Alkyl Benzoates Research Articles

Catalysis of the Transesterification Reaction of Alkyl Benzoates and Vegetable Oils by Carbonates, Carbene, and Anionite

Catalysis of the Transesterification Reaction of Alkyl Benzoates and Vegetable Oils by Carbonates, Carbene, and Anionite

Abstract 5566: Streamlining tissue sample preparation: A comparative study on the efficiency and reproducibility of the Omni-Stainer™ dewaxing and HIER protocol

Abstract The evolution of life sciences research has entailed a shift toward understanding cellular functions within tissue microenvironments, with an emphasis on cell- and tissue-specific relationships. A key challenge in these endeavors is the need for accurate data acquisition, which can be impeded by variability in the multistep manual assay preparations. In the quest for developing reliable and efficient tissue sample preparation workflows, two protocols using multiple dewaxing agents have been compared: the Omni-Stainer™ Dewaxing and HIER antigen retrieval protocol from Parhelia Biosciences, Inc. and the analogous one on Leica BOND Rx. The objective of this research was to assess the efficiency and reproducibility of these methods in the context of a four-color morphology immunostaining used for GeoMx DSP RNA and protein detection assays (Nanostring). We examined the efficiency of automated dewaxing using various non-toxic xylene alternatives, including C12-15 alkyl Benzoate, diethylene glycol, methyl octanoate or methyl decanoate, and compared them to the proprietary Leica Bond Dewaxing solution. Then, we compared the quality of post-HIER immunostaining using two different four-antibody panels on human jejunum samples. After several rounds of optimization, we found that the V4 of the open-source Omni-Stainer™ dewax-HIER protocol resulted in identical quality of morphology immunostaining compared to proprietary Leica Bond protocol. This study validates the Omni-Stainer™ Dewaxing and HIER protocol as a viable and efficient approach for automation of sample prep for GeoMx DSP studies. Citation Format: Nikolay Samusik, Yury Goltsev, Noemi Kedei. Streamlining tissue sample preparation: A comparative study on the efficiency and reproducibility of the Omni-Stainer™ dewaxing and HIER protocol [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5566.

Coenzyme Q10-loaded nanoemulsion hydrophilic gel: Development, characterization, stability evaluation and in vivo effects in skin

This study aimed to develop a physically and chemically stable hydrogel, which contains coenzyme Q10 (Q10)-loaded nanoemulsion, able to reduce transepidermal water loss (TEWL) and enhance skin hydration. Q10-loaded nanoemulsion was, after its characterization (particle size, polydispersity index (PDI), oxidation index, pH value, Q10-content, and electron microscopy) incorporated into a carbomer gel. The prepared Q10-loaded nanoemulsion gel was analyzed for its rheological parameters, pH value and Q10-content, after its preparation (48 h), after the stress test (5 cycles; 1 cycle: 24 h at 4 °C, 24 h at 20±2 °C and 24 h at 40 °C) and at predetermined time intervals during its storage at 20±2 °C and at 40 °C for six months. The Q10-loaded nanoemulsion gel, plain Q10-gel, Q10-free nanoemulsion gel and placebo carbomer gel were investigated in vivo for their effects in 15 human volunteers, during their 28 days’ application onto the skin. Skin hydration and TEWL were determined before starting the treatment, during 28 days of treatment, and 4 days after treatment completion. The results showed that the Q10-nanoemulsion was of a sufficiently low particle size (307,4 ± 0,5 nm) and homogeneity (PDI = 0.270 ± 0.002) for skin application, and that its characteristics were not changed by its incorporation into the gel. A shear-thinning plastic flow behavior was seen for the Q10-nanoemulsion gel. The stress test as well as storage at 20±2 °C and 40 °C did not change the rheological parameters of the gel. However, Q10-content decreased in the Q10-loaded nanoemulsion gel, but less compared to the Q10-gel. The developed Q10-nanoemulsion gel was able to significantly decrease TEWL compared to untreated skin (control), while it was not able, without the addition of a moisturizing agent (hyaluronic acid) and emollient (C12-15 alkyl benzoate) to increase skin hydration compared to control. Thus, besides the addition of a Q10-nanoemulsion into a hydrogel, it is necessary to add moisturizers and/or emollients to increase skin hydration.

