylata has been investigated by many different researchers. Even though an intensive research has been carried out of the local chemotypes, a very detail study has not been fully investigated to find out the complete chemical compounds from the plant essential oil and its content associated with their biological activities. In present paper, we assess the free radical scavenging of E. caryophylata collected from Moluccas islands, Indonesia. Essential oil was extracted from leaves, buds, and stems of plant by steam distillation and analyzed using GC-FID and GC-MS. The result showed that free radical activity of essential oil, main constituent and its derivatives were analized using in vitro method. Essential oil activity from stem obtained as (0.82±0.15 μg/mL) was higher than that from bud and leaf possessing both 1,1-diphenyl-2-picrylhydrazyl (DPPH) and (2,2'-azino-bis-3-ethylbenzthizoline-6-sulphonic acid (ABTS) radical scavenging assays by sinergism of eugenol, eugenyl acetate, β-caryophylene and humulene. The activity of isoeugenol (2) (3.59±0.54 μM) and (5.0±0.53 μM) scavenging DPPH and ABTS, respectively, as derivatives eugenol was higher than (3), (4) and (5). Although (6) was active originally, it was inactive after conversion of the ester. While the change of the double bond of location to conjungation structure caused more activity scavenging radicals than the starting molecule.
- Julianus Sohilait, Hanoch,Kainama, Healthy
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p. 422 - 428
(2019/08/01)
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- Degradation of lignin with aqueous ammonium-based ionic liquid solutions under milder conditions
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This study investigates the performance of two aqueous ionic liquids (ILs), dimethylbutylammonium acetate ([DMBA][Ac]) and dimethylbutylammonium butanoate ([DMBA][B]), solutions for depolymerizing alkali lignin into valuable phenolic compounds. The favorable operation conditions, including reaction temperature and reaction time, are explored. The extent of depolymerization of the lignin is evaluated by analysis with gel permeation chromatography (GPC). The results show that the average molecular weights of the depolymerized lignin samples can be reduced by as high as 93.8% and 86.8% after treating with the aqueous [DMBA][Ac] and [DMBA][B], respectively. Moreover, the aromatic chemical species in the depolymerized solutions are identified by using gas chromatography?mass spectrophotometry (GC-MS). The confirmation of the chemical species is further made by using a series of spectroscopic techniques, such as FT-IR, and 1H NMR and 13C NMR spectroscopy. Promising results have been achieved for the depolymerization of the lignin into valuable chemicals by using the proposed green media, aqueous solutions of ionic liquids [DMBA][Ac] and [DMBA][B], under milder conditions.
- Gupta, Bhupender S.,Lee, Ming-Jer,Tolesa, Leta Deressa
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p. 3357 - 3365
(2019/02/25)
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- Chemodivergent hydrogenolysis of eucalyptus lignin with Ni@ZIF-8 catalyst
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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.
- Liu, Xue,Li, Helong,Xiao, Ling-Ping,Sun, Run-Cang,Song, Guoyong
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supporting information
p. 1498 - 1504
(2019/03/26)
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- Lignin Valorization by Cobalt-Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds
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Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76 % of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the β-O-4′ bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system.
- Rautiainen, Sari,Di Francesco, Davide,Katea, Sarmad Naim,Westin, Gunnar,Tungasmita, Duangamol N.,Samec, Joseph S. M.
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p. 404 - 408
(2019/01/04)
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- Cleavage of lignin C-O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions
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Hydrogenolysis is one of the most popular strategies applied in the depolymerization of lignin for the production of aromatic chemicals. Currently, this strategy is mainly conducted under high hydrogen pressure, which can pose safety risks and is not sustainable and economical. Herein, we reported that heterogeneous rhenium oxide supported on active carbon (ReOx/AC) exhibited excellent activity in the selective cleavage of lignin C-O bonds in isopropanol. High yields of monophenols (up to 99.0%) from various lignin model compounds and aromatic liquid oils (>50%) from lignin feedstock were obtained under mild conditions in the absence of H2. The characterization of the catalyst by X-ray absorption fine structure, X-ray photoelectron spectroscopy and H2-temperature-programed reduction suggested that the activity of ReOx/AC could be attributed to the presence of ReIV-VI. The interaction between the surface oxygen groups of the active carbon and rhenium oxide could also play an important role in the cleavage of the C-O bonds. Notably, an ReOx/AC-catalyzed C-O bond cleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β-β linkages in lignin without destroying the aromatic ring. This study paves the way for the development of rhenium-based catalysts for the controlled reductive valorization of realistic lignin materials through a hydrogen transfer pathway.
