Showing papers on "Acetic acid published in 2003"
TL;DR: Grape seeds were powdered and the fatty material was extracted in a Soxhlet extractor with petroleum ether (60-80°C) for 6 hours, and the extracts were concentrated under vacuum to obtain crude extracts, which were analyzed by high performance liquid chromatography with UV detection at 280 nm as mentioned in this paper.
639 citations
TL;DR: Acetic acid has been proven to be the sole substance responsible for the increased aerobic stability, and this acid acts as an inhibitor of spoilage organisms, and stability increases exponentially with acetic acid concentration.
Abstract: The effects of various compounds on the aerobic stability of silages were evaluated. It has been observed that inoculation of whole-crop maize with homofermentative lactic acid bacteria leads to silages which have low stability against aerobic deterioration, while inoculation with heterofermentative lactic acid bacteria, such as Lactobacillus brevis or Lactobacillus buchneri, increases stability. Acetic acid has been proven to be the sole substance responsible for the increased aerobic stability, and this acid acts as an inhibitor of spoilage organisms. Therefore, stability increases exponentially with acetic acid concentration. Only butyric acid has a similar effect. Other compounds, like lactic acid, 1,2-propanediol, and 1-propanol, have been shown to have no effect, while fructose and mannitol reduce stability.
397 citations
TL;DR: A direct, selective, oxidative condensation of two methane molecules to acetic acid at 180°C in liquid sulfuric acid is reported, and carbon-13 isotopic labeling studies show that both carbons of acetic Acid originate from methane.
Abstract: Acetic acid is an important petrochemical that is currently produced from methane (or coal) in a three-step process based on carbonylation of methanol. We report a direct, selective, oxidative condensation of two methane molecules to acetic acid at 180°C in liquid sulfuric acid. Carbon-13 isotopic labeling studies show that both carbons of acetic acid originate from methane. The reaction is catalyzed by palladium, and the results are consistent with the reaction occurring by tandem catalysis, involving methane C-H activation to generate Pd-CH 3 species, followed by efficient oxidative carbonylation with methanol, generated in situ from methane, to produce acetic acid.
323 citations
TL;DR: In this article, fed-batch cultivation was studied as an alternative fermentation strategy for DHA production in Crypthecodinium cohnii, and the results showed that a feed consisting of acetic acid (50% w/w) resulted in a higher overall volumetric productivity of DHA (r(DHA)) than a feed of 50% (w/v) glucose (38 and 14 mg/L/h, respectively).
Abstract: The heterotrophic marine alga Crypthecodinium cohnii is known to produce docosahexaenoic acid (DHA), a polyunsaturated fatty acid with food and pharmaceutical applications, during batch cultivation on complex media containing sea salt, yeast extract, and glucose. In the present study, fed-batch cultivation was studied as an alternative fermentation strategy for DHA production. Glucose and acetic acid were compared as carbon sources. For both substrates, the feed rate was adapted to the maximum specific consumption rate of C. cohnii. In glucose-grown cultures, this was done by maintaining a significant glucose concentration (between 5 and 20 g/L) throughout fermentation. In acetic acid-grown cultures, the medium feed was automatically controlled via the culture pH. A feed consisting of acetic acid (50% w/w) resulted in a higher overall volumetric productivity of DHA (r(DHA)) than a feed consisting of 50% (w/v) glucose (38 and 14 mg/L/h, respectively). The r(DHA) was further increased to 48 mg/L/h using a feed consisting of pure acetic acid. The latter fermentation strategy resulted in final concentrations of 109 g/L dry biomass, 61 g/L lipid, and 19 g/L DHA. These are the highest biomass, lipid, and DHA concentrations reported to date for a heterotrophic alga. Vigorous mixing was required to sustain aerobic conditions during high-cell-density cultivation. This was complicated by culture viscosity, which resulted from the production of viscous extracellular polysaccharides. These may present a problem for large-scale industrial production of DHA. Addition of a commercial polysaccharide-hydrolase preparation could decrease the viscosity of the culture and the required stirring.
261 citations
TL;DR: Two non-Saccharomyces wine yeast strains, Hanseniaspora guilliermondii 11104 and Pichia anomala 10590, selected as good producers of acetate esters when grown on synthetic microbiological medium, have been tested in wine fermentations as mixed cultures together with Saccharomycing cerevisiae.