Renewable Platform Chemicals: Evaluation of Experimental Data for Alkyl Benzoates with Complementary Measurements, Structure–Property Correlations, and Quantum Chemical Calculations

Renewable Platform Chemicals: Evaluation of Experimental Data for Alkyl Benzoates with Complementary Measurements, Structure–Property Correlations, and Quantum Chemical Calculations

Specific Features of the Retention of Lutein Diesters on C16 Stationary Phases with Different Pore Diameters

It is shown that the column dead time determined from the retention of uracil is longer than the one determined from the retention of homologs—lutein diesters—for C16 reversed phases on three columns with sorbents with different pore diameters (80, 110, and 160 Å). This finding confirms the familiar assumption that the sorbate molecules 10% larger than the pore diameter can cause problems with the retention of the sorbate. It is found for smaller molecules (of alkyl benzoates) that the dead time determined from the retention of uracil is less than the one determined from the retention of the homologs on the same stationary phases, confirming that the main cause of the observed effect is the size factor.

Diversified chemical profiles of cuticular wax on alpine meadow plants of the Qinghai-Tibet Plateau.

The alpine meadow plants showed great intra- and inter-genera variations of chemical profiles of cuticular waxes. Developing an understanding of wax structure-function relationships that will help us tackle global climate change requires a detailed understanding of plant wax chemistry. The goal in this study was to provide a catalog of wax structures, abundances, and compositions on alpine meadow plants. Here, leaf waxes from 33 plant species belonging to 11 families were sampled from alpine meadows of the east side of the Qinghai-Tibet Plateau. Across these species, total wax coverage varied from 2.30μgcm-2 to 40.70μgcm-2, showing variation both within as well as between genera and suggesting that wax variation is subject to both environmental and genetic effects. Across all wax samples, more than 140 wax compounds belonging to 13 wax compound classes were identified, including both ubiquitous wax compounds and lineage-specific compounds. Among the ubiquitous compounds (primary alcohols, alkyl esters, aldehydes, alkanes, and fatty acids), chain length profiles across a wide range of species point to key differences in the chain length specificity of alcohol and alkane formation machinery. The lineage-specific wax compound classes (diols, secondary alcohols, lactones, iso-alkanes, alkyl resorcinols, phenylethyl esters, cinnamate esters, alkyl benzoates, and triterpenoids) nearly all consisted of isomers with varying chain lengths or functional group positions, making the diversity of specialized wax compounds immense. The comparison of species relationships between chemical data and genetic data highlighted the importance of inferring phylogenetic relationships from data sets that contain a large number of variables that do not respond to environmental stimuli.

One‐Electron Injection‐triggered Radical Reaction of Alkyl Benzoates Promoted by 1,4‐Bis(diphenylamino)benzene Photocatalysis

AbstractThe ester group is one of the most ubiquitous functional groups in natural products and synthetic organic molecules. Herein, we describe the photocatalytic generation of alkyl radicals from readily accessible alkyl benzoate esters. The excited organic photocatalyst 1,4‐bis(diphenylamino)benzene (BDB) plays a vital role as a one‐electron injector. The present photoredox‐catalytic system realizes the hydroxy‐1,1‐dialkylfluoroethylation of aromatic alkenes. Finally, a strategy is developed for generation of fluoroalkyl radicals from the corresponding readily available 2‐fluorinated 1,1‐dialkylethanols.

Vaporization thermodynamics of normal alkyl benzoates

Vaporization thermodynamics of normal alkyl benzoates

Molecular dynamics of alkyl benzoate liquid crystals in the bulk state and in the surface layer of their composites with oxide nanopowders

