Showing papers on "Benzoic acid published in 2020"

Sodium Benzoate and Benzoic Acid

Abstract: Benzoic acid is found naturally in a wide variety of plants. It was isolated in the sixteenth century, but not commercially produced until the end of the nineteenth century. Researchers discovered in 1875 that this compound had potent antifungal properties, was relatively tasteless in foods, easy to make, and inexpensive. Sodium benzoate was the first chemical preservative approved for use in foods. Benzoic acid is most effective against fungi, yeasts, and bacteria in acidic environments. Proposed mechanisms of action include changes in cell membranes, loss of energy generation, reduction of intracellular pH, and inhibition of specific enzymes. Acquired resistance to benzoic acid depends on several factors including the microorganism and the environment from which it was originally isolated. It can be directly metabolized by microorganisms both aerobically and anaerobically. Certain food constituents may also affect its potency. Benzoate does not appear to be accumulated in humans and may be effective in reducing the frequency of urinary tract infections. However, allergic reactions (asthma and skin rashes) can occur in sensitive individuals. Benzoic acid and sodium benzoate are used in many food systems worldwide. More recent applications include addition to processed meat products, and incorporation into polymer coatings and in “active” packaging for foods. One proposed application has been as a substitute for antibiotics used in livestock feeds. Because of the long history of benzoate use in foods, the present chapter offers an extensive review of both research and commercial applications for the reader. In the future, combinations of preservatives (e.g., sodium benzoate and potassium sorbate) may offer enhanced protective effects (synergism), especially if combined with hurdle technology. This may address greater demand for more unique foods with less processing and less addition of chemical preservatives.

Holey Lamellar High-Entropy Oxide as an Ultra-High-Activity Heterogeneous Catalyst for Solvent-free Aerobic Oxidation of Benzyl Alcohol

Abstract: The development of noble-metal-free heterogeneous catalysts is promising for selective oxidation of aromatic alcohols; however, the relatively low conversion of non-noble metal catalysts under solvent-free atmospheric conditions hinders their industrial application. Now, a holey lamellar high entropy oxide (HEO) Co0.2 Ni0.2 Cu0.2 Mg0.2 Zn0.2 O material with mesoporous structure is prepared by an anchoring and merging process. The HEO has ultra-high catalytic activity for the solvent-free aerobic oxidation of benzyl alcohol. Up to 98 % conversion can be achieved in only 2 h, to our knowledge, the highest conversion of benzyl alcohol by oxidation to date. By regulating the catalytic reaction parameters, benzoic acid or benzaldehyde can be selectively optimized as the main product. Analytical characterizations and calculations provide a deeper insight into the catalysis mechanism, revealing abundant oxygen vacancies and holey lamellar framework contribute to the ultra-high catalytic activity.

Ni, Co hydroxide triggers electrocatalytic production of high-purity benzoic acid over 400 mA cm−2

Abstract: With the increasingly prominent energy issues and environment problems, the electrocatalytic production of value-added fine chemicals by hybrid water electrolysis has shown much hope for replacing conventional energy-intensive chemical technology. However, the low current density caused by the competition of the oxygen evolution reaction at the anode has hindered the large-scale production of fine chemicals and H2. Besides, the separation of products from the complicated electrolyte also remains a significant barrier. Herein, we present the integration of hybrid water electrolysis and conventional crystallization separation for the first time, achieving the electrocatalytic production and separation of benzoic acid without impurities. An amorphous nanosheet composed of Ni, Co hydroxide supported on Ni foam (A-Ni-Co-H/NF), with a large active area and low charge transfer resistance, is prepared for the first time and applied to catalyze the electrocatalytic benzyl alcohol oxidation reaction. A-Ni-Co-H/NF enables us to achieve an industrial-scale current density over 400 mA cm−2 without the occurrence of the OER, and delivers ultrafast reaction kinetics. The yield of Ph-COOH is close to 100%, only spending 15 min at room temperature and atmosphere pressure. In situ Raman spectroscopy reveals that the as-made A-Ni-Co-H/NF catalyst features reversible structure evolution and recovery during the EBA reaction. The converted nickel oxyhydroxide containing Co species (Co-NiOOH) is confirmed as the real active species. This presents a novel electrocatalyst to achieve industrial-scale prodution for value-added chemicals and the novel integrated technology also provides guidance for the separation and collection of products during the electrocatalytic process.

