Acetic Anhydride Research Articles

(Dimethylamino)methylene hydantoins as building blocks in the synthesis of oxoaplysinopsins and parabanic acids with antifungal activity.

A short, efficient, and stereoselective methodology is described for the synthesis of 5-((dimethylamino)methylene)hydantoins and their conversion into oxoaplysinopsins and parabanic acids. A highly convergent one-pot, two-step reaction between methyl N-arylglycinates, isocyanates, and DMFDMA under microwave irradiation provided the corresponding (dimethylamino)methylene hydantoins as a single E-stereoisomer in high overall yields. The synthesis of (S)-1-(1-phenylethyl) chiral hydantoins, which undergo a stereoselective addition of acetic anhydride, aza-heterocycles, and amines, received special attention. The reaction with indole delivered a series of novel oxoaplysinopsins. Meanwhile, parabanic acids were prepared by a new approach, treating (dimethylamino)methylene hydantoins with mCPBA to generate the oxidative fragmentation of the exocyclic methylene. The antifungal evaluation of the prepared products was carried out on a series of Candida spp., finding potent growth inhibition. According to previous docking studies, this activity is probably due to the inhibitory interaction of the derivatives with the active site of the fungal HMGR enzyme.

Quantifying Geobacter sulfurreducens growth: A mathematical model based on acetate concentration as an oxidizing substrate.

We developed a mathematical model to simulate dynamics associated with the proliferation of Geobacter and ultimately optimize cellular operation by analyzing the interaction of its components. The model comprises two segments: an initial part comprising a logistic form and a subsequent segment that incorporates acetate oxidation as a saturation term for the microbial nutrient medium. Given that four parameters can be obtained by minimizing the square root of the mean square error between experimental Geobacter growth and the mathematical model, the model underscores the importance of incorporating nonlinear terms. The determined parameter values closely align with experimental data, providing insights into the mechanisms that govern Geobacter proliferation. Furthermore, the model has been transformed into a scaleless equation with only two parameters to simplify the exploration of qualitative properties. This allowed us to conduct stability analysis of the fixed point and construct a co-dimension two bifurcation diagram.

SYNTHESIS AND EVALUATION OF THE CYTOTOXICITY OF FURANOLABDANOIDS CONTAINING A 3-AMINOPROPANOYL SUBSTITUENT IN THE FURAN RING

15-Acetyl- and 16-acetylfuranolabdanoids were synthesised by the acetylation of the methyl ester of lambertianic acid with acetic anhydride in the presence of Mg(ClO4)2 and used as starting compounds for the preparation of 15- or 16-(3-aminopropanoyl)methyllambertianates. The proposed approach involved silylation of 15-acetyl- or 16-acetylmethyllambertianate and the Mannich reaction of the resulting enol silyl ester with N,N-disubstituted methyleneiminium salts. The synthesized compounds possessed cytotoxicity on tumour cell lines CCRF CEM, MCF7 and PC-3 (MTT test). The compounds containing a 3-morpholinopropanoyl or 3-pyrrolidinopropanoyl substituent at the C-16 position of methyl lambertianate selectively inhibited the growth of human T-cell leukemia cells (GI50 was 5.8-6.1 μM) and exhibited cytotoxicity an order of magnitude higher than the parent compound lambertianic acid.

Cellulose Nanocrystals Isolated from Bean Seed Hulls: Acetylation and Characterization

Bean seed hulls is an agro-waste with abundant content of lignocellulosic materials but are being wasted due to its underutilization. Cellulose nanocrystals (CNCs) were successfully extracted from bean seed hulls using alkali treatment, bleaching and sulphuric acid hydrolysis. Cellulose triacetate (CTA) was obtained from CNCs by acetylation using acetic anhydride with sulphuric acid as catalyst. CNCs is neutral pH whereas CTA is slightly acidic. CNCs was sparingly soluble in ethanol but CTA was completely soluble in ethanol. CTA has a higher melting point than CNCs. The density of both CNCs and CTA is approximately equal to the density of water. SEM analysis revealed that CNCs is irregular and fragmented in nature and has both more large surface area and porosity than CTA. FTIR analysis showed the presence of the dominant functional groups such as O-H stretch, N-H stretch, C-H stretch, C-O stretch and C-N stretch in both CNCs and CTA. GC-MS analysis revealed the presence of the prevalent organic compounds such as alkanes, alcohols, phenols, alkanones, phthalates, carboxylic acids, esters and triterpene in both CNCs and CTA. Therefore, the isolation of CNCs from bean seed hulls suggests great efficacy to recover the under-utilized agro-wastes thereby preventing air pollution.

