Equivalent Of Acetic Acid Research Articles

Novel report of Acinetobacter johnsonii as an indole-producing seed endophyte in Tamarindus indica L.

Plant-microbe associations have been regarded as an exciting topic of research due to their potential as environment friendly alternatives for stimulating crop growth and development. Seeds of Tamarindus indica L. have been chosen for the present study as seed endophytes prefer larger or nutritive cotyledon and hard seed coats for their colonization. The main objectives of our study were to isolate and identify the seed endophytes, their bioefficacy, and responsible chemical compounds. In a dose-dependent experiment, tamarind seed exudates (TSE) showed plant growth-promoting properties on Oryza sativa (53-81%), Daucus carota (10-31%), and Raphanus sativa (21-42%). Identification of the bacterial load in TSE through 16S rRNA sequencing revealed the existence of two bacterial species, Acinetobacter johnsonii and Niallia nealsonii. This is the first report of these two bacteria as seed endophytes of Tamarindus indica L. HRLC-MS analysis of TSE confirmed the presence of indole derivatives, primarily indole-3-lactic acid (ILA). The quantitative phytochemical estimation of bacterial culture filtrates revealed that indole-like substances were present in the extracts only in A. johnsonii at a concentration of 0.005mg/ml of indole acetic acid equivalent. Experimental results suggested that the stimulatory activity of TSE was caused by the presence of A. johnsonii, a potential plant growth-promoting bacteria that produced indole-like compounds. This study suggests tamarind seed exudates with its endophytic microbiota as a potent plant growth-promoting agent that may find use as a cheap and sustainable source of metabolites useful in the agro-industries.

Effect of Fluorescent-Producing Rhizobacteria on Cereal Growth Through Siderophore Exertion

Despite soil having an abundance of iron (Fe), it is unavailable for proper plant growth and development. One of the mechanisms plants use to deal with iron deficiency is the uptake of iron by chelating phytosiderophores. Pseudomonas fluorescence can produce pyoverdine-type siderophore and has potential application in agriculture as an iron chelator. Therefore, bacterial isolates collected from different areas of district Faisalabad were screened for their fluorescent, siderophore production and indole acetic acid equivalents. After selecting efficient strains from a screening test, they were evaluated for improving wheat and maize production under field conditions. The results showed that out of 15 isolates, 7 were found to have significant plant-beneficial microbial traits. Efficient strains promoted grain yield by 24.2% and 20.2%, plant height by 30.9% and 23.7%, total grain weight by 25.3% and 13.4% over control in wheat and maize, respectively. Similarly, significant improvements in the number of grains per cob/spike were also observed. Analyses of grain iron contents depicted 67% increase as compared to control in for maize. Therefore, based on the results, it is concluded that bio-fortification of cereal crops through fluorescent producing siderophoric microbes is an effective strategy favorable for plant growth and development through nutrient solubilization/mobilization.

Electrochemical Study of the Hydrogen Evolution Reaction using Coppe r(II) Thiacalix[4]arene-based Catalyst

Despite the interesting structure of the generic thiacalix[4]arene containing four coordinating sulfur atoms bridging four phenolic units, there are only a few reported examples of thiacalixarene-based coordination complexes that are used as electrocatalysts. Herein, we report electrocatalytic hydrogen evolution reaction (HER) by a thiacalix[4]arene-based copper(II) complex (1). As expected, two reduction waves were appeared (-0.48 V and -1.30 V vs Ag/AgCl) for Cu2+/Cu+ and Cu+/Cu reduction couples. The HER by proton reduction occurs at -1.03 V with a shift of 0.27 V compared to the second peak potential at -1.30 V. The increase in the number of acetic acid equivalents, from 0 to 17.5 with a frequency of 2.5 eq, was accompanied by an increase in the peak current that reached a maximum value of 183 and#181;A for 15 equivalents of acetic acid.

Safety evaluation of buffered vinegar as a food additive.

