- Copper-Catalyzed Selective Diphenylation of Carboxylic Acids with Cyclic Diaryliodonium Salts
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Herein, we describe a novel one-step copper-catalyzed diphenylation of readily available aliphatic or (hetero)aromatic carboxylic acids with cyclic hypervalent diaryliodonium reagents. The selective diphenylation of benzoic acids with high atom economy can be achieved without observation of the arylation at the phenyl hydroxyl/thio/amino position. The valuable biphenyl esters with an additional iodo-substituent were obtained in good to excellent yields, which can be further transformed to diversified building blocks for the synthesis of bioactive natural products, pharmaceuticals, and functional materials. A wide range of different functional groups are compatible under the optimized reaction conditions.
- Xie, Hao,Yang, Shuai,Zhang, Chunxia,Ding, Mingruo,Liu, Min,Guo, Jie,Zhang, Fengzhi
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Read Online
- Cu(OTf)2-mediated Chan-Lam reaction of carboxylic acids to access phenolic esters
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A Cu(OTf)2-mediated Chan-Lam reaction of carboxylic acids with arylboronic acids is described. It represents a facile and practical methodology to access phenolic esters in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxycarbonyl, acetoxy, free phenolic hydroxyl, vinyl, nitro, trifluoromethyl, methoxyl, bromo, chloro, iodo, and acetyl groups.
- Zhang, Lingli,Zhang, Guoying,Zhang, Manli,Cheng, Jiang
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Read Online
- Synthesis, characterization and catalytic activity studies on cordierite honeycomb coated with ZrO2 based solid super acids
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Cordierite honeycomb coated with solid acids such as ZrO2, Mo/ZrO2 and W/ZrO2 were synthesized. These solid acid catalysts were also synthesized in their powder forms. The catalytic materials were characterized for their physicochemical properties such as surface area, surface acidity, crystallinity and morphology by using techniques such as BET, NH3-TPD/n-butylamine back titration, powder XRD and SEM respectively. The catalytic activity of these catalytic materials was determined in an acid catalyzed transesterification reaction of methyl salicylate with phenol to synthesize phenyl salicylate (salol). The effect of concentration of Mo or W ions on ZrO2, nature of the catalyst (whether honeycomb coated or powder form), reaction temperature, reaction time and reusability of the catalytic material in transesterification was studied. Formation of diphenyl ether as a by-product was observed on increasing the concentration of Mo or W ions on ZrO2 and also at higher reaction temperature. The catalytic activity of catalytic materials was correlated with surface acidity and the crystalline phases of catalytic material. Transesterification reactions were also carried out with methyl salicylate and benzyl alcohol or cyclohexanol to synthesize their respective salicylate esters. A probable mechanism of transesterification of methyl salicylate with an alcohol is also proposed. The honeycomb catalysts were found to be efficient, ecofriendly, economical and reusable catalysts compared to their powder forms.
- Mohamed Shamshuddin,Shyam Sundar,Thimmaraju,Venkatesh,Vatsalya,Senthilkumar
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Read Online
- Synthesis of phenyl esters using SiO2-SO3H catalyst in conventional heating and microwave-irradiated esterification processes
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A SiO2-SO3H amorphous catalyst containing a small surface area of 115.0 m2g-1 and 1.32 mmol H+/g was prepared from fine construction sand and sodium carbonate and sulfonated with H2SO4. In a 10% (w/w) basis, it is very efficient for catalyzing the esterification of carboxylic acids with phenol. The reaction processes were performed using conventional heating and under microwave irradiation. The yields were higher in the microwave-irradiated esterification. The catalyst could be used for three esterification sequences in both processes.
- Barbosa, Sandro L.,Ottone, Myrlene,De Freitas, Milton,Lima, Camila D.,Nelson, David L.,Clososki, Giuliano C.,Caires, Franco J.,Klein, Stanlei I.,Hurtado, Gabriela R.