Effect of targeted acetylation on wood–water interactions at high moisture states

Acetylation is a wood modification used to increase the durability. Although it is known that the wood moisture content is lowered, the exact mechanisms behind the increased durability are not known. However, since fungi need water in different locations for different purposes the location and state of water is most probably of importance in addition to the total moisture content. In a previous study, we used targeted acetylation to alter the wood–water interactions in different parts of the wood structure in water saturated and hygroscopic moisture states. The main range for fungal degradation is, however, between these moisture ranges. This study investigated the effect of targeted acetylation on location, state and amount of water at non-saturated, high moisture states using the pressure plate technique. Specimens were modified using acetic anhydride by two approaches: (1) uniform modification (2) interface modification acting on the cell wall-lumen interface. They were then conditioned to eight moisture states between 99.64 and 99.98% relative humidity in both absorption and desorption and the location and state of water was studied using Low Field Nuclear Magnetic Resonance, X-ray computed tomography and Differential Scanning Calorimetry. Capillary water was present at all the included moisture states for all specimen types, but the amounts of capillary water in absorption were small. Increasing degree of interface modification increased the amount of capillary water compared to untreated wood. In addition, the uniformly modified wood often had higher amounts of capillary water than the untreated wood. The amount of cell wall water was decreased by uniform modification, but slightly or not reduced by the interface modification. The combination of targeted modification and conditioning to high well-defined moisture states thus gave very different amounts of capillary water and cell wall water depending on the conditioning history (absorption or desorption) and choice of modification. This opens new possibilities for designing materials and moisture states for fungal degradation experiments of wood.

Quantitative Analysis of Decoquinate Residues in Hen Eggs through Derivatization-Gas Chromatography Tandem Mass Spectrometry.

A novel precolumn derivatization-gas chromatography tandem mass spectrometry (GC-MS/MS) method was developed to detect and confirm the presence of decoquinate residues in eggs (whole egg, albumen and yolk). Liquid-liquid extraction (LLE) and solid phase extraction (SPE) were used to extract and purify samples. The derivatization reagents were pyridine and acetic anhydride, and the derivatives were subjected to GC-MS/MS detection. After the experimental conditions were optimized, satisfactory sensitivity was obtained. The limits of detection (LODs) and limits of quantification (LOQs) for the decoquinate in eggs (whole egg, albumen and yolk) were 1.4-2.4 μg/kg and 2.1-4.9 μg/kg, respectively. At four spiked concentration levels, the average recoveries were 74.3-89.8%, the intraday RSDs ranged from 1.22% to 4.78%, and the inter-day RSDs ranged from 1.61% to 7.54%. The feasibility and practicality of the method were confirmed by testing egg samples from a local supermarket.

Physicomechanical properties of Japanese cedar wood modified by high-temperature vapour-phase acetylation (HTVPA), a simultaneous acetylation and heat treatment modification process

Wood modification can be broadly categorized into chemical and physical processes, with acetylation and heat treatment being two of the most common methods in each category, respectively. This study, for the first time, combines these two modification methods and investigates the effects of high-temperature vapour-phase acetylation (HTVPA) on the physicomechanical properties of Japanese cedar (Cryptomeria japonica) wood in the temperature range of 145 to 220 °C for 2 to 16 h. Additionally, the acetylation variations within the wood were evaluated. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and near infrared spectroscopy (NIR) spectral analysis showed that the hydroxyl group of Japanese cedar wood reacted with acetic anhydride to form an acetyl group by HTVPA process. When the HTVPA temperature was 220 °C, dehydration and deacetylation of wood occurred. Furthermore, based on the weight percent gain (WPG) and physicomechanical properties of the treated wood, the 200 °C/8h was considered the optimal HTVPA treatment condition. The profiling analysis results showed that the acetylation depth in the longitudinal direction was 40 mm, while the depth in the tangential and radial directions was 3–4 mm. However, the theoretical WPG of the surface of HTVPA treated Japanese cedar wood was 30.0–31.6 %.

