Acetic Anhydride Research Articles

Alcohol Consumption and Autoimmune Diseases.

Alcohol is the second-most misused substance after tobacco. It has been identified as a causal factor in more than 200 diseases and 5.3% of all deaths and is associated with significant behavioral, social, and economic difficulties. As alcohol consumption may modulate the immune system's regulatory mechanisms to avoid attacking the body's tissues, it has been proven to play a dichotomic role in autoimmune diseases (ADs) based on the quantity of consumption. In this review, we report updated evidence on the role of alcohol in ADs, with a focus on alcohol addiction and the human biological immune system and the relationship between them, with alcohol as a risk or protective factor. Then, in this narrative review, we report the main evidence on the most studied ADs where alcohol represents a key modulator, including autoimmune thyroiditis, multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, diabetes, allergic rhinitis, and primary biliary cholangitis. Alcohol at low-moderate dosages seems mostly to have a protective role in these diseases, while at higher dosages, the collateral risks surpass possible benefits. The specific mechanisms by which low-to-moderate alcohol intake relieves AD symptoms are not yet fully understood; however, emerging studies suggest that alcohol may have a systemic immunomodulatory effect, potentially altering the balance of anti-inflammatory innate and adaptive immune cells, as well as cytokines (via the NF-κB or NLRP3 pathways). It might influence the composition of the gut microbiome (increasing amounts of beneficial gut microbes) and the production of their fatty acid metabolites, such as short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs), as well as elevated concentrations of acetate, high-density lipoprotein (HDL), and nitric oxide (NO). Unfortunately, a definite acceptable daily intake (ADI) of ethanol is complicated to establish because of the many mechanisms associated with alcohol consumption such that despite the interesting content of these findings, there is a limit to their applicability and risks should be weighed in cases of alcoholic drinking recommendations. The aim of future studies should be to modulate those beneficial pathways involved in the alcohol-protective role of ADs with various strategies to avoid the risks associated with alcohol intake.

Adsorption and separation of lead ions in phosphoric acid by co-doped carbon nanotubes with sulfur, oxygen, and manganese

The purpose of this study was to prepare a novel and efficient adsorbent for the removal of trace Pb(II) from phosphoric acid. Manganese oxide/sulfur-oxygen doped carbon nanotube composites (CNTs-S-O-Mn) were prepared from multi-walled carbon nanotubes modified with nitric acid, mercaptoacetic acid, acetic anhydride, concentrated sulfuric acid and potassium permanganate. Characterisation revealed that CNTs-S-O-Mn contained hydroxyl, sulphonate groups, MnO and Mn3O4. At 298 K, 15.362 mg·L-1 initial concentration of lead ions, and 18.4 % phosphoric acid concentration, the adsorption capacity of the composites for lead ions was 38.65 mg·g−1, which was higher than that of the unmodified CNTs, 8.04 mg·g−1. The adsorption kinetic data at 298 K conformed to the quasi-second-order kinetic equation, R2 = 0.997; 298, adsorption isotherms at 308 and 318 K conformed to the Langmuir equation, R2 = 0.990–––0.991. The adsorption capacity increased with decreasing phosphoric acid concentration. In this system, the adsorption is affected by a certain concentration of lead ions. Adsorption occurs via chemisorption and is exothermic. Sulfonic acid groups and hydroxyl groups on manganese oxides play an important role in the adsorption of Pb (II) through surface complexation with Pb (II). These results indicate that the removal of trace Pb (II) from phosphoric acid by modified carbon nanotubes is feasible, revealing a new use of carbon nanotubes for phosphoric acid purification.

