Esterification Of Alcohols Research Articles

Preparation of Biowax Esters in Continuous Flow Conditions

Biowaxes synthesized from vegetable fatty acids are an alternative to petrochemical paraffins. A simple way of access to these compounds involves Fisher-type esterification of long-chain acids and alcohols under acidic conditions, but long reaction times and harsh conditions are commonly required. In this study, for the first time in the literature, biowax esters are prepared under flow conditions cutting dramatically both reaction times (from 12 h to 30 min) and temperature conditions, with respect to batch procedures (from 90–120 °C to 55 °C). This approach brings substantial improvements to the biowax synthesis process from an economic and environmental point of view, thus making the method up-scalable to the industrial level.

Stereoselectivity-tailored chemo-enzymatic synthesis of enantiocomplementary poly (ω-substituted-δ-valerolactone) enabled by engineered lipase

The synthesis of chiral polyesters with customized (R)- or (S)-configurations is of great significance but challenging. Despite many advances in enzymatic stereoselective polymerization, the limitations of inherent stereoselectivity and the narrow substrate scope of the biocatalysts used should be overcome. Herein, we combined chemical polymerization and highly selective enzymatic dynamic kinetic resolution (DKR) with tailor-made (R)- or (S)-selectivity enabled by engineered lipase to offer an efficient chemo-enzymatic route for the synthesis of enantiocomplementary (R)- or (S)-poly(ω-substituted-δ-valerolactone) (ω-PVL). In the DKR of homoallylic alcohols, (R)-selective wild-type Candida antarctic lipase B (CALB) and an (S)-selective CALB mutant (W104V/A281L/A282K) were used, providing enantiocomplementary homoallylic alcohol esters with 99% conversion and up to 99% enantiomeric excess (ee), which were further transformed into enantiopure lactone monomers. Using these monomers, ring-opening polymerizations catalyzed by a diphenyl phosphate system successfully provided (R)- or (S)-ω-PVL with aromatic and aliphatic side chains. Additionally, their structure and thermal properties were characterized by nuclear magnetic resonance (NMR), circular dichroism (CD) spectra, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). (R)- or (S)-ω-PVL exhibited vertically mirrored negative and positive CD signals, and were thermally stable while having different decomposition temperatures (Td), which are highly dependent on their molecular weight and side chain structure. It was concluded that stereoregularity has significant influence on the crystallization of the polyesters.

A Bi-functional Cobalt and Nitrogen Co-doped Carbon Catalyst for Aerobic Oxidative Esterification of Benzyl Alcohol with Methanol and Oxygen Reduction Reaction

A bi-functional cobalt and nitrogen co-doped carbon catalyst was fabricated by calcinating the chelate compound containing citric acid, melamine and CoCl2·6H2O in N2, with the mixed salts of LiCl and KCl as the template. Co and N species are highly dispersed in the target catalyst, which has a high surface area of 1011 m2 g−1. Such structure enables it to efficiently catalyze the direct aerobic oxidative esterification of benzyl alcohol with methanol to the ester of methyl benzoate; meanwhile, it exhibits superior potential ability for the application of oxygen reduction reaction, which is a vital process happening on the cathode of fuel cells and metal-air batteries.

Palladium-Catalyzed Remote meta-C-H Bond Deuteration of Arenes Using a Pyridine Template.

Palladium-catalyzed meta-selective C-H deuteration of a series of substrates, including phenylacetic acids, hydrocinnamic acid, benzylphosphonate, benzylsulfonate, and benzyl and phenyl ethyl alcohol ester, is developed by using a pyridine-based directing template. The template is installed into the substrate through a practical ester linkage. Under mild reaction conditions, a variety of phenylacetic acids containing alkyl, methoxyl, and halo substituents are compatible in the reaction, resulting in high levels of D-incorporation at the meta position.