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Read Online
- Synthesis of salicylates from anionically activated aromatic trifluoromethyl group
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An efficient approach to salicylates via a novel transformation of anionically activated aromatic trifluoromethyl group is described. Anionically activated trifluoromethyl group can react with phenols/alcohols under alkaline conditions to afford aryl/alkyl salicylates in high yields. Mechanism studies indicate that the carbonyl oxygen atom of ester is from the H2O in the solvent.
- Lin, Chuankai,Liu, Jin-Biao,Wang, Ruixiang,Xie, Huilin
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supporting information
(2021/12/22)
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- Cerium photocatalyzed radical smiles rearrangement of 2-aryloxybenzoic acids
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We report herein a cerium photocatalyzed aryl migration from an aryl ether to a carboxylic acid group through radical-Smiles rearrangement. This operationally simple protocol utilizes inexpensive CeCl3as a photocatalyst and converted a variety of 2-aryloxybenzoic acids into aryl-2-hydroxybenzoates in good yields.
- Tripathy, Alisha Rani,Yatham, Veera Reddy,Yedase, Girish Suresh
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p. 25207 - 25210
(2021/08/05)
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- Rhodium-Catalyzed Carbonylative Synthesis of Aryl Salicylates from Unactivated Phenols
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A rhodium-catalyzed carbonylative transformation of unactivated phenols to aryl salicylates is described. This protocol is characterized by utilizing 1,3-rhodium migration as the key step to provide direct access to synthesize ohydroxyaryl esters. Various desired aryl o-hydroxybenzoates were produced in moderate to excellent yields with bis(dicyclohexylphosphino)ethane (DCPE) as the ligand. Interestingly, diphenyl carbonate was formed as the main product when 1,3-bis(diphenylphosphino)propane (DPPP) was used as the ligand. A plausible reaction mechanism is proposed.
- Ai, Han-Jun,Zhang, Youcan,Zhao, Fengqian,Wu, Xiao-Feng
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supporting information
p. 6050 - 6054
(2020/10/02)
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- Production process of phenyl salicylate
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The invention discloses a production process of phenyl salicylate, and relates to the field of production of phenyl salicylate. The production process mainly comprises the following steps: mixing diphenyl carbonate and a catalyst, heating to 180-260 DEG C, and reacting for 2-14 h to obtain phenyl salicylate. By adopting the technical scheme, diphenyl carbonate can be converted into phenyl salicylate through a one-step reaction, so that the subsequent application of diphenyl carbonate is broadened, and the production efficiency of phenyl salicylate is improved.
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Paragraph 0023-0038
(2020/09/23)
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- Influence of coordinating groups of organotin compounds on the Fries rearrangement of diphenyl carbonate
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In this paper, the Fries rearrangement of diphenyl carbonate (DPC) catalyzed by organotin compounds with different coordination groups was studied for the first time. The electronic effect and steric hindrance of the coordinating groups were discussed with respect to the reactivity of DPC rearrangement. The results showed that both the electronic effect and steric hindrance of the coordinating groups influenced the acidity of the active tin centers and then affected the catalytic performance of organotin as a Lewis acid for the rearrangement of DPC, and the influence of the electronic effect is greater than that of steric hindrance. The catalytic activity is in the order of BuSnO(OH) > Bu2SnO > Bu2Sn(OCOC11H23)2 > BuSnCl3 > Bu3SnOSnBu3 > Bu3SnCl, and Bu2SnO showed the best catalytic activity due to its strong electron absorption effect, small steric hindrance, and good stability. Under the optimum reaction conditions, the conversion of DPC was up to 93%, and the yields of phenyl salicylate (PS) and xanthone (XA) were 62% and 28%, respectively. In addition, a reaction mechanism of DPC rearrangement catalyzed by the organotin compounds was speculated. This research can provide vigorous theoretical data support to control the byproducts produced by DPC rearrangement in the process of DPC synthesis. It also provides a new route for the preparation of PS and XA.
