- Significant lability of guaiacylglycerol β-phenacyl ether under alkaline conditions
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It was observed that the β-O-4 bond cleavage of a dimeric phenolic lignin model compound with an α-carbonyl group at the B-ring, 2-(2-ethoxy-4-formylphenoxy)-1-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (I), is extremely fast in a mild anaerobic alkaline treatment (0.45 mol/L NaOH, 95°C, 0.8 MPa of N2). This phenomenon significantly contrasts with the case of a common dimeric phenolic lignin model compound without any specific functional group, 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy) propane-1,3-diol (II). The most plausible mechanism is the migration of the B-ring from the β- to the α-position following the SNAr mechanism. Because this migration affords the alkaline labile phenolic α-O-4-type compound (XI), the formation of the quinone methide as well as the cleavage of the originally alkaline very stable alkyl-aryl ether bond is promoted. This promotion of the quinone methide formation explains why a relatively large amount of 4-hydroxy-3-methoxybenzaldehyde (IV) is produced from I in an oxygen-alkali treatment.
- Imai, Alko,Yokoyama, Tomoya,Matsumoto, Yuji,Meshitsuka, Gyosuke
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- Solar-driven aromatic aldehydes: green production from mandelic acid derivatives by a Co(ii)/C3N4 combined catalyst in aqueous media
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According to the requirements for sustainable development, reclaiming fine chemicals from wastewater under mild conditions is an extremely significant line of research. A low-cost and high-efficiency polydentate chelate- and polymeric Co(ii)-based complex (Co-L)-loaded C3N4 photocatalyst (Co-L/C3N4) was constructed and used to convert aromatic mandelic acids in wastewater at room temperature. The BET specific surface area increased from 28 m2 g?1 to 68 m2 g?1, indicating its excellent absorptive character. The light absorption range of Co-L/C3N4 reached 650 nm, while the band energy reduced to 2.30 eV, which caused a significant enhancement in photocatalytic activity. The conversion of substituted mandelic acids was more than 90% due to the photoactivity of Co-L/C3N4. Time-resolved PL spectra indicated the remarkable separation of the photogenerated electron-hole pairs in Co-L/C3N4. Furthermore, the UV-vis and in situ FTIR spectra indicated the formation of aldehyde groups in the selective oxidation process, which provided support for the plausible catalytic mechanism.
- Dong, Zhenbiao,Jin, Lehong,Liu, Jibo,Mao, Haifang,Tang, Ting,Wang, Chaoyang,Wang, Hongzhao,Wu, Mi,Zheng, Wei
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p. 5245 - 5254
(2022/02/25)
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- Method for continuously preparing vanillin and syringaldehyde
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The invention relates to the technical field of organic synthesis, in particular to a method for continuously preparing vanillin and syringaldehyde. According to the method for continuously preparingthe vanillin and the syringaldehyde, the vanillin and the syringaldehyde are continuously synthesized and produced by taking the p-hydroxy benzaldehyde as the raw material, and the vanillin and the syringaldehyde are obtained by directly etherifying brominated products without refining in the process, so that the aims of shortening the process, improving the yield, reducing the cost, being safe and environment-friendly and easily realizing industrial production are achieved.
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Paragraph 0023-0031; 0032; 0033; 0034
(2020/01/08)
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- Coenzyme A-Conjugated Cinnamic Acids – Enzymatic Synthesis of a CoA-Ester Library and Application in Biocatalytic Cascades to Vanillin Derivatives
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We present a bioorthogonal method for the ligation of coenzyme A (CoA) with cinnamic acids. The reaction, which is the initial step in the biosynthesis of a multitude of bioactive secondary metabolites, is catalyzed by a promiscuous plant ligase and yields CoA conjugates with different functionalization in high purity and without formation of by-products. Its applicability in biosynthetic cascades is shown for the direct transformation of cinnamic acids into natural benzaldehydes (like vanillin) or artificial derivatives (e. g. ethylvanillin). (Figure presented.).
- Dippe, Martin,Bauer, Anne-Katrin,Porzel, Andrea,Funke, Evelyn,Müller, Anna O.,Schmidt, Jürgen,Beier, Maria,Wessjohann, Ludger A.
