Xi:Irritant;
123-08-0Relevant articles and documents
Selective synthesis of p-hydroxybenzaldehyde by liquid-phase catalytic oxidation of p-cresol
Rode, Chandrashekhar V.,Sonar, Mahesh V.,Nadgeri, Jayprakash M.,Chaudhari, Raghunath V.
, p. 873 - 878 (2004)
Liquid-phase oxidation of p-cresol over insoluble cobalt oxide (Co 3O4) catalyst under elevated pressure of air gave 95% selectivity to p-hydroxybenzaldehyde, an important flavoring intermediate. The selectivity to p-hydroxybenzaldehyde could be enhanced by manipulating the concentrations of p-cresol, sodium hydroxide, and catalyst and the partial pressure of oxygen in such a way that the byproducts normally encountered in this oxidation process were eliminated or minimized significantly.
Practical process for the air oxidation of cresols: Part B. evaluation of the laboratory-scale oxidation process
Barton, Benita,Logie, Catherine G.,Schoonees, Barbara M.,Zeelie, Bernard
, p. 70 - 79 (2005)
Mechanistic proposals and predictions made in a preceding paper (Part A) were evaluated by carrying out the catalytic air oxidation of p-cresol in an alternative solvent system, comprising either a mixture of ethylene glycol and acetic acid (for oxidations under acidic conditions) or ethylene glycol and water (for oxidations under basic conditions). The results obtained in these experiments confirmed that ethylene glycol acts as a nucleophile in these solvent systems, thereby stabilizing the quinomethide intermediate and resulting in highly efficient oxidations in both alkaline and acidic media. 4-Hydroxybenzaldehyde, the desired product, was thus obtained in isolated yields of up to 98% and purities >99%. The inherent draw-backs associated with alkaline methanol and aqueous acetic acid solutions were thus circumvented, and the result is a highly efficient process for the production of 4-hydroxybenzaldehyde.
Synthesis of Copolymers of N-Vinylpyrrolidone with Crotonic Acid Modified with 4-Oxybenzaldehyde
Solovskii,Borisenko,Tarabukina,Amirova
, p. 514 - 519 (2018)
Radical copolymerization of N-vinylpyrrolidone with crotonic acid in 2-propanol has afforded water-soluble products, which have been characterized in terms of composition as well as molecular and hydrodynamic parameters. The obtained copolymers have been modified with 4-oxybenzaldehyde. Structures of the products of the polymer analogous reaction, potential carriers of several bioactive substances, have been confirmed using elemental and functional analysis and spectroscopic data.
A novel practical cleavage of tert-butyl esters and carbonates using fluorinated alcohols
Choy, Jason,Jaime-Figueroa, Saul,Lara-Jaime, Teresa
, p. 2244 - 2246 (2010)
Thermolytic cleavage of t-butyl esters and t-butyl carbonates was accomplished using TFE (2,2,2-trifluoroethanol) or HFIP (hexafluoroisopropanol) as solvent. Thus, a practical method to cleanly convert t-butyl esters and carbonates into the corresponding carboxylic acids, decarboxylated products, or alcohols in nearly quantitative yields was developed. The product is recovered by a simple solvent evaporation. The practicality of this methodology was demonstrated on alkyl, aryl, and heteroaromatic esters.
Increased para Selectivity in the Reimer-Tiemann Reaction by Use of Polyethylene Glycol as Complexing Agent
Neumann, Ronny,Sasson, Yoel
, p. 569 - 570 (1986)
The para selectivity of the Reimer-Tiemann reaction was increased by use of polyethylene glycol in the reaction medium.The polyethylene glycol complexes the phenolate substrate masking the ortho position of the benzene nucleus increasing para selectivity without affecting the total yield.
Novel and efficient oxidation of benzyl ethers to benzaldehydes by DMSO/49% aq. HBr
Naik, Ramesh,Pasha
, p. 1723 - 1726 (2007)
Dimethylsulfoxide (DMSO) oxidizes benzyl ethers into corresponding benzaldehydes at 110°C; the reaction is accelerated by 49% aq. HBr. The conditions work well for different aryl-substituted benzyl ethers. This protocol is inert toward dialkyl ethers. Copyright Taylor & Francis Group, LLC.
