Reaction Of Phenol Research Articles

Synthesis of Coumarin Derivatives Through Pechmann Condensation Reaction of Phenols and β‐Ketoesters using Basalt Fiber Functionalized with 7‐aminonaphthalene‐1,3‐disulfonic acid as a New, Environment Friendly and Recyclable Catalyst

AbstractIn this paper, a series of coumarin derivatives were synthesized, through the Pechmann condensation reaction using basalt fiber functionalized with 7‐aminonaphthalene‐1,3‐disulfonic acid (BF@(CH2)3‐Cl‐ANDSA) as environmentally friendly and heterogeneous catalyst. The structure of the catalyst was identified by FT‐IR, XRD, EDS‐Mapp, FE‐SEM, and TGA analysis. The catalyst was found to be efficient for the synthesis of coumarin derivatives through Pechmann condensation. phenols were treated with β‐ketoesters to give coumarin derivatives, under green conditions. The current method has several advantages, such as non‐toxic, short reaction time, high thermal stability, recyclability, and reusability of the catalyst.

Tuning the 1O2 Oxidation of a Phenol at the Air/Solid Interface of a Nanoparticle: Hydrophobic Surface Increases Oxophilicity.

Although silica surfaces have been used in organic oxidations for the production of peroxides, studies of airborne singlet oxygen at interfaces are limited and have not found widespread advantages. Here, with prenyl phenol-coated silica and delivery of singlet oxygen (1O2) through the gas phase, we uncover significant selectivity for dihydrofuran formation over allylic hydroperoxide formation. The hydrophobic particle causes prenyl phenol to produce an iso-hydroperoxide intermediate with an internally protonated oxygen atom, which leads to dihydrofuran formation as well as O atom transfer. In contrast, hydrophilic particles cause prenyl phenol to produce allylic hydroperoxide, due to phenol OH hydrogen bonding with SiOH surface groups. Mechanistic insight is provided by air/nanoparticle interfaces coated with the prenyl phenol, in which product yield was 6-fold greater on the hydrophobic nanoparticles compared to the hydrophilic nanoparticles and total rate constants (ASI-kT) of 1O2 were 13-fold greater on the hydrophobic vs hydrophilic nanoparticles. A slope intersection method was also developed that uses the airborne 1O2 lifetime (τairborne) and surface-associated 1O2 lifetime (τsurf) to quantitate 1O2 transitioning from volatile to non-volatile and surface boundary (surface···1O2). Further mechanistic insights on the selectivity of the reaction of prenyl phenol with 1O2 was provided by density functional theory calculations.

Asymmetric para-Selective aza-Friedel–Crafts Reaction of Phenols Catalyzed by Bulky PyBidine-Ni(OAc)2

Asymmetric <i>para</i>-Selective aza-Friedel–Crafts Reaction of Phenols Catalyzed by Bulky PyBidine-Ni(OAc)₂

One-pot, simple, and facile synthesis of 4-(3-benzylbenzo[d]thiazol-2(3H)-ylidene)-cyclohexa-2,5-dien-1-one derivatives via a novel three-component reaction

In this study, a series of 4-(3-benzylbenzo[ d]thiazol-2(3 H)-ylidene)-cyclohexa-2,5-dien-1-one derivatives are efficiently synthesized in excellent yields by reactions of 2-chlorobenzothiazole, benzyl bromides, and phenols in acetonitrile under reflux and catalyst-free conditions in the presence of triethylamine for 2 h. The structures of the products are characterized by NMR, IR, EI-MS, and elemental analyses.

Enantioselective organocatalytic Friedel-Crafts reaction of electron-rich phenols and isatins by Takemoto's thiourea catalyst.

Takemoto's catalysts were used to organocatalyze the enantioselective Friedel-Crafts reaction with different electron-rich phenols and substituted isatins. The resulting 3-aryl-3-hydroxyl-2-oxindoles were obtained in good yields (85-96%) with up to 99% ee. The substrate scope was broadened with this methodology compared to reported examples catalyzed by cinchonidine thiourea.

