Esterification Of Alcohols Research Articles

Advances for Catalysts in One-Step Oxidative Esterification of Aldehydes and Alcohols with Alcohols to Esters

Advances for Catalysts in One-Step Oxidative Esterification of Aldehydes and Alcohols with Alcohols to Esters

How Two‐Dimensional Heterocovariance Spectroscopy and Data Fusion Level out the Inadequacies of Compact Spectrometers

ABSTRACTOver the past decade, sensors and compact spectrometers have emerged as a powerful means for real‐time monitoring of chemical and biochemical processes in the field of process analytical technologies (PATs). This is largely attributed to cost‐efficiency and their robustness in near‐line applications. In comparison to more sophisticated laboratory instruments, these devices exhibit limited sensitivity and resolution. In this study, a combination of near‐infrared, low‐field 1H nuclear magnetic resonance and compact Raman spectrometers were employed for the process monitoring of the acid‐catalyzed esterification of isoamyl alcohol and acetic acid to isoamyl acetate. The resulting real‐time data were transformed and visualized for interpretation using two‐dimensional heterocovariance spectroscopy. The data were also subjected to pretreatment, concatenation, and multivariate analysis in accordance with low‐ and mid‐level data fusion. The spectral interpretation derived from heterocovariance spectroscopy provided support for the data pretreatment during data fusion. By applying these computational techniques, the inherent limitations of sensitivity and resolution associated with compact spectroscopic instruments could be overcome, thereby facilitating the interpretation of data and yielding further insights into the process under study. A comparison of the process parameters resulting from the applied methods indicated that consistent data could be obtained. This study demonstrates that heterocovariance spectroscopy and data fusion allow to enhance compact, less expensive analytical instruments for process monitoring and to acquire process knowledge. This, in turn, enables material, financial, and energy resources to be conserved.

Cationic amphiphilic molecules as novel sclerosants for venous malformation treatment: A study on tranexamic acid-derived low-molecular-weight gels

Venous malformation (VM) is a prevalent congenital vascular anomaly characterized by abnormal blood vessel growth, leading to disfigurement and dysfunction. Sclerotherapy, a minimally invasive approach, has become a primary therapeutic modality for VM, but its efficacy is hampered by the rapid dilution and potential adverse effects. In this study, we introduced a series of cationic amphiphilic molecules, fatty alcohol esters (TA6, TA8, and TA9) of tranexamic acid (TA), which self-assembled into low-molecular-weight gels (LMWGs) in water. The TA9, in particular, is released slowly when hydrogel is injected into the vein locally. Then, it damages the venous wall by destroying cell membranes and precipitating proteins, causing inflammation and thrombosis, thickening of the venous wall, effectively inducing irreversible vein fibrosis. Additionally, TA9 can be rapidly degraded into TA in plasma to reduce toxicity caused by diffusion. Overall, this study suggests that the cationic amphiphilic molecule TA9 is a promising sclerosant for VM treatment, offering a novel, effective, and safe therapeutic option with potential for clinical translation.

Supramolecular structure and thermal transformations of modified resinous-asphaltene substances

A detailed study of the supramolecular structure of high molecular weight resinous-asphaltene substances (RAS) and the study of their stability to thermal-oxidative degradation processes in the presence of surfactants is a promising scientific direction and can become the basis for the development of additional oil treatment processes and, as a result, the intensification of thermal transformations of oil dispersed systems (ODS). In the work it has been established that the maximum modifying effect, which consists in reducing the amount of asphaltenes by 8–11 % and increasing the concentration of resins, saturated and aromatic hydrocarbons in the composition of the dispersion medium, is achieved by the interaction of ODS with octadecylpropylenediamine, alkyldiamine with the content of ethoxylated groups n = 3–6 and butyl coconut fatty alcohol ester with n = 10. This fact is due to a change in the geometric parameters of asphaltene nanoaggregates due to the adsorption of these surfactants on their surface. Thus, against the background of an increase in the interplanar distances of condensed aromatic layers dm from 3.66 to 3.85 Å and values of the intrachain distance from 5.71 to 5.80 Å, the average diameter of aromatic layers decreases by 0.67–2.36 Å and the average height of their pack by 1.52–2.64 Å, while the average number of layers in a pack is 5. Estimation of the results of thermal analysis indicates that the RAS thermograms have a similar form with three endoeffects with minima in the ranges of ~ 34.7–37.7 °C (I); 325.7–339.3 (II) and 434.8–438.7 °С (III) and one exoeffect with a maximum of ~ 460.5–475.3 °С (IV). With a decrease in the factor of crystallinity and aromaticity of RAS, their resistance to the processes of thermo-oxidative degradation in the temperature region of coke formation increases. The energy of thermal-oxidative destruction for modified systems by surfactants exceeds by 21.6 kJ/mol of this indicator for unmodified RAS and is 62.07 ÷ 66.13 kJ/mol.