The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of buffered vinegar as a new food additive. Buffered vinegar is a liquid or dried product prepared by adding sodium/potassium hydroxides (E 524 to E 525) and sodium/potassium carbonates (E 500 to E 501) to vinegar, compliant with European Standard EN 13188:2000 and exclusively obtained from an agricultural source origin (except wood/cellulose). The primary constituents of buffered vinegar are acetic acid and its salts. No biological or toxicological data obtained with the proposed food additive were submitted by the applicant as part of the dossier as, following oral ingestion, buffered vinegar dissociates into the acetic anion and acetate a natural constituent of the diet, and of the human body for which extensive data on their biological effects exist and for which EFSA in 2013 has previously concluded that the establishment of an acceptable daily intake (ADI) is not considered necessary. At the proposed maximum/typical use levels, the mean exposure to buffered vinegar from its use as a food additive expressed as acetic acid equivalents ranged from 8.9 mg/kg body weight (bw) per day in infants to 280.3 mg/kg bw per day in children. The 95th percentile of exposure to buffered vinegar ranged from 27.9 mg/kg bw per day in infants to 1,078 mg/kg bw per day in toddlers. The Panel concluded that there is no safety concern for the use of buffered vinegar as a food additive at the proposed maximum/typical use levels. The Panel could not conclude on the safety for the proposed uses at quantum satis as Group I food additive since the resulting exposure could not be estimated.

Synthesis and electrochemical properties of a nickel(II) thiacalix[4]arene-based electrocatalyst for the hydrogen evolution reaction

Thiacalix[4]arene with four sulfur-bridging atoms and four hydroxy coordinating groups in the lower rim is a promising candidate for powerful electrocatalytic hydrogen production. However, there are only a few examples reported in the literature where conjugated thiacalix[4]arene is used as a pre-catalyst for the hydrogen evolution reaction. The present work evaluates the electrocatalytic performance of a nickel(II) coordination complex based on generic thiacalix[4]arene. The coordination complex is characterized by cyclic voltammetry, where two reduction peaks are observed at −0.57 and −1.33 V for the two redox couples Ni2+/Ni+ and Ni+/Ni, respectively. The proton reduction occurs at the second peak potential with a slight shift at about −1.0 V, with increasing peak currents directly related to the number of acetic acid equivalents. The maximum peak current was observed to be at about 67 µA for 20 equiv. of acetic acid.

Catalytic Direct α-Amination of Arylacetic Acid Synthons with Anilines.

A unique α-amination approach using various anilines has been developed for arylacetic acids via adaptation as benzazoles. The reaction proceeds through a single electron transfer mechanism utilizing an iron-based catalyst system to access α-(N-arylamino)acetic acid equivalents. Modification of approved drugs, facile cleavage of the benzazole auxiliary, and tolerance of amide linkage forming conditions constitute the potential applicability of this strategy.

Synthesis of Sulfonimidamides from Sulfenamides via an Alkoxy-amino-λ6 -sulfanenitrile Intermediate.

Sulfonimidamides are intriguing new motifs for medicinal and agrochemistry, and provide attractive bioisosteres for sulfonamides. However, there remain few operationally simple methods for their preparation. Here, the synthesis of NH-sulfonimidamides is achieved directly from sulfenamides, themselves readily formed in one step from amines and disulfides. A highly chemoselective and one-pot NH and O transfer is developed, mediated by PhIO in iPrOH, using ammonium carbamate as the NH source, and in the presence of 1 equivalent of acetic acid. A wide range of functional groups are tolerated under the developed reaction conditions, which also enables the functionalization of the antidepressants desipramine and fluoxetine and the preparation of an aza analogue of the drug probenecid. The reaction is shown to proceed via different and concurrent mechanistic pathways, including the formation of novel S≡N sulfanenitrile species as intermediates. Several alkoxy-amino-λ6 -sulfanenitriles are prepared with different alcohols, and shown to be alkylating agents to a range of nucleophiles.

