Release Of Acetic Acid Research Articles

Aminonaphthalene and aminoquinoline photocages: meta-effect and photo-release of carboxylic acids and alcohols

Three series of compounds were tested as photocleavable protective groups (photocages), which are derivatives of 1,2-substituted aminonaphthalene 4, 1,3-substituted aminonaphthalene 5, or 5,6-substituted aminoquinolines 6. Their photophysical properties and photochemical reactivity in releasing alcohols and carboxylic acids were investigated. Moreover, mechanism of photochemical reaction was studied computationally and by transient absorption spectroscopy with time-resolution from femtoseconds to milliseconds. Photocages 4 and 5 are generally fluorescent molecules with high ΦF, whereas quinoline 6 is weekly fluorescent due to photoinduced charge transfer. Derivatives 4 release alcohol with low quantum yield (release of methanol from 4d is ΦR = 0.00010 ± 0.00005), but upon prolonged irradiation can be applied in organic synthesis to deprotect both aliphatic and aromatic alcohols. On the contrary, photocages 5 undergo relatively efficient release of carboxylic acids, (release of acetic acid from 5b is ΦR = 0.22 ± 0.01), in accord with the meta-effect in photochemistry, which is our main discovery that is based on the rational design of the chromophore. The photochemical reaction mechanism involves homolytic cleavage on the singlet excited state surface and formation of radicals which were detected by transient spectroscopy. The meta-effect did not promote the heterolytic cleavage as it was the case with aniline chromophores. The subsequent electron transfer delivers naphthalenmethyl carbocation and released carboxylates. The applicability of photocages 5 in organic synthesis was demonstrated on aliphatic and aromatic carboxylic acids. The potential use in biology was suggested due to their very weak photoinduced antiproliferative effect, which was essayed on three human cancer cell lines (MCF-7 breast carcinoma, HCT 116 colon carcinoma, and H460 lung carcinoma).

Ion mobility mass spectrometry uncovers regioselectivity in the carboxylate-assisted C-H activation of palladium N-heterocyclic carbene complexes.

Carboxylate-assisted Pd-catalyzed C-H bond activation constitutes a mild and versatile synthetic tool to efficiently and selectively cleave inert C-H bonds. Herein, we demonstrate a simple method to experimentally evaluate both reactivity and selectivity in such systems using mass spectrometry (MS) methods. The N-heterocyclic carbene (NHC) cations [(NHC)PdX]+, bearing as X- ligand bases commonly used to promote the C-H activation (carboxylates and bicarbonate), are generated in the gas-phase by ESI-MS. Their C-H bond activation at the N-bound groups of the NHC is then studied using Collision Induced Dissociation (CID) experiments. Ion Mobility Spectrometry (IM)-MS is exploited to identify a number of regioisomers associated with the distinctive site selective C-H activations. It is demonstrated that such C-H activation concomitant with acetic acid release occurs from a mixture of activated [(NHC-H)Pd(CH3CO2H)]+ and non-activated [(NHC)Pd(CH3CO2)]+ complexes. The identity of the X-type ligands (X = Cl-, carboxylates and bicarbonate) has a significant impact on the regioisomer branching ratio upon CID conditions. IM-MS in conjunction with a DFT mechanistic study is presented for the acetate-assisted C-H activation of the [(NHC)Pd(CH3CO2)]+ cation featuring butyl and aryl as N-donor groups.

Autohydrolysis pretreatment of corn stalk for improved 5-hydroxymethylfurfural production in molten salt hydrate/acetone

Molten salt hydrate (MSH) is unique in cellulose dissolution and in one-pot conversion of crystalline cellulose into 5-hydroxymethylfurfural (5-HMF). However, low yield of 5-HMF was obtained using raw biomass substrate in MSHs. Herein, we investigated conversion of raw biomass towards HMF using MSHs. We showed that the release of acetic acid from hemicellulose degradation in MSH is a key to influence the yield of 5-HMF. Thus, an autohydrolysis pretreatment method was proposed to remove hemicellulose before conversion of cellulose into 5-HMF. After being pretreated at 180 °C for 40 min, hemicellulose was removed from biomass with 91.8% yield of cellulose remained in solid part. By eliminating the negative effect of acetic acid, 5-HMF yield was significantly improved from 40.9% to 64.6%, together with 9.3% yield of glucose for cellulose conversion in MSH/acetone at 180 °C for 20 min.

