Methyl Benzoate Research Articles

Enzymatic acylation of rutin with benzoic acid ester and lipophilic, antiradical, and antiproliferative properties of the acylated derivatives.

Rutin (3',4',5,7-tetrahydroxy-flavone-3-rutinoside) was enzymatically acylated with benzoic acid and its esters (methyl benzoate and vinyl benzoate) using Thermomyces lanuginosus lipase (Lipozyme TLIM). The acylation reaction was optimized by varying the reaction medium, reaction temperature, acyl donor, substrate molar ratio, and reaction time. The highest conversion yield (76%) was obtained in tert-amyl alcohol (60 °C, 72 hr) using vinyl benzoate (molar ratio of 1:10) as acyl donor. The acylation occurred at the 2'''-OH and 4'''-OH of the rhamnose unit and the 2''-OH position of the glucose moieties. Three novel rutin acylated derivatives (compounds 1-3) were purified and characterized by HR-MS and 1D and 2D NMR spectroscopy. We found that acylation significantly improved lipophilicity, capacity to inhibit lipid peroxidation, anticancer capacity and substantially maintained the antioxidant activity of rutin. This research provides important insights in the acylation of flavonoids with different glycosyl moieties. PRACTICAL APPLICATION: In this study, three novel rutin derivatives were successfully synthesized and the highest conversion yield (76%) was obtained by reacting the rutin and vinyl benzoate at molar ratio of 1:10 in tert-amyl alcohol for 72 hr at 60 °C. Introducing a benzoic acid substituent into rutin molecule significantly improved their lipophilicity and inhibition of lipid peroxidation in lipophilic system. Furthermore, this study demonstrated that acylation significantly improved anticancer capacity and substantially maintained the antioxidant activity.

Coordinated and High-Level Expression of Biosynthetic Pathway Genes Is Responsible for the Production of a Major Floral Scent Compound Methyl Benzoate in Hedychium coronarium.

Methyl benzoate is a constituent of floral scent profile of many flowering plants. However, its biosynthesis, particularly in monocots, is scarcely reported. The monocot Hedychium coronarium is a popular ornamental plant in tropical and subtropical regions partly for its intense and inviting fragrance, which is mainly determined by methyl benzoate and monoterpenes. Interestingly, several related Hedychium species lack floral scent. Here, we studied the molecular mechanism of methyl benzoate biosynthesis in H. coronarium. The emission of methyl benzoate in H. coronarium was found to be flower-specific and developmentally regulated. As such, seven candidate genes associated with methyl benzoate biosynthesis were identified from flower transcriptome of H. coronarium and isolated. Among them, HcBSMT1 and HcBSMT2 were demonstrated to catalyze the methylation of benzoic acid and salicylic acid to form methyl benzoate and methyl salicylate, respectively. Methyl salicylate is a minor constituent of H. coronarium floral scent. Kinetic analysis revealed that HcBSMT2 exhibits a 16.6-fold lower Km value for benzoic acid than HcBSMT1, indicating its dominant role for floral methyl benzoate formation. The seven genes associated with methyl benzoate biosynthesis exhibited flower-specific or flower-preferential expression that was developmentally regulated. The gene expression and correlation analysis suggests that HcCNL and HcBSMT2 play critical roles in the regulation of methyl benzoate biosynthesis. Comparison of emission and gene expression among four Hedychium species suggested that coordinated and high-level expression of biosynthetic pathway genes is responsible for the massive emission of floral methyl benzoate in H. coronarium. Our results provide new insights into the molecular mechanism for methyl benzoate biosynthesis in monocots and identify useful molecular targets for genetic modification of scent-related traits in Hedychium.

Overexpression of a Rosa rugosa Thunb. NUDX gene enhances biosynthesis of scent volatiles in petunia.

