Amount Of Concentrated Sulfuric Acid Research Articles

CO2 utilization for ammonia removal in skim latex: Processing and rubber properties

An innovative CO2 utilization approach for skim rubber production was developed in this research. Traditionally, skim rubber is produced using a substantial amount of concentrated sulfuric acid to coagulate the rubber particles. Before acid addition, ammonia removal process is required to reduce the volume of acid used. This process, however, involves large operating area, long processing time, environmental issues, and health hazards. To minimize those drawbacks, as a process intensification technique in this study, CO2 microbubbles were applied as a feedstock to reduce the ammonia and hence the volume of acid addition. The properties and microstructure of skim rubbers produced via CO2 microbubbles (MBSL) were investigated in comparison with those produced by traditional processes. The MBSL exhibited smooth surface texture with enhanced tensile strength and thermal stability. Utilization of CO2 as a sustainable feedstock to coagulate skim latex has a potential for not only diminishing the limitations caused by traditional processes but also highlighting an environmental-friendly and cost-effective process with improved product properties.

Modified Greener Procedure for the Synthesis of Cucurbit[6]uril

A modified procedure for the synthesis of cucurbit[6]uril on the kilogram scale was elaborated. The procedure includes reaction of glycoluril with paraformaldehyde in the minimal amount of concentrated sulfuric acid, filtration of the product directly from the reaction mixture, and workup by dissolution and reprecipitation of the product in water, with a yield of up to 65%. The modifications made the procedure more environmentally friendly and suitable for large-scale synthesis.

A facile greener synthesis, antimicrobial evaluation and molecular modelling of new 4-aryl-2-(3-(2-(trifluoromethyl)phenyl)-1,8-naphthyridin-2-yl)phthalazin-1(2H)-one derivatives

The synthesis of 4-aryl-2-(3-(2-(trifluoromethyl)phenyl)-1,8-naphthyridin-2-yl)phthalazin-1(2H)-ones was performed by cyclization of 2-hydrazinyl-3-(2-(trifluoromethyl)phenyl)-1,8-naphthyridine with 2-aroylbenzoic acids in ethanol containing a catalytic amount of concentrated sulfuric acid under solid state conditions. All these synthesized compounds (8a–h) were screened for their in vitro antibacterial activity against gram-positive bacteria such as (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli) and also evaluated for their antifungal activity against Aspergillus Niger and Helmenthosphorium oryzae fungal strains. Some of the products demonstrate good antibacterial activity and moderate antifungal activity. In predominantly, 8b, 8d, 8g, and 8h compounds showed good to excellent antibacterial and antifungal activities. The antimicrobial activity of the compound 8 was further investigated with the help of in LibDock score docking study to predict the active sites.

Similarity and Differences in the Regioselectivities of Thermal and Acid-Catalyzed van Alphen–Hüttel Rearrangements in the Series of 3,3-Diphenyl-3H-pyrazoles Containing Electron-Withdrawing Substituents on C4 and C5

3,3-Diphenyl-3H-pyrazoles containing an electron-withdrawing substituent in the 5-position undergo van Alphen–Huttel rearrangement with migration of one phenyl group to C4 on heating in an aprotic solvent (benzene, toluene), as well as on keeping at 20°C in acetic acid in the presence of a catalytic amount of concentrated sulfuric acid. Under similar conditions, 3,3-diphenyl-3H-pyrazoles with a strong electronwithdrawing group (sulfo or cyano) on C4 isomerize to 1H-pyrazoles via migration of one phenyl group to N2. If a moderate electron-withdrawing substituent (alkoxycarbonyl or acetyl group) is present in the 4-position, the acid-catalyzed phenyl group migration is directed mainly to the C4 atom, while thermal migration, toward N2. Probable reasons for the observed similarity and differences in the regioselectivities of the thermal and acidcatalyzed van Alphen–Huttel rearrangements have been proposed.

