Conversion Of Benzoic Acid Research Articles

Stabilizing Highly Reactive Aryl Carbanions in Water Microdroplets: Electrophilic Ipso-Substitution at the Air-Water Interface.

The fleeting existence of aryl carbanion intermediates in the bulk phase prevents their direct observation and spectroscopic measurement. In sharp contrast, we report the direct interception of such unstable species at the air-water interface of microdroplets. We observed the transformation of three types of aryl acids (benzoic, phenylsulfinic, and phenylboronic acids) into phenyl carbanion (Ph-) in water microdroplets, as examined by mass spectrometry. Experimental and theoretical evidence suggests that the high intrinsic electric field at the microdroplet surface is likely responsible for cleaving the respective acid functional groups of these substrates, generating Ph-, which can subsequently be trapped by an electrophile, including a proton, to yield the corresponding ipso-substitution product. While catalyst-free decarboxylation at ambient temperature is challenging in the bulk phase, we report over 30% instantaneous conversion of benzoic acid to Ph- in sprayed aqueous microdroplets in less than a millisecond. Thus, this study lays the foundation of a green chemical pathway for the aromatic electrophilic ipso-substitution reaction by spraying an aqueous solution of aryl acids, eliminating the need for any catalyst or reagent.

Insight into the Better Collaboration of NiO and MnOx in NiMn2O4 Spinel for Enhanced the Catalytic Oxidation Performance of Toluene

AbstractNiMn oxides with different ratios (NixMnyOz) as well as spinel‐type NiMn2O4 oxides were synthesized and utilized in the catalytic oxidation of toluene. The results indicate that NiMn2Ox synthesized by the oxygen‐only roasting method exhibits superior catalytic activity due to the appropriate metal valence distribution. The catalytic activity is strongly related with the crystalline phase structures, NiMn2O4 spinel oxides catalyst shows the best low‐temperature performance with 90 % conversion (T90) at 230 °C. Characterization results reveal that the superb catalytic performance of NiMn2O4 spinel oxide is mainly profit by the larger surface area, more abundant surface fugacious oxygen, stronger toluene adsorption capacity than that of the other NixMnyOz catalysts, which in favor of the speedy conversion of benzoic acid, improving the toluene catalytic performance. This finding provides a novel design strategy of NiMn composite oxides for synthesis of high‐efficiency performance toluene catalysts.

Establishing efficient toluene elimination over cobalt-manganese bimetallic oxides via constructing strong Co–Mn interaction

Doping proves to be an efficacious method of establishing intermetallic interactions for enhancing toluene oxidation performance of bimetallic oxides. However, conventional bimetallic oxide catalysts are yet to overcome their inadequacy in establishing intermetallic interactions. In this work, the dispersion of Mn–Co bimetallic sites was improved by hydrolytic co-precipitation, strengthening the intermetallic interactions which improved the structural and physicochemical properties of the catalysts, thus significantly enhancing its catalytic behavior. MnCo–H catalysts fabricated by the hydrolytic co-precipitation method showed promising catalytic performance (T50 = 223 °C, T90 = 229 °C), robust stability (at least 100 h) and impressive water resistance (under 10 vol.% of water) for toluene elimination. Hydrolytic co-precipitation has been found to improve dispersion of MnCo elements and to enhance interaction between Co and Mn ions (Mn4+ + Co2+ = Mn3+ + Co3+), resulting in a lower reduction temperature (215 °C) and a weaker Mn–O bond strength, creating more lattice defects and oxygen vacancies, which are responsible for superior catalytic properties of MnCo–H samples. Furthermore, in situ DRIFTs showed that gaseous toluene molecules adsorbed on the surface of MnCo–H were continuously oxidized to benzyl alcohol → benzaldehyde → benzoate, followed by a ring-opening reaction with surface-activated oxygen to convert to maleic anhydride as the final intermediate, which further generates water and carbon dioxide. It was also revealed that the ring-opening reaction for the conversion of benzoic acid to maleic anhydride is the rate-controlling step. This study reveals that optimizing active sites and improving reactive oxygen species by altering the dispersion of bimetals to enhance bimetallic interactions is an effective strategy for the improvement of catalytic behavior, while the hydrolytic co-precipitation method fits well with this corollary.

A Ru/RuO2 heterostructure boosting electrochemistry-assisted selective benzoic acid hydrogenation.