- Liu, Tao,Yuan, Xiaoxue,Zhang, Gang,Zeng, Yi,Chen, Tong,Wang, Gongying
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p. 28112 - 28118
(2019/09/30)
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- A photoredox-neutral Smiles rearrangement of 2-aryloxybenzoic acids
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We report on the use of visible light photoredox catalysis for the radical Smiles rearrangement of 2-aryloxybenzoic acids to obtain aryl salicylates. The method is free of noble metals and operationally simple and the reaction can be run under mild batch or flow conditions. Being a redox neutral process, no stoichiometric oxidants or reductants are needed.
- Gonzalez-Gomez, Jose C.,Ramirez, Nieves P.,Lana-Villarreal, Teresa,Bonete, Pedro
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p. 9680 - 9684
(2017/11/30)
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- Efficient Aryl Migration from an Aryl Ether to a Carboxylic Acid Group To Form an Ester by Visible-Light Photoredox Catalysis
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We have developed a highly efficient aryl migration from an aryl ether to a carboxylic acid group through retro-Smiles rearrangement by visible-light photoredox catalysis at ambient temperature. Transition metals and a stoichiometric oxidant and base are avoided in the transformation. Inspired by the high efficiency of this transformation and the fundamental importance of C?O bond cleavage, we developed a novel approach to the C?O cleavage of a biaryl ether to form two phenolic compounds, as demonstrated by a one-pot, two-step gram-scale reaction under mild conditions. The aryl migration exhibits broad scope and can be applied to the synthesis of pharmaceutical compounds, such as guacetisal. Primary mechanistic studies indicate that the catalytic cycle occurs by a reductive quenching pathway.
- Wang, Shao-Feng,Cao, Xiao-Ping,Li, Yang
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supporting information
p. 13809 - 13813
(2017/10/24)
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- Compound and application of compound in preparation of medicines
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The invention discloses a compound and its application in a medicine. the invention specifically provides a compound as shown in the formula (I) or a stereisomer, a geometrical isomer, a tautomer, a racemate, nitric oxide, hydrate, a solvate, a metabolite, pharmaceutically acceptable salts or a prodrug of the compound as shown in the formula (I). The invention also discloses an application of the compound in preparation of a medicine. The medicine is used in treating cancers.
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Paragraph 0164; 0165; 0291
(2016/10/08)
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- Carboxyl radical-assisted 1,5-aryl migration through Smiles rearrangement
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We report herein, a silver(i)-catalyzed Smiles rearrangement of 2-aryloxy- or 2-(arylthio)benzoic acids to provide aryl-2-hydroxybenzoate or aryl-2-mercaptobenzoate dimer, respectively, through 1,5-aryl migration from oxygen or sulfur to carboxylate oxygen. Mechanistically, the aryl ether moiety undergoes an intramolecular ipso attack by the carboxyl radical followed by a C-O or C-S bond cleavage. Aryl-2-mercaptobenzoates undergo oxidative dimerization through a thiol moiety in situ.
- Hossian, Asik,Jana, Ranjan
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p. 9768 - 9779
(2016/10/31)
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- An antibacterial disinfectant method for synthesis of salicylic acid phenyl ester (by machine translation)
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An antibacterial disinfectant method for synthesis of salicylic acid phenyl ester, comprising the following steps : (i) in the is provided with a stirrer, thermometer, reflux condenser, dropping funnel in the reaction container, adding 1.31mol benzonitrile eyeball of, salicyate 1.21 the [...] 1.23mol, raising the temperature of the solution to 140 - - 145°C, control the stirring speed is 150 the [...] 170rpm, 30-40 min by adding thionyl chloride after the 0.2 [...] 0.23mol, after being added to maintain the reaction temperature at 135 - - 138°C, time control of reaction in the 3 [...] 4h, reducing the temperature of the solution to 70 - - 75°C, the reaction solution is divided into two layers, the upper layer is separated, is added to the 200 ml in the salt solution, curing, to pink solid, crushing with 500 ml of the potassium bicarbonate solution to wash the 3 [...] 6 times, desiccant dehydration, third eyeball solution for re-crystallization, salicylic acid phenyl ester obtained; wherein steps (i) the salt solution is a potassium bromide, any one of sodium chloride. (by machine translation)
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Paragraph 0014; 0015
(2016/10/31)
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- Method for one-step synthesis of phenyl salicylate from carbon dioxide and phenol
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The present invention relates to a method for one-step synthesis of phenyl salicylate from carbon dioxide and phenol, and belongs to the technical field of phenyl salicylate synthesis. By taking carbon dioxide and phenol as raw materials, the method, under a condition with certain carbon dioxide pressure and temperature, adopts a catalyst and an auxiliary agent to directly and catalytically synthesize the phenyl salicylate. According to the method, the phenyl salicylate is catalytically and synthesized in one step by taking the carbon dioxide and the phenol as raw materials; and a process route is simple, raw materials are easily available, cost is low, and use of raw materials and catalysts with high corrosion and high toxicity is avoided; the carbon dioxide is used as a reactant, thereby realizing chemical utilization of the carbon dioxide, reducing environmental pollution, providing a new thought for the chemical utilization of the carbon dioxide and emission reduction of greenhouse gas, and having an important economic and social meaning.