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supporting information
p. 5346 - 5350
(2019/11/29)
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- Magnetic nano-structured cobalt-cobalt oxide/nitrogen-doped carbon material as an efficient catalyst for aerobic oxidation of p-cresols
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Efficient aerobic oxidation has been developed for the selective preparation of a sequence of valuable p-hydroxybenzaldehydes from corresponding p-cresols, using a new magnetically separable catalyst of nano-structured cobalt-cobalt oxide/nitrogen-doped carbon (CoOx@CN) material. CoOx@CN showed high activity for the 2-methoxy-4-cresol oxidation to vanillin, giving great yield (90%) and with good turnover number (210), as well as other p-cresols in good to great yields. The catalytic performance was investigated and related to the structural, chemical and magnetic properties which determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The effects of base to substrate molar ratio, catalyst concentration, temperature, and solvent on the conversion and selectivity patterns also have been studied. The investigation revealed that remarkable catalytic properties of CoOx@CN could be ascribed to the active species cobalt oxide, doped nitrogen and porous carbon with large surface area. The size of the catalyst is a key factor for catalyst performance. The ferromagnetic property of catalyst enables to recycle easily by an external magnetic field and reuse six successive times without significant activity loss.
- Liang, Cheng,Li, Xuefeng,Su, Diefeng,Ma, Qiyi,Mao, Jianyong,Chen, Zhirong,Wang, Yong,Yao, Jia,Li, Haoran
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p. 121 - 131
(2018/05/22)
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- A 3, 4 - epoxy-cyclohexane METHYLAL glycol and its synthesis and use
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The invention discloses a 3,4-epoxy cyclohexyl methylal diol and a synthesis method thereof. The 3,4-epoxy cyclohexyl methylal diol can be used for synthesizing multiple vanillins and isovanillins. Compared with the existing synthesis process, the synthesis method disclosed by the invention has the advantages of simple steps and low discharge amount of three wastes.
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- A (3 - alkoxy - 4 - hydroxy) - cyclohexyl acetal glycol and its isomers of use
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The present invention discloses a (3-alkoxy-4-hydroxy)-cyclohexyl methylal diol, an (3-hydroxy-4-alkoxy)-cyclohexyl methylal diol and synthesis methods and use therefor. The (3-alkoxy-4-hydroxy)-cyclohexyl methylal diol and (3-hydroxy-4-alkoxy)-cyclohexyl methylal diol can be used for synthesis of a variety of vanillin and iso-vanillin. Compared to the existing synthetic method, the synthesis method has simple steps, and less discharge of "three wastes".
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- Practical Ligand-Free Copper-Catalysed Short-Chain Alkoxylation of Unactivated Aryl Bromides
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An efficient and practical short-chain alkoxylation of unactivated aryl bromides has been developed with special attention focussed on the applicability of the reaction. Sodium alkoxide is used as the nucleophile, and the corresponding alcohol as the solvent. The reaction requires neither precious metals nor organic ligands. It uses a catalytic system consisting of copper(I) bromide as a catalyst, the corresponding alkyl formate as a noncontaminating cocatalyst, and lithium chloride as an additive. A wide range of substrates and test cases highlight the synthetic utility of the approach. Considering the commercial accessibility and affordability of the feedstocks, this protocol shows promise as a new alternative for the sustainable preparation of aryl alkyl ethers.
- Guo, Ying,Fan, Xue-Min,Nie, Min,Liu, Hong-Wei,Liao, Dao-Hua,Pan, Xian-Dao,Ji, Ya-Fei
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p. 4744 - 4755
(2015/08/03)
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- Catalytic depolymerization of alkali lignin in subcritical water: Influence of formic acid and Pd/C catalyst on the yields of liquid monomeric aromatic products
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Alkali lignin was subjected to depolymerization in subcritical water at 265 °C, 6.5 MPa for reaction times between 1-6 h in a batch reactor and in the presence of formic acid (FA) and Pd/C catalyst. The oil products were extracted into diethyl ether and contained >90% of single-ring phenolic compounds. The reaction of lignin in subcritical water alone yielded 22.3 wt% oil containing 56% guaiacol as the main product. A maximum oil yield of 33.1 wt% was obtained when the lignin was reacted in the presence of formic acid alone. In the presence of FA, catechol became the predominant compound, with more than 80% of the ether extract after 6 h. The conversion of guaiacol to catechol in the presence of formic acid suggested the hydrolysis of O-CH3 ether bonds. In addition, the yields of alkyl guaiacols increased in the presence of FA. The use of 5 wt% Pd/C catalyst with FA slightly decreased the yields of oil products but led to compounds indicative of hydrogenolysis of aryl-O ether bonds as well as hydrogenation of CC bonds.
- Onwudili, Jude A.,Williams, Paul T.
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p. 4740 - 4748
(2014/12/11)
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- Direct composition analysis of a dynamic library of imines in an aqueous medium
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Dynamic Combinatorial Chemistry: Direct detection of imines in water and their adaptive re-equilibration in the presence of a target are possible by simple HPLC analysis. The equilibrating mixture is fixed by a fast drop in the pH during the analytical step. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Zameo, Sandrine,Vauzeilles, Boris,Beau, Jean-Marie
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p. 5441 - 5444
(2007/10/03)
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Beta-ketoester compounds
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The beta-ketoesters of formula I are useful as precursors for organoleptic compounds, especially for flavors, fragrances and masking agents and antimicrobial compounds.