Electrocatalytic hydrogenation of benzoic acid (BA) to cyclohexanecarboxylic acid (CCA) at ambient temperature and pressure has been recognized as a promising alternative to thermal hydrogenation since water is required as the hydrogen source. So far, only a few Pt-based electrocatalysts have been developed in acidic electrolyte. To overcome the limitations of reactant solubility and catalyst corrosion, herein, carbon fiber-supported Ru electrocatalysts with abundant Ru/RuO2 heterojunctions were fabricated via cyclic electrodeposition between -0.8 and 1.1 V vs. Ag/AgCl. In an alkaline environment, a Ru/RuO2 catalyst achieves an excellent ECH reactivity in terms of high BA conversion (100%) and selectivity towards CCA (100%) within 180 min at a current density of 200/3 mA cm-2, showing exceptional reusability and long-term stability. 1-Cyclohexenecarboxylic acid (CEA) was identified as the reaction intermediate, whose the selectivity is governed by the applied potential. Kinetic studies demonstrate that ECH of BA over Ru/RuO2 follows a Langmuir-Hinshelwood (L-H) mechanism. In situ Raman spectroscopy and theoretical calculations reveal that the Ru/RuO2 interface enhances the adsorption strength of CEA, thereby facilitating the production of fully hydrogenated CCA. This work provides a deep understanding of the ECH pathway of BA in alkaline media, and gives a new methodology to fabricate heterostructure electrocatalysts.

Simple and Practical Conversion of Benzoic Acids to Phenols at Room Temperature.

Phenols are important organic molecules because they have found widespread applications in many fields. Herein, an efficient and practical approach to prepare phenols from benzoic acids via simple organic reagents at room temperature is reported. This approach is compatible with various functional groups and heterocycles and can be easily scaled up. To demonstrate its synthetic utility, bioactive molecules and unsymmetrical hexaarylbenzenes have been prepared by leveraging this transformation as strategic steps. Mechanistic investigations suggest that the key migration step involves a free carbocation instead of a radical intermediate. Considering the abundance of benzoic acids and the utility of phenols, it is anticipated that this method will find broad applications in organic synthesis.

Highly selective electrocatalytic hydrogenation of benzoic acid over Pt/C catalyst supported on carbon fiber

Cyclohexanecarboxylic acid (CCA), an important chemical and pharmaceutical intermediate, is commonly produced from thermal catalytic hydrogenation of benzoic acid (BA) under high temperature and pressure. Herein, electrocatalytic hydrogenation (ECH) for highly selective conversion of BA into CCA using carbon fibers with different graphitization degree (carbon fiber paper (CFP), carbon fiber cloth (CFC)) supported commercial platinum carbon (Pt/C) electrode was reported for the first time without using external H2. Our experimental results show that, at room temperature and 1 atm, the BA conversion and the CCA selectivity are both as high as 100% in 0.05 M H2SO4 over carbon fiber paper (CFP)-supported Pt/C (Pt/C/CFP). Meanwhile, Pt/C/CFP electrode still maintains outstanding stability after 10 reaction cycles. In situ Raman results and theoretical calculations reveal that the adsorption strength of BA over Pt/C/carbon fibers electrode varies with the graphitization degree of carbon fibers along with the applied potential. The superior ECH performance of the Pt/C/CFP is mainly attributed to the high dispersity of Pt/C catalysts on CFP as well as unique electronic interaction, which improved the adsorption and activation of BA. Typically, CFP with few defects can induce the accumulation of electrons around the Pt regions and enhance the electron-deficient aromatic adsorption thus improving the ECH performance of Pt/C/CFP, which is the opposite for CFC with more defects.

КІНЕТИЧНІ ДОСЛІДЖЕННЯ ТА МОДЕЛЮВАННЯ ПРОЦЕСУ ЕСТЕРИФІКАЦІЇ БЕНЗОЙНОЇ КИСЛОТИ

The kinetic regularities of benzoic acid esterification with 1-butyl alcohol catalyzed by p-toluenesulfonic acid under stationary conditions have been studied. The study shows that the reaction has the first order with respect to benzoic acid. It is proposed a method for calculating the forward and reverse reaction constants, and the equilibrium constant using the determined effective rate constant of the esterification reaction. The preexponential factors and activation energies of the forward and reverse reactions as well as the thermal effect and the entropy change of the esterification reaction have been calculated. In particular, the thermal effect of benzoic acid esterification reaction with 1-butyl alcohol at a temperature of 365.2–389.4 K is 622 J∙mol-1, and the activation energies of the forward and reverse reactions are 58.40 and 57.70 kJ∙mol-1, respectively. The calculated kinetic characteristics of the esterification reaction were used in mathematical modeling of the butyl benzoate obtaining process under nonstationary conditions. Taking into account the kinetic characteristics of the reactions and the stages peculiarities of the butyl benzoate obtaining process the calculation of the change in the benzoic acid conversion over time was performed. The study shows that under optimal conditions the benzoic acid conversion in 120 min reaches 92 %. The use of the experimental results and the created mathematical model of benzoic acid esterification process with 1-butyl alcohol makes it possible to calculate of kinetic curves of the reagent consumption under nonstationary conditions. The experimentals can be used to improve the technological process of the butyl benzoate manufacture in the industry.