Response Surface Methodology for Optimization of Copper Leaching from Refractory Flotation Tailings

Response surface methodology is used to optimize the leaching process for refractory flotation copper tailings. The proportion of the refractory combination oxide copper (chrysocolla) is 64.84%. At present, few studies have examined the leaching of chrysocolla. In this study, we examine the effects of several variables, including the amount of concentrated sulfuric acid, leaching temperature, and leaching time, on leaching efficiency. Using a response surface methodology, we develop a quadratic model relanbting all the above experimental variables with leaching efficiency. The resulting model is highly consistent with experimental data. According to the model, the factor with the greatest influence on leaching efficiency is the amount of concentrated sulfuric acid. According to the model, the optimal leaching conditions are 85 kg/t concentrated sulfuric acid, a leaching temperature of 68.51 °C, and a leaching time of 4.36 h. The actual measured leaching efficiency under these conditions is 85.86%, which is close to the value of 86.79% predicted by the model. We study the leaching processes using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) surface scan analyses. Both methods allow us to explore the content of the main element and visually observe its distribution, allowing us to develop effective methods for treating low-grade oxide ores.

High-efficient Synthesis of Graphene Oxide Based on Improved Hummers Method.

As an important precursor and derivate of graphene, graphene oxide (GO) has received wide attention in recent years. However, the synthesis of GO in an economical and efficient way remains a great challenge. Here we reported an improved NaNO3-free Hummers method by partly replacing KMnO4 with K2FeO4 and controlling the amount of concentrated sulfuric acid. As compared to the existing NaNO3-free Hummers methods, this improved routine greatly reduces the reactant consumption while keeps a high yield. The obtained GO was characterized by various techniques, and its derived graphene aerogel was demonstrated as high-performance supercapacitor electrodes. This improved synthesis shows good prospects for scalable production and applications of GO and its derivatives.

Analysis of water-soluble polysaccharides in an edible medicinal plant Epimedium: method development, validation, and application.

Water-soluble polysaccharides are important constituents with evident health benefits in Epimedium. The aim of this study was to establish a specific, accurate, reproducible, and sensitive phenol-sulfuric acid method for the quantitative assay of Epimedium polysaccharides and to determine polysaccharides in Epimedium samples from Chinese markets. Galactose was adopted as the standard monosaccharide, and 486 nm was chosen as the detection wavelength. The optimal conditions for the color reaction were obtained using single factor experiments and an orthogonal test: temperature, 20 degrees C; amount of 5% phenol, 0.3 mL; amount of concentrated sulfuric acid, 3.5 mL; incubation time, 20 min; and addition sequence, phenol-sample-sulfuric acid. The colored sample solution after chromogenic reaction exhibited high stability within 2 h. The calibration curve was linear within the range 5.00-60.00 micro g/mL, and the correlation coefficient of the regression equation was 0.999. LOD and LOQ were 1.65 and 5.00 microg/mL, respectively. Recovery, intraday precision, interday precision, and accuracy were 97.43 to 103.80%, 0.73 to 3.48%, 1.21 to 2.75%, and 97.74 to 101.62%, respectively. Polysaccharides in 26 samples of Epimedium collected from different provinces of China were quantified by the proposed colorimetric method, and a large variation of contents of polysaccharides was observed among these samples.

ChemInform Abstract: Oxidative Substitution Reactions of Organostannyl Compounds with Lead Tetraacetate. A Convenient Route to 5-Alkylidene-2(5H)-furanones.

5-Substituted 2-tributylstannylfurans which were synthesized by the reaction of corresponding 5-substituted 2-lithiofurans with tributylstannyl chloride, were treated with two equimolar amounts of lead tetraacetate at room temperature to give corresponding 5-substituted 5-acetoxy-2(5H)-furanones in good yields. The 5-acetoxy-2(5H)-furanone was heated at 80 °C in acetic acid-acetic anhydride containing a catalytic amount of concentrated sulfuric acid to give 5-alkylidene-2(5H)-furanone in moderate yield.