Rosa rugosa is an important natural perfume plant in China. Rose essential oil is known as ‘liquid gold’ and has high economic and health values. Monoterpenes are the main fragrant components of R. rugosa flower and essential oil. In this study, a member of the hydrolase gene family RrNUDX1 was cloned from Chinese traditional R. rugosa ‘Tang Hong’. Combined analysis of RrNUDX1 gene expression and the aroma components in different development stages and different parts of flower organ, we found that the main aroma component content was consistent with the gene expression pattern. The RrNUDX1 overexpressed Petunia hybrida was acquired via Agrobacterium-mediated genetic transformation systems. The blades of the transgenic petunias became wider and its growth vigor became strong with stronger fragrance. Gas chromatography with mass spectrometry analysis showed that the contents of the main aroma components of the transgenic petunias including methyl benzoate significantly increased. These findings indicate that the RrNUDX1 gene plays a role in enhancing the fragrance of petunia flowers, and they could lay an important foundation for the homeotic transformation of RrNUDX1 in R. rugosa for cultivating new R. rugosa varieties of high-yield and -quality essential oil.

Electrophysiological and Behavioral Responses of an Ambrosia Beetle to Volatiles of its Nutritional Fungal Symbiont

Ambrosia beetles (Coleoptera: Scolytinae) cultivate their fungal symbiont within host substrates as the sole source of nutrition on which the larvae and adults must feed. To investigate a possible role for semiochemicals in this interaction, we characterized electrophysiological and behavioral responses of Xylosandrus germanus to volatiles associated with its fungal symbiont Ambrosiella grosmanniae. During still-air walking bioassays, X. germanus exhibited an arrestment response to volatiles of A. grosmanniae, but not antagonistic fungi Beauveria bassiana, Metarhizium brunneum, Trichoderma harzianum, the plant pathogen Fusarium proliferatum, or malt extract agar. Solid phase microextraction-gas chromatography-mass spectrometry identified 2-ethyl-1-hexanol, 2-phenylethanol, methyl benzoate and 3-methyl-1-butanol in emissions from A. grosmanniae; the latter two compounds were also detected in emissions from B. bassiana. Concentration-responses using electroantennography documented weak depolarizations to A. grosmanniae fungal volatiles, unlike the comparatively strong response to ethanol. When tested singly in walking bioassays, volatiles identified from A. grosmanniae elicited relatively weak arrestment responses, unlike the responses to ethanol. Xylosandrus germanus also exhibited weak or no long-range attraction to the fungal volatiles when tested singly during field trials in 2016–2018. None of the fungal volatiles enhanced attraction of X. germanus to ethanol when tested singly; in contrast, 2-phenylethanol and 3-methyl-1-butanol consistently reduced attraction to ethanol. Volatiles emitted by A. grosmanniae may represent short-range olfactory cues that could aid in distinguishing their nutritional fungal symbiont from other fungi, but these compounds are not likely to be useful as long-range attractants for improving detection or mass trapping tactics.

Fatty Acid Methyl Esters From the Coral-Associated Bacterium Pseudomonas aeruginosa Inhibit Virulence and Biofilm Phenotypes in Multidrug Resistant Staphylococcus aureus: An in vitro Approach.

In an attempt to study the antibacterial, antivirulence and antibiofilm potentials of bacteria residing the tissue and surface mucus layers of the pristine corals, we screened a total of 43 distinct bacterial morphotypes from the coral Favites sp. Among the isolates, Pseudomonas aeruginosa strain CBMGL12 with showed antibacterial, antivirulence and antibiofilm activity against multidrug resistant pathogenic strains of Staphylococcus aureus (reference strain: MTCC96; community-acquired methicillin resistant strain: CA-MRSA). Extracellular products (ECP) from the coral-associated bacterium P. aeruginosa were solvent extracted, fractionated by chromatographic techniques such as silica column and HPLC-UV with concomitant bioassays guiding the fractionation of metabolites. Identification of bioactive chemical moieties was performed by FT-IR analysis, GC-MS/MS equipped with NIST library, 1H and 13C NMR spectral studies. We report the differential production of extracellular and cell-associated virulence and biofilm phenotypes in multi-drug resistant strains of S. aureus, post-treatment with the ECP containing aromatic fatty acid methyl esters (FAME) such as methyl benzoate and methyl phenyl acetate produced by a coral-associated bacterium. In conclusion, this study has identified antibacterial, antibiofilm and antivirulent FAME from the coral-associated P. aeruginosa for its ability to attenuate virulence and biofilms phenotypes in multi-drug resistant pathogenic strains of S. aureus.