- Zhang, Bo,Qi, Zaojuan,Li, Xinxin,Ji, Jianwei,Zhang, Leilei,Wang, Hua,Liu, Xiaoyan,Li, Changzhi
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supporting information
p. 5556 - 5564
(2019/10/28)
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- From Syzygium aromaticum (clove) extracting Syzygium aromaticum (clove) phenol preparation of vanillin method (by machine translation)
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The present invention provides from Syzygium aromaticum (clove) extracting Syzygium aromaticum (clove) phenol preparation of vanillin method, comprises the following steps: (1) (1) Syzygium aromaticum (clove) phenol extraction and separation of: weighing Syzygium aromaticum (clove) flower drying bud, water vapor distillation, until clear distillate, non-oil bead to trickle out, stop heating, collecting distillate liquid, extraction, to obtain Syzygium aromaticum (clove) phenol; (2) the isomerization of Syzygium aromaticum (clove) phenol: to the rhodium is trichloride catalyst, through Syzygium aromaticum (clove) phenol of the isomerization reaction of preparing Syzygium aromaticum (clove) phenol; (3) phenol hydroxy protection: step (2) obtained in the different Syzygium aromaticum (clove) phenol and acetic anhydride reaction generating different Syzygium aromaticum (clove) acetate; (4) the oxidation reaction of olefinic: potassium permanganate in step (3) obtained in the different Syzygium aromaticum (clove) acetate oxidized into aldehyde group of the carbon-carbon double bond, preparation of vanillin acetate; (5) the preparation of vanillin. The method of the invention, using natural product as raw materials, is easy to obtain, resources are abundant, the production process is easy to control, easy separation of product, production cycle fast, there are extensive market application prospect. (by machine translation)
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Paragraph 0021; 0022; 0032; 0033
(2017/10/10)
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- Synthesis of potential bisphenol A substitutes by isomerising metathesis of renewable raw materials
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Isomerising metathesis is introduced as a sustainable method to produce dihydroxystilbene derivatives from eugenol, a clove oil ingredient, and cardanol from cashew nut shell liquid. Hydrogenation of the dihydroxystilbenes provided their di(hydroxyphenyl)ethane analogues. Initial studies to convert these monomers into polycarbonates and thiol-ene polymers support their potential to replace the petrol-derived bisphenol A (BPA). The estrogenic activity of the monomers derived from cardanol was found to be in the same range as that of BPA, a known endocrine disruptor. In contrast, eugenol-derived materials were found to be non-estrogenic, opening up new perspectives for bio-based food packaging materials.
- Trita,Over,Pollini,Baader,Riegsinger,Meier,Goo?en
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supporting information
p. 3051 - 3060
(2017/07/15)
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- Cobalt-Catalyzed Allylic C(sp3)-H Carboxylation with CO2
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Catalytic carboxylation of the allylic C(sp3)-H bond of terminal alkenes with CO2 was developed with the aid of a Co/Xantphos complex. A wide range of allylarenes and 1,4-dienes were successfully transformed into the linear styrylacetic acid and hexa-3,5-dienoic acid derivatives in moderate to high yields, with excellent regioselectivity. The carboxylation showed remarkable functional group tolerability, so that selective addition to CO2 occurred in the presence of other carbonyl groups such as amide, ester, and ketone. Since styrylacetic acid derivatives can be readily converted into optically active γ-butyrolactones through Sharpless asymmetric dihydroxylation, this allylic C(sp3)-H carboxylation showcases a facile synthesis of γ-butyrolactones from simple allylarenes via short steps.
- Michigami, Kenichi,Mita, Tsuyoshi,Sato, Yoshihiro
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supporting information
p. 6094 - 6097
(2017/05/08)
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- High Yield Production of Natural Phenolic Alcohols from Woody Biomass Using a Nickel-Based Catalyst
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Efficient depolymerization of woody biomass to produce natural phenolic alcohols not only preserves the original structure of lignin, but also makes the depolymerization process atom-efficient. Here, high yield production of natural phenolic alcohols (38.7 wt %) from woody biomass has been achieved using a Ni/C catalyst in a methanol–water co-solvent. The Ni-based catalyst can efficiently etherify the Cα?OH group in lignin β-O-4 motifs under hydrogen atmosphere, which can break the hydrogen bond between the Cβ?O oxygen and the Cα?OH proton to facilitate the Cβ?O cleavage. It was reported that water can also accelerate the etherification of raw lignin with methanol through in situ formation of acid. Our results suggest that breaking the intramolecular hydrogen bonds can accelerate the Cβ?O cleavage, keeping the original structure of lignin unchanged. This work highlights the significance of structure modification in lignin depolymerization and displays a clear potential for the valorization of whole biomass.