This paper presents the results concerning monotropic nematic liquid crystals 4-pentylphenyl 4′-alkyl benzoate (5PnB) (n = 3 or 5 carbon atoms in the alkyl chain). Their mesophase properties were supported by images of the polarized optical microscopy. Molecular dynamics in the bulk samples or in the composites prepared with aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range, appropriately chosen. Thermo gravimetric and infrared investigations were additionally performed. The data were compared with those of structurally related nematics like cyanophenyl pentyl benzoates, which have a cyan group instead of the pentyl chain. The dielectric spectra of the bulk 3P5B and 5P5B demonstrate a dielectric behavior with several relaxation processes as expected for nematic liquid crystals. The temperature dependence of the relaxation rates (and of the dielectric strength) seems to have two distinguished regimes. Thus, in the isotropic state, at higher temperatures the data obey the Vogel–Fulcher–Tammann law, whereas an Arrhenius law is fitted at lower temperature, in a close similarity to the behavior of a constrained dynamic glass transition. Samples with a high density of silica (larger than 7 g aerosil/1 g of 5PnB) were prepared to observe a thin layer adsorbed on the particle surface; it was estimated that almost each guest 5PnB molecule interacts with the aerosil surface. For the composites only one main relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in the surface layer. Infrared spectroscopy shows that these molecules interact with the surface by the ester carbonyl group leading to the monolayer self-assembly at liquid–solid interface. We note once more the importance of the functional unit(s) for the interaction with the hydroxyl groups on the aerosil surface.

Metal- and Solvent-Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5-Triazine Framework.

A new recyclable basic ionic liquid was introduced as an efficient catalyst for aldol condensation and transesterification reactions under environmentally friendly conditions. The catalyst was prepared based on methyl imidazolium moieties bearing hydroxide counter anions via the Hofmann elimination on a 1,3,5‐triazine framework. The ionic liquid with two functionalities including anion stabilizer and high basicity, was used as an efficient catalyst for aldol condensation as well as transesterification reaction of a variety of alkyl benzoates. All reactions were performed in the absence of any external reagent, co‐catalyst, or solvent, in line with environmental protection. The kinetics isotope effect (KIE) was conducted for the transesterification reaction to elucidate the mechanism and rate determining step (RDS). It worth noted that, the homogeneous catalyst could be recycled from the reaction mixture and reused for several consecutive runs with insignificant drop of basicity and conversion.

Hydrogen bonding probes electron density variations at the basic center in substituted alkyl benzoates: Theory and experiment

AbstractTheoretical computations of charge density parameters are juxtaposed to experimental spectroscopic shifts induced by hydrogen bonding for a series of 21 substituted in the aromatic ring ethyl and methyl benzoates. Strong correlations between atomic charges at the proton accepting atom and the shifts of methanol O–H frequencies are established. Hirshfeld, Charge Model 5 (CM5), and natural population analysis (NPA) atomic charges are evaluated using ωB97X‐D/6‐311++G(3df,2pd) and MP2/6‐311++G(3df,2pd) computations. The results obtained reveal the power of hydrogen bond measurements in characterizing the variations of electron densities at the proton accepting center within a series of structurally related molecules. The limits of application of the approach are outlined.

Formulation of Pickering emulsions for the development of surfactant-free sunscreen creams.

Pickering emulsions are increasingly used in the pharmaceutical and cosmetic fields, especially for topical applications, since these systems require solid particles as emulsifiers instead of surfactants which are known to cause skin irritation. The solid inorganic nanoparticles (TiO2 and ZnO) used as UV filters in sunscreen formulations may also stabilize emulsion droplets, so that the utility of surfactants may be questioned. Surfactant-free sunscreen emulsions solely stabilized by such nanoparticles (NPs) have been studied. The ability of these NPs to stabilize o/w emulsions containing a 'model' oil phase, the C12 -C15 alkylbenzoate, has been assessed. ZnO and hydrophilic silica-coated TiO2 NPs widely used in sunscreen products were used together with their mixtures. The emulsification efficiency, the control of droplet size and the stability of o/w Pickering emulsions solely stabilized by NPs were investigated. A ZnO/TiO2 NPs mixture characterized by a theoretical SPF of 45 was finally used as unique emulsifiers to develop a surfactant-free sunscreen emulsion. Stable Pickering emulsions containing 10 up to 60wt% of C12 -C15 alkyl benzoate were formulated with 2wt% ZnO in the aqueous phase. The droplet size was controlled by the solid NPs content with respect to oil and the emulsification process. Hydrophilic TiO2 NPs did not allow the stabilization of emulsions. The substitution of TiO2 for ZnO up to 60-70wt% in a 20/80 o/w emulsion was successfully performed. Finally, a ZnO/TiO2 NP mixture was tested as unique emulsifier system for the formulation of a sunscreen cream. Despite a lower viscosity, the obtained Pickering emulsion was stable and exhibited a photoprotective effect similar to the corresponding surfactant-based sunscreen cream with an in vitro SPF of about 45. Surfactant-free Pickering emulsions can be stabilized by the UV-filter nanoparticles for the manufacture of sunscreen products.