ChemInform Abstract: Synthesis of 3‐Aryl‐4(3H)‐quinazolinones from Anthranilic Acids and Triethyl Orthoformate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of 3-Aryl-4(3H)-quinazolinones from Anthranilic Acids and Triethyl Orthoformate

A one-step, convenient approach to the synthesis of 3-aryl-4(3H)-quinazolinones by the reaction of anthranilic acid with triethyl orthoformate in the presence of a catalytic amount of concentrated sulfuric acid has been developed. The possible reaction pathway was proposed.

High-Temperature Reaction of Kaolin with Sulfuric Acid

A new procedure is described in which kaolin and a small amount of concentrated sulfuric acid are heated in a furnace at temperatures between 150 and 1000 °C. Parameters studied were reaction temperature and time, proton to alumina molar ratio, calcination temperature and time, and amount of water in the reaction medium. Al yield grew sharply until reaching a maximum at a reaction temperature of 700 °C and decreasing sharply beyond this temperature. Ti reaction yield values were lower than the Al reaction yield, showing a maximum at 200 °C and decreasing steadily as the reaction temperature was increased. Fe reaction yield showed a maximum in the same range of reaction temperature as Al. Previous calcination of kaolin produced only slight increases in reaction yields. Brunauer−Emmett−Teller (BET) surface area tests indicated an increase of the BET surface area for short reaction times, reaching values above 100 m2/g. Products of the reaction were mostly Al2(SO4)3.

Syntheses of 2,6-Anhydro-3-Deoxy-D-Glycero-D-Galacto-Non-2-Enonic Acid (Kdn2En) and Its Hydrogenation Products1

Methyl 4,5,7,8,9-penta-O-acetyl-2,6-anhydro-3-deoxy-D-glycero-D-galacto-enonate (5) was synthesized from KDN methyl ester 2 with a catalytic amount of concentrated sulfuric acid in acetic anhydride, or from 2-chloro-KDN methyl ester 4 with DBU in good yield. Hydrogenation of 4 and 5 with 10% Pd-C gave 2-deoxy-2-Hax-KDN 8 and 2-deoxy-2-Heq-KDN derivative 11 in high yield, respectively. The structures of these compounds were elucidated from the MS, elemental analysis, 1H NMR and 13C NMR data. 1. Presented at the XVIIIth Znbmtional Carbohydrate Symposium, Milan, Italy, July 21-26, 1996.

Oxidative Substitution Reactions of Organostannyl Compounds with Lead Tetraacetate. A Convenient Route to 5-Alkylidene-2(5H)-furanones

Abstract 5-Substituted 2-tributylstannylfurans which were synthesized by the reaction of corresponding 5-substituted 2-lithiofurans with tributylstannyl chloride, were treated with two equimolar amounts of lead tetraacetate at room temperature to give corresponding 5-substituted 5-acetoxy-2(5H)-furanones in good yields. The 5-acetoxy-2(5H)-furanone was heated at 80 °C in acetic acid-acetic anhydride containing a catalytic amount of concentrated sulfuric acid to give 5-alkylidene-2(5H)-furanone in moderate yield.

Easy synthesis of 2,4-dialkyl substituted phenols and anisoles from p-bensoquinone

The reaction of p-benzoquinone ( 1) with several organolithium compounds (methyl-, ethyl-, n-butyl, phenyllithium) leads directly, after acid hydrolysis, to the corresponding 2,4-dialkylphenols 4a-d,resulting from a rearrangement/aromatization process of the corresponding intermediate diols 3. The use of two different alkyllithium reagents leads to the mixed products 4ef. Alternatively, the same results are obtained treating the crude isolated diols 3 with a catalytic amount of concentrated sulfuric acid. Applying this last methodology to the diethers 2, 2,4- dialkylanisoles 8 are obtained. A possible mechanism is proposed.

Acid-catalyzed regioselective acylation of .ALPHA.-silylallylic sulfides and its application to a novel cyclopentannelation and furan annelation.