Heteroaromatization of Coumarin Part II: Synthesis, Reactions, and Antimicrobial Activities of Novel Pyrido[2,3-d]pyrimidine Derivatives

Background: Condensation of 3-acetyl coumarin (1) with 2‐(4-methoxy- benzylidene) malononitrile (2) in ammonium acetate/acetic acid or absolute ethanol/piperidine affords pyridine (3) and chromen-2-one (4) derivatives, respectively. Methods: In this study, the reaction of 3 with an electrophilic reagent, namely, formic acid, acetic anhydride and formamide afforded the pyridopyrimidinone and pyridine derivatives (6- 9). Also, treatment of 3 with different aromatic aldehydes, carbon disulfide, NaN3/NH4Cl, 2- (4-methoxybenzylidene)malononitrile and acetophenone afforded pyridopyrimidinone, carbamodithioic acid, tetrazol-5-yl-chromen-2-one, 2H-chromen-2-one, and pyridine derivatives (10-14), respectively. Results: This study synthesized coumarins with antimicrobial activity and verified the structure and purity of the synthesized compounds using spectral data. Conclusion: The new compounds were evaluated in vitro for their antimicrobial activity against gram-positive bacteria (Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), in addition to fungus (Candida albicans). The investigated substances 3 and 14 presented good activity against MRSA, E. coli, P. aeruginosa and C. albicans, while compounds 9, 10a-c, 11, 12 and 13 exhibited good to moderate activity.

Synthesis and some chemical transformations of novel 1-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazine-8-carboxylic acids and their benzoannelated analogues

A preparatively convenient method is proposed for the synthesis of new 1-oxo-3,4-dihydro-1H-pyrrolo[2,1-с][1,4]oxazine-8- 4a-e and 4-oxo-4H-pyrrolo[2,1-c][1,4]benzoxazine-3-carboxylic acids 5a-f that is based on the interaction of methyl (2-oxomorpholin-3-ylidene)ethanoates 1a-e and methyl (2-oxo-2H-1,4-benzoxazine-3(4H)-ylidene)ethanoates 2a-f with 2-bromo-1,1-diethoxyethane. Obtained acids were transformed into the corresponding tert-butyl carbamates 6a-e, 7a-f and N-alkyl(aryl)carboxamides 11a-i, 12a-d. By treating tert-butyl carbamates 6a-e, 7a-f with hydrogen chloride, 8-amino-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazin-1-ones 8a-e and 3-amino-4H-pyrrolo[2,1-c][1,4]benzoxazin-4-ones 9a-f were obtained. By acylation of amines 8a-e, 9a-f with acetic anhydride, benzoyl chloride, methanesulfonyl chloride, and p-toluenesulfonyl chloride, corresponding N-acetamides 13a,b, 14, N-benzamides 15, 16, N-methanesulfonamides 17, 18, and N-p-toluenesulfonamides 19, 20 were synthesized. In total, 30 new derivatives of 1-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazinones and 27 new 4-oxo-4H-pyrrolo[2,1-c][1,4]benzoxazinones were obtained.

Constructing Bridge Hydroxyl Groups on the Ru/MOx/HZSM-5 (M = W, Mo) Catalysts to Promote the Hydrolysis Oxidation of Multicomponent VOCs.

Chlorinated and oxygenated volatile organic compounds (CVOCs and OVOCs) pose a significant threat to human health. Catalytic oxidation effectively removes these pollutants, but catalyst deactivation is a challenge. Our study focused on the hydrolysis oxidation of chlorobenzene (CB) and ethyl acetate (EA) over Ru/MOx/HZSM-5 (M = W, Mo). It was found that doping MoOx to the catalyst increased the structural hydroxyl amount and balanced surface acidity, thus significantly improving the catalytic stability, with Ru/MoOx/HZSM-5 exhibiting a better activity for CB and EA oxidation (T90% = 438 and 276 °C at space velocity = 20,000 mL g-1 h-1, respectively). Water vapor introduction considerably promoted hydrolysis oxidation and protected the active sites from being poisoned by cumulative chlorine. The synergistic interaction of the Mo-O(H)-Al structure in Ru/MoOx/HZSM-5 with the Si-OH-Al structure promotes the activation of H2O to form bridging hydroxyl groups, which provide a proton-rich environment for hydrolysis oxidation. It was also found that dissociated H2O reacted with adsorbed oxygen species to form highly active *OOH, accelerating the deep oxidation of intermediates. We believe that the present study can provide a unique strategy for the effective elimination of multicomponent VOCs under complex conditions.