Efficient photocatalytic toluene degradation over heterojunction of GQDs@BiOCl ultrathin nanosheets with selective benzoic acid activation

Photocatalytic toluene degradation has attracted tremendous attention because of the growing environmental problem. However, conventional photocatalytic materials used for toluene degradation usually suffer from low carrier separation efficiency and poor stability which will degrade the catalytic performance. Herein, we report the synthesis of a novel heterostructure of GQDs@BiOCl ultrathin nanosheets where the GQDs can rapidly capture and transport photogenerated electrons for effective charge separation, promoting the generation of more reactive oxygen species (·O2- and ·OH radicals) for toluene degradation. In situ DRIFTS measurement and theoretical calculation are performed to unveil the reaction intermediates and the underlying toluene oxidation mechanism. The GQDs@BiOCl heterojunction could facilitate the adsorption and conversion of toluene and the reaction intermediates. Especially, the heterojunction greatly enhances the activation and conversion of benzoic acid and thus expedites the complete toluene degradation. This work presents a new insight on the design of high-performance photocatalysts for efficient degradation of typical air pollutants.

Single Electron Activation of Aryl Carboxylic Acids

Aryl carboxylic acids are stable and readily available in great structural diversity both from natural and well-established synthetic procedures, which make them promising starting materials in organic synthesis. The conversion of benzoic acids into high-value molecules is of great importance and have gained much interest of synthetic chemists. The recent development of single-electron (1e−) activation strategy has been esteemed as a complementary method for the transformation of benzoic acids. In this context, carboxylate groups can be selectively transferred into reactive aryl carboxylic radical, aryl radical, and acyl radical by electrocatalysis, photocatalysis, or in the presence of some SET oxidants. Based on these radical species, remarkable advancements have been achieved for the rapid formation of various chemical bonds over the past 10 years. In this review, we summarize recent advances in single electron activation of aryl carboxylic acids, with an emphasis on reaction scope, catalytic system, limitation, and underlying reaction mechanism.

Hydrogenation of benzoic acid to benzyl alcohol over Pt/SnO2

Hydrogenation of benzoic acid in the liquid phase over Pt/SnO2 has afforded excellent selectivity to benzyl alcohol under mild reaction conditions (97 % at 98 % conversion of benzoic acid). DFT calculations have shown that the favoured mode of adsorption of benzoic acid switched from the aromatic ring to the acid carbonyl group with partial reduction of the SnO2 support. The switch in adsorption mode corroborates the experimentally observed selectivity with acid carbonyl group adsorption and hydrogenation occurring over Pt/SnO2. Reduction of Pt/SnO2 was observed by in-situ XPS forming a degree of metallic tin and complete reduction of Pt which could lead to Pt-Sn alloy phases and/or migration of SnOx onto Pt blocking sites for ring hydrogenation. No hydrogenation of benzene or the benzene ring of benzoic acid was observed over Pt/SnO2 with oxidic tin species at the interface of Pt particles proposed to activate the acid carbonyl group for hydrogenation.

Carbon Nanotubes-Supported Well-Dispersed Pd Nanoparticles for the Efficiently Selective Hydrogenation of Benzoic Acid to Synthesize Cyclohexane Carboxylic Acid

Pd and carbon nanotube (CNT) composites were prepared by well-dispersed deposition of Pd nanoparticles on commercial CNT, and applied to the selective hydrogenation of benzoic acid (BA) to synthesize cyclohexane carboxylic acid (CCA). The catalysts and the hydrogenation products were analyzed by XRD, TEM, TG, FTIR, UV-Vis absorption, GC and GC-MS, respectively. Hydrogenation process was also optimized through varying the reaction parameters. The results demonstrate that Pd/CNT catalysts possess the highest hydrogenation efficiency, give the full conversion of BA and 100.0% selectivity towards CCA at the optimal hydrogenation conditions, by comparing with some commercial hydrogenation catalysts and Pd/C catalysts with commercial carbonaceous supports. The excellent hydrogenation performance of Pd/CNT is attributed to the stable crystalline CNT support and the high dispersion of Pd nanoparticles. In addition, the protic solvent is also beneficial to lower the activation energy barrier of BA hydrogenation, and further to improve the hydrogenation rate. This work implies that CNT can be potentially chosen as an effective carbonaceous support to prepare Pd/C catalyst with an outstanding performance of BA selective hydrogenation.