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Paragraph 0029; 0030
(2017/03/14)
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- Direct synthesis of diphenyl carbonate from phenol and carbon dioxide over Ti-salen-based catalysts
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Various metal-salen catalysts were prepared for use in the direct synthesis of diphenyl carbonate (DPC) from phenol and carbon dioxide. We found that metal-salen complexes containing titanium as central metal species retained suitable Lewis acid property for the reaction. It was revealed that the catalytic activity of Ti-salen complexes could be controlled by introducing appropriate substituents into salen ligand. Insertion of phosphonium salts into para-position of aromatic aldehyde of salen ligand enhanced solubility of the catalyst in the methanol-phenol solution, and tert-butyl substituent in the salen ligand induced selective formation of DPC due to steric effect. In addition, introduction of various bridging groups into salen ligand caused change in electronic property of central metal atom. Among the catalysts tested, Ti-(t-butyl)salphen(PPh3) Cl showed the best catalytic performance at 100 °C and 60 bar. The catalytic system utilizing Ti-(t-butyl)salphen(PPh3) Cl catalyst was then optimized by conducting the reaction at various reaction temperatures and pressures.
- Kang, Ki Hyuk,Jun, Jin Oh,Han, Seung Ju,Kwon, Kihyeok,Kwon, O-Sung,Jang, Boknam,Song, In Kyu
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p. 8353 - 8358
(2015/11/24)
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- Honeycomb monolith coated with Mo(VI)/ZrO2 as a versatile catalyst system for liquid phase Transesterificaiton
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Solid acid Mo(VI)/ZrO2 with 2-10% Mo(VI) was coated on honeycomb monoliths by impregnation method. These catalytic materials were characterized by BET, NH3-TPD/n-butylamine back titration, PXRD and SEM techniques. Phe-nyl salicylate (Salol) was synthesized via transesterification of methyl salicylate and phenol over these catalytic materials. An excellent yield (91.0%) of salol was obtained under specific reaction conditions. The effect of poisoning of acid sites of the catalytic material by adsorbing different bases and its effect on total surface acidity, powder XRD phases and catalytic activity was studied. A triangular correlation between the surface acidity, powder XRD phases and catalytic activity of Mo(VI)/ZrO2 was observed. The thermally regenerated catalytic material was reused repeatedly with a consistent high yield of salol.