- Chen, Jiazhi,Lu, Fang,Si, Xiaoqin,Nie, Xin,Chen, Junsheng,Lu, Rui,Xu, Jie
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p. 3353 - 3360
(2016/12/16)
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- CSJ acting as a versatile highly efficient greener resource for organic transformations
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Simple, new, greener and efficient alternatives to the existing protocols have been developed for the reduction of aromatic aldehydes to their corresponding alcohols, decarboxylation of substituted benzoic acids (C6-C1) and substituted cinnamic acids (C6-C3) with a hydroxyl group at the para position with respect to the acid group to corresponding phenolic compounds and vinyl phenols respectively by using a natural feedstock, cucumber juice (CSJ), which acts as a greener solvent system, performing a substrate-selective reaction. Additionally, the hydrolysis of the acetyl as well as the benzoyl group of aromatic compounds has been carried out to afford excellent yield by CSJ.
- Maity, Himadri Sekhar,Misra, Kaushik,Mahata, Tanushree,Nag, Ahindra
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p. 24446 - 24450
(2016/03/15)
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- Catalytic isomerization of allyl functionalities in water by hexaaquaruthenium(II) tosylate
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The water-soluble coordination compound hexaaquaruthenium(II) p-toluene sulfonate (1) catalyzes olefin isomerization that makes it a useful catalyst in unmasking allyl ether and ester protecting groups in water. Allyl ethers of alcohols and acetic acid allyl ester are readily converted to the corresponding alcohols and acid in a catalytic fashion with compound 1 in water (50°C). A mechanistic investigation on ethylene glycol monoallyl ether reveals the intermediate vinyl ether resulting from olefn isomerization (ΔH? = 19.0 (±0.4) kcal/mol). This is followed by hydrolysis to the final ethylene glycol that is promoted by 1. This "one-pot" reaction provides a new useful coordination compound as a deprotection reagent in synthetic organic chemistry.
- Kuo, Louis Y.,Delaney, Frances E.
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p. 335 - 339
(2015/08/18)
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- A novel synthesis of isoeugenol, [ring-(U)-14C]
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A novel method for the preparation of isoeugenol, [ring-(U)-14C] is presented. Phenols and phenyl esters substituted in the para position with 1-hydroxyethyl or 1-hydroxypropyl acetate esters when treated with 1,8-diazabicyclo[5.4.0]undec-7-ene in dimethylformamide (DMF) eliminate the alkyl carboxylate function to give the unsaturated compound. The reaction fails with unsubstituted or ether substituted phenyl 1-hydroxyacetate esters.
- Immoos, John E.
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p. 419 - 424
(2015/11/18)
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- Function of metals and supports on the hydrodeoxygenation of phenolic compounds
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Hydrodeoxygenation (HDO) is an important process for removing oxygen from lignin-derived phenolic monomers to obtain chemicals that can be used as fuel or fuel additives. A systematic study is performed to check the effects of supports (acidic, neutral, basic) and noble metals (Pd, Pt, Ru) on the HDO of phenol, guaiacol, and eugenol. Evaluation of the combinations of metals and supports under the similar reaction conditions shows that the metals supported on a highly acidic support (SiO2-Al2O3) yield complete hydrogenation products with the possibility of C-O bond cleavage to achieve a real HDO activity, whereas on a mildly acidic support (γ-Al2O3), a complicated product distribution is achieved, and neutral (C) and basic (HT) supports give restricted hydrogenation activity but yield the products with very high selectivity. On the basis of the results, reaction pathways are suggested and deliberated. The catalysts show reproducible activity in recycle runs. The catalysts are characterized by various techniques (XRD, TEM, TPD, ICP-OES) to establish the catalyst activity-property relationship.
- Deepa, Ayillath K.,Dhepe, Paresh L.