Performance and Mechanism of Photocatalytic Toluene Degradation and Catalyst Regeneration by Thermal/UV Treatment.

Abstract: This work presents a new strategy for industrial flue gas purification with TiO2-based photocatalysis technology, which could be achieved by a novel dual-stage circulating photocatalytic reactor. A lab-scale fixed bed reactor is utilized to investigate the performance of photocatalytic toluene degradation and inactive catalyst regeneration by thermal/UV treatment. The relationships between operational conditions and toluene oxidation are surveyed and discussed in detail. The results show that the intermediates could be further removed and decomposed by introducing UV radiation, compared with heat treatment alone. To reveal the photocatalytic mechanism and identify the accumulated intermediates over anatase TiO2, the adsorbed toluene and aromatic intermediates are identified by XPS, in situ DRIFTS, and on-line MS. The aromatic ring and other covalent bonds (C═O, C-O, and O-H) are detected during photocatalytic oxidation. The reaction pathway involving hydrogen abstraction is referred as the dominant pathway for toluene degradation, and ring opening via ·OH radicals is crucial to make aromatic intermediates change into CO2 and H2O. The results indicate that benzoic acid and benzaldehyde are the main accumulation because of their high reaction energy. A possible reaction mechanism is proposed for toluene oxidation, deactivation, and regeneration of catalysts, which has a significant value for guiding the practical applications.

Distal γ‑C(sp 3 )−H Olefination of Ketone Derivatives and Free Carboxylic Acids

Abstract: Reported herein is the distal γ-C(sp3 )-H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino-acid directing group and using the ligand combination of a mono-N-protected amino acid (MPAA) and an electron-deficient 2-pyridone were critical for the γ-C(sp3 )-H olefination of ketone substrates. In addition, MPAAs enabled the γ-C(sp3 )-H olefination of free carboxylic acids to form diverse six-membered lactones. Besides alkyl carboxylic acids, benzylic C(sp3 )-H bonds also could be functionalized to form 3,4-dihydroisocoumarin structures in a single step from 2-methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ-C(sp3 )-H olefinated products.

Layered δ-MnO2 as an active catalyst for toluene catalytic combustion

Abstract: Layered δ-MnO2 was successfully synthesized by redox reaction precipitation between KMnO4 and n-butanol Then, the as-synthesized layered δ-MnO2 was used as catalyst for toluene catalytic combustion and showed excellent catalytic performance The T10 and T90 (the temperatures corresponded to the toluene conversion of 10 % and 90 %) were just 160 °C and 199 °C, respectively (1000 ppm toluene, GHSV = 60,000 mL/(g h, 20 vol%O2/N2) In addition, the layered δ-MnO2 showed well catalytic stability and humid resistance The as-prepared catalysts were characterized by XRD, N2 sorption, SEM, TEM, XPS, H2-TPR, O2-TPD and so on Compared with the referenced e-MnO2 and γ-MnO2, the higher catalytic activity of layered δ-MnO2 was ascribed to its higher specific surface area, stronger low-temperature reducibility and richer oxygen vacancy Finally, the toluene catalytic oxidation mechanism over δ-MnO2 was also proposed based on the results of in-situ DRIFTs And the key successively intermediate species for toluene oxidation over δ-MnO2 were benzyl alcohol, benzoic acid, maleic anhydride and acetate

The high selectivity for benzoic acid formation on Ca2Sb2O7 enables efficient and stable toluene mineralization