- Thimmaraju,Pratap,Senthil Kumar,Mohamed Shamshuddin
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p. 563 - 570
(2013/01/15)
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- A new group of potential antituberculotics: N-(2-pyridylmethyl) salicylamides and N-(3-pyridylmethyl)salicylamides
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As a part of our systematic study of antimycobacterially active derivatives of salicylamides, a series of nineteen derivatives of N-(2-pyridylmethyl) salicylamides and N-(3-pyridylmethyl)salicylamides was synthesised. The compounds exhibited in vitro activity against Mycobacterium tuberculosis and M. avium. Their lipophilicity, RM, was measured by thin layer chromatography on silica gel impregnated with trioctadecylsilane and the logarithm of the partition coefficient (octanol-water), logP, was calculated. Both the parameters of lipophilicity correlated. The quantitative relationship between the structure and antimycobacterial activity was calculated. Antimycobacterial activity increased with an increase in lipophilicity. The N-(2-pyridylmethyl)salicylamide derivatives were more active than the derivatives of isomeric N-(3-pyridylmethyl)salicylamides. The geometry of compounds was calculated and the calculation was verified by measuring the length of the hydrogen bond between hydroxyl and carbonyl groups on the salicylic moiety.
- Petrlikova, Eva,Waisser, Karel,Palat Jr., Karel,Kunes, Jiri,Kaustova, Jarmila
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experimental part
p. 52 - 59
(2012/01/14)
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- Direct synthesis of diphenyl carbonate by mediated electrocarbonylation of phenol at Pd2+-supported activated carbon anode
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Mediated electrocarbonylation of phenol to diphenyl carbonate (DPC) at a PdCl2-supported activated carbon anode in 1 atm CO at 298 K was studied. A dry CH2Cl2 or CH3CN solvent and a galvanostatic electrolysis of 1 mA were necessary for formation of DPC, while the addition of a base and a supporting electrolyte was also essential. A combination of triethylamine (Et3N) and tetrabutylammonium perchlorate (Bu4NClO4) was suitable in various combinations. The addition of 2 equiv. of Et3N to the electrolyte (C6H5OH/Bu4NClO4/CH 2Cl2) at 1-h intervals was more efficient in the formation of DPC than a single initial addition of the same amount of Et3N. The yield of DPC was 130% based on Pd and its current efficiency (CE) was 42% for 6 h. The CE of the CO2 formation was only 3%. Sodium phenoxide (PhONa) showed dual functionality as a base and supporting electrolyte. When the mediated electrocarbonylation was conducted in a C6H 5OH/PhONa/CH3CN electrolyte, DPC was produced in 172% yield and 40% CE for 6 h. The CE of the CO2 formation was 10%. DPC formed continuously after a single initial addition of 4 equiv. of PhONa. Li or K phenoxide also worked as promoters for the mediated electrocarbonylation of phenol to DPC.
- Murayama, Toru,Hayashi, Tomohiko,Arai, Yuji,Yamanaka, Ichiro
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scheme or table
p. 2926 - 2933
(2011/05/16)
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- Formation of dibenzofurans by flash vacuum pyrolysis of aryl 2-(allyloxy)benzoates and related reactions
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Flash vacuum pyrolysis (FVP) of aryl 2-(allyloxy)benzoates 5 and of the corresponding aryl 2-(allylthio)benzoates 6 at 650°C, gives dibenzofurans 19 and dibenzothiophenes 20, respectively. The mechanism involves generation of phenoxyl (or thiophenoxyl) radicals by homolysis of the O-allyl (or S-allyl) bond, followed by ipso attack at the ester group, loss of CO2 and cyclisation of the resulting aryl radical. Synthetically, the procedure works well for p-substituted substrates, which lead to 2-substituted dibenzofurans 19b-f (73-90%) and dibenzothiophenes 20b-c (90-94%). Little selectivity is shown in the cyclisation of m-substituted substrates and competing interactions of the radical with the substituent - and ipso-attack - complicate the pyrolyses of o-substituted substrates. FVP of related radical precursors including 2-(allyloxy)phenyl benzoates 43 gave no dibenzofurans, whereas 2-(allyloxy-5-methyl)azobenzene 44 gave a much reduced yield. No carbazoles were obtained by FVP of 4-methylphenyl 2-(allylamino)benzoate 42.
