Fuming Sulfuric Acid Research Articles

Insight into Synergistic Brønsted and Lewis Acidic Deep Eutectic Solvent for Beckmann Rearrangement of Cyclohexanone Oxime

ε‐Caprolactam (CPL) is industrially produced by Beckmann rearrangement of cyclohexanone oxime (CHO) under fuming sulfuric acid, resulting in corrosive and environmental issues. Herein, we prepared triethylamine hydrochloride (TEAHC) and ZnCl2 formed deep eutectic solvent (DES) [TEAHC:2ZnCl2] with Brønsted and Lewis acid sites for efficient liquid rearrangement, achieving 100% conversion of CHO and 95.5% yield of CPL at 80 oC for only 1 h. The results show that ZnCl2 in [TEAHC:2ZnCl2] can promote the detachment of proton, which acts as Brønsted acid site combined with another ZnCl2 molecule to synergistically catalyze the reaction. In the Brønsted acid catalyzed process, the nitrogen atom in CHO as reactive site can be readily attacked by the proton to form protonated CHO, which subsequently undergoes rearrangement. By adding ZnCl2 into TEAHC to obtain [TEAHC:2ZnCl2], the formation of ZnCl2‐CHO complex results in a significant reduction in reaction energy barrier through synergistic effect of Brønsted and Lewis acids. Particularly, the fitted reaction kinetics and low activation energy also confirm the rearrangement can occur under low reaction temperature. Thus, the DESs with efficient catalytic performances for ketoxime rearrangements provide a potential method to design active sites for Beckmann rearrangements of oximes under mild reaction conditions.

STUDY OF THE DYNAMICS OF THE PROCESS OF ADSORPTION OF AROMATIC HYDROCARBONS FROM ALKANE

In petrochemistry, normal paraffins are used mainly as raw materials for the production of alkylbenzenes, alkanesulfonates, synthetic fatty acids, secondary alcohols, a-olefins (thermocracking), internal olefins (dehydrogenation). Currently, the market for synthetic detergents (SMC) is one of the most dynamically developing in the world. According to the forecasts of the leading companies producing alkyl benzenes, in the next 10 years, the demand for intermediates for the production of synthetic detergents is expected to grow both in domestic markets and in the global market as a whole. At hydrotreatment units, a wide fraction of n-paraffins (C9–C20) is released from hydrotreated diesel fuel. After that, the C9–C20 fraction is sent to the pre-fractionation unit of the olefin production unit, where the C14–C17 fraction is separated from the wide fraction. This fraction is marketable and requires preliminary purification from aromatic hydrocarbons. Typically, the content of aromatic hydrocarbons in the crude fraction С14+ is from 0.5 to 2.0 wt%. The residual content of aromatic hydrocarbons in the purified fraction should not exceed 0.01% wt. To remove aromatic hydrocarbons, the С14+ fraction is fed to the oleum treatment unit. At the oleum purification unit, post-treatment is carried out using oleum with a concentration of 20–24% wt. After sulfonation, it is necessary to neutralize with caustic soda. Obtaining dearomatized liquid paraffins from diesel fuel using oleum purification has many disadvantages, since working with fuming sulfuric acid requires a high degree of protection of the human body and the strictest observance of safety regulations. Due to the difficulties in disposing of spent sulfuric acid, plant shutdowns and downtime are not uncommon. This article presents the results of a comprehensive study of the adsorption of aromatic hydrocarbons from higher alkanes on zeolite CaX. The main parameters of statics, dynamics and kinetics of adsorption are determined

Silica Gel Supported Chlorosulfonic Acid Catalyzed Beckmann Rearrangement of Cyclohexanone Oxime in Liquid Phase

The Beckmann rearrangement of cyclohexanone oxime in the liquid phase using fuming sulfuric acid as a catalyst is a traditional method, which brings many problems, such as environmental pollution, corrosion of equipment, and difficulty in treating the by-product ammonium sulfate. This paper designs and prepares a silica gel-supported chlorosulfonic acid solid acid catalyst for the liquid-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam. The factors affecting the preparation of the catalyst and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the best catalyst preparation conditions were as follows: mass ratio of silica gel: chlorosulfonic acid of 1:0.2, room temperature, stirring time of 3 hours, solvent dichloromethane, and silica gel mesh size of 100-200 mesh, and best Beckmann rearrangement conditions were as follows: mass ratio of cyclohexanone oxime: catalyst of 1:1, temperature of 140°C, solvent benzonitrile volume of 40 mL/g cyclohexanone oxime, reaction time of 5 hours. Under the above conditions, the conversion of cyclohexanone oxime is 74%, and the selectivity of caprolactam is 40%.