Transparent Figures: Researching and Preserving Objects of Cellulose Acetate

In 1935, the Deutsches Hygiene-Museum Dresden began to produce the so-called Transparent Figures, which became icons of the 20th century. This study aims to explore the effects of external agents such as humidity and temperature on the aging mechanism of the materials of the Transparent Figures and to slow it down through preventive measures. The focus is on cellulose acetate (CA), which was used for the outer skin of the Transparent Figures. The original objects were investigated using FTIR, Raman, and GC–MS. On some Transparent Figures, liquid leakage of additives occurs when the relative humidity rises above 50–60% RH and is accompanied by a release of acetic acid. Based on these findings, original CA used for the production of the Transparent Figures was artificially re-aged at 70 °C while varying the relative humidity. The specimens were analyzed with colorimetry and GC–MS. Additive content, degree of substitution and degree of polymerization were determined. The results showed that the degradation is slowed down at 30% RH compared to aging at 50% RH or 70% RH. Thus, lowering the relative humidity seems effective in slowing down the degradation of the CA of the Transparent Figures. A relative humidity of 30% RH and a temperature of 15 °C are recommended.

Infrared Spectroscopic Study of the Mechanism of Reaction of Zinc Acetylacetonate with Ozone Using Matrix Isolation and Theoretical Calculations.

The reaction of zinc acetylacetonate, Zn(C5H7O2)2, with O3 is reported using matrix isolation, infrared spectroscopy, and theoretical calculations to identify reaction products and provide inferences about the reaction mechanism. A new "flow over" deposition technique is also reported that was used along with twin-jet and merged-jet deposition to explore this reaction under different conditions. Oxygen isotopic labeling with 18O was used to help confirm product identities. The primary observed reaction products include methyl glyoxal, formic acetic anhydride, acetyl hydroperoxide, and acetic acid. Additional weak products, including formaldehyde, were formed as well. The reaction appears to occur through the initial formation of a zinc-bound primary ozonide that can release methyl glyoxal and acetic acid or rearrange to a zinc-bound secondary ozonide, followed by product release of formic acetic anhydride and acetic acid or acetyl hydroperoxide from the zinc-bound species.

Production of Acetic Indole Acid in Macrophomina phaseolina

The fungus Macrophomina phaseolina is a phytopathogen of great importance attacking various crops and causing severe losses especially in sorghum, beans, soybeans and others. Since acetic indole acid (AIA) is a hormone that some authors associate with the pathogenic power of other fungi such as Fusarium oxysporum, it was decided to perform this work to detect whether M phaseolina isolated from beans is layers of producing AIA and which synthesis pathways are involved in its production. The analyses performed using HPLC showed the production of indole acetamide (ACM) that occurs in the first 60 hours of incubation. Another compound produced is Indole (IND) which is released after 60 hours when ACM production has ceased. Similarly, the fungus can metabolize AIA in the culture medium and tryptophan, the main precursor of AIA, apparently has no effect on the amount of AIA synthesized.
 Conclusion: The phytopathogenic fungus Macrophomina phaseolina can produce indole acetic acid, a hormone that stimulates plant growth through the TRP-D pathway via indole acetamide, which occurs mainly in the first 60 hours of growth of the fungus in the culture medium. In addition, the presence of indole was detected, which allows us to estimate that the fungus uses another little explored route that is TRP-I and that from this compound the AIA can be synthesized directly or transformed into TRP. This means that when a metabolic pathway of IAA is turned off (ACM) it is replaced by another pathway (Indole). The convenient is to correlate the release of indole acetic acid with the pathogenicity of M phaseolina.

Plant Growth-Promoting Attributes of Zinc Solubilizing Dietzia maris Isolated from Polyhouse Rhizospheric Soil of Punjab.