DFT Studies on the Mechanism of Ligand-Regulated Palladium-Catalyzed Iodide-Assisted Hydrocarbonylation of Olefins with Formic Acid: Favored Reaction Routes and Selectivities.

DFT calculations have been performed to gain insight into the mechanism of hydrocarbonylation of olefins and the origin of regio- and chemoselectivity. It is shown that the most feasible mechanism involves five steps: (i) decomposition of acetic formic anhydride, (ii) hydropalladation of olefins, (iii) CO migratory insertion, (iv) iodide-assisted acetate-formate exchange, and (v) formylation or carboxylation. Importantly, carboxylation proceeds via the decomposition of anhydride, followed by reductive elimination instead of direct hydrolysis of anhydride. For phosphine-ligated palladium catalysis, on one hand, the lower stability of the transition state leading to 1,2-hydropalladation could be attributed to H···H steric hindrance. On the other hand, the high chemoselectivity for the aldehyde is ascribed to increased π back-donation effect and ligand-substrate noncovalent interactions, which stabilize the transition state and hence reduce the energy barrier. For ferrocenyl phosphine-ligated palladium catalysis, significant C-H···π interaction between the substrate and proximal phenyl moiety of the phenylphosphine and π-π interaction between formate and phenyl moiety can facilitate the carboxylation process. This in-depth mechanistic insight can account for reactivity and selectivity at an atomistic level and have implications for designing new generations of palladium catalysts.

Composite material from polylactic acid and modified fire flax: synthesis and properties

Abstract The paper presents data on the synthesis of a composite material based on polylactic acid and fire flax powder. To improve adhesion between the polymer matrix and the plant filler, the fire flax powder was modified (acylated) with acetic anhydride. The IR Fourier spectroscopy method established the acylation reaction of fire flax powder. After modification with acetic anhydride, an increase in the intensity of the following peaks is observed in the IR Fourier spectrum: at 1747 cm-1, at 1374 cm-1 and at 1234 cm-1. Composites based on polylactic acid were manufactured, which contained the modified filler in concentrations of 30%, 40% and 50% by weight. Physicomechanical, electron microscopic and thermal studies of the developed polymer composites are presented. The tensile strength of the studied composites was determined using standard methods according to ISO 527-2:2012. The composite containing 50 wt. % modified fire flax powder has the following characteristics: tensile strength – 6.53 MPa, relative elongation - 13.89%, density - 1.247 g/cm3, maximum permissible operating temperature (sample weight loss up to 5 wt. %) - 254 ° C. This study promotes the development of biodegradable materials by offering polylactide-based composites with the addition of fire flax as an alternative to non-degradable synthetic fillers. The use of agricultural waste not only reduces the cost of production, but also solves the problem of biomass utilization, which opens up prospects for the creation of environmentally friendly composites in various industries. The research methodology also makes it possible to modify natural components, expanding their use and potentially replacing traditional plastics.

Development and characterization of acetylated and acetylated surface-modified tapioca starches as a carrier material for linalool

Abstract Linalool compound is easily degraded when exposed to light and oxygen during processing or storage. Therefore, the objective of this work was to develop surface-modified tapioca starch as a carrier for linalool. Surface-modified starch was prepared by various treatments, i.e., enzyme treatment (using STARGEN 002 enzyme), alcohol–enzyme treatment, and acetylation; acetylation was carried out with 20% (w/w, starch dry basis) acetic anhydride. Acetyl percentage (Ac%) and degree of substitution (DS) of the acetylated samples significantly increased with different treatments due to the introduction of acetyl groups in the starch molecules. After acetylation, the percentage crystallinity as well as WR1047/1022 values decreased. The acetylated surface-modified starches showed a reduction in terms of thermal properties and gelatinization enthalpy values. Compared with native starch samples, the granules of acetylated surface-modified starch sample exhibited a rough surface and clumped structures. The encapsulation efficiency of linalool significantly increased from 3.63% to 66.76%. The encapsulated linalool with enzyme-acetylated starch showed significantly low values of linalool reduction (11.00%) over 28 days of storage due to its surface erosion and addition of acetyl groups on granular starch, as evidenced by scanning electron microscopy and Ac% as well as DS results. Among them, the enzyme-acetylated starch had the lowest values of linalool reduction, which could effectively encapsulate linalool and control the linalool reduction value.