Synthesis and characterization of AMO LDH-derived mixed oxides with various Mg/Al ratios as acid–basic catalysts for esterification of benzoic acid with 2-ethylhexanol

Proven to possess distinguishable physical and acid-base properties superior to conventional LDHs, Aqueous Miscible Organic solvent-Layered Double Hydroxides (AMO-LDHs) were thus synthesized and used as precursors to prepare the Mg/Al mixed oxide catalysts in this work. The AMO-LDH based oxide catalysts with various ratios of Mg/Al were studied for the chemical and physical properties and the activity on esterification of benzoic acid with 2-ethylhexanol. The catalysts were characterized using BET, XRD, TGA, and XPS. Moreover, the acid-base properties were studied by using NH3-TPD, CO2-TPD, and X-ray Absorption Spectroscopy (XAS) techniques, both XANES and EXAFS. As a result, the Mg/Al mixed oxides after calcination at 500 °C still had the clay structure, and were found to possess both acid and base sites. As the Mg/Al ratio increased, the total density of acid and basic sites decreased. Moreover, the acid-basic strength depended on their phase compositions and coordination number. The activity of calcined LDHs catalysts was tested for the esterification of benzoic acid with 2-ethylhexanol, aimed at producing 2-ethylhexyl benzoate as the desired chemical. The products were analyzed using GC–MS/TOF. In summary, the conversion of benzoic acid was enhanced significantly using the MgAl mixed oxides as the catalysts, owing to the acid-base sites (both Mg2+O2− and Al3+O2− pairs) of the catalysts. The catalyst with the Mg/Al ratio of 4:1 can convert 66% benzoic acid to 2-ethylhexyl benzoate. Moreover, the other products were composed of 2-ethylhexanal, 3-heptanone, and 3-heptanol because of acid-base pairs.

Application of Green Catalysts for the Esterification of Benzoic Acid with Different Alcohols

In this study, three different catalysts were applied as catalysts for esterification of benzoic acid with ethanol, butanol and hexanol. These catalysts are ionic liquid, deep eutectic solvent, ion exchange resin. Amberlyst 15, ion exchange resin, was used as control catalyst to observe the catalytic activity of new generation solvent, deep eutectic solvent. Deep eutectic solvents show the similar properties with ionic liquids and have great attraction due to ease of preparation, low cost and environmentally friendly nature. They have many advantages such as reusability, stability, catalytically activity and removal of the reaction mixture. Deep eutectic solvents (DES) are composed hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA). It has lower freezing point than that of individual constituents. In this study, p -toluene sulfonic acid (p-TSA) was used as HBD, benzyl tri-ethyl ammonium chloride (BTEAC) was used as HBA. DES formed by p-TSA and BTEAC was used as dual solvent-catalyst for esterification of benzoic acid with different alcohols. DES gave high catalytic activity among three different catalysts, 88.3, 87.8 and 67.5% conversion of benzoic acid for ethanol, butanol and hexanol, respectively. The effects of time, temperature, alcohol type and catalyst type were investigated in a batch reactor at specified conditions. It was found that DES provided the simple, efficient and environmentally friendly method for the synthesis of benzoic acid ester.

Conversion of benzoic acid into phenol in an ITMS under CI-MSn conditions. Recognition of ortho-chlorobenzoyl derivatives.

Isomeric chlorobenzoyl cations (m/z 139), under collision-induced experiments, fragment identically. Chlorobenzoyl cations can be efficiently converted into cholorophenol radical cations by the reaction with methanol in the ion trap analyzer under CI-MSn conditions. The substitution of the carbonyl group with a hydroxyl moiety is able to induce an ortho effect, which is absent in the startingortho-chlorobenzoyl cation. This transformation could be useful to recognize ortho-chlorinated benzoyl derivatives without the need of MS spectrum comparison of the whole set of isomers. The method reported in this study could be applicable to biologically active molecules that dissociate to form the chlorobenzoyl cations under CI or CI collision-induced dissociation conditions, such as indomethacin, the degradation products from the insect growth regulator 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea, and lorazepam.