- Black, Michael,Cadogan,McNab, Hamish
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experimental part
p. 2961 - 2967
(2010/09/06)
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- Vapour phase synthesis of salol over solid acids via transesterification
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The transesterification of methyl salicylate with phenol has been studied in vapour phase over solid acid catalysts such as ZrO2, MoO 3 and SO2-4 or Mo(VI) ions modified zirconia. The catalytic materials were prepared and characterized for their total surface acidity, BET surface area and powder XRD patterns. The effect of mole-ratio of the reactants, catalyst bed temperature, catalyst weight, flowrate of reactants, WHSV and time-on-stream on the conversion (%) of phenol and selectivity (%) of salol has been investigated. A good yield (up to 70%) of salol with 90% selectivity was observed when the reactions were carried out at a catalyst bed temperature of 200°C and flow-rate of 10 mL/h in presence of Mo(VI)/ZrO 2 as catalyst. The results have been interpreted based on the variation of acidic properties and powder XRD phases of zirconia on incorporation of SO2-4 or Mo(VI) ions. The effect of poisoning of acid sites of SO2-4 or Mo(VI) ions modified zirconia on total surface acidity, powder XRD phases and catalytic activity was also studied. Possible reaction mechanisms for the formation of salol and diphenyl ether over acid sites are proposed. Indian Academy of Sciences.
- Shamshuddin, S. Z. Mohamed,Nagaraju
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experimental part
p. 193 - 201
(2010/11/04)
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- Catalytic performance of metal oxide modified SiMcM-41 catalysts in diphenyl carbonate synthesis
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Decomposition of CCl4 into diphenyl carbonate (DPC) was examined over metal oxides modified SiMCM-41. ZnO/SiMCM-41 and Fe2O 3/SiMCM-41 showed high activity in DPC synthesis. Although many other metal oxides, such as La2O3, CuO, Al2O3 and alkali or alkaline earth oxide, were success in destruction of CCl4, they displayed nearly no activity on DPC synthesis. ZnO/SiMCM-41 and Fe2O3/SiMCM-41 were characterized by X-ray diffraction (XRD), UV-Raman, 29Si MAS NMR and N2 adsorption-desorption isotherms, and results showed that ferric and zinc oxide were supported onto SiMCM-41. The well ZnO dispersion in SiMCM-41 channels and the weak electrostatic interaction between chlorine anion and Zn2+ play an important role for the high activity of ZnO/SiMCM-41 in decomposition of CCl4 into DPC. Pleiades Publishing, Ltd., 2010.
- Su,Li,Cheng,Ren,Yu,Wang
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experimental part
p. 359 - 363
(2011/01/10)
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- Regiospecific phenyl esterification to some organic acids catalyzed by combined Lewis acids
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A new and efficient method for the preparation of various phenyl esters has been achieved by a simple reaction of an acid with phenol in the presence of anhyd. ZnCl2 and a catalytic amount of AlCl3. This combined Lewis acid also catalyzes the selective phenyl esterification to different dioic acids and is very simple and high yielding. Copyright Taylor & Francis Group, LLC.
- Roy,Mamun, A. H. Al
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p. 2975 - 2981
(2007/10/03)
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- Synthesis of diphenyl carbonate from CO2, phenoxide, and CCl4 with ZnCl2 as catalyst
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Direct synthesis of diphenyl carbonate (DPC) from phenoxide, CO2 and CCl4 in one pot was realized with ZnCl2 as catalyst. Trichloromethyl cation may act on potassium phenyl carbonate, which brings the carbonyl more easily attached on by the phenoxide. Onium salts promote the reaction greatly, especially with phenol and potassium carbonate instead of phenoxide as reactants. Moreover, the substituent on the aromatic ring has significant effects on the selectivity and yield of carbonate. Copyright
- Li, Zhenhuan,Qin, Zhangfeng,Zhu, Huaqing,Wang, Jianguo
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p. 784 - 785
(2007/10/03)
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- Piperidyl organosiloxanes and polymer substrates light-stabilized therewith
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Novel piperidyl organosiloxanes, well adapted for the light/UV-stabilization of a wide variety of polymer substrates, e.g., polyolefins and polyalkadienes, have the structural formula (I): STR1
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- Prodrugs - Part 1. Formylphenyl esters of aspirin
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The synthesis and study of a novel series of potential prodrugs of aspirin is reported. 2-, 3- and 4-formylphenyl aspirins, as well as a series of 4-substituted 2-formylphenyl aspirins, have been prepared. A study of their alkaline hydrolysis indicates that these compounds act as true prodrugs of aspirin which hydrolyse to aspirin and the formylphenol. The rates of hydrolysis and activation parameters indicate that hydrolysis of the 2-formylphenyl esters employs an intramolecular catalytic route.