Synergy and competition during the anaerobic degradation of N-acetylglucosamine in a methane-emitting, subarctic, pH-neutral fen.

Peatlands are invaluable but threatened ecosystems that store huge amounts of organic carbon globally and emit the greenhouse gasses carbon dioxide (CO2) and methane (CH4). Trophic interactions of microbial groups essential for methanogenesis are poorly understood in such systems, despite their importance. Thus, the present study aimed at unraveling trophic interactions between fermenters and methanogens in a nitrogen-limited, subarctic, pH-neutral fen. In situ CH4 emission measurements indicated that the fen is a source of CH4, and that CH4 emissions were higher in plots supplemented with ammonium compared to unsupplemented plots. The amino sugar N-acetylglucosamine was chosen as model substrate for peat fermenters since it can serve as organic carbon and nitrogen source and is a monomer of chitin and peptidoglycan, two abundant biopolymers in the fen. Supplemental N-acetylglucosamine was fermented to acetate, ethanol, formate, and CO2 during the initial incubation of anoxic peat soil microcosms without preincubation. Subsequently, ethanol and formate were converted to acetate and CH4. When methanogenesis was inhibited by bromoethanesulfonate, acetate and propionate accumulated. Long-term preincubation considerably increased CH4 production in unsupplemented microcosms and microcosms supplemented with methanogenic substrates. Supplemental H2-CO2 and formate stimulated methanogenesis the most, whereas acetate had an intermediary and methanol a minor stimulatory effect on methane production in preincubated microcosms. Activity of acetogens was suggested by net acetate production in microcosms supplemented with H2-CO2, formate, and methanol. Microbial community analysis of field fresh soil indicated the presence of many physiologically unresolved bacterial taxa, but also known primary and secondary fermenters, acetogens, iron reducers, sulfate reducers, and hydrogenotrophic methanogens (predominately Methanocellaceae and Methanoregulaceae). Aceticlastic methanogens were either not abundant (Methanosarcinaceae) or could not be detected due to limited coverage of the used primers (Methanotrichaceae). The collective results indicate a complex interplay of synergy and competition between fermenters, methanogens, acetogens, and potentially iron as well as sulfate reducers. While acetate derived from fermentation or acetogenesis in this pH-neutral fen likely plays a crucial role as carbon source for the predominant hydrogenotrophic methanogens, it remains to be resolved whether acetate is also converted to CH4 via aceticlastic methanogenesis and/or syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis.

Synthesis and Pharmacological Evaluation of 3-alkyl/aryl–2- methylquinazolin-4-one Derivatives

Quinazolin-4-ones with 2, 3-disubstitution is reported to possess significant analgesic, anti-inflammatory and anticonvulsant activities. We have developed an efficient method for the synthesis of 3-substituted-2-methylquinazolin-4-one by the condensation reaction of Anthranilic acid, acetic anhydride with various amines. The synthesized compounds were evaluated for anxiolytic activity by Elevated plus Maze Test and Light and Dark Test. It is observed that the aliphatic and aromatic substitution at 3-position of 2-methylquinazolin-4-one gives potent anxiolytic activity. In particular, ENA showed highest anxiolytic activity in Elevated plus Maze Test and EMQ and AMQ showed highest anxiolytic activity in Light and dark test model

Discovery of New Imidazolinones Derivatives as Potential Microbial Agents

A series of imidazolinone were prepared by heating the hippuric acid in presence of acetic anhydride and sodium acetate with different aromatic aldehydes gave 5-oxazolone derivatives which reacting with N-amino-2,3,4,5,6-pentafluoro benzamide in pyridine gave imidazolinone. All the synthesized compounds have been characterized on the basis of elemental analysis, IR, 1H-NMR and 13C-NMR spectral data. All the synthesized compounds have been screened against four different bacterial strains S. aureus, S. paratyphi-A, E. coli and B. subtilis and fungal strain F. molaniforme and A. niger. Some of the compound was endowed with a remarkable antibacterial as well as antifungal activity.