Synthesis of Sulfonimidamides from Sulfenamides via an Alkoxy‐amino‐λ6‐sulfanenitrile Intermediate

AbstractSulfonimidamides are intriguing new motifs for medicinal and agrochemistry, and provide attractive bioisosteres for sulfonamides. However, there remain few operationally simple methods for their preparation. Here, the synthesis of NH‐sulfonimidamides is achieved directly from sulfenamides, themselves readily formed in one step from amines and disulfides. A highly chemoselective and one‐pot NH and O transfer is developed, mediated by PhIO in iPrOH, using ammonium carbamate as the NH source, and in the presence of 1 equivalent of acetic acid. A wide range of functional groups are tolerated under the developed reaction conditions, which also enables the functionalization of the antidepressants desipramine and fluoxetine and the preparation of an aza analogue of the drug probenecid. The reaction is shown to proceed via different and concurrent mechanistic pathways, including the formation of novel S≡N sulfanenitrile species as intermediates. Several alkoxy‐amino‐λ6‐sulfanenitriles are prepared with different alcohols, and shown to be alkylating agents to a range of nucleophiles.

Effect of headspace gas composition on carboxylates production in open-culture fermentation of corn stover

In open-culture fermentation of lignocellulosic biomass, the gas composition in the fermentor headspace can suppress or favor certain fermentation pathways and thereby alter product concentrations. This study focuses on the effect of hydrogen and carbon dioxide concentrations in the headspace of open-culture fermentation of raw corn stover (80%) and chicken manure (20%). Four headspace gas compositions were evaluated at 2.05 × 105 Pa (abs): pure hydrogen, pure carbon dioxide, mixture of hydrogen and carbon dioxide (1:1), and pure nitrogen (control). Using pure hydrogen in the headspace increased the acetic acid equivalents by 13%, but did not change the product spectrum considerably. Using pure carbon dioxide in the headspace reduced the acetic acid equivalents by 4%, but shifted the acid spectrum from short toward medium-chain carboxylic acids. Using hydrogen:carbon dioxide (1:1) in the fermentor headspace increased the acetic acid equivalents by 29%.

Quinazolin-4(3H)-ones and 5,6-Dihydropyrimidin-4(3H)-ones from β-Aminoamides and Orthoesters

Quinazolin-4(3H)-ones have been prepared in one step from 2-aminobenzamides and orthoesters in the presence of acetic acid. Simple 2-aminobenzamides were easily converted to the heterocycles by refluxing in absolute ethanol with 1.5 equivalents of the orthoester and 2 equivalents of acetic acid for 12–24 h. Ring-substituted and hindered 2-aminobenzamides as well as cases incorporating an additional basic nitrogen required pressure tube conditions with 3 equivalents each of the orthoester and acetic acid in ethanol at 110 °C for 12–72 h. The reaction was tolerant towards functionality on the benzamide and a range of structures was accessible. Workup involved removal of the solvent under vacuum and either recrystallization from ethanol or trituration with ether-pentane. Several 5,6-dihydropyrimidin-4(3H)-ones were also prepared from 3-amino-2,2-dimethylpropionamide. All products were characterized by melting point, FT-IR, 1H-NMR, 13C-NMR, and HRMS.

Process analysis of hydrothermal carbonization of corn Stover with subcritical H2O

This work investigates the influence of temperature on the performance of hydrothermal carbonization of corn Stover between 175 and 250 °C, 240 min, 2.0 °C/min, and biomass-to-water ratio of 1:10. The performance analyzed for yields, energy densification and recovery. Aqueous phase analyzed for pH, acetic acid equivalent (HAc), HPLC, and GC, solid phase for dry and organic matter, ash, and elemental analysis. Solid yield (62.92–35.82%) increases with temperature, showing an inflection region between 200 and 225 °C, while that of liquid (35.43–54.59%) decreases in a similar behavior, and gas yield (1.49–9.59%) increases exponentially. GC identified alcohols, carboxylic acids, and furans. The concentration of furfural and Hidroxymethylfurfural (HMF) decreases exponentially and as a sigmoid with temperature, being not detectable at 250 °C. Carbon content increases, while oxygen and hydrogen decreases with temperature. The high heating values (HHV) increase, and the energy efficiency decreases with temperature.