Toward biomass-based single-atom catalysts and plastics: Highly active single-atom Co on N-doped carbon for oxidative esterification of primary alcohols

Supported single-atom catalysts (SACs) have attracted much attention as their advantageous performances in heterogenous catalysis. Here, we report a general synthesis approach to produce SACs on nitrogen-doped carbon (M SAs-N@C, where M = Fe, Co, Ni, Cu) by engineering bioinspired metal-lignin coordination complexes. The Co SAs-N@C catalyst shows extraordinary reactivity for the oxidative esterification of primary alcohols via aldehyde intermediates, achieving a high turnover frequency (TOF, 55.6 mol methyl benzoate mol−1Co h−1) for benzyle alcohol, which is approx. 18 times of Co nanoparticles. Experiments and theoretical calculations reveal that the atomically dispersed Co species in Co SAs-N@C are active sites for this reaction. As a proof-of-concept, we demonstrate an integrated biorefinery that lignin-based catalyst enables the effective transformation of carbohydrate-derived furans into building block of plastics and fragrance. Our technique not only provides a facile, low-cost and scalable method to atomically dispersed catalysts but also opens new avenue toward lignin valorization and biomass economy.

Imidazolium Chloride Immobilized Fly Ash as a Heterogenized Organocatalyst for Esterification Reaction under Microwave Irradiation Heating

An efficient solventless one-pot procedure for the synthesis of imidazolium-based ionic liquid under microwave irradiation is described in which 1-methylimidazole was modified by organosilane (3-chloropropyl triethoxysilane). This ionic liquid 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride (TMICl) is immobilized on Mechanically activated Fly Ash (MFA) by co-condensation method to develop an active organocatalyst (TMICl/MFA). The mechanical activation has generated significant number of silanol groups suitable for immobilizing ionic liquids. For characterization of various materials, different techniques viz, XRD, FTIR, SEM-EDX, TGA, BET surface area, H1NMR are used. The prepared TMICl/MFA exhibited high catalytic activity for a series of microwave assisted esterification of aliphatic alcohols and salicylic acid for four successive reaction cycles under optimized conditions.

Acidic chitosan membrane as an efficient catalyst for biodiesel production from oleic acid

Via the crosslinking of chitosan and sulfosuccinic acid (SSA), the acidic chitosan membrane (ACM) was prepared for biodiesel production from esterification of oleic acid and methanol. ATR-FTIR, TGA, XRD, SEM and EDX were applied to characterize the prepared ACM. The acidic site density and swelling capacity of the prepared ACM were investigated. The ACM possessed the 4.62 mmol/g of acidic site density, which was just a little less than 4.76 mmol/g of Amberlyst-15, meanwhile, ACM was proven to be much higher than Amberlyst-15 in swelling capacity. Under the same reaction, the 98.76% of conversion can be obtained while the Amberlyst-15 only reached 44.30%. The optimization of process variables was conducted by the combination of single factor experiment and Box-Behnken design (BBD) response surface methodology. The catalytic activity of ACM in different esterification of fatty acids and alcohols was also investigated. And the catalytic mechanism of esterification catalyzed by ACM was clarified. Based on the catalytic mechanism, the kinetic model was established to describe the esterification and obtain relevant kinetic parameters (Ea+, Ea−, A+ and A-), meanwhile, the kinetic results were compared to the same reaction with different catalysts in detail. Besides, the reusability of the prepared ACM was studied.

A Seamless Gene Deletion Method and Its Application for Regulation of Higher Alcohols and Ester in Baijiu Saccharomyces cerevisiae.