Mechanism regulation over dual-atom catalyst enables high-performance oxidative alcohol esterification

The development of heterogeneous catalysts with well-defined uniform isolated or multiple active sites is of great importance for understanding catalytic performances and studying reaction mechanisms. Herein, we present a CoCu dual-atom catalyst (CoCu-DAC) where bonded Co–Cu dual-atom sites are embedded in N-doped carbon matrix with a well-defined Co(OH)CuN6 structure. The CoCu-DAC exhibits higher catalytic activity and selectivity than the Co single-atom catalyst (Co-SAC) and Cu single-atom catalyst (Cu-SAC) counterparts in the catalytic oxidative esterification of alcohols and a variety of methyl and alkyl esters have been successfully synthesized. Kinetic studies reveal that the activation energy (29.7 kJ mol−1) over CoCu-DAC is much lower than that over Co-SAC (38.4 kJ mol−1) and density functional theory (DFT) studies disclose that two different mechanisms are regulated over CoCu-DAC and Co-SAC/Cu-SAC in three-step esterification of alcohols. The bonded Co–Cu and adjacent N species efficiently catalyze the elementary reactions of alcohol dehydrogenation, O2 activation and ester formation, respectively. The stepwise alkoxy pathway (O–H and C–H scissions) is preferred for both alcohol dehydrogenation and ester formation over CoCu-DAC, while the progressive hydroxylalkyl pathway (C–H and O–H scissions) for alcohol dehydrogenation and simultaneous hemiacetal dehydrogenation are favored over Co-SAC and Cu-SAC. Characteristic peaks in the Fourier transform infrared spectroscopy analysis may confirm the formation of the metal-C intermediate and the hydroxylalkyl pathway over Co-SAC.

Phytochemical Analysis and In Vivo Antimalarial Activities of Ethyl Acetate Fraction of Spilanthes filicaulis on Mice Subjected to Plasmodium berghei.

Background and Objectives: Malaria airs a life-threatening risk in Tropical African countries, stemming from infection by Plasmodium species. This region is richly endowed by nature with a wealth of diverse and largely unexplored plants that hold the potential for managing this protozoan parasite. The currently accessible over-the-counter drugs for disease management often present affordability challenges for the average person, exacerbated by the parasite's increasing resistance to them. This study investigated the phytoconstituents present in the ethyl acetate fraction of Spilanthes filicaulis (EFSF) and explored the antimalarial effects of EFSF on mice infected with Plasmodium berghei. Methods: Standard methods and gas chromatography-mass spectrometry (GC-MS) were used to identify phytoconstituents. Chloroquine phosphate-sensitive P. berghei (NK-65) was intraperitoneally inoculated into Swiss mice. The invivo antimalarial activity of EFSF was assessed at dose levels of 250, 500, and 750 mg/kg, using 4-day suppressive and curative antimalarial models. Parameters evaluated in the inoculated mice included rectal temperature (RT), body weight (BW), packed cell volume (PCV), level of parasitemia, and mean survival time (MST). Results: Steroids, alkaloids, flavonoids, tannins, saponins, terpenoids, and cardiac glycosides were the identified phytochemicals present in EFSF, and GC-MS alongside reveals the presence of 20 bioactive compounds predominantly fatty acids and alcohol esters. Significant prevention of reductions in RT, BW, and PCV was observed in the EFSF-treated groups dose dependently relative to the untreated group. In addition, EFSF-treated groups significantly (p < 0.05) suppressed parasitemia and exhibited chemosuppression of 79.46% and 77.38% in 4-day suppressive, whereas suppression of 59.74% and 58.66% in curative treatment, respectively, at 500 and 750 mg/kg thus consequently extending the MST of infected treated mice compared with the untreated group. Interpretation and Conclusion: Put together, the EFSF exhibited enhanced antimalarial efficacy against mice infected with P. berghei thus affirming that plants still maintain lead way as a potential source of novel antimalarial remedies.