Effect of acetic acid concentration on obtaining cellulose acetate from oil palm mesocarp fibers (Elaeis guineensis Jacq.)

This work aimed to produce cellulose acetate from the mesocarp fibers of palm oil treated with sodium hydroxide (MFA) and bleached with sodium chlorite. Cellulose acetate was obtained from the different materials by homogeneous acetylation in the mass proportions of: 1:5, 1:10 and 1:15 (acetic acid), 1:15 (acetic anhydride) and 1:0.1 (sulfuric acid). The degree of substitution was determined by chemical methods and by 1H-NMR. The cellulose acetate obtained from the combination of alkaline treatments followed by bleaching showed degree of substitution of 2.81 (CAAB5), 3.02 (CAAB10) and 3.07 (CAAB15), corresponding to yield values (w/w) of 50.45%, 65.5% and 97.21%. Based on the analysis of the results, we can say that the amount of acetic acid and the type of treatment used in the fibers of the mesocarp of oil palm directly influenced the quality and yield of cellulose acetate, with CAAB15 being the best reaction condition.

Upcycling of Polystyrene to Aromatic Polyacids by Tandem Friedel-Crafts and Oxidation Reactions.

Due to the high demand and the increasing production rate of plastic materials, vast amounts of wastes are generated every year. An important fraction of these wastes contain polystyrene (PS), which is seldom recycled, neither mechanically nor chemically. While several chemical recycling strategies have been developed, they are either very energy-demanding or produce chemicals that can hardly be employed in the synthesis of plastics (e.g., benzene and benzoic acid). Here, we report the upcycling of PS waste into aromatic polyacids, useful in polyester synthesis, such as polyethylene terephthalate (PET). To this end, a conventional Friedel-Crafts acylation was first investigated, to produce an acylated PS chain, using acetic anhydride and stoichiometric amounts of AlCl3. As a catalytic alternative, the alkylation of PS was studied, using InCl3 and isopropyl acetate. The acylated and alkylated PS samples were then oxidized to produce terephthalic (TA), isophthalic (IPTA), benzoic (BA), and trimesic (TMA) acid.

Synthesis of Modern Amides Thiazolidine Derived From L-Cysteine and Investigation of Their Biological Effects on Cancer Cells

The study included the preparation and characterization of new compounds called thiazolidine-4-carboximaide in three main steps. In the first step, compound (R) was reacted from the reaction of cysteine ​​with different aromatic aldehydes. Then the compound (R)was reacted with acetic anhydride to prepare the compound (RA). The compound (RA) was reacted with the aromatic amine (phenyl hydrazine) and DCC,HOBT to obtain different amides-4-thiazolidine compounds. All compounds were diagnostic using organic description techniques, FT-IR,magnetic resonance spectroscopy, 1HNMR, and 13CNMR, mass spectroscopy, every the prepared Compounds gave perfect returns. and biological effect prepared compounds:]ML1 ,ML2, ,ML4,ML7 ML8,ML9 [ was studied against cancer cells for two types of cancer lines: human breast cancer line (MCF7) cells, women’s cervical cancer line (Hela), The biological effectiveness of the prepared compoundsML1,ML2, ML4 ML7,ML8 and ML9, was studied against cancer cells for two types of cancer lines, a Michigan cancer foundation (MCF7) and a female cervix carcinoma (Hela). The results of the inspection showed that the compounds ] ML1,ML2, ML4,ML8 ,ML9 [ had high efficacy against a mankind breast cancer cell line and a cell line. Cervical cancer and compound] ML7[ showed little activity on the two types of cancer cell lines. and calculated Inhibition percentage (% ) of prepared compounds effects a Michigan cancer foundation (MCF7) and a female cervix carcinoma (Hela).