Zinc solubilizing rhizobacteria (ZSR) enhance the phyto-availability of Zn by converting its insoluble forms into usable forms that are essential for the growth and nutritional quality of crops. In the present study, a potential ZSR, hereafter referred to as strain N14, was isolated from the polyhouse rhizospheric soil of Punjab, India. The isolated rhizobacteria was found to be Gram-positive, aerobic, rod-shaped, and demonstrated a solubilization index of 63.75 on the Bunt Rovira (BR) medium. The 16S rRNA gene sequence analysis revealed that isolated strain N14 matches substantially with type strain Dietzia maris DSM 43672T. In its ZnO broth assay, a significant amount of soluble Zn was detected along with a simultaneous decrease in pH of the broth. Ultra-performance liquid chromatography analysis revealed the release of organic acids, specifically, lactic acid and acetic acid by D. maris strain N14 which could be the reason for the decrease in broth pH. The production of indole acetic acid (29.91µg/ml), gibberellic acid (4.72µg/ml), ammonia (38.87µg/ml), siderophore (0.89%), along with the release of HCN and appearance of phosphate solubilization zone (14.4mm) with this strain suggested its possible plant growth-promoting (PGP) characteristics. Therefore, this strain was employed in the formulation of pellets which were applied for in vivo PGPstudies using tomato plants. The developed bioformulated pellets showed a significant enhancement in plant growth as compared to control and vermicompost treated plants. To the best of our knowledge, this is the first report describing the Zn solubilizing and PGP characteristics of D. maris.

A chemo-enzymatic transformation of linalyl acetate to estragole, a phenyl propanoid ether using recombinant esterase in acetone reaction system

The esterase gene from Bacillus subtilis E9 was expressed in E. coli BL21 (DE3) using the pTAC Bs-est recombinant plasmid and the enzyme was purified to determine its biocatalytic ability on the natural ester, linalyl acetate. The substrate affinity of the esterase enzyme was confirmed through docking studies on the interaction between the modelled esterase protein with the ligand. Recombinant esterase transformed linalyl acetate both in buffer and acetone containing reaction system to an alcohol, linalool through hydrolysis within four hours of incubation. This enzymatic hydrolysis involved the release of acetic acid, making the environment acidic. However, after 20 h of enzyme treatment, unlike that of aqueous reaction system, in acetone reaction system this acid condition favoured further chemical conversion of linalool to a cyclic phenyl propanoid ether, estragole. The presence of organic solvent-acetone in the reaction phase could have contributed to the structural modification of the enzyme, facilitating the hydrolysis of linalyl acetate to form linalool and further cyclization to estragole. The overall substrate conversion rate of linalyl acetate to the transformed products, linalool and estragole in acetone containing reaction system was 84 %.

Highly specific fluorescent probes toward acetic acid via structural transformation of zinc complexes

Acetic acid probes based on Zinc complexes with high stability and selectivity were successfully prepared by reacting the H2tBuCarPy ligand with ZnBr2, which exhibit reversible vapor-chromism during the uptake and release of acetic acid.

Improvement of acid solutions for stimulation of compacted high-temperature carbonate collectors

The object of research in this work is the intensification of hydrocarbon production. The most problematic task of the study is the efficiency of intensification of compacted high-temperature carbonate reservoirs. Despite the gradual transition to renewable energy sources, natural gas and oil will play a dominant role in the world's energy balance in the next 20–30 years. Carbonate rocks have significant mining potential, but low filtration properties require intensification to improve reservoir permeability. High temperatures and pressures at great depths require the improvement of existing hydrocarbon production technologies. The most popular method for treating reservoirs containing carbonates is acid treatments in different variations, but for effective treatment it is necessary to achieve deep penetration of the solution into the formation. The study solves the problem of selection of effective carrier liquids for the preparation of acid solutions for the treatment of compacted high-temperature reservoirs with high carbonate content. To ensure quality treatment, acid solutions must have low viscosity and surface tension coefficient, low reaction rate, their chemical properties must ensure the absence of insoluble precipitates in the process of reactions with fluids and rocks, as well as be environmentally friendly. To select the most optimal carrier liquid, experiments were conducted to determine which candidate liquids provide the minimum reaction rate of acidic solutions with carbonates. Based on the analysis of industrial application data and literature sources, water, nephras, methanol, ethyl acetate, and methyl acetate were selected for further research. Widely studied acetic acid was chosen as the basic acid. Studies have shown that methyl acetate has a number of advantages, namely low reaction rate, low viscosity and surface tension coefficient. As well as the possibility of hydrolysis in the formation with the release of acetic acid, which significantly prolongs the reaction time of the solution with the rock and the depth of penetration of the active solution into the formation.