The security of engineering Saccharomyces cerevisiae is becoming more focused on industrial production in consideration of the public concern regarding genetically modified organisms. In this work, a rapid and highly efficient system for seamless gene deletion in S. cerevisiae was developed through two-step integration protocol combined with endonuclease I-SCEI expression. The factors affecting the frequency of the second homologous recombination were optimized, and studies indicated that the mutant strains with 500 bp direct repeats and that have been incubating in galactose (0.5 g/100 mL) medium at 30°C and 180 r/min for 24 h permit high frequency (6.86 × 10−4) of the second homologous recombination. Furthermore, DNA sequence assays showed only self-DNA in native location without any foreign genes after deletion using this method. The seamless gene deletion method was applied to the construction of the engineering strains with BAT2 (encoding aminotransferase) deletion and ATF1 (alcohol acetyltransferases) overexpression. The mutants exhibited significant effects on higher alcohol reduction and ester improvement after Baijiu fermentation. The engineered strains can be used in industrial production in security, thereby meeting the requirements of modern science and technology.

Enzyme‐Catalyzed Synthesis of Esters in Water

AbstractMsAcT catalyzes the esterification of primary alcohols in water. When utilizing acid and alcohol as starting materials low yields dictated by thermodynamics were observed. However, with activated esters such as ethyl acetate and vinyl acetate very high yields of the desired ester can be achieved in combination with the appropriate alcohol. This study investigated both the intrinsic kinetic properties of MsAcT for the hydrolysis and transesterification of esters in water as well as the thermodynamics of the reaction. In comparison to the chemical or enzymatic ester synthesis using either toxic reagent, and harsh organic solvents, the MsAcT‐catalyzed synthesis of esters of primary alcohols can be achieved efficiently in water without neutralization steps.

Synthesis and evaluation of haloperidol ester prodrugs metabolically activated by human carboxylesterase

Two types of haloperidol prodrugs in which a chemical modification was carried out on the hydroxyl group or carbonyl group were synthesized, and their metabolic activation abilities were evaluated in a human liver microsome (HLM) solution, a human small intestine microsome (HIM) solution and solutions of human recombinant carboxylesterases (hCESs). The metabolic activation rates of alcohol ester prodrugs in HLM solution were similar to those in hCES2 solution, and haloperidol pentanoate and haloperidol hexanoate showed high metabolic activation rates in the synthesized alcohol ester prodrugs. In addition, haloperidol acetate and haloperidol 2-methylbutanoate were hydrolyzed as slowly as haloperidol decanoate. The results suggested that haloperidol prodrugs with a small chain or a branched chain are useful as prodrugs for sustained release. The metabolic activation rate of the enol ester prodrug in HLM solution was similar to that in hCES1 solution, and the enol ester prodrug was found to behave differently from alcohol ester prodrugs, which were metabolically activated by hCES2.

Comparative analyses of cuticular waxes on various organs of faba bean (Vicia faba L.)

Cuticular waxes cover the plant surface and serve as hydrophobic layer, exhibiting various wax profiles between plant species and plant organs. This paper reports comprehensive analysis of the waxes on organs exposed to air, including leaf, stem, pod pericarp, and petals (banner, wing and keel), and on seed coat enwrapped in pod pericarp of faba bean (Vicia faba). In total 7 classes of wax compounds were identified, including fatty acids, primary alcohols, alkyl esters, aldehydes, alkanes, cinnamyl alcohol esters, and alkylresorcinols. Overall, primary alcohols dominated the waxes on leaves and the seed coat enwrapped in pod pericarp, alkanes accumulated largely in stem and petals, whereas alkylresorcinols were observed in leaf, stem and pod pericarp. Organs exposed to air had higher coverage (>1.2 μg/cm2) than those on seed coat (<0.8 μg/cm2), and keel having the highest wax coverage. Meanwhile, the wax coverage on seed coat reduced during the seed development. The variations of wax coverages, compound class distributions and chain length profiles among organs suggested that wax depositions were associated with their ecophysiological functions, and the enzymes involved in wax biosynthesis also showed organ-specific.