Preparation of carboxylic arylphosphines by hydrolysis of the trifluoromethyl group.

Triarylphosphines substituted with carboxylic and trifluoromethlyl groups have been prepared by the hydrolysis of trifluoromethyl groups using fuming sulfuric acid and boric acid. The reaction has been studied in a set of homoleptic and heteroleptic trifluoromethylated triarylphosphines and offers a new synthetic procedure for the preparation of carboxylic phosphines with a relatively simple methodology. The degree of carboxylation is modulated by the reaction conditions and is sensitive to the substitution pattern of the starting trifluoromethylated phosphines. A pH-dependent procedure based on the amphiphilic character of these phosphines was developed for their separation and purification. The electronic properties of the synthesized carboxylic-trifluoromethylated phosphines have been analyzed by 31P NMR of the corresponding selenide derivatives. Finally, the structures of two palladium complexes, containing the para and meta carboxylic-trifluoromethylated phosphines are also described, showing different dimeric structures.

Saccharification of cellulose using biomass-derived activated carbon-based solid acid catalysts

We prepared activated carbon-based solid acid catalysts derived from coconut shells via chemical activation with phosphoric acid under air and subsequent sulfonation. Their catalytic activities were evaluated in the saccharification of cellulose, and the parameters required for the activation and sulfonation processes were investigated. A catalyst activating temperature of 400 °C was found to be optimal, and the catalyst treated with chlorosulfuric acid exhibited a similar monosaccharide yield to that treated with fuming sulfuric acid. The prepared catalysts were characterized by various analytical techniques. The catalysts exhibited high specific surface areas and micropore volumes but low external specific surface areas. The catalysts had high contents of acidic functional groups when low activating temperatures were employed. For these catalysts, the surface chemical structure had a more dominant effect on the catalytic activity than that caused by the porous texture, while high acidic group contents led to high catalytic activities.

Amphiphilic Biaryl Monophosphine Ligands by Regioselective Sulfonation.

Amphiphilic ligands are valued for their ability to facilitate organometallic reactions in the presence of water. The regioselective sulfonation of a series of commercially available biaryl monophosphines to generate amphiphilic ligands is presented. In this one-step protocol, the temperature and addition of fuming sulfuric acid were carefully controlled to arrive at sulfonated biaryl monophosphine ligands in high yields with >95% regioselectivity without the need for chromatographic purification.

The mixing sensitivity of toluene and ethylbenzene sulfonation using fuming sulfuric acid studied in a rotor-stator spinning disc reactor

The mixing sensitivity was studied for the sulfonation of two alkylbenzenes (ArH’s), toluene and ethylbenzene, by using a rotor-stator spinning disc reactor (SDR). Fuming sulfuric acid (FSA), containing 30 wt. % free sulfur trioxide, was used as a sulfonating agent, which resulted in a fast, exothermic, and viscous liquid-liquid reaction system. Experiments were conducted by varying the SDRs’ rotational speed between 50 and 9000 rpm. In addition, different molar flow ratios (ArH:FSA) were investigated, ranging from 0.8 to 3.2, while operating at a maximum residence time of 7.1 s. The selectivity towards mono-sulfonated products was found to increase significantly at a higher rotational speed. This was observed consistently for both alkylbenzenes and all molar flow ratios, confirming the mixing sensitivity of the two alkylbenzene sulfonation reactions. Furthermore, it was proposed that the mixing sensitivity arises from a competition that exists between the desired and highly reactive primary sulfonation and the much less reactive consecutive sulfonation step to disulfonic acids.

Surface functional group investigation of oxidized, nanodiamond-derived carbon nano-onions

Soluble, oxidized, nanodiamond-derived carbon nano-onions (ON-CNOs) were synthesized by treatment of nanodiamond-derived carbon nano-onions (N-CNOs) with a mixture of fuming sulfuric acid (20 % SO3 in H2SO4, oleum) and conc. nitric acid. ON-CNOs dissolve in polar organic solvents and water due to the presence of acidic functional groups on both the nano-onion surface and adsorbed polycyclic aromatic adsorbents, also called carboxylated carbonaceous fragments (CCFs). The CCFs were removed by either base treatment or thermal desorption and characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The structure and distribution of functional groups on ON-CNOs before and after CCF removal were studied by thermogravimetric analysis, transmission electron microscopy, pH-titrimetry, Raman spectroscopy and Fourier-transform infrared spectroscopy (FT-IR).