239 citations
TL;DR: In this paper, the esterification of isoamyl alcohol and acetic acid in gaseous phase was studied using tungstophosphoric acid (TPA) supported on different carriers, silica materials, carbon and alumina.
Abstract: New supported Keggin heteropolyacid (HPA) catalysts were prepared in order to make a contribution to the field of catalyzed acid reactions by means of ecofriendly technologies. The esterification of isoamyl alcohol and acetic acid in gaseous phase was studied using tungstophosphoric acid (TPA) supported on different carriers, silica materials, carbon and alumina. These catalysts were characterized by FT-IR, DRS, TPR and their acidity was evaluated through the isopropanol dehydration test reaction. The higher acidic catalysts prepared with silica materials led to the greatest activities due to the higher proton availability which, in turn, was related to the lower interaction and dispersion of the active species. In order to perform this acid reaction in heterogeneous liquid phase and to avoid the tungstophosphoric or molybdophosphoric acid (MPA) solubilization during reaction, functionalized silica and SiMCM-41, and polyvinyl alcohol hydrogel–polyethylenglycol (PVA-PVG) beads were used as new supports. The physical–chemical characterization of the supported catalysts by FT-IR, XRD, 31 P MAS NMR and TG-DTA showed mainly undegraded primary Keggin structure. The solids exhibited low or negligible solubilization and their acidity, measured by potentiometric titration with n-butylamine, was high. The SiMCM-41 and polymeric bead-supported catalysts lead to obtain attractive activity in the isoamyl acetate synthesis through esterification reaction.
232 citations
TL;DR: In this article, Escherichia coli W3110 was genetically engineered for acetate production by using an approach that combines attributes of fermentative and oxidative metabolism (rapid growth, external electron acceptor) into a single biocatalyst.
Abstract: Microbial processes for commodity chemicals have focused on reduced products and anaerobic conditions where substrate loss to cell mass and CO2 are minimal and product yields are high. To facilitate expansion into more oxidized chemicals, Escherichia coli W3110 was genetically engineered for acetate production by using an approach that combines attributes of fermentative and oxidative metabolism (rapid growth, external electron acceptor) into a single biocatalyst. The resulting strain (TC36) converted 333 mM glucose into 572 mM acetate, a product of equivalent oxidation state, in 18 h. With excess glucose, a maximum of 878 mM acetate was produced. Strain TC36 was constructed by sequentially assembling deletions that inactivated oxidative phosphorylation (ΔatpFH), disrupted the cyclic function of the tricarboxylic acid pathway (ΔsucA), and eliminated native fermentation pathways (ΔfocA-pflB ΔfrdBC ΔldhA ΔadhE). These mutations minimized the loss of substrate carbon and the oxygen requirement for redox balance. Although TC36 produces only four ATPs per glucose, this strain grows well in mineral salts medium and has no auxotrophic requirement. Glycolytic flux in TC36 (0.3 μmol⋅min−1⋅mg−1 protein) was twice that of the parent. Higher flux was attributed to a deletion of membrane-coupling subunits in (F1F0)H+-ATP synthase that inactivated ATP synthesis while retaining cytoplasmic F1-ATPase activity. The effectiveness of this deletion in stimulating flux provides further evidence for the importance of ATP supply and demand in the regulation of central metabolism. Derivatives of TC36 may prove useful for the commercial production of a variety of commodity chemicals.
206 citations
TL;DR: The oxidative coupling reaction of benzenes with alkenes was successfully achieved by the Pd(OAc)(2)/molybdovanadophosphoric acid (HPMoV)/O(2) system.
Abstract: The oxidative coupling reaction of benzenes with alkenes was successfully achieved by the Pd(OAc)(2)/molybdovanadophosphoric acid (HPMoV)/O(2) system. For example, the reaction of benzene with ethyl acrylate by the above catalytic system in acetic acid afforded ethyl cinnamate as a major product in satisfactory yield.
204 citations
TL;DR: In this paper, the photocatalytic reduction of selenium anions, selenate (Se(VI)) and selenite (Se-IV) to elemental seenium (Se) over UV-illuminated TiO2 was performed using formic acid, acetic acid, methanol, ethanol, sucrose and salicylic acid as the organic hole scavengers.