THE DEVELOPMENT OF TECHNOLOGY FOR OBTAINING OF TENESTROL SUBSTANCE OF ESTROGENIC AC-TION FROM THE AERIAL PARTS OF FERULA TENUISECTA

Extraction of the sum of esters of the sesquiterpene alcohols from the aerial part of Ferula tenuisecta and purification of obtained extract were studied, allowing in following to get the final substance without green coloration. It was determined the optimum adsorbent – actuated coal and its amount for removing the green coloration of water-alcohol extract from used raw materials. It was found that for the purification of the bottoms of water-alcohol extract, five-fold treatment with extractive petrol in a volume ratio of water solution – solvent 2:1 is necessary, and for extraction esters from a purified water solution – three-fold extraction with ethyl acetate in a volume ratio of water solution – solvent 2:1.&#x0D; It was used a filler to effective drying the substance of Tenestrol. The microcrystalline cellulose in a weight ratio from 1:8 to 1:10 to the raw material was chosen as the optimum filler.&#x0D; Technology for obtain of substance of esters of sesquiterpene alcohols with estrogenic action from the aerial part of Ferula tenuisecta was developed and called “Tenestrol”. From this technology substance "Tenestrol" with yield of 3.8% by weight of the raw material is obtained, which contains not less 20% of the esters.

PROSPECTS OF CELLULOSE NITRATES FROM UNCONVENTIONAL FEEDSTOCKS FOR USE IN COMPOSITE EX-PLOSIVES

Research on the synthesis of in-demand industrial-grade cellulose nitrates from unconventional feedstocks such as Miscanthus, oat hulls, intermediate flax straw is of the most immediate interest due to a lack of national cotton and to encountered problems with wood cellulose. The celluloses derived herein from the said unconventional feedstocks are inhomogeneous in nature, are composed mostly of short fibers, and have non-cellulosic constituents as opposed to elite cotton – these all pose certain difficulties in developing such a nitrocellulose production technology. Besides, it is worth noting that cellulosic fibers of the said feedstocks are peculiar in nature on their own. The findings obtained herein suggest that the research problem can successfully be solved. The pulp samples obtained in this study from the unconventional biomasses by the nitric-acid process have 85−95% α-cellulose and 580−1420 degree of polymerization. These specimens similar in properties to industrial Colloxylin were obtained under optimal synthetic conditions for highly soluble cellulose nitrates by using commercial mixed acid: 11.97–12.29% N, 8–15 mPa∙s, and 98% solubility in alcohol–ester mixture. The morphological features of the resultant cellulose nitrates were characterized by scanning electron microscopy. Infrared spectroscopy revealed the intrinsic frequencies (2560–2550, 1670–1660, 1650–1620, 1280–1270, 830–810, 750–740, 680–670 cm-1) that identify the resultant products as cellulose nitroesters. The practical importance of this research is that the nitrocelluloses obtained from the unconventional non-woody feedstocks can be used as the promising component in the manufacture of explosive formulations.

Polyvinyl alcohol covalently grafted CNT for free-standing, flexible, and high-performance thermoelectric generator film

We introduce a strategic approach to synthesize covalntly cross-linked carbon nanotube (CNT)-polymer nanocomposites, which can be applied as a free-standing and flexible organic thermoelectric generator film. Esterification of polyvinyl alcohol (PVA) to render PVA-COOH followed by an amide reaction with single-walled CNTs (SWCNTs) functionalized with amino groups (SWCNT-NH2) yielded a covalently grafted PVA/SWCNT composite film with an excellent dispersion of SWCNTs within the polymer matrix as confirmed using Fourier-transform infrared spectroscopy and scanning electron microscopy. This amide reaction could be further optimized with the addition of a small amount of Triton™ X-100, which resulted in a better dispersion of SWCNT prior to the amide condensation reaction. Consequently, a covalently cross-linked PVA/SWCNT composite film showed better Seebeck coefficients than those of previously reported non-covalently, physically wrapped polymer/CNT composite films, resulting in a high power factor up to 275 μW m−1 K−2. Furthermore, a covalent amide-linking between PVA and SWCNT yielded a free-standing film (30 × 30 mm) with excellent flexibility and notable shelf stability as confirmed by negligible changes in thermoelectric parameters after bending test for 10 000 times with a bending radius of 2 mm and also shelf stability test in ambient condition without any passivation layer for 30 d.