Metal‐free Catalytic Esterification of Aryl Alkyl Ketones with Alcohols via Free‐radical Mediated C(sp3)−H Bond Oxygenation

AbstractA novel metal‐free catalytic one‐pot approach has been developed for the esterification of aralkyl ketones with alcohols under open‐air atmospheric conditions. The inexpensive iodide/oxone reagent system allowed the cascade C(sp3)−H bond oxygenation, selective C−C bond cleavage and esterification through the both radical and ionic pathways in a stepwise manner in one‐pot. This mild, convenient and economically viable catalytic method tolerates the various functional groups to provide the corresponding alkyl benzoates in up to 98% yields with up to 99% selectivity. The efficiency and feasibility of scale‐up of the present catalytic system was demonstrated with gram scale experiments (up to 10 gram scale).

Synthesis of propyl benzoate by solvent-free immobilized lipase-catalyzed transesterification: Optimization and kinetic modeling.

The present study aimed to analyze reaction kinetics and mechanism for the synthesis of propyl benzoate in solvent-free conditions. Lipase was immobilized on Hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) polymer blend by entrapment method. Among different lipases immobilized on a support, Candida cylindracea (CCL) showed excellent activity. Systematic studies were done to optimize the reaction conditions. The activation energy was found to be 16.2kcal/mol for immobilized CCL. Kinetic parameters were calculated, which depicted that propyl benzoate synthesized using immobilized CCL followed the ternary complex model in which propanol inhibits lipase activity at higher concentrations. Recyclability of the catalyst was checked up to four catalytic cycles and 40% retention of activity was observed up to the fourth cycle. Finally, the applicability of developed protocol to synthesize various alkyl benzoates was explored.

Effect of emollients on UV filter absorbance and sunscreen efficiency

The idea of increasing the performance of sunscreens without adding more UV-filters is very attractive. Early studies reported an influence of solvents on the absorbing properties of UV-absorbers which was shown to be connected to the solvent polarity. However, the polarity differed a lot between tested solvents and most were unsuitable UV-filter solubilizers. The aim of the present study was to focus exclusively on emollients pertinent for sunscreens and investigate their impact on the performance of UV-filter combinations. The UV absorbance of Bis-ethylhexyloxyphenol Methoxyphenyl Triazine, Ethylhexyl Triazone, Diethylamino Hydroxybenzoyl Hexyl Benzoate, and Ethylhexyl Methoxycinnamate was measured in suncare relevant emollients comprising C12–15 Alkyl Benzoate, Dibutyl Adipate, Caprylic/Capric Triglyceride, Coco-caprylate, Isopropyl Myristate, Dicaprylyl Carbonate. The wavelength of maximum absorbance (λmax) and specific extinction at λmax (E1,1 (λmax)) were assessed for each UV-filter – emollient system. The performance of market relevant UV-filter combinations based on the studied UV-filters was simulated for each emollient with a computational method using the absorbance values measured for each UV-filter - emollient system. The difference in polarity of emollients led to a 2-3 nm bathochromic shift and a variation of the E1,1 (λmax) ranging from 4 to 20% for tested UV-filters. The emollient type showed nearly no influence on the sun protection factor (SPF) of market relevant UV-filter combinations probably due to a different influence an emollient shows on the UVB filters resulting in cancelling of the corresponding effect. Conversely, for all UV-filter combinations the UVA protection decreased with a decrease in the emollient polarity. Whilst the SPF was not impacted by standardly used cosmetic oils, the results advocate to use polar emollients to optimize the UVA protection. This is of advantage since polar emollients better dissolve crystalline UV-filters. From tested emollients, Dibutyl Adipate performed the best for both SPF and PPD factors.

Skin Irritation Testing beyond Tissue Viability: Fucoxanthin Effects on Inflammation, Homeostasis, and Metabolism.