Catalytic oxidation of ethyl acetate over Y (Y = Cu, Mn, Co)-modified CeO2 derived from Ce-MOF

A series of YCe catalysts were prepared using Y-loaded (Y = Cu, Co, Mn) Ce-based metal–organic framework as a precursor. Mn-loaded CeO2 exhibited significantly better catalytic activity in the catalytic oxidation of ethyl acetate (EA) than noble metal catalyst. The relationship between the physicochemical properties of YCe catalysts and catalytic activity was studied by different characterization methods. The enhanced catalytic activity was attributed to the strong interaction between the transition metals and Ce, high specific surface area, abundant lattice defects, more oxygen vacacies and higher Olatt/(Olatt + Oads + Ow) molar ratios. The main intermediates in the oxidation of EA were ethanol, acetic acid, acetone, acetaldehyde and diethyl ether.

Process optimization, thermal hazard evaluation and reaction mechanism of m-xylene nitration using HNO3-Ac2O as nitrating reagent

Nitro-m-xylenes (NMX) was synthesized in semi-batch mode via m-xylene nitration using nitric acid-acetic anhydride (HNO3-Ac2O) as nitrating reagent in this work. The nitration process was optimized by response surface methodology. The yield of NMX could reach 92.40% under the optimal conditions of jacket temperature of 20 °C, 0.15 mol of HNO3 and 0.19 mol of Ac2O. Corresponding large reaction enthalpy (ΔH=240.9 kJ/mol) and adiabatic temperature rise (ΔTad,r =398.1 K) indicated the serious hazards of nitration in a thermal runaway scenario. Pyrolysis of nitration products occurred at about 320–400 °C by differential scanning calorimetry tests. The reaction order of the pyrolysis was determined to be 1.2 by adiabatic kinetic analysis. Thermal risk of the nitration process was assessed to be acceptable and level 1 via the risk matrix and Stoessel criticality diagram analyses, respectively. Furthermore, detailed nitration mechanisms for NO2+ generation and aromatic substitution were presented. The activation free enthalpy and free energy parameters for each step were calculated by density functional theory (DFT). These findings can help understand the exothermic sources of m-xylene nitration and guide the intrinsically safer design and scale-up of the process.

In-situ derivatisation, extraction, and preconcentration of some phenolic compounds from water and wastewater samples through cold-induced homogenous liquid-liquid extraction followed by dispersive liquid-liquid microextraction

ABSTRACT In this study, an efficient sample preparation method for the extraction and preconcentration of some phenolic compounds was developed before their analysis with gas chromatography equipped with a flame ionisation detector. Initially, cold-induced homogeneous liquid-liquid extraction was performed for the extraction of polar target compounds from petrochemical, pharmaceutical, well water, and city sewage samples. In the following for more preconcentration, dispersive liquid-liquid microextraction was carried out to enhance enrichment factors. For this purpose, in a glass test tube, a mixture of acetonitrile and acetic anhydride (derivatisation agent) was added to the sample solution in which sodium chloride and sodium carbonate were dissolved. A homogeneous solution was obtained. The solution was frozen by immersion of the tube in liquid nitrogen for a few seconds. The frozen solution was removed from the bath and let stand for a few minutes at room temperature. The organic phase (acetonitrile) was melted and collected on the solidified aqueous solution. The organic phase containing the derivatised phenols was removed and mixed with µL-level of 1,2-dibromoethane and injected into an aqueous solution of sodium chloride. The created cloudy solution was centrifuged and 1 μL of the sedimented phase was injected into the separation system. The effective parameters including the type and amount of base, amount of derivatisation agent, ionic strength of solutions, type and volume of solvents, and vortexing time were investigated. High extraction recoveries (80–92%) and enrichment factors (412–478), wide linear ranges, and satisfactory limits of detection (4.82–9.27 μg L−1) and quantification (14.25–30.86 μg L−1) were obtained.