Enzyme‐Like Catalysis of Vinyl Copolymer Carrying Boron Directly Connected to Backbone: Catalytic Esterification through Cooperation of Boron with Neighboring Carboxylic Anhydride

AbstractAlternating‐rich copolymer of vinylboronic acid pinacol ester (VBpin) and maleic anhydride (MAH) was found to catalyze direct dehydrative esterification of carboxylic acid and alcohol. The key to the catalytic function is the activation of the MAH unit by the neighboring Lewis acidic boron directly connected to the backbone through the formation of five‐membered ring. The effects of the side‐chain cooperation were clarified through comparisons with the polymers having similar structures and a conventional titanium catalyst as well as the analyses of reactions with carboxylic acid or alcohol. The catalytic activity was enhanced as the molecular weight was higher, which is owing to the structural feature that boron is directly attached to the backbone. The cooperative catalysis is of interest because of its conceptual similarity with enzyme.

A GC-MS Metabolic Study on Lipophilic Compounds in the Leaves of Common Wheat Triticum aestivum L.

Common wheat (Triticum aestivum L.) is one of the most valuable cereal crops worldwide. This study examined leaf extracts of 30 accessions of T. aestivum and its subspecies using 48 h maceration with methanol by GC-MS and GCxGC-MS. The plants were grown from seeds of the wheat genetics collection of the Wheat Genetics Sector of the Institute of Cytology and Genetics, SB RAS. The analysis revealed 263 components of epicuticular waxes, including linear and branched alkanes, aliphatic alcohols, aldehydes, ketones, β-diketones, carboxylic acids and their derivatives, mono- and diterpenes, phytosterols, and tocopherols. Hierarchical cluster analysis and principal component analysis were used to identify and visualize the differences between the leaf extracts of different wheat cultivars. Three clusters were identified, with the leading components being (1) octacosan-1-ol, (2) esters of saturated and unsaturated alcohols, and (3) fatty acid alkylamides, which were found for the first time in plant extracts. The results highlight the importance of metabolic studies in understanding the adaptive mechanisms and increasing wheat resistance to stress factors. These are crucial for breeding new-generation cultivars with improved traits.

Efficient separation of alcohol ester via extractive distillation and pressure swing distillation based on molecular interaction mechanism analysis

N-amyl alcohol, n-amyl formate, n-propanol and n-propyl formate are all organic solvents with important industrial application value. In industrial production, related alcohol ester azeotropic systems are often generated. Therefore, it is necessary to study the refining process of these substances. The work designed purification processes for two different azeotropic systems of alcohol esters via extractive distillation and pressure swing distillation methods. The required binary interaction parameters were obtained through vapor–liquid equilibrium experiments. Based on experimental data, a suitable entrainer was determined through different methods of analysis. The processes were optimized with the economic cost as the objective. In addition, it evaluated and analyzed different processes from multiple perspectives. This work explores the purification process of alcohol ester systems, providing theoretical guidance for achieving efficient separation of alcohol ester systems.