Abstract: The photocatalytic reduction of selenium anions, selenate (Se(VI)) and selenite (Se(IV)) to elemental selenium (Se) over UV-illuminated TiO2 was performed using formic acid, acetic acid, methanol, ethanol, sucrose and salicylic acid as the organic hole scavengers. Photoreduction was only observed in the presence of formic acid, methanol or ethanol. The fastest rate of Se ions photoreduction was observed in the presence of formic acid followed by methanol and ethanol. This was attributed to the ability of formate ions to adsorb onto TiO2 in the presence of Se ions, its fast mineralisation rate and its ability to form reducing radicals quickly. For the methanol and ethanol systems, these two organic compounds could not compete with Se ions for the TiO2 surface and were not easily mineralised. The photocatalytic reduction of Se ions observed in the presence of these two organic compounds was attributed to their ability to form reducing radicals. When formic acid was used, optimum pH values at pH 3.5 and 4.0 was encountered for the Se(VI) and Se(IV) photoreduction, respectively. When methanol and ethanol were used as the hole scavenger in the pH range of 2.2–4.0, the greatest extent of Se ions photoreduction was encountered at pH 2.2. This suggests the different role of formic acid and methanol/ethanol in the photoreduction of Se ions.
200 citations
Patent•
18 Nov 2003TL;DR: In this article, a process for the production of acetic acid by carbonylation of methanol, and reactive derivatives thereof, in a reaction mixture using a rhodium-based catalyst in low water conditions is described.
Abstract: The invention relates to a process for the production of acetic acid by carbonylation of methanol, and reactive derivatives thereof, in a reaction mixture using a rhodium-based catalyst in low water conditions. The process is used to achieve reaction rates of at least 15 g mol/l/hr. The high rate reactions proceed at water concentrations of less than 2.0 wt. %. Under certain conditions, the water concentration in the reaction mixture of the process is maintained at a desired concentration by at least one process step including adding a compound such as methyl acetate, dimethyl ether, acetic anhydride, or mixtures of these compounds to the reaction system. The process step of adding the components to the reaction mixture may be combined with other process steps for controlling water concentrations in reaction mixtures for the carbonylation of methanol.
198 citations
TL;DR: In this article, the use of phosphine ligands for the rhodium-catalyzed carbonylation of methanol has been studied and a review of the recent research results and implications in developing new multifunctional ligands is presented.
Patent•
07 Jan 2003TL;DR: In this paper, a cost-saving scheme to bypass the methyl acetate processing at production or plant facilities and utilize the methylacetate in an integrated methanol carbonylation unit is discussed.
Abstract: The present invention is directed to using methyl acetate from a vinyl acetate -based or a vinyl-or ethylene-alcohol based polymer or copolymer process directly for use in a methanol carbonylation production process to produce acetic acid, acetic anhydride, or a coproduction of each. Methyl acetate is a by-product of commercial polyvinyl-alcohol or alkene vinyl alcohol copolymer-based processes. Generally, this material is processed to recover methanol and acetic acid. Discussed herein is a cost-saving scheme to by-pass the methyl acetate processing at production or plant facilities and utilize the methyl acetate in an integrated methanol carbonylation unit. The scheme discussed eliminates an expensive hydrolysis step often associated with the polymer process.
TL;DR: In this paper, the Eley-Rideal model has been used for the esterification of acetic acid with isobutanol in the presence of catalysts.
Abstract: Kinetic data on the esterification of acetic acid with isobutanol have been obtained from both the uncatalyzed and heterogeneously catalyzed reactions using a stirred batch reactor in dioxane. The equilibrium constant, which is independent of temperature ranging from 318 to 368 K, was found to be 4. The uncatalyzed reaction was proved to be second-order reversible. In the presence of the catalyst, on the other hand, the reaction has been found to occur between an adsorbed alcohol molecule and a molecule of acid in the bulk fluid (Eley–Rideal model). It has also been observed that the initial reaction rate decreases with alcohol and water concentrations and it linearly increases with that of acid. The temperature dependency of the constants appearing in the rate expression were also determined.
TL;DR: In this paper, in situ Fourier transform infrared (FTIR) spectroscopy was used to study the adsorptive and catalytic interactions of gas phase acetic acid with surfaces of alumina, titania and ceria on heating from room temperature up to 400°C.