Magnetite-boosted syntrophic conversion of acetate to methane during thermophilic anaerobic digestion.

Using a batch thermophilic anaerobic system established with 60 mL serum bottles, the mechanism on how microbial enrichments obtained from magnetite-amended paddy soil via repeated batch cultivation affected methane production from acetate was investigated. Magnetite-amended enrichments (MAEs) can improve the methane production rate rather than the methane yield. Compared with magnetite-unamended enrichments, the methane production rate in MAE was improved by 50%, concomitant with the pronounced electrochemical response, high electron transfer capacity, and fast acetate degradation. The promoting effects might be ascribed to direct interspecies electron transfer facilitated by magnetite, where magnetite might function as electron conduits to link the acetate oxidizers (Anaerolineaceae and Peptococcaceae) with methanogens (Methanosarcinaceae). The findings demonstrated the potential application of MAE for boosting methanogenic performance during thermophilic anaerobic digestion.

Experimental and kinetic modeling study of acetic acid oxidation and hydrolysis in supercritical water

The oxidation and hydrolysis of 0.11–0.14 M acetic acid in supercritical water (SCW) have been investigated at temperatures of 773–873 K and a pressure of 25.0 MPa in a flow reactor. CO and CO2 were the main products at oxygen-rich conditions. For hydrolysis experiments, CH4 and CO2 were produced in nearly equal amounts while the yield of CO was negligibly small. A detailed chemical kinetic model was developed by revising the kinetic parameters of key elementary reactions. The model performance was evaluated by comparison to the present data as well as data from literature. The model predicted the kinetic behavior of acetic acid oxidation fairly well, despite of slight underprediction of CO and overprediction of CH4. It also reproduced satisfactorily the species concentrations during acetic acid hydrolysis at high temperatures. Based on the model, kinetic analyses were further conducted to identify important elementary steps and to infer reaction mechanisms.

Extraction and preconcentration of parabens from the human follicular fluid through dispersive micro solid phase extraction using microporous MIL-68 (In) followed by in-situ effervescence-boosted dispersive liquid-liquid microextraction

For the first time in this study, a microextraction method was developed to perform follicular fluid safety assessment analysis. The drastic importance of follicular fluid safety on the proper nourishment and development of oocytes caused the development of the present method. Since women are regularly exposed to parabens through cosmetics, healthcare, and hygienic products, the infection of body fluids is probable in long-term exposures. Also, for the first time, MIL-68 (In) was applied in an analytical method. Moreover, a new method called in-situ effervescence-boosted dispersive liquid-liquid microextraction was adopted for the simultaneous derivatization and preconcentration of the target parabens. To perform the method, 25 mg of MIL-68 (In) was dispersed into the solution of follicular fluid by vortexing. Then, 1.0 mL of 2-propanol was used to elute the analytes from the absorbent via vortexing. The analyte-enriched organic phase was mixed with 100 µL of acetic anhydride (derivatization agent) and 27 µL 1,2-dibromoethane (extraction solvent) which was swiftly injected into a sodium carbonate solution. Following the centrifugation, the extraction solvent was sedimented at the bottom of a conical bottom glass test tube and an aliquot of it was injected into a gas chromatograph equipped with a flame ionization detector. Wide linear ranges (120–25000 µg L-1), satisfactory extraction recoveries (31–79%) and enrichment factors (31−79), and appreciable limits of detection (7–36 µg L-1) and quantification (25–120 µg L-1) were recorded. The high surface area of MIL-68 (In) (608.82 m2 g-1) and its significantly low average pore diameter (13.829 A°) provide an ideal platform for the extraction of parabens from the complex matrix of follicular fluid.

