108-46-3Relevant articles and documents
-
Lock
, p. 1759,1764 (1933)
-
Deoxygenation of polyhydroxybenzenes: An alternative strategy for the benzene-free synthesis of aromatic chemicals
Hansen, Chad A.,Frost
, p. 5926 - 5927 (2002)
New synthetic connections have been established between glucose and aromatic chemicals such as pyrogallol, hydroquinone, and resorcinol. The centerpiece of this approach is the removal of one oxygen atom from 1,2,3,4-tetrahydroxybenzene, hydroxyhydroquinone, and phloroglucinol methyl ether to form pyrogallol, hydroquinone, and resorcinol, respectively. Deoxygenations are accomplished by Rh-catalyzed hydrogenation of the starting polyhydroxybenzenes followed by acid-catalyzed dehydration of putative dihydro intermediates. Pyrogallol synthesis consists of converting glucose into myo-inositol, oxidation to myo-2-inosose, dehydration to 1,2,3,4-tetrahydroxybenzene, and deoxygenation to form pyrogallol. Synthesis of pyrogallol via myo-2-inosose requires 4 enzyme-catalyzed and 2 chemical steps. For comparison, synthesis of pyrogallol from glucose via gallic acid intermediacy and the shikimate pathway requires at least 20 enzyme-catalyzed steps. A new benzene-free synthesis of hydroquinone employs conversion of glucose into 2-deoxy-scyllo-inosose, dehydration of this inosose to hydroxyhydroquinone, and subsequent deoxygenation to form hydroquinone. Synthesis of hydroquinone via 2-deoxy-scyllo-inosose requires 2 enzyme-catalyzed and 2 chemical steps. By contrast, synthesis of hydroquinone using the shikimate pathway and intermediacy of quinic acid requires 18 enzyme-catalyzed steps and 1 chemical step. Methylation of triacetic acid lactone, cyclization, and regioselective deoxygenation of phloroglucinol methyl ether affords resorcinol. Given the ability to synthesize triacetic acid lactone from glucose, this constitutes the first benzene-free route for the synthesis of resorcinol. Copyright
Synthetic Study on Acremoxanthone A: Construction of Bicyclo [32.2]nonane CD Skeleton and Fusion of AB Rings
Hirano, Yoichi,Tokudome, Kensei,Takikawa, Hiroshi,Suzuki, Keisuke
, p. 214 - 220 (2017)
Toward the total synthesis of acremoxanthone A, a model study has revealed a convergent approach to construct the ABCDE ring system. The key steps include: (1) an effective construction of the bicyclo[3.2.2]nonane skeleton, (2) protocol for generating the bridgehead anion and trapping, and (3) 1,3-dipolar cycloaddition of a nitrile oxide to the internal alkene.
Spectroscopy of hydrothermal reactions 23: The effect of OH substitution on the rates and mechanisms of decarboxylation of benzoic acid
Li, Jun,Brill, Thomas B.
, p. 2667 - 2673 (2003)
The decarboxylation rates of aqueous benzoic acid and 12 mono-, di-, and trihydroxy derivatives of benzoic acid were compared by using spectra from a flow reactor FTIR spectroscopy cell operating at 275 bar in the temperature range of 120-330 °C. Each compound was investigated at its natural pH and as the neutral acid (pH = 1.3-1.5). The decarboxylation reactions followed the first-order (or pseudo-first-order) rate law enabling the rate constants and corresponding Arrhenius parameters of the undissociated acids to be obtained. Based on the half-lives of the reactions at 200 °C, the thermal stability of the OH substituted benzoic acids follow the order: 2,4,6 > 2,4 > 2,3,4 > 2,6 > 2,5 > 2,3 > 3,4,5 > 2 > 3,4 > 4. Solutions of 3,5-dihydroxybenzoic and 3-hydroxybenzoic acids and unsubstituted benzoic acid had the highest thermal stability, whereas no decarboxylation was observed up to 330 °C at a residence time of about 45s. In general, the rate order is multiple ortho, para-OH substitution > ortho substitution > para substitution > meta substitution. The range of activation energies for the decarboxylation of OH substituted benzoic acids is 90-97 kJ/mol, and the rate differences are controlled mainly by activation entropy. The transition state structures were determined using density functional theory. Starting from the anti carboxylic hydrogen conformers in the gas phase, the activation energies to the transition state structures having the four-member C-C(O)-O-H ring are 213-260 kJ/mol using B3LYP/6-31G//B3LYP/6-31G and 202-246 kJ/mol using B3LYP/6-31+G(d,p)//B3LYP/6-31G(d). Incorporation of one water molecule forms a six-member cyclic structure, which dramatically reduces the activation energy by about 120-130 kJ/mol using B3LYP/6-31G//B3LYP/6-31G and by about 75 kJ/mol using B3LYP/6-31+G(d,p)//B3LYP/6-31G(d). In the water-catalyzed transition state structure, the water molecule acts as a bridge linked by two hydrogen bonds which enables concerted proton transfer and C-(CO2H) bond cleavage to occur. Although the calculated activation energy approximately follows the trend of the experimental half-lives, the experimental activation entropy appears to dominate in determining the rates.