Chemoselectivity in the Synthesis of 1,2,3-Triazoles from Enolizable Ketones, Primary Alkylamines, and 4-Nitrophenyl Azide

In recent years, several organocatalytic/metal-free synthetic pathways towards 1,2,3-triazoles have been reported. One of them is a general metal-free route towards the synthesis of 1,5-di- or fully-substituted 1,2,3-triazoles, designed by our group and named the ‘triazolization’ reaction of ketones. Limitations of this route were encountered in reactions with more activated ketones, where the corresponding 1-(4-nitrophenyl)-1,2,3-triazole was found back as the major product. Interestingly, three different triazoles are formed when 1,3-diphenylacetone is used as the ketone. In the present work, 1,3-diphenylacetone was used as a model substrate to investigate the chemoselectivity of our metal-free route under different reaction circumstances. This led to the conclusion that the formation of the desired 1,2,3-triazole is favored in apolar solvents, at high temperatures, and in the presence of acetic acid. By using one equivalent of acetic acid, previously inaccessible fully decorated 1,2,3-triazoles can be synthesized from simple α-arylketones in moderate to high yields.

Fermentation of wet-exploded corn stover for the production of volatile fatty acids

Volatile fatty acids (VFA) have been used as platform molecules for production of biofuels and bioproducts. In the current study, we examine the VFA production from wet-exploded corn stover through anaerobic fermentation using rumen bacteria. The total VFA yield (acetic acid equivalents) was found to increase from 22.8g/L at 2.5% total solids (TS) to 40.8g/L at 5% TS. It was found that the acetic acid concentration increased from 10g/L to 22g/L at 2.5% and 5% TS, respectively. An increased propionic acid production was seen between day 10 and 20 at 5% TS. Valeric acid (4g/L) was produced at 5% TS and not at 2.5% TS. Composition analysis showed that 50% of the carbohydrates were converted to VFA at 5% TS and 33% at 2.5% TS. Our results show that rumen fermentation of lignocellulosic biomass after wet explosion can produce high concentrations of VFA without addition of external enzymes of importance for the process economics of lignocellulosic biorefineries.

Exploration and Optimization of an Efficient One‐pot Sequential Synthesis of Di/tri‐substituted Thiazoles from α‐Bromoketones, Thioacids Salt, and Ammonium Acetate

Exploration of scope of an optimized one‐pot sequential procedure for preparing of 2,4‐di‐ and 2,4,5‐tri‐substituted thiazoles has been accomplished. The synthesis was performed by the initial formation of a β‐keto‐thioester intermediate from nucleophilic substitution of α‐bromoketones with thioacid potassium salts, followed by treatment with ammonium acetate and one equivalent of acetic acid in toluene to form imine intermediate eventually leading to cyclization yielding thiazoles. This procedure should be highlighted with a flexible way to control the substitution pattern around thiazole ring by choosing appropriately substituted α‐bromoketones even containing acid labile functionality and thioacid potassium salts, and thus its applicability is very wide.

ChemInform Abstract: A Mild and Efficient AgSbF6‐Catalyzed Synthesis of Fully Substituted Pyrroles Through a Sequential Propargylation/Amination/Cycloisomerization Reaction.

Abstract Development of an efficient synthesis of fully substituted pyrroles via a sequential propargylation/amination/cycloisomerization was accomplished using AgSbF6 as a catalyst. The one-pot three-component reaction of propargylic alcohols, 1,3-dicarbonyl compounds, and primary amines proceeds at a mild temperature, which prevents the formation of furan by-product. The reaction was also successfully applied to the more basic aliphatic amines with the addition of 1.1 equiv of acetic acid.