Abstract: Adsorptive and catalytic interactions of gas phase acetic acid with surfaces of alumina, titania and ceria were observed by in situ Fourier-transform infrared (FTIR) spectroscopy on heating from room temperature up to 400 °C. The results revealed that, on alumina the acid was irreversibly, non-dissociatively adsorbed in the form of hydrogen-bonded molecules, and dissociatively in the form of bidentate bound acetate species over the full range of temperature scanned. In the gas phase, no chemical change was observed. On titania, the gas phase remained unchanged on heating up to 300 °C, but at 400 °C the acetic acid was largely converted into acetone (as well as CO 2 and H 2 O) and minor products of isobutene and methane. Similar changes to the gas phase were observed on ceria, however, at 300 °C. The acetic acid conversion on ceria was almost complete. The appearance of acetone molecules in the gas phase was pertained by the emergence of IR absorptions implying the formation on the surface of unsaturated carbonyl species. Thus, the formation of these surface species, together with isobutene and CH 4 molecules in the gas phase, was considered consequent to the occurrence of further surface reactions of acetone molecules. Observance of structural and chemical stability of the surface and bulk of TiO 2 and CeO 2 throughout the reaction was taken to emphasize the catalytic nature of the acetic acid conversion into acetone in the gas phase, a process that is evidently more simple and economic than the conventional pyrolytic synthesis of acetone from metal acetate compounds in the solid state. The catalytic sites were suggested to be Lewis acid–base pair sites, with the Lewis acid sites (Ti 4+ or Ce 4+ ) being reducible. Mechanistic pathways were proposed for the observed adsorptive and catalytic interactions of acetic acid molecules on the test oxides.
TL;DR: In this article, a simple effective synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, using boric acid as catalyst, from aromatic aldehydes, 1,3-dicarbonyl compounds and urea in glacial acetic acid is described.
TL;DR: In this paper, the xylose production by hydrolysis of sorghum straw with hydrochloric acid at 122°C was studied and several concentrations of HCl (2-6%) and reaction time (0-300min) were evaluated.
TL;DR: In this paper, the authors investigated the performance of methanol conversion in the presence of carbon dioxide under the conditions of dielectric-barrier discharge plasmas, where the grounded electrode is covered by the dielectrics material (quartz).
TL;DR: Strikeromyxobacter dehalogenans strain 2CP-C is a promising model organism for the study of the interaction of these potentially competing processes in contaminated environments.
Abstract: Anaeromyxobacter dehalogenans strain 2CP-C has been shown to grow by coupling the oxidation of acetate to the reduction of ortho-substituted halophenols, oxygen, nitrate, nitrite, or fumarate. In this study, strain 2CP-C was also found to grow by coupling Fe(III) reduction to the oxidation of acetate, making it one of the few isolates capable of growth by both metal reduction and chlororespiration. Doubling times for growth of 9.2 and 10.2 h were determined for Fe(III) and 2-chlorophenol reduction, respectively. These were determined by using the rate of [ 14 C]acetate uptake into biomass. Fe(III) compounds used by strain 2CP-C include ferric citrate, ferric pyrophosphate, and amorphous ferric oxyhydroxide. The addition of the humic acid analog anthraquinone 2,6-disulfonate (AQDS) increased the reduction rate of amorphous ferric iron oxide, suggesting AQDS was used as an electron shuttle by strain 2CP-C. The addition of chloramphenicol to fumarate-grown cells did not inhibit Fe(III) reduction, indicating that the latter activity is constitutive. In contrast, the addition of chloramphenicol inhibited dechlorination activity, indicating that chlororespiration is inducible. The presence of insoluble Fe(III) oxyhydroxide did not significantly affect dechlorination, whereas the presence of soluble ferric pyrophosphate inhibited dechlorination. With its ability to respire chlorinated organic compounds and metals such as Fe(III), strain 2CP-C is a promising model organism for the study of the interaction of these potentially competing processes in contaminated environments.
TL;DR: The data suggest that naturally occurring mutations can alter the ability of S. aureus to catabolize acetate, a surprising discovery, as TCA cycle function has been demonstrated to be involved in the virulence, survival, and persistence of several pathogenic organisms.