Selective hydrogenation of benzoic acid to cyclohexane carboxylic acid over microwave-activated Ni/carbon catalysts

High yields of cyclohexane carboxylic acids were obtained by direct hydrogenation of aromatic carboxylic acids over different Ni/carbon catalysts having distinctive surface properties. The catalysts were characterized by SEM, TEM, H2-TPR and N2 adsorption isotherms for the determination of BET surface area and porosity. The hydrogenation reaction was carried out in batch pressure reactor in gas-liquid phase at 200°C. High selectivity (100%) of cyclohexane carboxylic acids at 86.2mol% conversion of benzoic acid was achieved over microwave-activated biochar supported non-precious metal Ni catalyst. The 10%Ni/CSC-b catalyst has been investigated for hydrogenation of benzoic acid to cyclohexane carboxylic acids and shown little deactivation in stability test. The effects of Ni loading, high dispersion of Ni species, appropriate power of microwave heating and strong interaction of Ni species with carbon are of benefit to the reaction.

Removal of Benzoic Acid in Heavy Oils by Esterification Using Modified Ferrierite: Roles of Brønsted and Lewis Acid Sites

A utilization of heavy crude oils having a high total acid number (TAN) has been increased recently as a result of its lower price, and deacidification processes by esterification or thermal decarboxylation using heterogeneous catalysts can be a possible way to remove or neutralize acidic components in heavy oils. A conversion of benzoic acid as a model component of naphthenic acids was investigated using metal-modified H-form ferrierite in a batch reactor to verify the separate contributions of Bronsted and/or Lewis acid sites for esterification and decarboxylation reactions with methanol. The surface acid properties of metal-modified ferrierite with K, Zr, and P species significantly altered the extent of decarboxylation and esterification activities by showing a higher removal rate of benzoic acid on K-modified ferrierite. The amount of Lewis acid sites on metal-modified ferrierite was well-correlated with the conversion of benzoic acid. An increased esterification activity on K-modified ferrierite was...

Titanium Dioxide/Graphene Oxide Nanocomposites as Heterogeneous Catalysts for the Esterification of Benzoic Acid with Dimethyl Carbonate.

Graphene oxide (GO) was prepared by modified Hummers' method starting from commercially available graphite. Different amounts of titanium dioxide nanoparticles (TiO2 ) were loaded on the sheets of GO to obtain titanium dioxide/graphene oxide (TiO2 /GO) nanocomposites. The as-synthesized 5 wt % TiO2 /GO nanocomposite was characterized by UV/Vis spectroscopy, photoluminescence spectroscopy, FTIR, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy techniques. The catalytic activity of the 5 wt % TiO2 /GO nanocomposite was evaluated in the esterification of benzoic acid using dimethyl carbonate (DMC) as a green methylating agent. Furthermore, the activity of this nanocomposite for the conversion of benzoic acid was higher than that of the parent GO, TiO2 , TiO2 /activated carbon, and TiO2 /graphite.

A Simple and Efficient Two-Step Synthesis of 1,2,3-Triiodoarenes via Consecutive C–H Iodination/ipso-Iododecarboxylation Strategy: A Potential Application towards ortho-Diiodoarenes by Regioselective Metal–Iodine Exchange Reaction

A general, robust, and efficient method for the conversion of benzoic acids to 1,2,3-triiodoarenes and 1,2,3-trihaloarenes via a two-step synthesis is reported. Commercially available benzoic acids were used that can allow the reactions to be performed on multi-gram scales with good-to-excellent yields. This report discloses a practical method for the synthesis of 1,2,3-triiodoarenes and 1,2,3-trihaloarenes that is general in scope, scalable, and easy to workup and purify. A potential application of the target compounds as precursors for novel regioselective metal–iodine exchange reaction of 1,2,3-triiodoarenes was also demonstrated. It provided ortho-diiodoaryl derivatives in a high regioselective fashion that are useful intermediates in synthesis and indeed are hard to synthesize by any other means.

Green synthesis of 4-methoxybenzophenone from anisole and benzoic acid catalyzed by tungstophosphoric acid supported on MCM-41

An efficient method was established for the green synthesis of 4-methoxybenzophenone using benzoic acid as acylating agent catalyzed by tungstophosphoric acid (HPW) supported on MCM-41 (HPW/MCM-41). The conversion of benzoic acid reached 97.2 % and the selectivity for 4-methoxybenzophenone was 87.4 % under the optimum conditions over a 50 wt.% HPW/MCM-41 catalyst. HPW is proven to be well deposited on MCM-41, which leads to dealumination of MCM-41 and then offers more active centers, as demonstrated by inductively coupled plasma analysis and NH3 temperature-programmed desorption, accounting for the high catalytic activity of HPW/MCM-41.

Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: A kinetic approach

The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.