Total synthesis of the proposed structures of gladiosides I and II
Hussain, Nazar,Delar, Emmanilo,Piochon, Marianne,Groleau, Marie-Christine,Tebbji, Faiza,Sellam, Adnane,Déziel, Eric,Gauthier, Charles
, (2021)
Burkholderia gladioli is a Gram-negative bacterium that biosynthesizes a cocktail of potent antimicrobial compounds, including the antifungal phenolic glycoside sinapigladioside. Herein, we report the total synthesis of the proposed structures of gladiosides I and II, two structurally related phenolic glycosides previously isolated from B. gladioli OR1 cultures. Importantly, the physical and analytical data of the synthetic compounds were in significant discrepancies with the natural products suggesting a misassignment of the originally proposed structures. Furthermore, we have uncovered an acid-catalyzed fragmentation mechanism converting the α,β-unsaturated methyl carbamate-containing gladioside II into the aldehyde-containing gladioside I. Our results lay the foundation for the expeditious synthesis of derivatives of these Burkholderia-derived phenolic glycosides, which would enable to decipher their biological roles and potential pharmacological properties.
Aqueous selective photocatalytic oxidation of salicyl alcohol by TiO2 catalysts: Influence of some physico-chemical features
Yurdakal, Sedat,Bellardita, Marianna,Pibiri, Ivana,Palmisano, Leonardo,Loddo, Vittorio
, p. 16 - 24 (2021)
Partial photocatalytic oxidation of salicyl alcohol (2-hydroxybenzyl alcohol) to salicylaldehyde in water was investigated under environmental friendly conditions in the presence of home-prepared and commercial TiO2 (Merck and Aeroxide P25) samples under UVA irradiation. The photocatalysts were characterized by using BET, XRD, SEM and/or TEM techniques. The effects of crystallinity degree, pH (3–11) and presence of a hole trap (ethanol) on the photocatalytic activity and product selectivity were investigated. 4-Hydroxybenzyl alcohol was also used to study the influence of the position of the substituent group in the aromatic ring. High alcohols conversion and product selectivity values were obtained at pH = 11 by using well crystallized TiO2 samples. The conversion values significantly decreased by increasing the hole trap concentration, whereas the selectivity values increased slightly. The selectivity towards the corresponding aldehyde after 30% of alcohol conversion was significantly higher for 4-HBA (48%) than for 2-HBA (32%), due to the role of the para position of the substituent group. In order to clarify the different selectivity of the products, various experiments have been also performed starting from the products; these results indicate that the selectivity is also strongly dependent on the stability of the formed products under the experimental conditions used. By concluding, this article reports that the conversion and selectivity values for the studied reaction depend both on the TiO2 type and on the substrate.
Iron-Catalyzed Synthesis of the Hexahydrocyclopenta[c]furan Core and Concise Total Synthesis of Polyflavanostilbene B
Wang, Xujie,Liu, Fu,Yun, Juping,Feng, Ziming,Jiang, Jianshuang,Yang, Yanan,Zhang, Peicheng
, p. 10127 - 10131 (2018)
The first synthesis of polyflavanostilbene B (1), which has seven contiguous stereocenters including two quaternary carbon centers, from abundant polymeric (?)-epicatechin gallate on a gram scale in three steps without the use of protecting groups is reported. The key transformations of this strategy include a regioselective and stereoselective substitution of resveratrol to give the 4-derivative of (?)-epicatechin 3-gallate and an iron-catalyzed cyclization reaction. The possible radical cyclization mechanism in the formation of the hexahydrocyclopenta[c]furan core is also discussed.
Oxidation of p-cresol to p-hydroxybenzaldehyde with molecular oxygen in the presence of CuMn-oxide heterogeneous catalyst
Wang, Feng,Yang, Guanyu,Zhang, Wei,Wu, Wenhai,Xu, Jie
, p. 633 - 638 (2004)
A high-yield synthesis of p-hydroxybenzaldehyde from p-cresol and molecular oxygen was achieved over a CuMn-oxide supported carbon catalyst. The reaction parameters such as pressure, stirring speed, reaction temperature, solvent, and the amount of sodium hydroxide in the reaction media were optimized. As a result, a high conversion of p-cresol (99%) and a high selectivity to p-hydroxybenzaldehyde (96%) were realized at the same time. Catalyst separation and recycling tests clearly showed that the reaction proceeded on the heterogeneous catalyst but not on dissolved species.