Abstract: Recently, we reported that the prototypical Staphylococcus aureus strain RN6390 (a derivative of NCTC 8325) had significantly reduced aconitase activity relative to a diverse group of S. aureus isolates, leading to the hypothesis that strain RN6390 has impaired tricarboxylic acid (TCA) cycle-mediated acetate catabolism. Analysis of the culture supernatant from RN6390 confirmed that acetate was incompletely catabolized, suggesting that the ability to catabolize acetate can be lost by S. aureus. To test this hypothesis, we examined the carbon catabolism of the S. aureus strains whose genome sequences are publicly available. All strains catabolized glucose and excreted acetate into the culture medium. However, strains NCTC 8325 and N315 failed to catabolize acetate during the postexponential growth phase, resulting in significantly lower growth yields relative to strains that catabolized acetate. Strains NCTC 8325 and RN6390 contained an 11-bp deletion in rsbU, the gene encoding a positive regulator of the alternative sigma factor σB encoded by sigB. An isogenic derivative strain of RN6390 containing the wild-type rsbU gene had significantly increased acetate catabolism, demonstrating that σB is required for acetate catabolism. Taken together, the data suggest that naturally occurring mutations can alter the ability of S. aureus to catabolize acetate, a surprising discovery, as TCA cycle function has been demonstrated to be involved in the virulence, survival, and persistence of several pathogenic organisms. Additionally, these mutations decrease the fitness of S. aureus by reducing the number of progeny placed into subsequent generations, suggesting that in certain situations a decreased growth yield is advantageous.
TL;DR: In this paper, the thermal degradation of pure cellulose acetate and cellulose acacetate with mono ammonium phosphate and boric acid as physically incorporated additives was investigated using thermogravimetry analysis, thermal volatilization analysis and characterization of the degradation products by infrared spectroscopy.
TL;DR: The two-phase process clearly showed a better performance in management of cheese-whey wastewater over the single-phase anaerobic system, and also showed a higher rate in combined productions of acetic and butyric acids than that at optimum conditions forbutyric acid production.
TL;DR: In this paper, the relationship between the state of Ru on CeO 2 and catalytic activity in the wet oxidation of acetic acid was investigated for Ru/CeO 2 catalysts prepared by different methods.
Abstract: The relationship between the state of Ru on CeO 2 and catalytic activity in the wet oxidation of acetic acid was investigated for Ru/CeO 2 catalysts prepared by different methods. The temperature programmed reduction (TPR) experiments of Ru/CeO 2 showed that the oxygen species of RuO 2 was reduced at different temperatures depending upon the methods of preparation. Ru species reduced at low temperatures could not be observed by TEM and XRD. It was concluded that RuOCe bonds in the well-dispersed Ru species are highly fragile and its mobile oxygen is the active species in the wet oxidation.
TL;DR: The gene expression changes after adaptation to acetate or propionate were not caused solely by uncoupling or osmotic effects but represented specific characteristics of the long-term response of E. coli to either compound.
Abstract: In its natural environment, Escherichia coli is exposed to short-chain fatty acids, such as acetic acid or propionic acid, which can be utilized as carbon sources but which inhibit growth at higher concentrations. DNA microarray experiments revealed expression changes during exponential growth on complex medium due to the presence of sodium acetate or sodium propionate at a neutral external pH. The adaptive responses to acetate and propionate were similar and involved genes in three categories. First, the RNA levels for chemotaxis and flagellum genes increased. Accordingly, the expression of chromosomal fliC'-'lacZ and flhDC'-'lacZ fusions and swimming motility increased after adaptation to acetate or propionate. Second, the expression of many genes that are involved in the uptake and utilization of carbon sources decreased, indicating some kind of catabolite repression by acetate and propionate. Third, the expression of some genes of the general stress response increased, but the increases were more pronounced after short-term exposure for this response than for the adaptive response. Adaptation to propionate but not to acetate involved increased expression of threonine and isoleucine biosynthetic genes. The gene expression changes after adaptation to acetate or propionate were not caused solely by uncoupling or osmotic effects but represented specific characteristics of the long-term response of E. coli to either compound.
TL;DR: In this article, the direct synthesis of acetic acid from carbon dioxide and carbon dioxide was investigated and the results showed the formation of an adsorbed acetate on both a 5% Pd/carbon and 5% Pt/alumina catalyst when the catalyst was exposed to a mixture of carbon dioxide at a temperature of about 400°C.
TL;DR: In this paper, a new source of acetic acid toward the high-mass hot molecular core source G34.2 was detected using a temperature range between 70 and 185 K. This gave a relative CH3COOH/HCOOCH3 abundance ratio of ~3.3+0.2.