Chloride‐Induced Highly Active Au Catalyst for Methyl Esterification of Alcohols

Summary of main observation and conclusionChloride is generally regarded as a harmful species for the heterogeneous catalysts, especially Au catalysts. In this work, a series of active Au/NiOx catalysts were successfully prepared with co‐precipitation method by tracking the concentrations of chloride in the re‐dispersed aqueous solutions. For methyl esterification of alcohols, the highest active Au/NiOx catalysts could be prepared from aqueous solutions containing 8‐13 ppm chloride, the yield of methyl benzoate of catalyst Au/NiOx‐9 was 99%. The catalyst structures and the role of chloride in catalysts were explored by ICP, BET, XPS, TEM and EXAFS characterizations. It was found that the appropriate amount of residual chloride in Au catalysts was beneficial to their catalytic activities. Especially for Au/NiOx‐9, the appropriate amount of residual chloride had positive effects on the physicochemical properties of Au/NiOx catalyst, the position of Au nanoparticles (NPs) located on NiOx crystallites and the ratio of Auδ+/Au0 in catalyst, which together resulted in its high reactivity.

Research of Influence of Plasticizers on the Low-Temperature and Mechanical Properties of Rubbers

In this paper, influence of new plasticizers on the mechanical and low-temperature properties of rubbers is studied. The subjects of the research are rubbers based on BNKS-18 butadiene-nitrile rubber and Hydrin T-6000 epichlorohydrin rubber (ECHR). As used plasticizers: DINP (diisononylphthalate), TOTM (trioctyltrimellitate), DOA (dioctyladipate), Alphaplast (complex plasticizer based on esters of organic alcohols and acids). For identification the efficiency, rubbers with the studied plasticizers compared with standard rubber, in which plasticizers have not introduced, as well as with rubber in which a widely used industrial plasticizer DOF (dioktilphthalate) was added. Research of the mechanical properties of rubbers based on BNKS-18 showed that the introduction of plasticizers leads to an increase in elasticity and a slight decrease in the strength of rubbers and on the contrary for rubbers based on ECHR. Low-temperature properties of rubbers with all studied plasticizers have an increased level in comparison with standard rubber. In rubber based on BNKS-18, the highest values of the coefficient of frost resistance at-45°C are observed with the introduction of plasticizers Alphaplast and DOA, an increase in the index compared to standard rubber is more than 50%. The same plasticizers have shown the greatest contribution to the increase in frost resistance of rubbers based on ECHR.

Effect of Bases on Catalytic Properties of Cobalt-Nitrogen-Carbon Composites in Oxidative Esterification of Benzyl Alcohol with Methanol

This paper focuses on specific features of the low-temperature (60°C) oxidative esterification reaction of benzyl alcohol with methanol on cobalt-nitrogen-carbon heterogeneous catalyst produced by carbonization of a ZIF-67 metal-organic framework structure. The optimal temperature range of pyrolysis for preparing high-activity catalyst samples was determined. The influence exerted by bases, such as K2CO3, Na2CO3, triethylamine, para-dimethylaminopyridine, and other additives on the rate and selectivity of the catalytic reaction was examined. It was shown that the esterification occurs via the intermediate formation of benzaldehyde, which is rapidly transformed to methyl benzoate in the presence of a base.