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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- Process for the preparation of isovanillin
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The present invention relates to a novel process for the preparation of isovanillin. The process for the preparation of isovanillin according to the invention is characterized in that it consists in dealkylation being carried out using a strong acid, selectively in the 3-position, on a 3-alkoxy-4-methoxybenzaldehyde wherein said alkoxy group has at least two carbon atoms.
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- Syntheses of long-chain quaternary ammonium salts from fatty alcohols by microwave irradiation
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The phase-transfer catalysts, long-chain quaternary ammonium salts, were rapidly synthesized from fatty alcohols by the reactions with hydrogen halides in the presence of trialkyl amines under microwave irradiation. The catalysts could be widely applied in a variety of quick and new organic reactions, whether by conventional heating or under microwave irradiation. The reaction efficiencies under microwave irradiation were higher than those obtained with conventional heating.
- Jiang,Hu,Pang,Yuan
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p. 847 - 850
(2007/10/03)
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- Process for nucleophilic fluoroalkylation of aldehydes
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Aryl difluoromethyl sulfone adds to alkehydes under phase transfer conditions to give novel substituted alcohols of the general formula wherein R is an aryl, cycloaliphatic, sec- or tert-aliphatic, or heterocyclic group and Ar is an aryl group. The substituted alcohols of formula I are of particular utility as intermediates in the synthesis of a variety of useful end products. For example, the products of formula I may be utilized in desulfonylation reactions, oxidation reactions and fluorination reactions.
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- Process for the preparation of hydroxy benzene carboxaldehydes
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A process is provided for the preparation of hydroxy benzene carboxaldehydes having the formula: STR1 wherein: R is selected from the group consisting of alkyl, alkoxy, cycloalkyl, aryl, alkoxyalkyl, fluoroalkyl, and hydroxyalkyl oxyalkylene having from one to about twenty carbon atoms; hydroxyalkyl having at least two to about twenty carbon atoms; hydroxy; aldehyde CHO; and halogen; n1, n2 and n3 are zero or 1; and at least one of n1, n2 and n3 is 1; and x is zero, 1, 2, 3 or 4, which comprises: (1) condensing with a formaldehyde compound a phenol having the formula: STR2 wherein R is selected from the group consisting of alkyl, alkoxy, hydroxyalkyl, cycloalkyl, aryl, alkoxyalkyl, fluoroalkyl, and hydroxyalkyl oxyalkylene having from one to about twenty carbon atoms; hydroxy; and halogen; and x is zero, 1, 2, 3 or 4, and unsubstituted in at least one ortho or para position in an aqueous reaction medium comprising phenol:HCHO in a molar ratio within the range from about 1:0.1 to about 1:3 and alkali in a molar ratio alkali:phenol within the range from about 1:0.1 to about 1:2 and an alkali concentration not exceeding 30% by weight at a temperature within the range from about 0° to about 120° C. and obtaining a reaction mixture comprising a mixture of monomethylol and polymethylol phenols having the formula: STR3 wherein R is selected from the group consisting of alkyl, alkoxy, hydroxyalkyl, cycloalkyl, aryl, alkoxyalkyl, fluoroalkyl, and hydroxyalkyl oxyalkylene having from one to about twenty carbon atoms; hydroxy; and halogen; n1, n2 and n3 are zero or 1; and at least one of n1, n2 and n3 is 1; and x is zero, 1, 2, 3 or 4; (2) subjecting the reaction mixture without separation of the monomethylol species from polymetholol species to oxidation under conditions favoring oxidation of methylol species to the corresponding aldehyde species in the presence of oxygen and an amount of alkali that is at least stoichiometrically equal to the amount of phenol and a platinum or palladium oxidation catalyst, preferably but optionally with a promoter selected from the group consisting of bismuth, lead, silver, tellurium, cadmium, and tin in the form of the metal and/or compounds thereof at a temperature within the range from about 0° to about 100° C. and a pH within the range from about 11 to about 13.5; and then (3) separating and recovering the desired aldehyde in the reaction mixture. A process also is provided for selectively decarbonylating any undesired aldehyde species to remove all or selected aldehyde groups in certain ring positions, either to yield more desirable aldehyde species or for recycling as starting material.
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- Fluoroaliphaticsulfonyl substituted ethylenes
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Fluoroaliphaticsulfonyl substituted ethylenes, useful as catalysts in polymerization of monomers, e.g., epoxide, vinyl ether, and N-vinyl monomers, are prepared by condensation of precursor fluoroaliphaticsulfonyl methanes with aldehydes or N-formyl compounds.
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