Rapid Electrochemical Methane Functionalization Involves Pd-Pd Bonded Intermediates.

High-valent Pd complexes are potent agents for the oxidative functionalization of inert C-H bonds, and it was previously shown that rapid electrocatalytic methane monofunctionalization could be achieved by electro-oxidation of PdII to a critical dinuclear PdIII intermediate in concentrated or fuming sulfuric acid. However, the structure of this highly reactive, unisolable intermediate, as well as the structural basis for its mechanism of electrochemical formation, remained elusive. Herein, we use X-ray absorption and Raman spectroscopies to assemble a structural model of the potent methane-activating intermediate as a PdIII dimer with a Pd-Pd bond and a 5-fold O atom coordination by HxSO4(x-2) ligands at each Pd center. We further use EPR spectroscopy to identify a mixed-valent M-M bonded Pd2II,III species as a key intermediate during the PdII-to-PdIII2 oxidation. Combining EPR and electrochemical data, we quantify the free energy of Pd dimerization as <-4.5 kcal/mol for Pd2II,III and <-9.1 kcal/mol for PdIII2. The structural and thermochemical data suggest that the aggregate effect of metal-metal and axial metal-ligand bond formation drives the critical Pd dimerization reaction in between electrochemical oxidation steps. This work establishes a structural basis for the facile electrochemical oxidation of PdII to a M-M bonded PdIII dimer and provides a foundation for understanding its rapid methane functionalization reactivity.

Effects of sulfonated carbon on the catalytic carbonization and smoke suppression of sawdust board

In this study, sulfonated carbon was obtained by sulfonating pine carbon with fuming sulfuric acid. Characterized by elemental analyzer, fourier transform infrared spectroscopy and X-ray photoelectron spectrometry, it showed that –SO3H was successfully bonded onto the pine carbon’ skeleton in the sulfonation reaction. The effects of pine carbon and sulfonated carbon on the catalytic carbonization and smoke suppression of sawdust boards, and its flame-retardant mechanism were investigated by cone calorimetry, thermogravimetric analysis, scanning electron microscopy, and pyrolysis–gas chromatography–mass spectrometry. And the results demonstrated that sawdust boards containing sulfonated carbon showed superior performance, determined by comparing the peak heat release rate, total heat release, smoke release rate, and total smoke product. Furthermore, with the addition of sulfonated carbon, a carbon layer was formed with a strong oxygen-containing hybrid structure and carbohydrate structure, the pyrolysis of sawdust boards was inhibited, and its char yield was increased.

Sulfonated Polyaniline as Zwitterionic and Conductive Interfaces for Anti-Biofouling on Open Electrode Surfaces in Electrodynamic Systems.

Electrodynamic systems for bioanalytical applications constantly suffer from biofouling due to electrical field-induced nonspecific bioadsorption on electrode surfaces. To minimize this issue, surface modification using anti-biofouling and conductive materials is necessary to not only protect the electrode surface from nonspecific bioadsorption but also maintain desired electrodynamic properties for electrode operation. In this study, we designed and prepared a conductive, zwitterionic, and self-doped sulfonated polyaniline (SPANI) coating on Au electrode surfaces for anti-biofouling applications. The zwitterionic coating was fabricated by electrochemical polymerization of aniline on the Au electrode surface functionalized with cysteamine (HS-CH2CH2-NH2) and then a post-polymerization treatment with fuming sulfuric acid. We found that the SPANI-coated electrodes exhibited an excellent anti-biofouling ability in dielectrophoresis (DEP) capturing-and-releasing processes, with a very low average residual mass rate of 1.44% for the SPANI-5s electrode, whereas electrodes modified with poly(ethylene glycol) (PEG) gave an average residual mass rate of 14.30%. Even under continuous operation for more than 1 h, the SPANI-5s electrode still showed stable anti-biofouling ability for an 11-cycle E. coli capturing-and-releasing DEP process, with the residual mass rate for all 11 cycles being kept at or below 2.18% to give an average residual mass rate of 1.62% with a standard deviation of 0.40%. This study demonstrates that electrodynamic systems with zwitterionic SPANI coated on open electrode surfaces can excellently function with decent conductance and anti-biofouling performance.