Micron-Sized Hierarchical Beta Zeolites Templated by Mesoscale Cationic Polymers as Robust Catalysts for Acylation of Anisole with Acetic Anhydride

Hierarchical Beta zeolites with interconnected intracrystalline mesopores and high structural stability are highly attractive for catalytic applications involving bulky reactants. Here, by introducing a suitable amount of polydiallyldimethylammonium chloride into the initial synthesis system, micron-sized Beta zeolite crystals with abundant hierarchical porosity (Beta-H) were hydrothermally synthesized. The sample named Beta-H_1 exhibited very high catalytic activity and durability for the Friedel–Crafts acylation of anisole with acetic anhydride. A 92% conversion rate of acetic anhydride could be achieved after 1 h of reaction in a fixed bed reactor, and 71% conversion still remained after 10 h, much better than the rate for conventional Beta zeolite (which decreased rapidly from 85% to 37% within 10 h). The enhanced catalytic performance of Beta-H zeolites could be mainly attributed to the relatively lower strong acid density and the faster transport rate of the hierarchical zeolites. In addition, Beta-H showed high structural stability and could be easily regenerated via high-temperature calcination without obvious loss in catalytic activity, demonstrating its great potential for catalytic applications in the industrially important Friedel–Crafts acylation process.

Effects of Wood Content and Modification on Properties of Wood Flour/Polybutylene Adipate Terephthalate Biocomposites.

Biodegradable polymers have recently become attractive and have been increasingly used as matrix materials to replace fossil plastics due to concerns about the environmental issue. However, their application areas are limited due to their high costs and natural properties. In this study, we fabricated ecofriendly and economical polybutylene adipate terephthalate (PBAT) composites loaded with various concentrations of wood flour (WF) to investigate the effects on the PBAT and WF interfaces as well as the physical properties of the WF/PBAT biocomposites. Then, WF was acetylated with acetic anhydride, and the effect of WF acetylation on the mechanical and thermal properties of the biocomposites were investigated. The results showed that the tensile strength, tensile modulus, flexural strength and flexural modulus increased with WF loading in the composites, and acetylation could not only further increase these properties, but also increase the impact strength and elongation at break. The incorporation of WF would weaken the thermal stability of PBAT, but the thermal stability of the biocomposite could be improved after WF acetylation. The cold crystallization temperature and hydrophobicity of the WF/PBAT samples would be increased with the increasing load of the WF, while the melting enthalpy and the crystallinity of the samples reduced gradually. A morphological analysis of the modified composites revealed that the matrix exhibited greater interfacial interactions with the WF compared to the WF/PBAT. Considering the much lower cost of WF compared to PBAT, the improved properties of WF/PBAT biocomposites will make it economically competitive with other commercial polymers, and these biocomposites should have much wider application areas.

Utilization of catfish fat by-products for the biological base oils synthesis

In this work, catfish fat by-product was utilized as feedstock in the synthesis of biological base oils. The study performs the effect of parameters on the reaction yield. 91.2% in (H2O2/CH3COOH/C=C) molar ratio of 4.5/1.5/1.0, the temperature of 50 oC, and 3 hours reaction time. The yield of the ring-opening reaction of epoxy with acetic anhydride reached at 90.2% in (acetic anhydride/epoxy) molar ratio of 1.5/1.0, the temperature of 95 oC, and 4.5 hours reaction time. The main functional groups of catfish oil starting material, epoxy catfish oil, and polyester catfish oil final product were identified by FT-IR and 1H-NMR spectral analysis methods. The observed results show that the catfish oil epoxidation reaction with a mixture of H2O2 and CH3COOH and the ring-opening reaction of epoxy with (CH3CO)2O, H2SO4 catalyst has occurred strongly and obtained product of catfish polyester oil could use as an alternative to mineral base oils and an environmentally friendly product.

Wetting and swelling behaviour of N-acetylated thin chitosan coatings in aqueous media