Syntheses and evaluation of novel 3-hydroxy-1,3-diaryl-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromides as potential anticancer agents

New 3-hydroxy-1,3-diaryl-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromides have been designed, synthesized, and characterized by 1Н NMR, 13C NMR, and LCMS. The cyclic structure of the condensation products of aryl-(3,4,5,6-tetahydropyridin-2-yl)amines with α-bromoketones has been proven. It has been shown that heating 3-hydroxy-1,3-bis-(41-methoxyphenyl)-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromide in acetic anhydride accompanied by elimination of water to form 1,3-bis-(41-methoxyphenyl)-5,6,7,8-tetrahydro-imidazo[1,2-a]pyridine-1-ium bromide. Antitumor activity of 1,3-bis-(41-ethoxyphenyl)-3-hydroxy-2,3,5,6,7,8-hexahydro-imidazo[1,2-a]pyridine-1-ium bromide and 1,3-bis-(41-methoxyphenyl)-5,6,7,8-tetrahydro-imidazo[1,2-a]pyridine-1-ium bromide have been studied. The fully aromatic imidazo[1,2-a]pyridine-1-ium bromide system was shown to have a higher antitumor effect. According to the screening results, the tested compound showed a significant level of anticancer effect on cancer cells of colon COLO 205 (lgGI50 = -5.35, lgTGI = –4.70 and lgLC50 = –4.19) and melanoma SK-MEL-5 (lgGI50 = –5.57, lgTGI = –4.81 and lgLC50 = –4.17).

Deciphering the role of biochar pseudocapacitance strengthening in promoting syntrophic methanogenesis: Microbial capacitance-tropism in propionate metabolism

The redox functional groups of biochar can act as pseudocapacitance, alleviating acid accumulation and facilitating electron transfer in anaerobic digestion. Fe modification further enhances its pseudocapacitance properties. However, the specific role of pseudocapacitance strengthening in the electron transfer of volatile fatty acid syntrophic methanogenesis, as well as the factors inducing the enrichment behavior and metabolic mechanisms of microbes on its surface, remain unclear. In this study, experiments using acetate and propionate as substrates were conducted with the addition of biochar and electro-enhanced biochar, while 16S rRNA gene amplicon sequencing and metagenomic analysis were employed to investigate the underlying mechanisms. The results demonstrate that strengthening biochar’s pseudocapacitance significantly facilitates the electron shunt by accepting electrons, accelerating NADH/NAD+ conversion and ATP synthesis. This further promotes the oxidative degradation of propionate and acetate through the methylmalonyl-CoA (MMC) and syntrophic acetate oxidation (SAO) pathways. During methanogenesis, biochar directly transfers electrons to methanogens, with the strengthened pseudocapacitance further accelerating electron transfer through the CO2 reduction pathway and specifically promoting the methanation of propionate rather than acetate. Moreover, during propionate metabolism, Coprothermobacter and Methanosarcina exhibit capacitance-tropism in their enrichment on biochar, serving as key functional contributors to the biochar-microbial aggregates. These findings provide valuable insights for selecting exogenous materials in engineering applications to alleviate acid accumulation in anaerobic digestion systems.

Microwave Mediated Acylation of Alcohols, Phenols and Thiophenols in Neat Acetic Anhydride.

A microwave-based method for the acylation of alcohols, phenols, and thiols has been developed without the need of a catalyst or base additives. The reaction is far more rapid than previously reported acylation methods, tolerates a wide variety of functional groups, and provides easy isolation of products in excellent yields without the need for chromatography. Most products can be isolated directly via evaporation under reduced pressure or by pouring the reaction mixture into water and filtering.

Recent Advances in the Development of Indolizine Scaffolds: Synthetic Methodology and Mechanistic Insights