Abstract: The selectivity for different intermediates in VOCs degradation process may lead to different reaction paths, which determines the overall pollutant degradation efficiency. In this work, Ca2Sb2O7 shows a superior photocatalytic activity and stability in gaseous toluene degradation as compared to P25. To shed light on the mechanism of efficient and stable toluene degradation, particularly the role of selectivity for intermediates during the reaction process, the theoretical and experimental approaches were closely combined. Owing to the promoted charge transfer between the absorbents (such as O2, H2O, toluene and other intermediates) and Ca2Sb2O7, both the ROS generation and principal intermediates adsorption are significantly enhanced, which leads to a high selectivity for benzoic acid formation. That is confirmed by in suit DRIFTS and theoretical calculations. Enhanced generation of benzoic acid on Ca2Sb2O7 surface could improve the efficiency of toluene ring-opening and over-all degradation due to lower energy barrier for toluene transformation into benzoic acid. Thus, this could enable efficient and stable degradation of toluene and prevent the catalyst from deactivation. This work provides new insight into the mechanistic understanding of photocatalytic VOCs degradation reaction.

Biologically Active Compounds of Plants: Structure-Related Antioxidant, Microbiological and Cytotoxic Activity of Selected Carboxylic Acids.

Abstract: Natural carboxylic acids are plant-derived compounds that are known to possess biological activity. The aim of this review was to compare the effect of structural differences of the selected carboxylic acids (benzoic acid (BA), cinnamic acid (CinA), p-coumaric acid (p-CA), caffeic acid (CFA), rosmarinic acid (RA), and chicoric acid (ChA)) on the antioxidant, antimicrobial, and cytotoxic activity. The studied compounds were arranged in a logic sequence of increasing number of hydroxyl groups and conjugated bonds in order to investigate the correlations between the structure and bioactivity. A review of the literature revealed that RA exhibited the highest antioxidant activity and this property decreased in the following order: RA > CFA ~ ChA > p-CA > CinA > BA. In the case of antimicrobial properties, structure-activity relationships were not easy to observe as they depended on the microbial strain and the experimental conditions. The highest antimicrobial activity was found for CFA and CinA, while the lowest for RA. Taking into account anti-cancer properties of studied NCA, it seems that the presence of hydroxyl groups had an influence on intermolecular interactions and the cytotoxic potential of the molecules, whereas the carboxyl group participated in the chelation of endogenous transition metal ions.

A New Multifunctional Zinc–Organic Framework with Rare Interpenetrated Tripillared Bilayers as a Luminescent Probe for Detecting Ni2+ and PO43– in Water

Abstract: Herein, we synthesized two isostructural metal–organic frameworks (MOFs) [(CH3)2NH2]6[M6(OBA)6(L1)3(SO4)2]·SO4·x(solvent) (M: Zn for 1, Co for 2, H2OBA = 4,4′-oxybis(benzoic acid), L1 = 4-amino-3,5...

Absorption spectra of benzoic acid in water at different pH and in the presence of salts: insights from the integration of experimental data and theoretical cluster models.