Scope and Mechanistic Studies on the Ruthenium-Catalyzed Multicomponent Deaminative C–H Coupling Reaction of Phenols with Aldehydes and Enamines for the Formation of Xanthene and Dioxacyclic Derivatives

The in situ generated catalytic system from the tetranuclear Ru–H complex [(PCy3)(CO)RuH]4(O)(OH)2 (1) with 3,4,5,6-tetrachloro-1,2-benzoquinone (L1) has been found to mediate a multicomponent deaminative coupling reaction of phenols with aldehydes and enamines to form xanthene products. The multicomponent C–H coupling reaction of phenols with 2-hydroxybenzaldehydes and cyclic enamines efficiently installed the tricyclic 1,3-dioxacin derivatives, while the analogous coupling reaction of phenols with 2-hydroxybenzaldehydes and triethylamine selectively formed bicyclic 1,5-dioxacyclic derivatives. The density functional theory (DFT) calculations established two energetically viable mechanistic pathways for the formation of xanthene products, in which both pathways identified the C–O bond cleavage step as the turnover limiting step. A Hammett plot from the coupling reaction of 3,5-dimethoxyphenol with an enamine and para-substituted benzaldehydes p-X-C6H4CHO (X = OMe, Me, H, Cl, CF3) showed a negative slope (ρ = −0.98). The calculated energy analysis showed a similar trend (ρ = −0.59) for the mechanism via the C–O cleavage rate-limiting step. The combined experimental and DFT computational results support a mechanistic path that involves the dehydrative C–H coupling of phenol with aldehyde, followed by the deaminative coupling reaction with an enamine in forming the xanthene product.

Catalytic Asymmetric Synthesis of Aza-Quaternary Carbon Cyclohexadieneones Enabled by Aminative Dearomatization of Phenols.

Reported herein is the catalytic asymmetric aminative dearomatization reaction of common phenols. As opposed to the well-studied indoles and naphthols, phenols are supposed to be challenging substrates for catalytic asymmetric dearomatization reactions in terms of their strong aromaticity and regioselectivity issues. Under the catalysis of a chiral phosphoric acid, the C4-regiospecific aminative dearomatization of phenols with azodicarboxylates readily occurred at ambient temperature, delivering an array of biologically and synthetically important aza-quaternary carbon cyclohexadieneones in good yields and with excellent enantioselectivities (29 examples, up to 98% yield, and >99% ee).

Generation and structure elucidation of a red colorant formed by oxidative coupling of chlorogenic acid and tryptophan

In view of the poor acceptance of synthetic food colorants by consumers, there is intense interest in novel natural compounds, preferably from plant-derived sources. We oxidized chlorogenic acid using NaIO4 and reacted the resultant quinone with tryptophan (Trp) to obtain a red-colored product. The colorant was precipitated, freeze-dried, purified by size exclusion chromatography, and subsequently characterized using UHPLC-MS, high-resolution mass spectrometry, and NMR spectroscopy. Additional mass spectrometric studies were performed on the reaction product generated with Trp educts labeled with 15N and 13C. The data obtained from these studies allowed the identification of a complex compound consisting of two Trp and one caffeic acid moieties, and the proposition of a tentative pathway of its formation. Thus, the present investigation expands our knowledge about the formation of red colorants based on the reaction of plant phenols and amino acids.

ReaxFF-MD simulation investigation of the degradation pathway of phenol for hydrogen production by supercritical water gasification

Wastewater from the thermochemical conversion of coal and biomass contains a significant amount of phenolic structures compounds. The degradation of these phenolic compounds to hydrogen-rich gasses can prevent environmental pollution and save energy. Supercritical water (SCW) gasification of phenol is experimentally studied and a reactive force field molecular dynamics (ReaxFF-MD) simulation is conducted to investigate the catalytic mechanism of Ni/Al2O3 in the phenol degradation. The experimental results indicate that Ni/Al2O3 facilitates the conversion of phenol to 1-ethoxy butane via ring opening, which is a crucial step for complete gasification. The ReaxFF-MD simulation demonstrated that Ni facilitates the formation of H3O free radicals and Ni-phenol intermediates. H3O free radicals can be decomposed into H2 and OH free radicals. Both the generated OH free radical and Ni-phenol intermediate promote the ring-opening reaction of phenol. Ni promotes the direct decomposition of phenol into C1, C2, and C3 fragments, which is beneficial for further complete gasification.