Preparation of functionalized graphene and ionic liquid co-doped polypyrrole solid phase microextraction coating for the detection of benzoates preservatives

A novel solid-phase microextraction coating based on polypyrrole (Ppy) with manganese dioxide modified 6-aminohexanoic acid functionalized graphene (MnO2-fGr) and 1-allyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide ([AVIm]NTf2) as dopants (Ppy/MnO2-fGr/[AVIm]NTf2) was successfully prepared by electrochemical method. The composite coating was characterized by scanning electron microscope (SEM), Fourier infrared spectrum (FT-IR) and thermogravimetry (TG). The composite coating showed coarse structure, which could improve the specific surface area of it, and according to the TG curve, it also had good thermal stability. The composite coating was used for the headspace-solid phase microextraction (HS-SPME) and chromatographic analysis of benzoates (i.e. methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate)，by coupling with gas chromatography with hydrogen flame ionization detector (GC-FID). Under optimal conditions, their enrichment factors were 140–460, linear detection ranges were 25–60000 ng L−1, and detection limits were 2.84–6.42 ng L−1. The standard deviations for five consecutive extractions of 100 μg L−1 analytes were 3.00–10.20%, while the standard deviation for the extractions of 100 μg L−1 analytes with five different coatings were 5.70–13.80%. The proposed method was applied for the detection of the benzoates in cosmetics, and the recoveries for the spiked benzoates were 82.8–116.8%.

Scent emissions and expression of scent emission-related genes: A comparison between cut and intact carnation flowers

Although the physiological states of intact and cut flowers are expected to be significantly different, the floral scent emissions of these two conditions has yet to be compared. We compared the scent emissions from intact and cut flowers using carnation (Dianthus caryophyllus L.) cultivars with two different scent-types—a fruity scent based on benzenoid methyl benzoate and a spicy scent based on eugenol. Methyl benzoate or eugenol, which were the principal scent components, always had the highest percentage (> 30 %) in both intact and cut flowers from flower opening to wilting. The total emissions from intact flowers remained at a similar level for approximately 6 days after flower opening, and then gradually decreased with flower senescence. The total emissions from cut flowers were highest on the day of flower opening and then decreased more rapidly than emissions from intact flowers. Furthermore, the duration of noticeable scent of cut flowers was estimated to be shorter than that of intact flowers. The expression of various scent emission-related genes encoding floral volatile benzenoid/phenylpropanoid biosynthesis enzymes, adenosine triphosphate-binding cassette transporters, and MYB transcription factors increased with flower opening and were accompanied by scent emissions. However, the expressions of most of these genes were not affected by cutting, suggesting that the decrease in scent emissions from cut flowers is unlikely due to changes in gene expression. Recently, we reported that cutting accelerates the decrease in sugar content and increases ethylene production in carnation petals, resulting in hastened flower senescence. Therefore, the rapid decrease in scent emissions from cut flowers may be due to a decrease in sugars, which are substrates for the scent components.

Analysis of volatile compounds and flavor fingerprint in Jingyuan lamb of different ages using gas chromatography–ion mobility spectrometry (GC–IMS)

In this study, gas chromatography coupled to an ion mobility spectrometry (GC–IMS) was used for analyzing some volatile components and flavor fingerprint in samples from Jingyuan lambs of different ages (2, 6, and 12 months). The data obtained from ion mobility were processed using laboratory analysis view processing software for fingerprint recognition, and the principal component analysis (PCA) was performed. GC–IMS provided information on the characteristics and strength of 66 volatile flavor compounds (monomers and dimers). The differences in flavoring substances between lambs of different ages were observed. The compounds with higher intensity peaks in the lamb meat samples were alcohols (1-octen-3-ol, ethanol, (E)-2-hexen-1-ol, 1-pentanol, and 2-propanol), ketones (2-pentanone, 2-heptanone, 3-hydroxy-2-butanone, 2-hexanone, 2-butanone, 2-propanone, and 4-methyl-2-pentanone), aldehydes (n-nonanal, octanal, heptanal, 3-methylbutanal, hexanal, pentanal, 2-methylbutanal, (E)-2-octenal, (E)-2-nonenal, methional, and phenylacetaldehyde), esters (methyl benzoate), furan (2-pentylfuran), and thiazole (trimethylthiazole). The results showed that the flavor fingerprint in samples from Jingyuan lambs of different ages (2, 6, and 12 months) can be established by GC–IMS and PCA based on the identified volatile compounds. This method might be used for the rapid and comprehensive analysis of volatile components in lamb meat.