Enhanced Antioxidant Effect of Domestic Wheat Vinegar using Mugwort

In this study, we investigated the production of vinegar using domestic wheat and mugwort and their antioxidant activity. Alcohol fermentation of saccharized whole wheat powder suspension was carried out by inoculation of Saccharomyces cerevisiase KCCM 11215. After 4 days of static fermentation at 30°C, 6% of alcohol was produced. Acetic fermentation was carried out using Acetobacter pasteurianus A8 by static condition for 20 days. Optimum conditions for acetic fermentation of alcoholic substrate were 35°C, and 5%(v/v) of seed inoculation rate, respectively. After 20 days of static fermentation at optimal condition, 5.6% of acetic acid equivalent was produced. Total organic acid contents of the domestic wheat vinegar with mugwort were 5.63 g%. Free amino acid contents of the domestic wheat vinegar with mugwort were 485.8 mg%. The DPPH radical scavenging activity and total phenolic contents of domestic wheat vinegar with mugwort was higher than those from domestic wheat vinegar. These results suggest that the production of domestic wheat vinegar with mugwort which contains rich free amino acid and phenolic compound was possible and this vinegar may be use as a functional food.

Enantioselective Diamination with Novel Chiral Hypervalent Iodine Catalysts

Vicinal diamines constitute one the most important functional motif in organic chemistry because of its wide occurrence in a variety of biological and pharmaceutical molecules. We report an efficient metal‐free, highly stereoselective intramolecular diamination using a novel chiral hypervalent iodine reagent together with its application as an efficient catalyst for the synthesis of diamines.

A mild and efficient AgSbF6-catalyzed synthesis of fully substituted pyrroles through a sequential propargylation/amination/cycloisomerization reaction

Development of an efficient synthesis of fully substituted pyrroles via a sequential propargylation/amination/cycloisomerization was accomplished using AgSbF6 as a catalyst. The one-pot three-component reaction of propargylic alcohols, 1,3-dicarbonyl compounds, and primary amines proceeds at a mild temperature, which prevents the formation of furan by-product. The reaction was also successfully applied to the more basic aliphatic amines with the addition of 1.1 equiv of acetic acid.

Regeneration of an Iridium(III) Complex Active for Alkane Dehydrogenation Using Molecular Oxygen

(dmPhebox)Ir(OAc)2(OH2) (1a) has previously been found to promote stoichiometric alkane dehydrogenation, affording alkene, acetic acid, and the corresponding Ir hydride complex (dmPhebox)Ir(OAc)(H) (2a) in high yield. In this study, we describe the use of oxygen to quantitatively regenerate 1a from 2a and HOAc. Distinct reaction intermediates are observed during the conversion of 2a to 1a, depending upon the presence or absence of 1 equiv of acetic acid, highlighting potential mechanistic implications regarding alkane dehydrogenation catalysis and the use of oxygen as an oxidant in such systems.

Regioselective Silyl/Acetate Exchange of Disaccharides Yields Advanced Glycosyl Donor and Acceptor Precursors

Glycoconjugates are composed of carbohydrate building blocks linked together in a multitude of ways giving rise to diverse biological functions. Carbohydrates are especially difficult to synthetically manipulate because of the similar reactivity of their numerous and largely equivalent hydroxyl groups. Hence, methodologies for both the efficient protection and selective modification of carbohydrate alcohols are considered important synthetic tools in organic chemistry. When per-O-TMS protected mono- or disaccharides in a mixture of pyridine and acetic anhydride are treated with acetic acid, regioselective exchange of silicon for acetate protecting groups occurs. Acid concentration, thermal conditions, and microwave assistance mediate the silyl/acetate exchange reaction. Regiocontrol is achieved by limiting the equivalents of acetic acid, and microwave irradiation hastens the process. We coined the term Regioselective Silyl Exchange Technology (ReSET) to describe this process, which essentially sets the protecting groups anew. To demonstrate the scope of the reaction, the conditions were applied to lactose, melibiose, cellobiose, and trehalose. ReSET provided rapid access to a wide range of orthogonally protected disaccharides that would otherwise require multiple synthetic steps to acquire. The resulting bifunctional molecules are poised to serve as modular building blocks for more complex glycoconjugates.