Nanoemulsion for skin drug delivery

The use of nanoemulsion in augmenting dermal and transdermal effectiveness of drugs has now well established. The development of nanoemulsion based semisolid dosage forms is an active area of present research. However, thickening or liquid-to-semisolid conversion of the nanoemulsions provides opportunities to the formulation scientist to explore novel means of solving instability issues during transformation. Extending knowledge about the explicit role of nature/magnitude of zeta potential, types of emulsifiers and selection of appropriate semisolid bases could place these versatile carriers from laboratory to industrial scale. Nanoemulsions are termed as biphasic (O/W or W/O) or multiple nanoemulsions (W/O/W). Oil phase components include fatty acids (e.g., oleic acid), esters of fatty acids and alcohols (e.g., isopropyl myristate, isopropyl palmitate, ethyl oleate), medium chain triglycerides, triacetin, terpenes (e.g., limonene, menthol, cineole) and other penetration enhancers. Till date several approaches have been employed to develop nanoemulsions (size range 20–200 nm) which are High-energy emulsification and Low-energy emulsification. NanoemulsionS are found effective to treat psoriasis, dermatitis and cancer.

SEASONAL FEATURES OF METABOLISM OF WOODY GREENERY OF THE SHRUB LAYER BOREAL FORESTS

A common juniper (Juniperus Communis L.) is a representative of shrub layer of boreal forests. In this work seasonal dynamics of quantitative content of main group of juniper woody greenery extractive substances is considered. Sampling was carried out during the spring-summer-autumn period in the Arkhangelsk region outside the zone of anthropogenic impact. Forest type – blueberry, mixed spruce-pine forest stand, class of Bonita-IV. In study samples content of mineral, water-soluble, alcohol-soluble and removing by steam distillation compounds and lipids content have been determined. According to these data, content of alcohol-soluble components is from 27.1 to 33.3%. It has maximum in April which is the last month of subarctic plants resting phase. The start of growth season in May is followed by sharp decrease of alcohol-soluble components content till it is the least value. Part of the components of alcohol extracts is precipitated when cooled in the form of wax (esters of fatty acids and alcohols or sterols with an admixture of fatty acids, hydrocarbons, pigments). The maximum content (4.3%) of wax substances falls on April, the minimum (1.4%) was detected in May. Lipids content ranges from 8.6 to 12.2%. This is somewhat below in comparison with pine tree, fir and other coniferous species. The three minimums of lipids content (in May, August and December), which were extracted with petroleum ether, in juniper woody greenery are observed in annual dynamic, and one maximum (July). The content of essential oil varies slightly by season and the number (2.4–2.8%) is second only to the DZ of fir. In the group of water-soluble substances there are two highs (June and November) and a low of August. The first maximum is associated with the flow of aqueous solutions from the soil, the second corresponds to the period of phenol accumulation. The minimum is explained by the slowing down of the aspiration current through the water supply channels at the end of the summer.&#x0D; It has been established that seasonal dynamics of main group of extractive substances content of juniper woody greenery as a whole is correspond to phenological cycle.

New adducts of turpentine and rosin with citraconic anhydride and itaconic acid

The reaction of pine gum rosin, turpentine and its components (α-pinene, ∆3-carene, α-terpinene) with citraconic anhydride and itaconic acid was investigated. It was shown that α-terpinene, in contrast to α-pinene and ∆3-carene, reacts with citraconic anhydride to give the unknown cycloaddition reaction product. Its structure was studied by the 2D NMR spectroscopy. Turpentine reacts with itaconic acid forming a complex mixture that contains esters of terpenic alcohols and itaconic acid. Reaction of rosin with citraconic anhydride was studied at 140–180 °С within 0.5–8 hrs in presence of catalytic amounts of H2SO4, MgCl2, AlCl3, FeCl3and new citraconopimaric adducts containing up to ~70 % of citraconopimaric acid as a mixture of two С15–CH3and С16–CH3isomers in equimolar ratio. The highest content of С15–CH3isomer of citraconopimaric acid (35.5–36.0 %) in the adducts was reached within 4–8 hrs at 180 °С in presence of 1–2 mass. % H2SO4. The reaction of rosin with citraconic anhydride at 140–160 °С leads to the formation of adduct containing up to 30–50 % of citraconopimaric acid isomers. The synthesized adducts may be used for production of composite materials for different applications (adhesives, polymer composite additives including rubber blends for tire production, components of grease-cooling liquids).