Application of polymer-bound Cu(II) complex of 2-phenylbenzimidazole towards oxidative bromination and oxidative esterification of organic substrates

Application of polymer immobilized Cu(II)(PS-Cu(II)PBMZL) complex of 2-phenylbenzimidazole in oxidative bromination and oxidative esterification of organic compounds is reported. The complex has been characterized by CHNS analysis, UV-Vis/DRS, FT-IR, ESR spectroscopic studies, magnetic moment measurements and TG analysis. A shift in νC=N in the polymer-bound complex compared with the ligand indicates its complexation to Cu(II) center. A distorted octahedral coordination of Cu(II) in PS-Cu(II)PBMZL is confirmed by the electronic spectral data and the efficient binding of PBMZL is ascertained by adecrease in the intensity of νCH2Cl peak in the PS-PBMZL compared to the polymer support. An array of experiments has been carried out to assess the influence of various reaction parameters on the performance of PS-Cu(II)PBMZL. The activity of the polymer-bound complex is higher than the unbound complex. In the case of oxidative bromination, PS-Cu(II)PBMZLH displayed a 65% phenol conversion with 61% 2-bromophenol selectivity. The % benzaldehyde conversion and methyl benzoate selectivity in the case of oxidative esterification has been found to be 79 and 82%. Compiling all these results along with the knowledge obtained regarding the most probable reactive species, tentative mechanisms have been proposed.

Methyl Benzoate Is Superior to Other Natural Fumigants for Controlling the Indian Meal Moth (Plodia interpunctella).

Simple SummaryGlobally, the Indian meal moth is an insect pest of stored goods and manufactured foodstuffs. Synthetic fumigants, such as phosphine and methyl bromide, are widely used agents to control this species. However, due to the development of resistance and increasing concern about the potential adverse effects of synthetic fumigants, it is now necessary to identify environmentally friendly alternatives. Naturally occurring compounds, such as essential oils (EOs), are perhaps the most promising alternative sources; many have been successfully used as active ingredients in contact-based control products, repellents, and fumigants. Methyl benzoate (MBe) is an environmentally friendly, food-safe, natural insecticide that offers a possible alternative to synthetic equivalents. Here, we evaluated the fumigant toxicity of MBe against adults of the Indian meal moth and found that it had great potential for the control of these insect pests in stored products.The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), is an insect pest that commonly affects stored and postharvest agricultural products. For the control of insect pests and mites, methyl benzoate (MBe) is lethal as a fumigant and also causes contact toxicity; although it has already been established as a food-safe natural product, the fumigation toxicity of MBe has yet to be demonstrated in P. interpunctella. Herein, we evaluated MBe as a potential fumigant for controlling adults of P. interpunctella in two bioassays. Compared to the monoterpenes examined under laboratory conditions, MBe demonstrated high fumigant activity using a 1-L glass bottle at 1 μL/L air within 4 h of exposure. The median lethal concentration (LC50) of MBe was 0.1 μL/L air; the median lethal time (LT50) of MBe at 0.1, 0.3, 0.5, and 1 μL/L air was 3.8, 3.3, 2.8, and 2.0 h, respectively. Compared with commercially available monoterpene compounds used in pest control, MBe showed the highest fumigant toxicity (toxicity order as follows): MBe > citronellal > linalool > 1,8 cineole > limonene. Moreover, in a larger space assay, MBe caused 100% mortality of P. interpunctella at 0.01 μL/cm3 of air after 24 h of exposure. Therefore, MBe can be recommended for use in food security programs as an ecofriendly alternative fumigant. Specifically, it provides another management tool for curtailing the loss of stored food commodities due to P. interpunctella infestation.