Fabrication of bio-based polymer microcapsule containing fragrances via interfacial photo-initiated crosslinking

Home fragrance (F) products such as laundry detergent and fabric softener use fragrance or essential oils as key components. Typically, the fragrance is enclosed within a polymer. The shell enhances the longevity of the scent due to its durability. However, there is growing environmental concern about utilizing fossil polymers, which decompose slowly and harm the ecology and food chain. Biopolymers are also highly expected to be used as alternative polymers to prepare environmentally friendly microcapsules. This research aims to use poly cinnamyl methacrylate (PCMA) as a biopolymer to prepare microcapsules encapsulated fragrance via interfacial photo-initiated crosslinking. The CMA monomer was prepared by the esterification of cinnamyl alcohol with methacrylic anhydride and synthesized via radical polymerization to form PCMA with a molecular weight of 6,400 g/mol. The PCMA and PCMA/F particles were obtained when the PCMA and PCMA/F droplets dispersed in water were UV-irradiated at 60 W for 8h, giving PCMA and PCMA/F particles contained the highest crosslinking (60–75%). Both PCMA and PCMA/F particles were spherical and smooth outer surfaces where their particle sizes of ∼2 and 7 µm for PCMA and PCMA/F particles were obtained, respectively. The larger size of PCMA/F particles was due to encapsulation, where the encapsulation efficiency of fragrance in PCMA/F particles was approximately 100%. Moreover, the fragrances remaining in the microcapsule particles after 40 days of storage were over 90%. This technique was simple, had high potential microencapsulation, and was environmentally friendly, so the developed microcapsules would express great potential for textiles and laundry formulations.

Enzyme-Like Catalysis of Vinyl Copolymer Carrying Boron Directly Connected to Backbone: Catalytic Esterification through Cooperation of Boron with Neighboring Carboxylic Anhydride.

Alternating-rich copolymer of vinylboronic acid pinacol ester (VBpin) and maleic anhydride (MAH) was found to catalyze direct dehydrative esterification of carboxylic acid and alcohol. The key to the catalytic function is the activation of the MAH unit by the neighboring Lewis acidic boron directly connected to the backbone through the formation of five-membered ring. The effects of the side-chain cooperation were clarified through comparisons with the polymers having similar structures and a conventional titanium catalyst as well as the analyses of reactions with carboxylic acid or alcohol. The catalytic activity was enhanced as the molecular weight was higher, which is owing to the structural feature that boron is directly attached to the backbone. The cooperative catalysis is of interest because of its conceptual similarity with enzyme.

Esterification and Etherification of Aliphatic Alcohols Enabled by Catalytic Strain-Release of Donor-Acceptor Cyclopropane.

We herein disclose a highly efficient protocol for the esterification and etherification of alcohols, leveraging a Sc(OTf)3-catalyzed ring-strain release event in the meticulously designed, chromatographically stable mixed anhydrides or benzyl esters that incorporate an intramolecular donor-acceptor cyclopropane (DAC). This versatile method facilitates the straightforward functionalization of sugar, terpene, and steroid alcohols under mild acidic conditions, as showcased by the single-catalyst-driven, dual protection of sugar diol.

Strategies to Design Chemocatalytic Racemization of Tertiary Alcohols: State of the Art & Utilization for Dynamic Kinetic Resolution.

The synthesis of enantiomerically pure tertiary alcohols is an important issue in organic synthesis of a range of pharmaceuticals including molecules such as the anti-HIV drug Efavirenz. A conceptually elegant approach to such enantiomers is the dynamic kinetic resolution of racemic tertiary alcohols, which, however, requires efficient racemization strategies. The racemization of tertiary alcohols is particularly challenging due to various side reactions that can occur because of their high tendency for elimination reactions. In the last few years, several complementary catalytic concepts for racemization of tertiary alcohols have been developed, characterized by efficient racemization and suppression of unwanted side-reactions. Besides resins bearing sulfonic acid moieties and a combination of boronic acid and oxalic acid as heterogeneous and homogeneous Brønsted-acids, respectively, immobilized oxovanadium and piperidine turned out to be useful catalysts. The latter two catalysts, which have already been applied to different types of substrates, also have proven good compatibility with lipase, thus leading to the first two examples of chemoenzymatic dynamic kinetic resolution of tertiary alcohols. In this review, the difficulties in racemizing tertiary alcohols are specifically described, and the recently developed complementary concepts to overcome these hurdles are summarized.