-
Nunn,Rapson
, p. 3151,3155 (1949)
-
Ledwith,Woods
, p. 1422 (1970)
Chirikdjian et al.
, p. 1105 (1969)
Polymorphism in isomeric dihydroxybenzoic acids
Sarma, Bipul,Sanphui, Palash,Nangia, Ashwini
, p. 2388 - 2399 (2010)
Multifunctional molecules are capable of assembling via different supramolecular synthons, or hydrogen bond motifs, between the same or different functional groups, leading to the possibility of polymorphism. We have employed sublimation and melt crystallization to generate two new crystalline polymorphs of 3,5-dihydroxybenzoic acid (DHBA), and a second form for 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid each. Since hydroxybenzoic acids tend to give solvate/hydrate crystal structures by solution crystallization, solvent-free methods are necessary to obtain single crystals of unsolvated forms. In addition to guest-free polymorphs, a new hydrate polymorph of 3,4-dihydroxybenzoic acid was crystallized from cold water. Polymorphs of dihydroxybenzoic acids differ in the number of symmetry-independent molecules (Z'), the nature of the hydrogen bond synthon, the molecular packing, and the unit cell parameters. Structural and thermal characterization of polymorphic phases shows that the commercial material matches with the high Z' phase for 2,3-DHBA, 3,5-DHBA, and 3,4-DHBA hydrate even though a low Z' crystal structure is known in each case. Solventless crystallization conditions at high temperature are a practical method to generate new guest-free polymorphs and high Z' crystal structures for high affinity functional group compounds.
A {110} facet predominated Bi6O6(OH)3(NO3)3·1.5H2O photocatalyst: Selective hydrothermal synthesis and its superior photocatalytic activity for degradation of phenol
Yang, Li-Min,Zhang, Guo-Ying,Liu, Yue,Xu, Yan-Yan,Liu, Chun-Mei,Liu, Jing-Wang
, p. 79715 - 79723 (2015)
A basic bismuth(iii) nitrate photocatalyst with the composition of Bi6O6(OH)3(NO3)3·1.5H2O (BBN) was facilely synthesized using a hydrothermal strategy via incomplete hydrolysis of bismuth nitrate. Characterization of the composition, morphology, microstructure, optical absorption, BET surface area, and photocatalytic behavior was systematically explored. The results indicated that BBN architectures built up of multilayered meshing-teeth structures with predominant {110} side facets can be selectively obtained by fine-tuning the reaction parameters. The sample exhibits an obviously superior photocatalytic activity for the degradation of phenol compared with BBN sheets with dominant top {001} planes and commercial P25, with the rate constant k improved by 3.6 and 2.8 fold, respectively. The excellent photocatalytic behavior combined with the rather low BET surface area of 0.0453 m2 g-1 indicate that the highly reactive {110} facets in BBN are responsible for the photocatalysis. The active oxidation species and main intermediates in the phenol/BBN system are ascertained using scavenger experiments and high performance liquid chromatography (HPLC) techniques. Combining the band edge of BBN and the redox potentials of the active species, a possible migration mechanism of photogenerated e-/h+ pairs on the surface of BBN is proposed. This work provides some new insights for the rational design and synthesis of active-facet exposed basic salt photocatalysts with excellent efficiency.