- Bowden,Huntington,Powell
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p. 987 - 993
(2007/10/03)
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- A concise synthesis of arnottin I via internal biaryl coupling reaction using palladium reagent
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Total synthesis of arnottin I (1) was accomplished via the internal arylaryl coupling reaction of iodo-ester (2) by the palladium-assisted cyclization reaction.
- Harayama, Takashi,Yasuda, Hirotake
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- Formation and synthetic use of oxygen-centred radicals with (diacetoxyiodo)arenes
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o-Alkyl- or o-aryl-benzenecarboxylic acids and alcohols containing an aromatic ring are treated with a (diacetoxyiodo)arene-iodine system to give the corresponding cyclized products such as phthalide, benzocoumarin and chromane derivatives in moderate to good yields via the corresponding oxygen-centred radicals. For the carboxylic acids, [bis(trifluoroacetoxy)iodo]benzene functions effectively, while (diacetoxyiodo)benzene is effective for the alcohols. Chromane and its derivatives are obtained as iodinated compounds by hypoiodite species derived from (diacetoxyiodo)benzene and iodine. Copyright 1997 by the Royal Society of Chemistry.
- Togo, Hideo,Muraki, Takahito,Hoshina, Yoichiro,Yamaguchi, Kentaro,Yokoyama, Masataka
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p. 787 - 793
(2007/10/03)
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- Method of producing aromatic carbonate
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The present invention relates to a method of producing an aromatic carbonate by reacting an aromatic hydroxy compound, carbon monoxide and oxygen using a catalyst system for suppressing the production of aryl aromatic o-hydroxycarboxylate as a by-product. The catalyst system consists of the following compounds: (A) at least one selected from palladium and palladium compounds; (B) at least one selected from lead compounds; and (C) at least one halide selected from quaternary ammonium halides and quaternary phosphonium halides; and if required, (D) at least one selected from copper and copper compounds. The method of the present invention can increase the yield of an aromatic carbonate per palladium (the turnover number of palladium).
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- Formation of Dichloromethyl Phenyl Ethers as Major Products in Photo-Reimer-Tiemann Reaction without Base
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Photolysis of phenols 1a-d in chloroform or carbon tetrachloride afforded the corresponding di- or trichloromethyl phenyl ethers (2a-d or 6a-d, respectively).In chloroform, hydroxybenzaldehydes 4a-d or 5 and phenyl formates 3a-d were obtained as minor photoproducts.In carbon tetrachloride, traces of salicyloyl chloride (7), phenyl salicylate (8) and phenyl p-hydroxybenzoate (9) were detected starting from the parent phenol (1a).The obtained results agree with the involvement of an electron transfer mechanism.
- Jimenez, M. Consuelo,Miranda, Miguel A.,Tormos, Rosa
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p. 5825 - 5830
(2007/10/02)
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- Process for producing an organic carbonate
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A process for producing an organic carbonate which comprises reacting an organic hydroxy compound, carbon monoxide and oxygen in the presence of a catalyst comprising(a) palladium or a palladium compound, (b) a cuprous or cupric compound such as cupric acetate, (c) a quinone or an aromatic diol formed by reduction of the quinone or a mixture thereof such as hydroquinone, and (d) a halogenated onium compound such as (C4 H9)NBr is disclosed. According to the invention, an organic carbonate such as diphenyl carbonate can be produced efficiently and economically.