Biocatalysts engineering by varying the binary CNTs-silica composition and the physicochemical characteristics of adsorbents for the immobilization of recombinant T. lanuginosus lipase

Biocatalytic engineering was carried out by varying monotonically the binary CNTs-silica composition and, accordingly, the physicochemical characteristics of adsorbents developed for immobilization of recombinant T. lanuginosus lipase (rPichia/lip). The adsorbents based on composite carbon-silica materials (CCSMs) were produced by impregnating finely dispersed multi-walled carbon nanotubes with silica hydrosol followed by calcination in argon at 350°C; the mass ratio of the hydrophobic and the hydrophilic components varied over a wide range. Biocatalysts (BCs) for green low-temperature synthesis of various esters in a non-aqueous medium of organic solvents were prepared by adsorption of rPichia/lip with subsequent drying under ambient conditions. The characteristics of the CCSMs and BCs were characterized by thermogravimetry, nitrogen porosimetry and electron microscopy. The catalytic properties of BCs, such as enzymatic activity, substrate conversion and specificity, as well we their operational stability depending on the chemical composition of CCSMs were extensively studied in the esterification of saturated monocarboxylic acids (C4, C7, C18) and primary aliphatic alcohols (C2, C4, C16) in hexane at 20°C. It was found that the esterifying activity manyfold decreased with increasing the silica content primarily due to a decrease in adsorption ability of CCSMs toward rPichia/lip. The substrate specificity and operational stability of the lipase-active BCs did not greatly depend on the composition of CCSMs. Biocatalysts retained more than half of their initial esterifying activity after 10 reaction cycles.

Protein engineering of lipase A from Candida antarctica to improve esterification of tertiary alcohols.

Chiral tertiary alcohols are important organic compounds in science as well as in industry. However, their preparation in enantiomerically pure form is still a challenge due to their complex structure and steric hindrances compared with primary and secondary alcohols, so kinetic resolution could be an attractive approach. Lipase A from Candida antarctica (CAL-A) has been shown to catalyze the enantioselective esterification of various tertiary alcohols with excellent enantioselectivity but low activity. Here we report a mutagenesis study by rational design to improve CAL-A activity against tertiary alcohols. Single mutants of CAL-A were selected, expressed, immobilized and screened for esterification of the tertiary alcohol 1,2,3,4-tetrahydronaphthalene-1-ol. A double mutant V278S+S429G showed a 1.5-fold higher reaction rate than that of the wild type CAL-A, while maintaining excellent enantioselectivity.

Relay Catalysis for Selective Aerobic Oxidative Esterification of Primary Alcohols with Methanol.

Esters are bulk and fine chemicals and ubiquitous in polymers, bioactive compounds, and natural products. Their traditional synthetic approach is the esterification of carboxylic acids or their activated derivatives with alcohols. Herein, a bimetallic relay catalytic protocol was developed for the aerobic esterification of one alcohol in the presence of a slowly oxidizing alcohol, which has been identified as methanol. A concise synthesis of phlomic acid was executed to demonstrate the practicality and potential of this reaction.

Intensification of Enzymatic Sorbityl Laurate Production in Dissolved and Neat Systems under Conventional and Microwave Heating.

Glycolipids such as sugar alcohol esters have been demonstrated to be relevant for numerous applications across various domains of specialty. The use of organic solvents and, more recently, deep eutectic solvents (DESs) to mediate lipase-supported bioconversions is gaining potential for industrial application. However, many challenges and limitations remain such as extensive time of production and relatively low productivities among others, which must be solved to strengthen such a biocatalytic process in industry. In this context, this study focuses on the intensification of sorbityl laurate production, as a model biocatalyzed reaction using Novozym 435, investigating the relevance of temperature, heating method, and solvent system. By increasing the reaction temperature from 50 to 90 °C, the space-time yield and product yield were considerably enhanced for reactions in DES and the organic solvent 2M2B, irrespective of the heating method (conventional or microwave heating). However, positive effects in 2M2B were more pronounced with conventional heating as 98% conversion yield was reached within 90 min at 90 °C, equating thus to a nearly 4-fold increase in performance yielding 118.0 ± 3.6 g/(L·h) productivity. With DES, the overall yield and space-time yield were lower with both heating methods. However, microwave heating enabled a 2-fold increase in both performance parameters when the reaction temperature was increased from 50 to 90 °C. Compared to conventional heating, a 7-fold increase in space-time yield at 50 °C and a 16-fold increase at 90 °C were achieved in DES by microwave heating. Furthermore, microwave irradiation enabled the usage of a neat, solvent-free system, representing an initial proof of concept with productivities of up to 13.3 ± 2.3 g/(L·h).