Polyhedral Pt vs. spherical Pt nanoparticles on commercial titanias: Is shape tailoring a guarantee of achieving high activity?
Kovács,Fodor, Sz.,Vulpoi,Schrantz,Dombi,Hernádi,Danciu,Pap, Zs.,Baia
, p. 156 - 167 (2015)
As shape tailoring is gaining more attention in the field of photocatalysis, exploration of the impact of noble metal (Pt) nanoparticles' morphology on the activity of TiO2-Pt nanocomposites is inevitable. Spherical and polyhedral Pt nanoparticles have been synthesized by chemical reduction, while Aldrich anatase, Aldrich rutile, and Aeroxide P25 were used as base photocatalysts. The nanocomposites were analyzed using DRS, XRD, and HRTEM to uncover morphological, optical, and structural peculiarities of the composite photocatalysts. The importance of the Pt nanoparticles' geometry was proven at three levels: (i) UV light-driven photodegradation of three model pollutants: phenol, methyl orange, and oxalic acid; (ii) the primary degradation intermediates' evolution profile in the case of phenol degradation; and (iii) photocatalytic H2 production.
-
Davis,Harrington
, p. 129,131 (1934)
-
Black TiO2 nanotube arrays decorated with Ag nanoparticles for enhanced visible-light photocatalytic oxidation of salicylic acid
Plodinec, Milivoj,Gr?i?, Ivana,Willinger, Marc G.,Hammud, Adnan,Huang, Xing,Pan?i?, Ivana,Gajovi?, Andreja
, p. 883 - 896 (2019)
Novel forms of black TiO2 nanotubes-based photocatalysts for water purification were prepared. Two features were combined: decoration of TiO2 nanotube arrays with Ag nanoparticles (sample TiO2-NT's@Ag) and further hydrogenation of this material (TiO2-NT's@Ag-HA). Obtained photocatalysts show high efficiency for degradation of salicylic acid, a typical water-borne pollutant. The photocatalysts considerably exceed the photocatalytic properties of TiO2 nanotubes and commercial TiO2 P25 taken as a reference for modeling of the photocatalytic process. The comparison of photocatalytic activities between novel photocatalyst was based on a numerical approach supported by the complex kinetic model. This model allowed a separate study of different contributions on overall degradation rate. The contributions include: salicylic acid photolysis, photocatalysis in UVB, UVA and in the visible part of applied simulated solar irradiation. The superior photocatalytic performance of the photocatalyst TiO2-NT's@Ag-HA, particularly under visible irradiation, was explained by the combined effect of a local surface plasmon resonance (LSPR) due to Ag nanoparticles and creation of additional energy levels in band-gap of TiO2 due to Ti3+ states at nanotube surfaces. The presence of Ag also positively influence charge separation of created electron-holes pairs. The synergy of several effects was quantified by a complex kinetic model through the factor of synergy, fSyn. Stability testing indicated that the catalysts were stable for at least 20 h. The novel design of catalysts, attached on Ti foils, presents a solid base for the development of more efficient photocatalytic reactors for large-scale with a long-term activity.
Raney ni-al alloy mediated hydrodehalogenation and aromatic ring hydrogenation of halogenated phenols in aqueous medium
Liu, Guo-Bin,Zhao, Hong-Yun,Zhang, Jie,Thiemannb, Thies
, p. 342 - 344 (2009)
Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a very powerful reducing agent and is highly effective for the reductive dehalogenation of polyhalogenated phenols and aromatic ring hydrogenation of phenols to the corresponding cyclohexanols.
Aqueous-phase hydrodeoxygenation of highly oxygenated aromatics on platinum
Yang, Jin,Williams, C. Luke,Ramasubramaniam, Ashwin,Dauenhauer, Paul J.