Increased substrate availability reveals the potential of scentless lisianthus flowers in producing fragrant benzenoid-phenylpropanoids.

Lisianthus (Eustoma grandiflorum), a leading plant in the cut flower industry, is scentless. Here we show that lisianthus flowers have potential to produce several fragrant benzenoid-phenylpropanoids when substrate availability is not limited. To enable hyperaccumulation of substrates for the production of volatile benzenoid-phenylpropanoids, lisianthus commercial hybrid "Excalibur Pink" was transformed via floral dipping with a feedback-insensitive Escherichia coli DAHP synthase (AroG*) and Clarkia breweri benzyl alcohol acetyltransferase (BEAT), under constitutive promoters. The T1 progeny of "Excalibur Pink" plants segregated into four visual phenotypes, with pink or white colored petals and multiple or single petal layers. Interestingly, transformation with AroG* and BEAT caused no significant effect in the pigment composition among phenotypes, but did increase the levels of down-stream fragrant volatile benzenoids. All the transgenic lines exclusively accumulated methyl benzoate, a fragrant benzenoid, either in their petals or leaves. Furthermore, feeding with benzyl alcohol resulted in the accumulation of two novel benzenoids, benzyl acetate (the product of BEAT) and benzoate, as well as a dramatic increase in the concentrations of additional benzenoid-phenylpropanoid volatiles. Presumably, the degree of benzaldehyde overproduction after benzyl alcohol feeding in both leaves and flowers revealed their reverse conversion in lisianthus plants. These findings demonstrate the concealed capability of lisianthus plants to produce a wide array of fragrant benzenoid-phenylpropanoids, given high substrate concentrations, which could in turn open opportunities for future scent engineering.

Solar photothermal catalytic effect promotes carbonylation reaction based on palladium doped g-C3N4 catalyst

Palladium catalyzed carbonylation reaction is used as an effective method in the industrial to prepare carbonyl-containing compounds. Besides, the complex ligands are needed to improve the yields and selectivity of reactions, which will increase the cost for production. Thus, it is very meaningful to build a simple and efficient catalytic system. Here, the graphitic carbon nitride (g-C3N4) nanosheets (ECN) doped with palladium metal (Pd/ECN) were prepared by microwave-assisted deposition method. The results indicated that the yield of methyl benzoate was 77 % based on Pd/ECN under the light irradiation with a wavelength of ≥ 400 nm, which was higher than that of the homogeneous catalysts and heterogeneous catalysts commonly used in commercialization such as palladium on activated charcoal (Pd/C) and palladium chloride (PdCl2).

Comparative predictions of viscosities in functional materials MB + 1-Octanol at temperature T = 303.15 K

Viscosities have been evaluated for functional binary liquid mixtures of MB (Methyl Benzoate) + 1-Octanol using Bingham relation, Kendall-Munroe relation, Arrhenius- Eyring relation, Croenaurer-Rothfus-Kermore relation and Gambrill relation. The validity of these theories has been verified by respective deviations between calculated values and experimental values. The results of all the theories are comparatively in good agreement with experimental results.

Quantitative vapor delivery for improved canine threshold testing.