Comprehensive SummaryIndolizine is a nitrogen‐containing heterocycle with strong aromaticity, possessing a delocalized 10π‐electron system. Based on the indolizine scaffolds, numerous molecules with biological activity and organic functional materials have been synthesized. Since 2016, over 110 papers have been published on the synthesis of indolizine scaffolds, but the reviews on synthesizing indolizine scaffolds have been incomplete and not up‐to‐date. Herein, from the perspective of the structure of indolizine with the combination of pyrrole and pyridine ring, we focus on the construction of indolizine scaffolds through the diversity of starting substrates, including pyridine derivatives (N1‐substituted pyridinium salt derivatives, C2‐substituted pyridine derivatives, N1‐ and C2‐free substituted pyridine derivatives), pyrrole derivatives and unoriginal ring substrates. Furthermore, the corresponding reaction mechanisms of synthetic methodologies are also elaborated. Therefore, this review not only paves the way for indolizine synthesis but also provides insight into exploring new reaction modes for constructing nitrogen‐containing heterocycles. Key ScientistsIndolizine was discovered by Angeli in 1890 and first prepared by Scholtz in 1912 from α‐picoline and acetic anhydride. A general approach was developed by Chichibabin in 1927, that is of practical value for the preparation of 2‐alkyl‐ or 2‐arylindolizines. The Chichibabin reaction was the ring closure of quaternary pyridinium halides. At the begining of the 21st century, Basavaiah introduced a new dimension in the Baylis‐Hillman chemistry leading to a novel facile convenient methodology for synthesis of indolizine scaffolds in one‐pot operation. In 2010, Barluenga reported Cu(I)‐catalyzed regioselective [3+2] cyclization of unsubstituted pyridines toward alkenyldiazoacetates leading to functionalized indolizine derivatives, that was the first successful example of metal‐catalyzed cyclization of a π‐deficient heterocyclic system with alkenyldiazo compounds. In 2019 and 2022, Xi and Liu exploited the methods of non‐pyridine derivatives as starting materials to synthesize indolizines, respectively. In 2022, Guo developed an environmentally benign electrooxidative approach for constructing formyl‐ and acyl‐substituted indolizines.

A polymeric form of basic iron(III) acetate with an acetic acid ligand.

A new crystalline compound, catena-poly[hexa-μ-acetato-(acetic acid)-μ3-oxido-triangulo-triiron(III)]-μ-acetato], [Fe3(C2H3O2)7O(C2H4O2)]n, incorporating the basic ferric acetate unit, has been obtained from an acetic anhydride solution of hydrated iron(III) nitrate. The crystals have the composition Fe3O(OAc)7(HOAc) (HOAc is acetic acid) and include the well-known [Fe3O(OAc)6]+ unit, in which the FeIII centres are linked to a central coplanar μ3-oxido ligand. Acetate ions provide bridges between pairs of FeIII centres. These individual [Fe3O(OAc)6]+ units are linked by additional bridging acetate anions to form zigzag chains. The bridging acetate ions coordinate to a position trans to the oxido group on two of the FeIII centres. Remarkably, the trans site on the third FeIII centre is occupied by the carbonyl group of an acetic acid molecule. This is the first reported case of an acetic acid molecule coordinating to an FeIII centre. Not surprisingly, the acetic acid molecule is only weakly coordinating, resulting in a short Fe-O(oxido) bond trans to the carbonyl group. The trans influence apparent in this structure provides an interesting contrast with the structurally similar MnIII analogue, in which the corresponding pair of trans bonds are both elongated because of the Jahn-Teller effect.

Process simulation and economic evaluation of the industrial production of triacetin from glycerol: Comparing acetic acid and acetic anhydride as possible reagents

The objective of this work was to simulate, in Aspen HYSYS® v12.1, the process of obtaining triacetin from glycerol through three chemical routes: via acetic acid (Route 1), acetic anhydride (Route 2), and a combination of acetic acid and acetic anhydride in two separate reactors (Route 3). Additionally and as a novelty, it was investigated the technical and economic viability of a multipurpose plant to this end. It was verified that Route 1 resulted in the best triacetin breakeven prices, even though it would still not be competitive in the considered economic context. On the other hand, Route 2 presented the worst performance due to low conversion (11 %) and higher price of acetic anhydride. The combined route resulted in intermediate breakeven prices for triacetin, despite achieving the highest conversion (79 %) and highest final product purity (96 %). Yield/selectivity and the separation steps were identified as the main bottlenecks in these processes, with reactors and distillation columns accounting for more than 95 % of the equipment costs. The multipurpose plant proved technically possible, and it can be economically interesting depending on the market prices for acetic acid and acetic anhydride.