, p. 675 - 682 (2014)
Utilization of renewable sugars from biomass by a hybrid chemical process produces highly oxygenated aromatic compounds, such as phloroglucinol, which require catalytic reduction for desirable aromatic products. Aqueous phase hydrodeoxygenation of phloroglucinol on carbon-supported platinum produces resorcinol, phenol, cyclohexanol, cyclohexanone, and 1,3-cyclohexanediol by combinations of carbon-oxygen bond cleavage and carbon-carbon double bond hydrogenation. Carbon-carbon σ-bond cleavage was not observed. Hydrodeoxygenation was the primary reaction of phloroglucinol, leading to the production of resorcinol in the overall rate-limiting reaction, with an activation energy barrier of Ea = 117 kJ mol-1. Subsequent reactions of resorcinol produced 1,3-cyclohexanediol and phenol with similar energy barriers, Ea = 46 and Ea = 54 kJ mol-1, respectively. Further hydrogenation of phenol (Ea = 42 kJ mol -1) occurs through the intermediate, cyclohexanone, which is further reduced (Ea = 14 kJ mol-1) to the dominant product, cyclohexanol.
Copper phthalocyanine as an efficient and reusable heterogeneous catalyst for direct hydroxylation of benzene to phenol under mild conditions
Farahmand, Shohreh,Ghiaci, Mehran,Razavizadeh, Jala.S.
, p. 174 - 179 (2019)
The liquid-phase oxidation of benzene to phenol over copper phthalocyanine as a heterogeneous catalyst was studied at room temperature. Acetonitrile was chosen as the preferred solvent and hydrogen peroxide as an eco-friendly oxidant. The yield and selectivity of 13.9% and 100% were obtained, respectively. The catalyst was characterized by FT-IR, UV-Vis, XRD, TGA, XPS, 1H NMR, 13C NMR, CHN, BET, FE-SEM, TEM, and EDX analysis. The effects of different parameters on the catalytic performance of CuPc were also investigated. The reusability of the catalyst was studied, and the results showed that after five cycles the yield of phenol did not change noticeably, probably due to its stability in the reaction conditions.
Catalytic wet oxidation of phenol with Fe-ZSM-5 catalysts
Yan, Ying,Jiang, Songshan,Zhang, Huiping
, p. 3850 - 3859 (2016)
Fe-ZSM-5 and Fe2O3/ZSM-5 zeolite catalysts were prepared and tested for catalytic wet oxidation of phenol. First, Fe-ZSM-5 and Fe2O3/ZSM-5 zeolite catalysts were prepared by the hydrothermal synthetic and incipient wetness impregnation method and characterized to determine the framework and extra-framework Fe3+ species. Second, the catalytic properties of Fe-ZSM-5 in the oxidation of phenol were systematically studied to determine the optimum technological parameters by investigating the effects of reaction temperature, pH, catalyst concentration and stirring rate on the conversion of phenol. In addition to the phenol conversion, selectivity to CO2 and concentration of aromatic intermediates in the oxidation of phenol with the two catalysts were analyzed under the same optimum conditions. Leaching of iron from the catalysts, as well as the catalytic stability of Fe-ZSM-5, was also tested. Finally, the kinetics of catalytic wet oxidation of phenol with Fe-ZSM-5 was studied. The experimental results showed that both the framework and extra-framework Fe3+ species were present in Fe-ZSM-5. The oxidation reaction with Fe-ZSM-5 was performed well at a temperature of 70 °C, pH of 4, catalyst concentration of 2.5 g L-1, stirring rate of 400 rpm and reaction time of 180 min. The conversion of phenol reached 94.1%. From the catalytic results of the two catalysts, it can be concluded that the framework Fe3+ species may be more efficient in phenol oxidation than the extra-framework Fe3+ species, the stability of Fe-ZSM-5 was better and a relatively low decrease in activity could be found after three consecutive runs. The activation energy of 27.42 kJ mol-1 was obtained for phenol oxidation with Fe-ZSM-5.
Cleavage of Catechol Monoalkyl Ethers by Aluminum Triiodide-Dimethyl Sulfoxide
Sang, Dayong,Tian, Juan,Tu, Xiaodong,He, Zhoujun,Yao, Ming
, p. 704 - 712 (2019)
Using eugenol and vanillin as model substrates, a practical method is developed for the cleavage o -hydroxyphenyl alkyl ethers. Aluminum oxide iodide (O=AlI), generated in situ from aluminum triiodide and dimethyl sulfoxide, is the reactive ether cleaving species. The method is applicable to catechol monoalkyl ethers as well as normal phenyl alkyl ethers for the removal of methyl, ethyl, isopropyl, and benzyl groups. A variety of functional groups such as alkenyl, allyl, amide, cyano, formyl, keto, nitro, and halogen are well tolerated under the optimum conditions. Partial hydrodebromination was observed during the demethylation of 4-bromoguaiacol, and was resolved using excess DMSO as an acid scavenger. This convenient and efficient procedure would be a practical tool for the preparation of catechols.