Study on improving toughness of phenolic resin via introducing triolein during synthesis

ABSTRACT Phenolic resin modified by triolein was synthesized by a two-step process. First, the modified resin was prepared by electrophilic addition reaction of phenol with triolein in acidic environment, then reacted with formaldehyde. The impact strength of modified phenolic resin increased by19~71% compared to that of pure phenolic resin. The maximum elongation at break of modified phenolic resin was higher by about 271% than that of pure phenolic resin. Toughness of modified phenolic resin was greatly improved through triolein treatment by bringing in the methylene, ester bond and aliphatic long chains. In terms of thermal properties, the addition of triolein has increased Tg of the modified phenolic resin a. The viscosity of phenolic resin also increased significantly by introducing triolein into phenolic resin. The preparation method developed here is simple and easy, which can expand the application of phenolic resin in adhesive production.

One-Pot Synthesis of Diverse 1,4-[60]Fullerephenols via Three-Component Umpolung Cascade Coupling of Phenols, C60 , and Nucleophiles.

A three-component umpolung cascade coupling reaction of phenols, C60 , and different nucleophiles which includes H2 O, alcohols, triphenylamines and carbazoles was developed. Furthermore, one-pot 1,4-bisphenol coupling on C60 has been realized by this method. This practical protocol features high chemo- and regioselectivity, wide substrate range, easy operation and low cost, thus providing a robust method for the one-pot synthesis of various unsymmetrical 1,4-[60]fullerephenols.

Reactions of phenol and its derivatives with levoglucosenone

Reactions of phenol and its derivatives with levoglucosenone

Atroposelective Three-Component Coupling of Cyclic Diaryliodoniums and Sodium Cyanate Enabled by the Dual-Role of Phenol.

A copper-catalyzed atroposelective ring-opening reaction of cyclic diaryliodoniums, sodium cyanate (NaOCN) and phenols is reported. The reaction chemoselectively affords axially chiral carbamates by sequential coupling of cyclic diaryliodonium and NaOCN, followed by phenol. Mechanistic investigations revealed that phenol is not only a reagent to trap highly active intermediate isocyanates, but it also activates the copper catalyst as a standby ligand. The carbamates were readily transformed into highly functionalized urea derivatives within a simple nucleophilic substitution reaction.

Atroposelective Three‐Component Coupling of Cyclic Diaryliodoniums and Sodium Cyanate Enabled by the Dual‐Role of Phenol

AbstractA copper‐catalyzed atroposelective ring‐opening reaction of cyclic diaryliodoniums, sodium cyanate (NaOCN) and phenols is reported. The reaction chemoselectively affords axially chiral carbamates by sequential coupling of cyclic diaryliodonium and NaOCN, followed by phenol. Mechanistic investigations revealed that phenol is not only a reagent to trap highly active intermediate isocyanates, but it also activates the copper catalyst as a standby ligand. The carbamates were readily transformed into highly functionalized urea derivatives within a simple nucleophilic substitution reaction.

Enhanced visible-light photocatalytic activity of Ni(1-x)BixTiO3 prepared by solvothermal method

In this study, a new Ni(1-x)BixTiO3 tannate-based perovskite with excellent photocatalytic properties under visible light was developed. Ni(1-x)BixTiO3 was prepared by a solvothermal method coupled with a sol–gel method. The Ni(1-x)BixTiO3 photocatalyst showed better light absorption than NiTiO3 in the UV and visible light regions. The bandgap energy (∼2.21 eV) of Ni(1-x)BixTiO3 was also smaller than that of NiTiO3. In the decomposition reaction of methylene blue and phenol under visible light (550–650 nm), the decomposition efficiency of the Ni(1-x)BixTiO3 photocatalyst was higher than that of NiTiO3. Among the Ni(1-x)BixTiO3 photocatalysts, Ni0.8Bi0.2TiO3 showed the highest visible light photocatalytic performance.