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p. 1573 - 1583
(2015/02/02)
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- Allyl/propenyl phenol synthases from the creosote bush and engineering production of specialty/commodity chemicals, eugenol/isoeugenol, in Escherichia coli
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The creosote bush (Larrea tridentata) harbors members of the monolignol acyltransferase, allylphenol synthase, and propenylphenol synthase gene families, whose products together are able to catalyze distinct regiospecific conversions of various monolignols into their corresponding allyl- and propenyl-phenols, respectively. In this study, co-expression of a monolignol acyltransferase with either substrate versatile allylphenol or propenylphenol synthases in Escherichia coli established that various monolignol substrates were efficiently converted into their corresponding allyl/propenyl phenols, as well as providing proof of concept for efficacious conversion in a bacterial platform. This capability thus potentially provides an alternate source to these important plant phytochemicals, whether for flavor/fragrance and fine chemicals, or ultimately as commodities, e.g.; for renewable energy or other intermediate chemical purposes. Previous reports had indicated that specific and highly conserved amino acid residues 84 (Phe or Val) and 87 (Ile or Tyr) of two highly homologous allyl/propenyl phenol synthases (circa 96% identity) from a Clarkia species mainly dictate their distinct regiospecific catalyzed conversions to afford either allyl- or propenyl-phenols, respectively. However, several other allyl/propenyl phenol synthase homologs isolated by us have established that the two corresponding amino acid 84 and 87 residues are not, in fact, conserved.
- Kim, Sung-Jin,Vassao, Daniel G.,Moinuddin, Syed G.A.,Bedgar, Diana L.,Davin, Laurence B.,Lewis, Norman G.
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- An electrostatically-anchored rhodium(I) catalyst for the hydroformylation and tandem hydroformylation/acetalization of biorenewable allyl benzenes
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A rhodium catalyst anchored in a commercial anion exchange resin (IRA900/TPPMS/Rh) was prepared straightforwardly through a simple protocol from readily available precursors. The material was used as a heterogeneous catalyst for the hydroformylation and tandem sequence hydroformylation/acetalization of eugenol and estragole under mild conditions. The regioselectivity for linear products was ca. 62percent, but for the allyl benzenes the branched isomer are also valuable. The performance of the anchored catalyst in hydroformylation was comparable to that of the conventional homogeneous rhodium system; however, its efficiency in the acetalization step was significantly higher. The material can be separated from the reaction solutions by decantation and re-used without a significant loss in activity and selectivity. This simple catalytic method represents an economically attractive route to commercially valuable fragrance compounds starting from the substrates easily available from natural bio-renewable sources.
- Carvalho, Glenda A.,Gusevskaya, Elena V.,Santos, Eduardo N. Dos
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p. 2370 - 2377
(2015/04/16)
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- PROCESS FOR THE CONVERSION OF LIGNIN TO LIQUID HYDROCARBONS
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Process for the conversion of lignin to liquid hydro-carbons comprising: subjecting the lignin to hydrogenolysis in the presence of at least one hydrogenolysis catalyst, at a temperature ranging from 250° C. to 350° C., preferably ranging from 290° C. to 320 ° C., so as to obtain depolymerized lignin; subjecting said depolymerized lignin to hydrotreating so as to obtain a mixture of liquid hydrocarbons. Said liquid hydrocarbons can be used as such (biofuels) for the production of reformulated gasolines, or they can be used for the production of gasolines or of gas oils through conventional refining processes.
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Paragraph 0153-0168
(2013/03/26)
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- DEPOLYMERIZATION OF LIGNIN USING SOLID ACID CATALYSTS
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The invention provides for a process for the depolymerization of lignin in an inert atmosphere to result in substituted phenolic monomer compounds. The process is catalysed by heterogeneous solid acid catalysts and is carried out in batch or continuous mode.
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Page/Page column 6; 7
(2012/12/13)
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- Hydroaminomethylation of eugenol with di-n-butylamine catalyzed by rhodium complexes: Bringing light on the promoting effect of Br?nsted acids
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The hydroaminomethylation of eugenol with di-n-butylamine was performed employing a bis[(1,5-ciclooctadiene)(μ-methoxy)rhodium(I)] as pre-catalyst. In the absence of phosphines, the catalyst was efficient in the process, but the regioselectivity for amines was poor. For phosphine-promoted catalyst, the chemoselectivity at the hydroformylation step improved, but the hydrogenation of enamine intermediates was hampered. The regioselectivity within the class of amines was surprisingly high (>96%) for the linear product. The addition of triflic acid (10-20 mol%) improved significantly the efficiency of HAM. Employing the 2,2′-bis((diphenylphosphino)methyl)-1,1′-binaphthyl as ancillary and triflic acid as a promoter, the linear product was obtained in up to 93% yield.