-
Petersen,Baehr-Predari
, p. 126 (1871)
-
Study of the Reactivity of the [(PE1CE2P)Ni(II)] (E1, E2 = O, S) Pincer System with Acetonitrile and Base: Formation of Cyanomethyl and Amidocrotononitrile Complexes versus Ligand Decomposition by P-S Bond Activation
Hasche, Patrick,Spannenberg, Anke,Beweries, Torsten
, p. 4508 - 4515 (2019)
Nickel(II) chloride complexes with PE1CE2P (E = O, S) pincer ligands were used as precursors for the generation of cyanomethyl complexes in order to investigate the influence of variations (O vs S) in the side arms of the ligands on reactivity and stability of such compounds. In this regard, five hitherto unknown Ni(II) compounds were synthesized and fully characterized. Reaction of the Ni(II) chloride complex [(iPrPOCSPiPr)NiCl] (2-Cl) with 1 equiv of base and nitrile furnishes the cyanomethyl complex [(iPrPOCSPiPr)NiCH2CN] (2-CM). Increase of the amount of base and nitrile results in the formation of 3-amidocrotononitrile complexes [(iPrPOCOPiPr)NiNHC(CH3)CHCN] (1-ACN) and [(iPrPOCSPiPr)NiNHC(CH3)CHCN] (2-ACN). In contrast, similar reactions of the bis(thiophosphinite) complex 3-Cl resulted in formation of a tetranuclear Ni cluster (4) or a dinuclear 1,3-dithiolate-bridged PSCSP complex 5 by unexpected cleavage of P-S bonds of the pincer ligand.
Photocatalytic synthesis of phenols mediated by visible light using KI as catalyst
Huiqin, Wei,Wu, Mei
supporting information, (2021/11/30)
A transition-metal-free hydroxylation of iodoarenes to afford substituted phenols is described. The reaction is promoted by KI under white LED light irradiation and uses atmospheric oxygen as oxidant. By the use of triethylamine as base and solvent, the corresponding phenols are obtained in moderate to good yields. Mechanistic studies suggest that KI and catalysis synergistically promote the cleavage of C-I bond to form free aryl radicals.
Isotruxene-based porous polymers as efficient and recyclable photocatalysts for visible-light induced metal-free oxidative organic transformations
Zhang, Haowen,Zhang, Xiao,Zheng, Ying,Zhou, Cen
supporting information, p. 8878 - 8885 (2021/11/27)
Two new isotruxene-based porous polymers were prepared and demonstrated to be highly efficient, metal-free heterogeneous photocatalysts for oxidative transformations using air as the mild oxidant under visible-light irradiation. Both catalysts show excellent recyclability. In addition, the reactions can be performed in water, further indicating the greenness of this method. This journal is
Highly recyclable Ti0.97Ni0.03O1.97catalyst coated on cordierite monolith for efficient transformation of arylboronic acids to phenols and reduction of 4-nitrophenol
Hegde, M. S.,Prasanna,Usha, K. M.
supporting information, p. 14223 - 14234 (2021/10/25)
A stable Ni2+substituted TiO2catalyst (Ti0.97Ni0.03O1.97) has been synthesized by a solution combustion method with an average crystallite size of 7.5 nm. Ti1?xNixO2?x(x= 0.01-0.06) crystallizes in the TiO2anatase structure with Ni2+substituted in Ti4+ion sites and Ni taking a nearly square planar geometry. This catalyst is found to be highly active in the transformation of diverse arylboronic acids to the corresponding phenols. The catalyst coated cordierite monolith can even be recycled for up to 20 cycles with a cumulative TOF of 1.8 × 105h?1. In scale-up reactions, various phenols are synthesized by employing a single cordierite monolith. It also shows high performance in the reduction of 4-nitrophenol.