Abstract: The absorption spectra of molecular organic chromophores in aqueous media are of considerable importance in environmental chemistry. In this work, the UV-vis spectra of benzoic acid (BA), the simplest aromatic carboxylic acid, in aqueous solutions at varying pH and in the presence of salts are measured experimentally. The solutions of different pH provide insights into the contributions from both the non-dissociated acid molecule and the deprotonated anionic species. The microscopic interpretation of these spectra is then provided by quantum chemical calculations for small cluster models of benzoic species (benzoic acid and benzoate anion) with water molecules. Calculations of the UV-vis absorbance spectra are then carried out for different clusters such as C6H5COOH·(H2O)n and C6H5COO-·(H2O)n, where n = 0-8. The following main conclusions from these calculations and the comparison to experimental results can be made: (i) the small water cluster yields good quantitative agreement with observed solution experiments; (ii) the main peak position is found to be very similar at different levels of theory and is in excellent agreement with the experimental value, however, a weaker feature about 1 eV to lower energy (red shift) of the main peak is correctly reproduced only by using high level of theory, such as Algebraic Diagrammatic Construction (ADC); (iii) dissociation of the BA into ions is found to occur with a minimum of water molecules of n = 8; (iv) the deprotonation of BA has an influence on the computed spectrum and the energetics of the lowest energy electronic transitions; (v) the effect of the water on the spectra is much larger for the deprotonated species than for the non-dissociated acid. It was found that to reproduce experimental spectrum at pH 8.0, additional continuum representation for the extended solvent environment must be included in combination with explicit solvent molecules (n ≥ 3); (vi) salts (NaCl and CaCl2) have minimal effect on the absorption spectrum and; (vii) experimental results showed that B-band of neutral BA is not sensitive to the solvent effects whereas the effect of the water on the C-band is significant. The water effects blue-shift this band up to ∼0.2 eV. Overall, the results demonstrate the ability to further our understanding of the microscopic interpretation of the electronic structure and absorption spectra of BA in aqueous media through calculations restricted to small cluster models.

Intermetallic compound PtMny-derived Pt−MnOx supported on mesoporous CeO2: Highly efficient catalysts for the combustion of toluene

Abstract: Intermetallic compounds are a kind of important materials in heterogeneous catalysis. In this work, we first synthesized the PtMny intermetallic nanocrystals using the polyvinyl pyrrolidone-assisted ethylene glycol reduction method, and then loaded them on the surface of mesoporous CeO2 (meso-CeO2) derived from a KIT-6-templating route, generating the mPt−nMnOx/meso-CeO2 (m = 0−0.39 wt%, n = 0−1.21 wt%) catalysts after calcination at 500 °C in air. It is found that the as-obtained catalysts displayed an ordered mesoporous architecture with surface areas of 95−108 m2/g. The 0.37Pt−0.16MnOx/meso-CeO2 sample exhibited the best catalytic performance for toluene combustion (T50 % =162 °C and T90 % =171 °C at space velocity = 40,000 mL/(g h)). Kinetic analysis reveals that the apparent activation energy (57 kJ/mol) obtained over the best-performing 0.37Pt−0.16MnOx/meso-CeO2 sample was lower than those (63−75 kJ/mol) obtained over the other samples. Furthermore, the 0.37Pt−0.16MnOx/meso-CeO2 sample possessed good thermal stability and water-resistant performance. Benzyl alcohol, benzoic acid, and maleic anhydride were proven to be the main intermediates of toluene combustion, hence, toluene combustion might take place through a sequence of toluene → benzyl alcohol and benzoic acid → maleic anhydride → carbon dioxide and water, which might obey the Eley−Rideal reaction mechanism. It is concluded that loading of Pt and MnOx enhanced the adsorbed oxygen and Mn2+ species concentration and low-temperature reducibility, thus promoting toluene combustion over 0.37Pt−0.16MnOx/meso-CeO2.

Modulator-Induced Zr-MOFs Diversification and Investigation of Their Properties in Gas Sorption and Fe3+ Ion Sensing.

Abstract: In this paper, we synthesized three Zr-MOFs (Zr-SXU-1, Zr-SXU-2, and Zr-SXU-3) composed of identical ligands and metal clusters by using tetratopic carboxylic ligand PBPTTBA as the ligand and benzoic acids as modulators. These three Zr-MOFs showed different structures and topologies, and the connectivity of the Zr clusters varied from 8 in Zr-SXU-3, to 10 in Zr-SXU-1, and finally to 12 in Zr-SXU-2 due to the modulators used. Among them, Zr-SXU-1 represents an unusual 6-node network and [6(10)(11)7] transitivity. Besides, Zr-SXU-2 can only be obtained by using ditopic carboxylic acid as a second modulator when using benzoic acid as the main modulator, which is not reported in other Zr-MOFs synthesis. The adsorption and luminescence tests demonstrated their potential as gas reservoirs, separators, and sensors and also showed the importance of structure topologies to the applications.