Ruppert‐Prakash Reagent (TMSCF3)‐Catalyzed Chemoselective Esterification of Weinreb Amides

AbstractA straightforward TMSCF3‐catalyzed conversion of Weinreb amides into esters through the treatment with sodium alkoxides is reported. The procedure documents a genuine selectivity for the esterification of primary alcohols with Weinreb amides featuring diverse substitution pattern. The constitutive N‐methoxy fragment of these acylating agents is responsible for the unique reactivity they display, thus enabling to explore alkoxides as competent nucleophilic elements. The protocol is compatible with the fully transfer of stereochemical information embodied in the starting material, as well as, guarantees the preparation of pharmaceuticals. Mechanistic investigations revealed that under the adopted reaction conditions (NaOR, R primary) TMSCF3 does not release the trifluoromethyl (CF3−) anion – as occurs with tertiary alkoxides – but rather it catalytically activates the amidic bond.

Azoles display promising anticonvulsant effects through possible PPAR-α activation

Azoles such as nafimidone, denzimol and loreclezole are known for their clinical efficacy against epilepsy, and loreclezole acts by potentiating γ-aminobutyric acid (GABA)-ergic currents. In the current study, we report a series of azole derivatives in alcohol ester and oxime ester structure showing promising anticonvulsant effects in 6 Hz and maximal electro shock (MES) models with minimal toxicity. The most promising of the series, 5f, was active in both 6 Hz and MES tests with a median effective dose (ED50) of 118.92 mg/kg in 6 Hz test and a median toxic dose (TD50) twice as high in mice. The compounds were predicted druglike and blood–brain barrier (BBB) penetrant in silico. Contrary to what was expected, the compounds showed no in vitro affinity to GABAA receptors (GABAARs) in radioligand binding assays; however, they were found structurally similar to peroxisome proliferator-activated receptors alpha (PPAR-α) agonists and predicted to show high affinity and agonist-like binding to PPAR-α in molecular docking studies. As a result, 5f emerged as a safe azole anticonvulsant with a wide therapeutic window and possible action through PPAR-α activation.

Consumer insights into the at-home liking of commercial beers: Integrating nonvolatile and volatile flavor chemometrics.

Consumer acceptability of beers is influenced by product formulation and processing conditions, which impart unique sensory profiles. This study used multivariate techniques to evaluate at-home consumer sensory acceptability of six commercial beers considering their style, fermentation type, and chemical composition. Samples included top-fermented beers (American India Pale Ale and Stout) and bottom-fermented beers (Pilsner, zero-alcohol Pilsner, Vienna Lager, and Munich Dunkel). Beer consumers (n = 50) conducted sensory hedonic, check-all-that-apply (CATA) and just-about-right (JAR) tests. Chemometric variables included iso-alpha-acids, hordenine, and volatile aromatic compounds, quantified by chromatographic methods, whereas bitterness units (IBU) were determined spectrophotometrically. Lager beers had higher acceptability than top-fermented beer (p < .05) for all attributes. Light-colored beers and medium-height foams had the highest liking scores for visual sensory attributes. Higher concentrations of bitter-tasting molecules, hordenine, and acidity decreased the liking scores of top-fermented (Ale) beers, as a sensory penalty analysis suggested. In contrast, the most favored beers (Pilsners and Munich Dunkel) contained higher fusel alcohol esters linked to fruity aromatic notes. Although a low conversion rate of fatty acids into fruity esters was noted in nonalcoholic Pilsner, its overall liking score was not statistically different from the alcoholic version. However, consumers perceived the nonalcoholic Pilsner as less bitter than its alcoholic counterpart even when IBUs were nonsignificantly different. This study emphasized the significance of understanding beer chemometrics to comprehend consumer acceptability, highlighting the crucial role of bitter molecules. Hence, hordenine, acidity, and volatile contents provided additional and valuable insights into consumer preferences.