Chitosan nanocoatings (thickness range of 120–540 nm) were produced on glass, zinc and silicon substrates with dip-coating and spin coating techniques to study their pH-dependent wetting and swelling behaviour. The coatings were N-acetylated with the methanolic solution of acetic anhydride to increase the degree of acetylation from 36 % to 100 % (according to ATR-FTIR studies). The measured contact angles of Britton–Robinson (BR) buffer solutions (pH 6.0, 7.4 and 9.0) were lower on the acetylated surfaces (ca. 50°), than that of their native counterparts (ca. 70°) and does not depend on the pH. Contrary, contact angles on the native coating deteriorated 10°-15° with increasing the pH. In addition, for native coatings, the decrease of the contact angles over time also showed a pH dependence: at pH 9.0 the contact angle decreased by 7° in 10 min, while at pH 6.0 it decreased by 13° and at a much faster rate. The constraint swelling of the coatings in BR puffer solutions was studied in situ by scanning angle reflectometry. The swelling degree of the native coatings increased significantly with decreasing pH (from 250 % to 500 %) due to the increased number of protonated amino groups, while the swelling degree of acetylated coatings was ca. 160 % regardless of the pH. The barrier properties of the coatings were studied by electrochemical tests on zinc substrates. The analysis of polarization curves showed the more permeable character of the acetylated coatings despite the non-polar character of the bulk coating matrix. It can be concluded that in the case of native coatings, 49 % of the absorbed water is in bound form, which does not assist ion transport, while in the case of acetylated coatings, this value is only 33 %.

Preparation of polyimide hollow particles using chemical imidization

Abstract Hollow polyimide (PI) particles were successfully prepared using chemical imidization with acetic anhydride and pyridine as the chemical imidization reagents. The imidization reagents were added to the dispersion in which N,N-dimethylformamide (DMF) droplets with dissolved poly(amic acid) (PAmA, the precursor of PI) were dispersed in a cyclohexane medium. In the absence of poly(n-butyl methacrylate) (P[n-BMA]) in PAmA/DMF droplets, approximately 10% of the PI particles had hollow structures. Conversely, in the presence of a small amount of P(n-BMA) in PAmA/DMF droplets (0.2∼1 wt%), all PI particles had hollow structures. The P(n-BMA) would affect the phase separation of the PI in the droplets, thereby promoting the formation of a hollow structure.

Development of simple purification method for oligonucleotides synthesized using phosphoramidite for 5′-end modification as capping reagent

Oligonucleotide therapeutics are generally prepared via solid-phase synthesis, and many impurities derived from the synthesis process are present in crude oligonucleotides. Among the various impurities typical of oligonucleotide synthesis, shortmers, which lack a few residues from the desired oligonucleotide therapeutics, are difficult to remove using conventional high-performance liquid chromatography (HPLC) purification because they have similar structures and physical properties to the desired oligonucleotide. In this study, we developed a simple purification method for oligonucleotide therapeutics. In our strategy, the retention of shortmers on the reversed-phase HPLC column was increased by using a highly lipophilic phosphoramidite, which is a reagent for 5′-end modification of oligonucleotides, instead of acetic anhydride during solid-phase synthesis, and only the target oligonucleotide could be eluted from a reversed-phase HPLC pretreatment column.

MIL-68 (Ga) for the extraction of derivatized and non-derivatized parabens from healthcare products

This study was the first-ever attempt to apply MIL-68 (Ga) in developing an analytical method. The method extracts and preconcentrates some parabens from mouthwash and hydrating gel samples. The variable extraction parameters were optimized, and the figures of merit were documented. Avogadro software was used besides discussing intermolecular interactions to clarify the absorption process. ComplexGAPI software was also exploited to assess the greenness of the method. After the derivatization of the parabens using acetic anhydride in the presence of sodium carbonate, sodium chloride was added to the solution and vortexed to dissolve. A few milligrams of MIL-68 (Ga) were added into the solution and vortexed. Centrifugation separated the analyte-loaded absorbent, which was treated with mL volume of methanol through vortexing for desorption aim. A few microliters of 1,2-dibromoethane were merged with the methanolic phase and injected into a sodium chloride solution. One microliter of the extracted phase was injected into a gas chromatograph equipped with a flame ionization detector. High enrichment factors (200–330), reasonable extraction recoveries (40–66%), wide linear ranges (265–30,000 µg L−1), and appreciable coefficients of determination (0.996–0.999) were documented. The applicability of dispersive solid phase extraction for extracting polar analytes, imposing no additional step for performing derivatization, the capability of MIL-68 (Ga) for the absorption of both derivatized and non-derivatized parabens, the use of only 10 mg absorbent, and one-pot synthesis besides no high temperature or long reaction time in the sorbent provision are the highlights of the method.