Development of Abraham model correlations for solute transfer into 2-ethyl-1-hexanol from both water and the gas phase based on measured solubility ratios

Abstract: Experimental solubilities have been determined by spectrophotometric methods for 1-chloro-4-bromobenzene, 1,4-dibromobenzene, 1,4-dichloro-2-nitrobenzene, benzoic acid, 4-nitrobenzoic acid, 3,5-din...

Molecularly Imprinted Polymer and Computational Study of (E)-4-(2- cyano-3-(dimethylamino)acryloyl)benzoic Acid from Poly(ethylene terephthalate) Plastic Waste

Abstract: Molecularly imprinted polymers (MIPs) are utilized in the separation of a pure compound from complex matrices. A stable template-monomer complex generates MIPs with the highest affinity and selectivity for the template. In this investigation, degradation of Poly(ethylene terephthalate) PET afforded the (E)-4-(2-cyano-3-(dimethylamino) acryloyl) benzoic acid (4) (TAM) which used TAM as template which interacts with Methacrylic Acid (MAA) monomer, in the presence of CH3CN as progen. The TAM-MMA complex interactions are dependent on stable hydrogen bonding interaction between the carboxylic acid group of TAM and the hydroxyl group of MMA with minimal interference of porogen CH3CN. The DFT/B3LYP/6-31+G model chemistry was used to optimize their structures and frequency calculations. The binding energies between TAM with different monomers showed the most stable molar ratio of 1:4 which was confirmed through experimental analysis. The present work describes the synthesis of (E)-4-(2-cyano-3-(dimethylamino) acryloyl) benzoic acid (4) (TAM) from PET waste and formation of molecularly imprinted polymer from TAM with the methacrylic acid monomer. The optimization of molecular imprinted was stimulated via DFT/B3LYP/6-31G (d). The imprinted polymer film was characterized via thermal analysis, pore size, FT-IR and scanning electron microscopy. The most stable molecularly imprinted polymers (MIPs) showed binding energy of TAM(MMA4)=-2063.456 KJ/mol with a small value of mesopores (10-100 Å). Also, the sorption capability of TAM-MIPs showed 6.57 mg/g using STP-MIP-9VC. Moreover, the average pore size ranged between 0.2-1 nm with the BET surface about 300 m2/g. The proposed TAM exhibited a high degree of selectivity for MMA in comparison with other different monomers through hydrogen bond interaction, which was thermally stable, good reproducibility and excellent regeneration capacity and elucidated in the computational study and analytical analysis.

Iron Oxide as a Promoter for Toluene Catalytic Oxidation Over Fe–Mn/γ-Al 2 O 3 Catalysts

Abstract: Fe–Mn/γ-Al2O3 catalysts that prepared by the wet-impregnation method were used to degrade toluene, a VOCs model compound. The results indicated that the 10Fe–15Mn/γ-Al2O3 exhibited 95% of toluene conversion as well as 95% of CO2 yield at 300 °C. The Fe–Mn/γ-Al2O3 showed a better toluene oxidation activity with respect to the Fe/γ-Al2O3 and Mn/γ-Al2O3. The introduction of Fe into the Mn/γ-Al2O3 resulted in higher surface area, higher Mn3+/(Mn3+ + Mn4+) ratio, lower reduction temperature, and homogenous distribution of Mn. Meanwhile, the co-exist of the Fe3+ and Mn3+ over the 10Fe–15Mn/γ-Al2O3 also favored for the oxygen transfer, which may enhance the catalytic oxidation performance. The initial toluene was adsorbed on surface of the catalysts and formed benzoyl oxide (C6H5–CH2–O), and then the benzoyl oxide (C6H5–CH2–O) was oxidized to benzaldehyde. Furthermore, the benzaldehyde was further oxidized to form benzoic acid that could be converted to CO2 and H2O.