Heterogeneous Photodegradation Reaction of Phenol Promoted by TiO2: A Kinetic Study

Phenol is widely used in industry. Due to its high stability and toxicity, it represents a threat to the environment and human health. In this study, a kinetic investigation of phenol heterogeneous photodegradation was conducted using commercial Aeroxide P-25, performing experiments in a wide range of conditions. In detail, a negligible adsorption effect was detected. An activation energy of Ea = 14.3 ± 0.5 kJ mol−1 was measured, and the catalyst loading effect indicated an optimal condition due to the shield of the catalyst particles to the UV irradiation. The catalyst was most active at pH = 7 and it was stable for 25 h of reaction time; thus, it will be worth to investigate its application in flow.

Brønsted acid-catalyzed asymmetric dearomatization for synthesis of chiral fused polycyclic enone and indoline scaffolds.

In the past two decades, substantial advances have been made on the asymmetric alkyne functionalization by the activation of inert alkynes. However, these asymmetric transformations have so far been mostly limited to transition metal catalysis, and chiral Brønsted acid-catalyzed examples are rarely explored. Here, we report a chiral Brønsted acid-catalyzed dearomatization reaction of phenol- and indole-tethered homopropargyl amines, allowing the practical and atom-economical synthesis of a diverse array of valuable fused polycyclic enones and indolines bearing a chiral quaternary carbon stereocenter and two contiguous stereogenic centers in moderate to good yields with excellent diastereoselectivities and generally excellent enantioselectivities (up to >99% enantiomeric excess). This protocol demonstrates Brønsted acid-catalyzed asymmetric dearomatizations via vinylidene-quinone methides.

Reactivity of Bromine Radical with Dissolved Organic Matter Moieties and Monochloramine: Effect on Bromate Formation during Ozonation.

Bromine radical (Br•) has been hypothesized to be a key intermediate of bromate formation during ozonation. Once formed, Br• further reacts with ozone to eventually form bromate. However, this reaction competes with the reaction of Br• with dissolved organic matter (DOM), of which reactivity and reaction mechanisms are less studied to date. To fill this gap, this study determined the second-order rate constant (k) of the reactions of selected organic model compounds, a DOM isolate, and monochloramine (NH2Cl) with Br• using γ-radiolysis. The kBr• of all model compounds were high (kBr• > 108 M-1 s-1) and well correlated with quantum-chemically computed free energies of activation, indicating a selectivity of Br• toward electron-rich compounds, governed by electron transfer. The reaction of phenol (a representative DOM moiety) with Br• yielded p-benzoquinone as a major product with a yield of 59% per consumed phenol, suggesting an electron transfer mechanism. Finally, the potential of NH2Cl to quench Br• was tested based on the fast reaction (kBr•,NH2Cl = 4.4 × 109 M-1 s-1, this study), resulting in reduced bromate formation of up to 77% during ozonation of bromide-containing lake water. Overall, our study demonstrated that Br• quenching by NH2Cl can substantially suppress bromate formation, especially in waters containing low DOC concentrations (1-2 mgC/L).

Generation of Ru(III)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme.

The reaction of [(Me/BnTPEN)RuII(NCCH3)]2+ (BnTPEN = N1-benzyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine and MeTPEN = N1-methyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine) with mCPBA in the presence of chloride ions in CH3CN : H2O generated a novel (Me/BnTPEN)RuIII-OCl species at room temperature. This hypochlorite adduct could also be obtained by the direct reaction of NaOCl and HClO4 with (L)RuII complexes. The current study mimics the synthesis of a metal hypochlorite adduct in a similar fashion as in the heme-dependent haloperoxidase enzyme. As an electrophilic oxidant, the ruthenium hypochlorite adduct catalyzes hydrogen atom abstraction reactions of phenols and their derivatives.

Rh(III)-catalyzed (5 + 2)-cycloaddition reactions of ortho-hydroxyethyl phenols with internal alkynes: efficient synthesis of benzoxepines.

An unprecedented (5 + 2)-cycloaddition reaction of ortho-hydroxyethyl phenol and internal alkyne was developed. This Rh(III)-catalyzed reaction provided benzoxepine derivatives which have very high biological significance. A wide range of ortho-hydroxyethyl phenols and internal alkynes were studied to provide the benzoxepines in high yields.