Abstract: We have surveyed 12 Galactic hot molecular cores for interstellar acetic acid (CH3COOH). This is the most extensive search for acetic acid to date. We have detected a new source of acetic acid toward the high-mass hot molecular core source G34.3+0.2. Using a temperature range between 70 and 185 K, we find a CH3COOH column density range of (0.77-1.64) ? 1015 cm-2 toward G34.3+0.2. This gives a relative CH3COOH/HCOOCH3 abundance ratio of ~3.3 ? 10-2, which is comparable to the abundance ratio of (3-6) ? 10-2 found toward Sgr B2(N-LMH) and W51e2 by Remijan and colleagues. All currently known acetic acid sources are within 7 kpc of the Galactic center. Furthermore, our survey suggests that hot molecular cores that have a mass range between 200 and 2000 M? and do not show a distinct differentiation between O and N chemistry may be the best places to search for acetic acid and the structurally similar biologically important molecule glycine.
TL;DR: A comparison with 10 usual antioxidants indicated that oligomers with three or more (epi)catechin units are by far the most efficient, even expressed in relative monomeric efficiency units.
Abstract: Of three different solvents (acetone, ethanol, and methanol) mixed with water and acetic acid, the acetone/water/acetic acid mixture (70:28:2, v/v) proved to be best for extracting dark-chocolate procyanidins. High-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-MS-ESI) was further used to identify oligomers found in the extract. After HPLC fraction collection, the reduction power of flavanoid fractions was measured in the AAPH [2,2'-azobis(2-amidinopropane)dihydrochloride] assay, where oxidation of linoleic acid is induced in an aqueous dispersion. Even expressed in relative monomeric efficiency units, the oxidation-inhibiting power of polymerized oligomers is much stronger than that of monomers. A comparison with 10 usual antioxidants indicated that oligomers with three or more (epi)catechin units are by far the most efficient.
TL;DR: In this article, the formation of corrosion products and the corrosion sensitivity of copper and lead were studied under experimental conditions in which formaldehyde (methanal), formic(methanoic) and acetic acid concentration, relative humidity (RH) and duration of exposure were varied.
Abstract: The formation of corrosion products and the corrosion sensitivity of copper and lead were studied under experimental conditions in which formaldehyde (methanal), formic (methanoic) and acetic (ethanoic) acid concentration, relative humidity (RH) and duration of exposure were varied. Levels offormic acid above 0.4 parts per million based on volume (ppmv) affect the appearance of copper at 75% RH, and at levels above 4 ppmv the copper gains weight at both 54 and 75% RH. The main compound found on copper was cuprite, copper(I) oxide. Lead has a higher sensitivity to formic acid: at levels as low as 0.04 ppmv lead becomes darker, and at above O.1 ppmv weight gains were measurable at both 54 and 75% RH. In the presence of different levels of mixed carbonyl vapours at 75% RH, copper reacted mainly with formic acid. On the other hand, the reaction of lead was more complex. Acetic acid tends to form a thick white layer (composed mainly of plumbonacrite and possibly lead acetate compounds) on the lead surf...
TL;DR: In this article, sugar cane bagasse was hydrolyzed under different concentrations of hydrochloric acid (2-6), reaction times (0-300 min), and temperatures (100-128°C).
Abstract: Sugar cane bagasse was hydrolyzed under different concentrations of hydrochloric acid (2–6%), reaction times (0–300 min), and temperatures (100–128°C). Sugars obtained (xylose, glucose, arabinose, and glucose) and deg-radation products (furfural and acetic acid) were determined. Based on the Saeman model and the two-fraction model, kinetic parameters for predicting these compounds in the hydrolysates were developed. The influence of temperature was studied using the Arrhenius equation. The optimal conditions selected were 128°C, 2% HCl, and 51.1 min. Using these conditions, 22.6g xylose/L, 3.31 garabinose/L, 3.77 g glucose/L, 3.59 g acetic acid/L, and 1.54 g furfural/L were obtained.
TL;DR: A simple procedure for the preparation of amorphous silica containing thiol groups which quantitatively affords sulfonic acid groups has been developed, resulting in site densities and activity for the esterification of acetic acid with methanol greater than a commercial Nafion silica composite.