- Oliveira, Kelley C.B.,Santos, Alexandra G.,Dos Santos
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p. 204 - 208
(2013/02/23)
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- A mild method for the deprotection of tetrahydropyranyl (THP) ethers catalyzed by iron(III) tosylate
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A mild method for the deprotection of THP ethers catalyzed by iron(III) tosylate (2.0 mol %) in CH3OH has been developed. Iron(III) tosylate, Fe(OTs)3·6H2O, is a commercially available solid that is inexpensive, noncorrosive, and easy to handle. The room temperature reaction conditions make this method attractive for deprotection of a range of THP ethers.
- Bockman, Matthew R.,Angeles, Veronica V.,Martino, Julia M.,Vagadia, Purav P.,Mohan, Ram S.
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experimental part
p. 6939 - 6941
(2012/02/05)
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- Biphasic hydroformylation of substituted allylbenzenes with water-soluble rhodium or ruthenium complexes
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The water-soluble complexes [Rh(CO)(Pz)(L)]2 and [HRu(CO)(CH3CN)(L)3][BF4] [L = TPPMS (m-sulfonatophenyl-diphenylphosphine) and TPPTS (tris-m-sulfonato- phenylphosphine)] were used for the first time as catalyst precursors for the hydroformylation of eugenol, estragole, safrole and trans-anethole under moderate conditions in biphasic media. Under mild reaction conditions the substrates showed the following reactivity order: eugenol > estragole ≈ safrole > trans-anethole. The use of cetyl-trimethylammonium chloride (CTAC) as phase transfer agent inhibits the isomerization reaction, reaching high selectivity for the hydroformylation products (80-94%). The catalytic phase can be recycled up to four times with a decrease in the activity over time but maintaining its high selectivity.
- Melean, Luis G.,Rodriguez, Mariandry,Romero, Marynell,Alvarado, Maria L.,Rosales, Merlin,Baricelli, Pablo J.
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experimental part
p. 117 - 123
(2012/01/03)
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- Rhodium-catalyzed one-pot hydroformylation-cyclization of allylbenzene derivatives: Simple and efficient route to 5,6-dihydronaphthalenes
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The one-pot hydroformylation-cyclization of allylbenzene derivatives by the catalyst system Rh(CO)2acac/ultranox626/CO/H2/CH2Cl2 led chemoselectively to 5,6-dihydronaphthalene derivatives 5a-d in good yields. The addition of a catalytic amount of H3PO4 enhanced in situ the cyclization process via the nucleophilic attack on the carbonyl group of the linear aldehyde, and finally the elimination of alcohol. The type of substitution on phenyl group of the allylbenzene is of great importance in enhancing the cyclization process.
- Alhaffar, Mouheddin,Suleiman, Rami,Ali, Bassam El
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experimental part
p. 778 - 782
(2010/07/06)
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- New selectivities from old catalysts. Occlusion of Grubbs' catalysts in PDMS to change their reactions
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This article describes new selectivities for Grubbs' first and second generation catalysts when occluded in a hydrophobic matrix of polydimethylsiloxane (PDMS). Occlusion of catalysts in mm-sized slabs of PDMS is accomplished by swelling with methylene chloride then removing the solvent under vacuum. The catalysts are homogenously dissolved in PDMS yet remain catalytically active. Many substrates that react by olefin metathesis with Grubbs' catalysts freely dissolved in methylene chloride also react by olefin isomerization with occluded catalysts. Eleven examples of substrates that exhibit dual reactivity by undergoing olefin isomerization with occluded catalysts and olefin metathesis with catalysts dissolved in methylene chloride are reported. Most of these substrates have olefins with allylic phosphine oxides, carbonyls, or ethers. Control experiments demonstrate that isomerization is occurring in the solvent by decomposition of the catalyst from a ruthenium carbene to a proposed ruthenium hydride. This work was extended by heating occluded Grubbs' first generation catalyst to 100 °C in 90% MeOH in H2O in the presence of various alkenes to transform the Grubbs' catalyst into an isomerization catalyst for unfunctionalized olefins. This work demonstrates that occlusion of organometallic catalysts in PDMS has important implications for their reactions and can be used as a method to control which reactions they catalyze.
- Brett Runge,Mwangi, Martin T.,Bowden, Ned B.