The canine olfactory system is a highly efficient and intricate tool often exploited by humans for detection for its many attributes, including impressive sensitivity to trace analyte vapors. Canine detectors are often touted as having lower limits of detection, or olfactory detection threshold (ODT), than other field-relevant detection technologies; however, previous attempts to quantify canine ODTs have resulted in reported estimates spanning multiple orders of magnitude, even for the same analyte. A major contributor to these discrepancies is the vapor delivery method used for testing, where losses due to adsorption and dilution are often unaccounted for, and the presence of unattended compounds in the vapor stream due to carryover may go unnoticed. In this research, a trace vapor generator (TV-Gen) was used to deliver quantitatively accurate amounts of vapor reproducibly over time for canine testing. Analyte losses due to adsorption to surfaces in the flow path, dilution in the sniff port at the outlet, and analyte carryover were considered. Computational fluid dynamic (CFD) modeling was used to visualize analyte vapor spread throughout the port. CFD simulations revealed the need for a diffuser to encourage the diffusion of the analyte throughout the port. As a result, the modified vapor generator provides analyte air as a diffuse flow that is evenly distributed through the custom sampling orifice, as opposed to a narrow stream of air at the chosen concentration which exits directly into the environment. Laboratory validations were carried out for three analytes, amyl acetate, 2,4-dinitrotoluene (DNT), and methyl benzoate. A linear response across more than two orders of magnitude vapor concentration range was achieved for all analytes. These efforts will be applied in further research utilizing this TV-Gen vapor delivery system for canine ODT testing, eliminating many quantitative changes seen previously. Graphical abstract.

Pollinators of Hoya pottsii: Are the strongest the most effective?

Hoya floral characters are highly elaborate and associated with a complex and specialised pollination mechanism. The pollination of two Hoya species has been studied previously, but little is known about the specific nature and interactions between flower morphology, pollinators, and their environment. Here we investigate the pollination of Hoya pottsii, where pollinaria are transferred onto several insects’ legs and arolia including moths in the Erebidae family, ants, and a praying mantis. Hypopyra vespertilio (Erebidae, Erebinae) was the most effective at both carrying and depositing the pollinaria, Colobopsis leonardii (Formicidae) was shown to successfully insert only one pollinium whereas Hymenopus coronatus (Hymenopodidae) could only attach the pollinaria between its two euplantulae.Several Hoya species were used to compare the effectiveness of pollinaria removal and insertion, pollinator size which was correlated to strength, floral scent, and morphology of the guide rail. The floral scent was dominated by Linalool, Methyl benzoate and Benzaldehyde which are known to attract moth, other species displayed similar scents but also showed many different compounds.The effectiveness of a medium-sized moth in pollinating H. pottsii could be explained by the morphology of the guide rail which comprises a landing platform for the arolium. In Hoya carnosa the guide rail lacks a landing platform which could explain why stronger and larger moths were more effective in this species. The importance of the interaction between insect arolia and guide rails in the pollination of Hoya is illustrated and we suggest that their morphology corresponds with pollinator strength and how smoothly and precisely the pollinia can be inserted.

One-pot synthesis of benzaldehyde derivatives in PdCl2-catalyzed reactions with H2O2 in alcoholic solutions

The activity of the palladium salt catalysts was investigated on the benzaldehyde reactions with H2O2. The PdCl2 salt was the most efficient catalyst for the formation of the goal products. In CH3OH, benzaldehyde was selectively oxidized to benzoic acid and posteriorly esterified to methyl benzoate. In this process, the reaction of the PdCl2 catalyst with aqueous H2O2 provided H+ ions, which also promoted the esterification and acetalization reactions. The oxidant load played a key role in the selectivity controlling; while a large excess (9:1) gave benzoic acid (90%), with a lower ratio (3:1), acid and ester were formed with selectivity of 58 and 35%, respectively. With H2O2 at an equimolar ratio, the Pd(0) reduced the benzaldehyde to benzyl alcohol (30%). In absence of the oxidant, PdCl2 (2.5 mol %) condensated benzaldehyde and alcohol to acetal (90%). Therefore, PdCl2 directly catalyzed the oxidation and reduction reactions, and participated in acid-catalyzed reactions (i.e., condensation and esterification), generating H+ ions, demonstrating to be a highly versatile catalyst. An adequate adjusting of reaction conditions allowed to control the reaction selectivity toward the desired products (i.e., benzoic acid or ester benzyl, acetal, or benzyl alcohol).