Embryonic Development of Avian Pineal Secretory Activity-A Lesson from the Goose Pineal Organs in Superfusion Culture.

The embryonic ontogeny of pineal secretory activity in birds has been investigated almost exclusively in chickens. This study aimed to characterize this process in domestic geese. The pineal organs of embryos aged 18–28 days were incubated in superfusion culture under different light conditions for 4–5 days and treated with norepinephrine (NE). Melatonin (MLT) was measured by radioimmunoassay and other indoles by HPLC with fluorescence detection. Additionally, pineal organs were collected from embryos at 14–28 days of age and used to measure catecholamines by HPLC with electrochemical detection. MLT secretion increased with embryo age, most intensively between the 22nd and 24th days of life. The daily changes in MLT secretion under the 12 L:12D cycle occurred on the first day of culture, starting from an embryonic age of 24 days. MLT secretion was controlled by the light-dark cycle in all age groups studied. However, exposure to light during the scotophase did not alter the secretion of MLT. The endogenous oscillator expressed its activity in regulating MLT secretion in the pineal organs of embryos aged 24 days and older but could not generate a rhythm after one cycle. The rhythm of 5-hydroxytryptophan release during the first day of culture was found in the pineal organs of all embryos, while the rhythmic release of N-acetylserotonin and 5-methoxyindole acetic acid started at the age of 24 days. The proportion of released indoles changed with embryo age. NE caused a decrease in MLT secretion and provoked an increase in serotonin release. Incubation of the pineal organs induced the development of MLT secretory machinery and its diurnal rhythmicity. The pineal content of catecholamines increased prominently at the end of embryonic development.

Identification and characterization of an acetyl xylan esterase from Aspergillus oryzae

In this study, we report the identification and characterization of an acetyl xylan esterase, designated as AoAXEC, which was previously annotated as a hypothetical protein encoded by AO090023000158 in the Aspergillusoryzae genomic database. Based on its amino acid sequence, a low sequence identity to known acetyl xylan esterases was observed in the sequence of characterized acetyl xylan esterase. The gene fused with α-factor signal sequence of Saccharomyces cerevisiae instead of the native signal sequence was cloned into a vector, pPICZαC, and expressed successfully in Pichia pastoris as an active extracellular protein. The purified recombinant protein had pH and temperature optima of 7.0 and 50°C, respectively, and was stable up to 50°C. The optimal substrate for hydrolysis by the purified recombinant AoAXEC, among a panel of α-naphthyl esters (C2-C16), was α-naphthyl propionate (C3), with an activity of 0.35 ± 0.006 units/mg protein. No significant difference of the Km value was observed between C3 (2.3 ± 0.7mM) and C2 (1.9 ± 0.4mM). In contrast, kcat value for C3 (18 ± 3.9 s-1) was higher compared to C2 (4.5 ± 0.7 s-1). The purified recombinant enzyme displayed a low activity toward acyl chain substrates containing eight or more carbon atoms. Recombinant AoAXEC catalyzed the release of acetic acid from wheat arabinoxylan. However, no activity was detected on methyl esters of ferulic, p-coumaric, caffeic, or sinapic acids. Additionally, the liberation of phenolic acids, such as ferulic acid, from wheat arabinoxylan was not exhibited by the recombinant protein.

Acetic acid release at Texas plant kills 2 workers

Acetic acid release at Texas plant kills 2 workers

Chimeric bi-functional enzyme possessing xylanase and deacetylase activity for hydrolysis of agro-biomass rich in acetylated xylan

Here, a chimeric bifunctional enzyme was developed for two activities xylanase and deacetylase. Chimeric enzyme was designed by combining the relevant amino acid stretches from two different parent sequences, such as polysaccharide/xylan deacetylase (ref id: MT682066) and xylanase (ref id WP_110897546.1). Five different hypothetical chimeras were developed and one of the best predicted chimeric protein GA_2(syn_SKYAP01) was synthesized. The GA_2(syn_SKYAP01) possessed the specific activity of 14.905 ± 0.8 U/mg for deacetylase and 100.87 ± 14.2 U/mg for xylanase. Optimum level of both the activities together was achieved at pH 5 and 60 °C. The chimeric protein was also found to be stable at higher temperature of 71°C. Functionality of the developed chimeric protein for both the activities was confirmed by the hydrolysis of commercial xylan into xylooligosaccharides and the release of acetic acid from glucose pentacetate and 7-amino cephalosporin. The designed bifunctional enzyme was found to be highly efficient.