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p. 5278 - 5288
(2007/10/03)
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- Fine particulate matter (PM) and organic speciation of fireplace emissions
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This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an ongoing project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory- built fireplaces. RWC wood smoke particles 10 μm (PM10) consist primarily of a mixture of organic compounds that have condensed into droplets; therefore, the size distribution and total mass are influenced by temperature of the sample during its collection. During the series 1 tests (15 tests), the dilution tunnel used to cool and dilute the stack gases gave an average mixed gas temperature of 47.3 °C and an average dilution ratio of 4.3. Averages for the PM2.5 (particles 2.5 μm) and PM10 fractions were 74 and 84%, respectively. For the series 2 tests, the dilution tunnel was modified, reducing the average mixed gas temperatures to 33.8 °C and increasing the average dilution ratio to 11.0 in tests completed to date. PM2.5 and PM10 fractions were 83 and 91%, respectively. Since typical winter time mixed gas temperatures would usually be less than 10 °C, these size fraction results (even from the series 2 tests) probably represent the lower bound; the PM10 and PM2.5 size fractions might be higher at typical winter temperatures. The particles collected on the first stage (cutpoint ? 11.7 μm) were light gray and appeared to include inorganic ash. Particles collected on the remainder of the stages were black and appeared to be condensed organics because there was noticeable lateral bleeding of the collected materials into the filter substrate. Total particulate emission rates ranged from 10.3 to 58.4 g/h; corresponding emission factors ranged from 3.3 to 14.9 g/kg of dry wood burned. A wide range of Environmental Protection Agency (EPA) Method 8270 semivolatile organic compounds were found in the emissions; of the 17 target compounds quantified, major constituents are phenol, 2-methylphenol, 4- methylphenol, 2,4-dimethylphenol, and naphthalene. An account is given on fireplace particle size and organic speciation data gathered to date in an ongoing project. Total particulate matter emission rates and the results of analyses for semivolatile organics in the emissions are discussed.
- Purvis, Carol R.,Mccrillis, Robert C.,Kariher, Peter H.
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p. 1653 - 1658
(2007/10/03)
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- Nucleophilicity and Basicity of Phenols in the Aminolysis of Corresponding Aryl Acetates with Piperidine
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A correlation was found between the nucleophilicity and basicity of phenols in the aminolysis of corresponding aryl acetates with piperidine. The correlation is satisfactorily described by the Bronsted equation. The nucleophilicity of low-molecular-weight phenols and phenol oligomers of vegetable origin (lignins) was estimated.
- Kurzin,Platonov,Evstigneev,Maiorova
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p. 1475 - 1477
(2007/10/03)
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- Selective dealkylations of alkyl aryl ethers in heterogeneous basic media under microwave irradiation
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Ethyl isoeugenol and 2-ethoxyanisole could be selectively deethylated using potassium t-butoxide in the presence of crown ether under solvent-free conditions. By addition of ethylene glycol, selectivity was reversed to demethylation. In both cases, strong enhancements were observed under focused microwaves.
- Oussaid, Abdelouahad,Thach, Le Ngoc,Loupy, Andre
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p. 2451 - 2454
(2007/10/03)
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- A simplified Wittig synthesis using a solid/liquid transfer process. VIII. Specific behaviour of methyltriphenylphosphorane during condensation with phenolic aldehydes
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Vinylphenols are obtained in a single-step reaction using phenolic aldehydes according to easy operating conditions involving high temperature in the reaction medium. Phenolic compounds are separated by ion-exchange resins.
- Bettach,Le Bigot,Mouloungui,Delmas,Gaset
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p. 513 - 518
(2007/10/02)
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- Photosensitized oxidation of isoeugenol in protic and aprotic solvents
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Sensitized photooxygenation of isoeugenol gave seven products in methanol, seven products in ethanol, six products in acetone, and five products in acetonitrile. One of the products is a 7,7'-linked lignan of a type which has not yet been observed in nature. The structures of these products were elucidated and the mechanisms of their formation are discussed.
- Kuo,Chen,Wang
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p. 2196 - 2200
(2007/10/02)
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- Potassium Fluoride on Alumina - a Versatile Reagent for Isomerisation of Olefins
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Olefins undergo smooth isomerization to the thermodynamically more stable form on treatment with potassium fluoride coated on alumina.
- Radhakrishna, A.S.,Suri, S.K.,Rao, K.R.K.Prasad,Sivaprakash, K.,Singh, B.B.
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p. 345 - 348
(2007/10/02)
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