A New Megastigmane Glucoside and Other Constituents from Desmodium gangeticum

A new megastigmane glycoside, gangeticoside (1), and three known compounds leonuriside A (2), methyl benzoate 2-O-β-D-glucopyranoside (3), and tortoside A (4) were isolated from the aerial part of Desmodium gangeticum. Their structures were determined by 1D and 2D NMR spectra. The isolated compounds were evaluated for their inhibitory effect on NO production in LPS-stimulated RAW264.7 cells. Among them, compounds 1, 2, and 3 exhibited strong effect with the IC50 values of 22.3, 15.6, 7.3 μM, respectively.

Investigation of the Effect of Alkyl Chain Length on Molecular Interactions Between Methyl Benzoate with Alcohols: A Study of Physicochemical Properties

Densities, speeds of sound, and viscosities of binary mixtures of methyl benzoate (MB) with ethanol, 1-propanol, and 1-butanol were measured at temperature ranging from T = 293.2 to 313.2 K and refractive indices were determined at T = 303.2 K. Excess molar volumes, VE, isentropic compressibility deviations ∆κs and viscosity deviations, Δη, were obtained and fitted with the Redlich–Kister equation with satisfactory results. Based on the measured and derived physicochemical properties, the influence of the alkyl chain length of the alcohol on the molecular interactions of the studied mixtures was explored. The results show that both hydrogen bond interaction between carbonyl group of MB and hydroxyl group of alcohol and the packing efficiency, such as accommodation of alcohol in the interstice of MB, play an important role in the microstructure of the mixtures, which leads to the disruption of alcohol with the addition of MB. Moreover, by comparing VE, ∆κs and Δη values of MB (1) + alcohol (2) systems at T = 303.2 K, it is found that the strength of hydrogen bond interaction and the packing efficiency significantly weakens with increasing alkyl chain length of alcohol in going from ethanol to 1-butanol, resulting in the VE values of the studied systems gradually changing from a negative deviation to an S shape, the ∆κs and Δη values have negative deviations, and the ∆nD values have positive deviations. The obtained results will provide thermodynamic guidance for the industrial purification of methyl benzoate.

Structures and spectral properties of 5-phenyl-5H-benzo[b]phosphindole 5-oxide and its substituted derivatives: The substitutional effect study based on density functional theory calculations

The properties of phosphole-based π-conjugated compounds could be well tuned via simple chemical modification. Four π-conjugated groups with different electronic nature including naphthalen-2-yl, 4-methoxyphenyl, 4-Methyl benzoate, and 4-benzonitrile were introduced to the C8 position of 5-phenylbenzo[b]phosphindole 5-oxide (PhBPO) to reveal the relationship between structures and properties. Density functional theory (DFT) calculations were carried out to comparatively study the ground state geometries, orbital energy gaps, infrared (IR) spectra, UV–vis spectra, and fluorescence (FL) spectra of the five PhBPO derivatives. Good correspondences between the simulated and experimental IR and UV–vis spectral properties were found, proving the feasibility of the DFT method. The IR and Uv-vis spectra were assigned and explained in detail on the basis of the calculation results and the substituional effect of different substituents on the structure and spectral properties was revealed. The large FL oscillator strengths indicate these PhBPO derivatives are good candidates for fluorescent materials. PhBPO derivatives possess easy-to-modify sites and thus can be further utilized as functional materials.

Aerobic Oxidative Cleavage and Esterification of C(OH)–C Bonds

Summary C(OH)–C bonds are widely distributed in naturally renewable biomass, such as carbohydrates, lignin, and their platform molecules. Selective cleavage and functionalization of C(OH)–C bonds is an attractive strategy in terms of producing value-added chemicals from biomass. However, effective transformation of alcohols into esters by activation of C(OH)–C bonds has not been achieved so far. Herein, for the first time, we report selective cleavage and esterification of C(OH)–C bonds, catalyzed by inexpensive copper salts, using environmentally benign oxygen as the oxidant, to afford methyl esters in excellent yields. A diverse range of phenylethanol derivatives that contain C(OH)–C bonds were effectively converted into methyl benzoates. Detailed analysis revealed that the high efficiency and selectivity resulted mainly from the fact that, in addition to the major esterification reaction, the side products (e.g., olefins and acids) were also transformed in situ into esters in the reaction system.