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- Transparent cosmetic composition that reflects infrared radiation and its use for protecting the human epidermis against infrared radiation
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Transparent cosmetic composition that reflects infrared radiation and its use for protecting the human epidermis against infrared radiation. The invention relates to a transparent cosmetic composition comprising, by way of an agent that reflects infrared radiation for protecting the human epidermis, a substance which is dispersible in the cosmetic medium used, possessing a reflectance (R) of infrared radiation equal to at least 45%, and of which a 2% strength dispersion in vaseline possesses an optical transmission in the visible of at least 85%, chosen from a diatom of particle size less than 100 microns, hollow glass microspheres of size less than 100 microns, a bismuth oxychloride of particle size less than 75 microns and zirconium powder covered ceramic microparticles of particle size less than 8 microns. This cosmetic composition can also contain 0.5 to 20% by weight of UV-A, UV-B or broad-band screening agents.
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- Evaluation of glycolamide esters and various other esters of aspirin as true aspirin prodrugs
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A series of glycolamide, glycolate, (acyloxy)methyl, alkyl, and aryl esters of acetylsalicylic acid (aspirin) were synthesized and evaluated as potential prodrug forms of aspirin. N,N-Disubstituted glycolamide esters were found to be rapidly hydrolized in human plasma, resulting in the formation of aspirin as well as the corresponding salicylate esters. These in turn hydrolyzed rapidly to salicylic acid. The largest amount of aspirin formed from the esters were 50 and 55% in case of the N,N-dimethyl- and N,N-diethylglycolamide esters, respectively. Similar results were obtained in blood with the N,N-dimethyl- and N,N-diethylglycolamide esters. Unsubstituted and monosubstituted glycolamide esters as well as most other esters previously suggested to be aspirin prodrugs were shown to hydrolyze exclusively to the corresponding salicylic acid esters. Lipophilicity parameters and water solubilities of the esters were determined, and structural factors favoring ester prodrug hydrolysis at the expense of deacetylation to yield salicylate ester are discussed. The properties of some N,N-disubstituted glycolamide esters of aspirin are highlighted with respect to their use as potential aspirin prodrugs.
- Nielsen,Bundgaard
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p. 727 - 734
(2007/10/02)
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- A New Deprotection Method for Levulinyl Protecting Groups under Neutral Conditions
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Sulfit ion-induced cleavage of the levulinyl group under neutral conditions provides a convenient and mild deprotection method especially for alkali labile and/or oxygen sensitive compounds.
- Ono, Mitsunori,Itoh, Isamu
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p. 585 - 588
(2007/10/02)
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- The Reaction of N-Carboalkoxy Reissert Analogs with Carboxylic Acids
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The reaction of N-carboalkoxy Reissert analogs in the presence of carboxylic acids yields the corresponding ester and heterocyclic base.Use of methoxy substituted benzoic acids yields, instead of the ester, the respective anhydride.Amides can also be prepared in a similar fashion.
- Popp, Frank D.,Duarte, Frederick F.,Uff, Barrie C.
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p. 1353 - 1355
(2007/10/02)
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- Catalysts for alkoxylation reactions
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Catalysts producing a sharply peaked alkoxylation distribution during the alkoxylation of organic materials comprise mixtures of BF3 and metal alkyls or metal alkoxides, SiF4 and metal alkyls or metal alkoxides, or mixtures of these catalysts.
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- Methods of alkoxylation
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Catalysts comprising mixtures of HF and metal alkoxides and mixed metal alkoxides produce a sharply peaked alkoxylation distribution during the alkoxylation of organic materials.
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- Catalysts for alkoxylation reactions
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Catalysts and a method of using said catalysts for the alkoxylation of a variety of materials is disclosed. Catalysts so described produce alkoxylates having a very sharp alkoxylate distribution. The catalysts are supported and unsupported dialkoxy and dialkyl metal fluorides and halides and alkyl metal difluorides and dihalides.
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- Aromatic salicylate process
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An aromatic salicylate process comprising contacting a phenol, carbon monoxide, a base, a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum and recovering at least a portion of an aromatic salicylate. The resulting aromatic salicylates are useful in plastics and lacquers as well as in pharmaceuticals.
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