UV light catalyzes the ozone formation from air pollutants, like nitrogen oxides. Since ozone reacts with cutaneous sebum lipids to peroxides and, thus, promotes inflammation, tumorigenesis, and aging, even broad-spectrum sunscreens cannot properly protect skin. Meanwhile, xanthophylls, like fucoxanthin, proved their antioxidant and cytoprotective functions, but the safety of their topical application in human cell-based models remains unknown. Aiming for a more detailed insight into the cutaneous fucoxanthin toxicity, we assessed the tissue viability according to OECD test guideline no. 439 as well as changes in inflammation (IL-1α, IL-6, IL-8), homeostasis (EGFR, HSPB1) and metabolism (NAT1). First, we proved the suitability of our 24-well-based reconstructed human skin for irritation testing. Next, we dissolved 0.5% fucoxanthin either in alkyl benzoate or in ethanol and applied both solutions onto the tissue surface. None of the solutions decreased RHS viability below 50%. In contrast, fucoxanthin ameliorated the detrimental effects of ethanol and reduced the gene expression of pro-inflammatory interleukins 6 and 8, while increasing NAT1 gene expression. In conclusion, we developed an organ-on-a-chip compatible RHS, being suitable for skin irritation testing beyond tissue viability assessment. Fucoxanthin proved to be non-irritant in RHS and already showed first skin protective effects following topical application.

Molecular dynamics in bulk and surface species of cyanophenyl alkyl benzoates with 2, 3 and 7 carbon atoms in the alkyl chain: comparison in the whole homologous series

ABSTRACTMolecular mobility of cyanophenyl alkylbenzoates (CPnBs) (n = 2, 3, 7 – number of carbon atoms in the alkyl chain) in the bulk and in composites with aerosil A380 is investigated by broadband dielectric spectroscopy, while thermal analysis and infrared spectroscopy were applied to characterise the molecular species. The work completes preliminary results obtained for the members with n = 4 … 6. An interaction by hydrogen bonding, between aerosil surface – OH groups and – CN or ester groups of the CPnB molecules takes place. It slows down the relaxation process as observed for related composites in comparison to the pure materials. The existence of two types of bonding might be the reason that Vogel temperature for the relaxation process in the surface layer does not show the odd-even effect. Temperature dependence of the relaxation rates for composites shows a crossover behaviour from a high to a low temperature regime. Moreover, the temperature dependence of the dielectric strength is unusual. As the loading degree is similar, comparison of the dielectric, spectroscopic and thermal data obtained here and with the results obtained for the composites with n = 4 … 6 can be directly done. Increasing the number of the members of the homologous series confirms and hardens the preliminary conclusions.

Structural optimization and neurotrophic activity evaluation of neurotrophic gentiside derivatives.

C14 alkyl benzoate ABG001, derived from naturally occurring gentisides, was reported to exhibit neurotrophic activity which is similar to NGF (Nerve Growth Factor). In this research, ABG001 was modified by the strategy of isosteric replacement and conformational restriction with the purpose of improving the bioactivity. The cellular neurotrophic activity of those ABG001 derivatives were evaluated, among which 3-hydroxyquinolin-2-(1H)-one A3 and 4-decylphenol ester B7 displayed much better neurotrophic activity compared with ABG001, which highlights the potential of those novel scaffolds for future neurotrophic agent development.

Efficient Preparation of Alkyl Benzoates by Heteropolyacid‐Catalysed Esterification of Benzoic Acid under Solvent‐Free Condition

AbstractThis study reports a high‐yielding, solvent‐free, and scalable synthesis of alkyl benzoates from benzoic acid and its derivatives using heteropolyacids (HPA) as efficient and recyclable acid catalysts. The alkyl benzoates were obtained in excellent isolated yields (>85%) within 4 h at 120 °C using 1.5 equivalent of the alcohol reagent and only 0.4 mol% of the phosphotungstic acid (PTA) catalyst. The PTA catalyst was conveniently recovered and reused for three consecutive cycles without significant loss in mass or activity.

Copper-Catalyzed Three-Component Coupling Reaction of Aryl Iodides, a Disilathiane, and Alkyl Benzoates Leading to a One-Pot Synthesis of Alkyl Aryl Sulfides

A copper-catalyzed three-component coupling reaction of aryl iodides, hexamethyldisilathiane and alkyl benzoates leading to alkyl aryl sulfides has been demonstrated. A disilathiane acted as both a sulfur source and a promoter of the sulfidation, and the alkyl moiety of the alkyl benzoate was effectively introduced on one side of the sulfide. Moreover, we found that the protocol can be expanded to the preparation of ethyl phenyl selenide with diphenyl diselenide.