Storage and handling of pretreated lignocellulose affects the redox chemistry during subsequent enzymatic saccharification

The decomposition of lignocellulose in nature, as well as when used as feedstock in industrial settings, takes place in a dynamic system of biotic and abiotic reactions. In the present study, the impact of abiotic reactions during the storage of pretreated lignocellulose on the efficiency of subsequent saccharification was investigated. Abiotic decarboxylation was higher in steam-pretreated wheat straw (SWS, up till 1.5% CO2) than in dilute-acid-catalysed steam-pretreated forestry residue (SFR, up till 3.2% CO2) which could be due to higher iron content in SFR and there was no significant CO2 production in warm-water-washed slurries. Unwashed slurries rapidly consumed O2 during incubation at 50 °C; the behaviour was more dependent on storage conditions in case of SWS than SFR slurries. There was a pH drop in the slurries which did not correlate with acetic acid release. Storage of SWS under aerobic conditions led to oxidation of the substrate and reduced the extent of enzymatic saccharification by Cellic® CTec3. Catalase had no effect on the fractional conversion of the aerobically stored substrate, suggesting that the lower fractional conversion was due to reduced activity of the lytic polysaccharide monooxygenase component during saccharification. The fractional conversion of SFR was low in all cases, and cellulose hydrolysis ceased before the first sampling point. This was possibly due to excessive pretreatment of the forest residues. The conditions at which pretreated lignocellulose are stored after pretreatment significantly influenced the extent and kind of abiotic reactions that take place during storage. This in turn influenced the efficiency of subsequent saccharification. Pretreated substrates for laboratory testing must, therefore, be stored in a manner that minimizes abiotic oxidation to ensure that the properties of the substrate resemble those in an industrial setting, where pretreated lignocellulose is fed almost directly into the saccharification vessel.

Biohydrogen production from photodecomposition of various cellulosic biomass wastes using metal-TiO2 catalysts

Biohydrogen generation from direct photocatalytic decomposition of lignocellulose biomass waste was investigated using TiO2 with metal co-catalysts. The behavior of the photocatalyst was explored by studying the effect of metal co-catalysts (Pd, Cu, Ni, Ce) and the amount of metal loading. The reactivity of TiO2 was found to vary depending on the metal co-catalysts, with the order of reactivity being Pd > Cu > Ni = Ce. Cellulose samples extracted from coconut husk, fern fiber, and cotton linter were characterized using XRD, FTIR, and SEM analysis. Crystallinity index (CI), degree of polymerization (DP), and α-cellulose and hemicellulose concentrations were correlated with hydrogen yield. Cotton linter cellulose with high CI and DP produced 131 μmol of H2 in 3 h followed by cellulose extracted from coconut husk at 38 μmol and fern fibers at 6 μmol. High concentrations of hemicellulose enhanced the rate of H2 production due to the release of acetic acid during photodecomposition and accelerated the hydrolysis. Sugar fractions containing glucose and fructose obtained from hydrothermal treatment of cotton linter cellulose improved H2 yield, which suggests that the rate limiting step of the reaction is the dissociation of β(1→4)-glycosidic bonds to form sugar monomers.

Identification, characterization, and immobilization of a novel YbfF esterase from Halomonas elongata

The YbfF esterase family, which has a bifurcated binding pocket for diverse ligands, could serve as excellent biocatalysts in industrial and biotechnological applications. Here, the identification, characterization, and immobilization of a novel YbfF esterase (YbfFHalomonas elongata) from Halomonas elongata DSM 2581 is reported. Biochemical characterization of YbfF was carried out using activity staining, chromatographic analysis, kinetic analysis, activity assay, acetic acid release, and pH-indicator-based hydrolysis. YbfFH.elongata displayed broad substrate specificity, including that for p-nitrophenyl esters, glucose pentaacetate, tert-butyl acetate, and β-lactam-containing compounds, with high efficiency. Based on a homology model of YbfFH.elongata, Trp237 in the substrate-binding pocket, a critical residue for catalytic activity and substrate specificity was identified and characterized. Furthermore, crosslinked enzyme aggregates and nanoflower formation were explored to enhance the chemical stability and recyclability of YbfFH.elongata. The present study is the first report of a YbfF esterase from extremophiles, and explains its protein stability, catalytic activity, substrate specificities and diversities, kinetics, functional residues, amyloid formation, and immobilization.