Introduction of a silyl group at the a-position of allylic sulfides, followed by the aluminum chloride-catalyzed reaction of the resulting α-silylallylic sulfides with acid chlorides resulted in regioselective acylation at the γ-position of the allylic system to give γ-acylated vinylic sulfides, chemically equivalent to 1, 4-dicarbonyl compounds. Heating of the products in refluxing benzene with an equimolar amount of p-toluenesulfonic acid produced 2-cyclopentenone derivatives. Treatment of the acylated products with an equimolar amount of concentrated sulfuric acid gave α-phenylthiofuran derivatives. These procedures provide a novel method for cyclopentannelation and furan annelation.

Cleavages of ethers by chlorotrimethylsilane and acetic anhydride

Methyl and benzyl ethers have been cleaved with a combination of reagents consisting of chlorotrimethylsilane and acetic anhydride containing a catalytic amount of concentrated sulfuric acid. Methylthiomethyl ethers yield the corresponding acetoxymethyl ethers with chlorotrimethylsilane and acetic anhydride. Comparative study with the borontrifluoride etherate and acetic anhydride method of ether cleavage suggests that chlorotrimethylsilane and acetic anhydride (con. H 2SO 4 catalysis) could be a useful alternative to it.

ChemInform Abstract: REACTIONS OF 3‐ACETYLTROPOLONE AND ITS METHYL ETHERS WITH O‐AMINOPHENOL

AbstractDie Tropolonverbindung (Ia) und ihre Methylether (Ib) bzw. (V) reagieren mit o‐Aminophenol (II) in Ethanol zu den Anilinotroponen (III) bzw. (VI) . Diese cyclisieren beim Erhitzen in Essigsäure/Hz S04 zu den Benzoxazinen (IV) bzw. (VII).

Reactions of 3-Acetyltropolone and Its Methyl Ethers with o-Aminophenol

Abstract 3-Acetyltropolone (1) and 2-acetyl-7-methoxytropone (2a) reacted with o-aminophenol in ethanol to afford 2-acetyl-7-(o-hydroxyanilino)tropone (3). The reaction of 3-acetyl-2-methoxytropone (2b) gave 3-acetyl-2-(o-hydroxyanilino)tropone (5). The compounds 3 and 5 were cyclized to 6-acetyl- and 10-acetylcyclohepta[b][1,4]benzoxazines (4 and 6), respectively, by heating their acetic acid solutions in the presence of a trace amount of concentrated sulfuric acid. The compounds 4 and 6 were also obtained directly from 1 (or 2a) and 2b, respectively, by the reaction with o-aminophenol in acetic acid. The compound 5 exists as a tautomeric mixture with 5′.

A reliable synthesis of 1,1‐dimethylpyrazolium 5‐oxides

AbstractReliable syntheses of compounds having the novel 1,1‐dimethylpyrazolium 5‐oxide ring system are reported. The method involves treating the dimethylhydrazone of a β‐ketoester with a small amount of concentrated sulfuric acid or other catalyst and heating under reduced pressure for 1–24 hours. In this manner two new members of the series have been prepared and characterized.

Combination of Sulfuric Acid with Cellulose during the Hydrolysis with a Small Amount of Concentrated Sulfuric Acid

Abstract The combination of sulfuric acid with cellulose occurring during the hydrolysis of cellulose in a small amount of concentrated sulfuric acid has been investigated. The amounts of the soluble and the insoluble glucose polymers produced from cellulose, and the amount of sulfuric acid combined with them, have been estimated. To obtain an effective concentration of sulfuric acid on the cellulose, the concentration of the sulfuric acid must be greater than about 60%. The sulfuric acid concentration in the cellulose-sulfuric acid-water system can not exceed 75%, even when the initial concentration exceeds 85%. The amount of soluble glucose polymer (g.) produced by the action of 100 g. of sulfuric acid is given by 0.0384 exp(0.0958C+4.06r)/[1+0.00132 exp(0.0815C+4.06r)] (C is “initial” concentration of sulfuric acid (%) and r, sulfuric acid-cellulose ratio).