Influence of acetic and butyric acid and gas release modes on immobilized Clostridium acetobutylicum (DSMZ 792) in repeated batch experiments

The effects of supplementation of standard media with metabolic intermediates (2 g/L butyric acid, 2 g/L butyric acid + 1.5 g/L acetic acid) on butanol and hydrogen production/yield were evaluated. Fermentations were conducted with immobilized Clostridium acetobutylicum (DSMZ 792). Additionally, the influence of gas release modes (constant gas release vs. interval gas release) was tested in all setups to evaluate butanol and hydrogen production and yields. Fermentations were implemented in repeated batch mode (48 h, 37 °C, 100 rpm). Overpressure conditions had a negative impact on volumetric hydrogen production and hydrogen yield and a positive impact on butanol yield. Supplementation significantly increased the butanol concentrations in constant gas release mode, by 23.6%. When interval gas mode was applied in the supplemented fermentations, the butanol concentrations decreased by 8.4% when butyric acid was fed, and reached similar concentrations when both acids were added. The highest butanol concentration and volumetric butanol production rate of 9.6 ± 0.6 g/L and 0.2 ± 0.0 g/L*h, respectively, were reached with butyric acid supplementation and constant gas release mode. The highest volumetric hydrogen production was reached with the constant gas release mode in fermentations conducted with the addition of both acids, and reached 165 ± 9 mL/L*h.

Effect of surface covering on the release of formaldehyde, acetaldehyde, formic acid and acetic acid from particleboard

An important aspect for indoor air quality is the control of potential sources of organic pollutants. However, many building products, in particular wood-based materials, are coated under real conditions, while the emission behavior is usually examined without coating. For a reliable estimate of indoor air concentrations, it is therefore necessary to determine the influence of surface coatings on their emission behavior. In this work, the effect of various types of coatings (wallpaper, plaster, wall paint, latex paint) on particleboards with regard to the emission of formaldehyde, acetaldehyde, formic acid and acetic acid was investigated. The measurements were carried out in four steps. I: raw particleboard; II: particleboard with primer; III: particleboard with primer and top coating; IV: particleboard with primer and top coating after three months of storage. Applying the primer reduced the formaldehyde concentration in the chamber by 10–20%. With the final coating, the formaldehyde reduction was between 70% and 90% after 900 h. There was no increase in formaldehyde concentration after three months. Regardless of the coating, a constant decay in concentration was observed for acetaldehyde. The release of formic acid could be reduced by the primer for a short time, only the application of the final coating brought a lasting effect. The results were indifferent for acetic acid. One reason for this is that some of the coatings contained acetates. Overall, surface coatings make a significant contribution to reducing the emissions of wood-based materials. This is particularly evident where the substance formaldehyde is concerned.

Chemical and Mechanical Differences between Historic and Modern Scots Pine Wood

Timber is one of the most common historic building materials, but relatively little is known about how it ages in situ. Here we investigate historic and modern Scots pine to determine any chemical or mechanical differences between them. Fourier-transform infrared (FTIR) microscopy was used to investigate differences in the chemical composition of Scots pine (Pinus sylvestris L.) timber, comparing small samples from historic beams about 500 years old with modern timber. The hemicellulosic acetyl content was reduced by about half in the historic samples, uniformly across the thickness of the beams. A chemical mechanism was therefore suggested for the loss of acetyl groups, as has been observed in paper. In paper, deacetylation and the resulting release of acetic acid are accompanied by loss of strength. Mechanical testing of the historic timber was difficult because the available length of the samples along the grain was only 20 mm. After developing a miniaturized compression test developed for the purpose, it was shown that the relative stiffness of the historic Scots pine samples was reduced by about half compared to modern material.