Investigation of Synthesis and Dielectric Properties of c-C4F8O With Its CO2/N2 Mixtures as SF6 Alternatives in Gas-Insulated Applications

The usage and emission of SF 6 has been regulated because of high Global Warming Potential (GWP) and long atmospheric lifetime as an insulator in high voltage power transmission equipment. This paper proposes c-C 4 F 8 O and its mixtures as a substitute for SF 6 with low GWP and superior insulation performance. c-C 4 F 8 O is synthesized by 1,4-diiodoperfluorobutane and fuming sulfuric acid with the yield of 55.7% under optimal conditions. The GWP of c-C 4 F 8 O is about one-third that of SF6 and its dielectric strength is about 1.2-1.4 times that of SF 6 . CO 2 and N 2 are mixed with c-C 4 F 8 O to lower liquefaction temperature and GWP. The investigation of breakdown voltage and self-recoverability of gas mixtures has shown that the insulation performance and stability of c-C 4 F 8 O-N 2 is better than c-C 4 F 8 O-CO 2 mixtures. The decomposition process of c-C 4 F 8 O might produce some nonflammable or inexplosive by-products, such as C 2 F 4 , c-C 2 F 4 O, c-C 3 F 6 - and CF 2 O simulated by Gaussian 09. The results indicate that c-C 4 F 8 O and N 2 mixtures have potential to replace SF 6 in electrical equipment.

MODIFICAÇÃO QUÍMICA DO POLIPROPILENO ATRAVÉS DA INTRODUÇÃO DE GRUPOS SULFÔNICOS PARA APLICAÇÃO COMO CATALISADOR EM REAÇÕES DE ESTERIFICAÇÃO

CHEMICAL MODIFICATION OF POLYPROPYLENE THROUGH THE INTRODUCTION OF SULPHONIC GROUPS FOR APPLICATION AS CATALYST IN ESTERIFICATION REACTIONS. In this work, the chemical modification of pristine polypropylene was carried out through sulfonation reactions with concentrated sulfuric acid (PPS1) and fuming sulfuric acid (PPS2), for production of heterogeneous catalysts used in esterification reactions. Fourier transform infrared spectroscopy, elemental analysis, degree of substitution and ion exchange capacity showed that both sulfonation agents were effective to promote the functionalization of polypropylene, with the fuming sulfuric acid capable of promoting a greater chemical modification. The materials catalytic activity in esterification reaction of oleic acid with methanol was evaluated at 100 ºC, methanol: oleic acid molar ratio of 78:1 and with 5 wt% of catalyst (referred to oleic acid weight). It was observed that reaction catalyzed by PPS1 converted 68.02% of oleic acid to methyl oleate in 3 hours of reaction, while PPS2 reached 86.47% conversion in five hours, showing even greater catalytic efficiency than the commercial ion exchange resin, Amberlyst 15. Therefore, the conditions employed for the sulfonation of polypropylene were satisfactory to produce materials with acid characteristics necessary to catalyze the esterification reaction of oleic acid with methanol.

Optimization of Synthesis Conditions of Indigotindisulfonate Lithium Based on Orthogonal Experimental Design Method

With the developing research on anode materials for lithium ion batteries, organic anode materials have gained increasing attention nowadays. Compared with inorganic anode materials, organic anode materials have numerous material options and extensive sources. Moreover, they consume low energy and can enter carbon cycles, which are environment friendly. indigotindisulfonate lithium is characterized with a unique redox reaction and can be used as an anode material. Indigotindisulfonate Lithium can be produced by using indigo as a raw material sulfonated with fuming sulfuric acid, and further reacted with Li2CO3. Regarding this issue, impacts of various factors under different conditions were investigated, and an orthogonal experimental design method was proposed based on optimization conditions. This method was established through T-6 new century ultraviolet spectrophotometer to determine the influence of different conditions, and develop a best combination based on different microwave powers (w), temperatures (°C), and time lengths (min). In this experiment, the maximum absorption peak was determined by scanning wave length, under which the absorbency was identified and the standard curve was established. In order to determine the optimized synthesis condition of indigotindisulfonate lithium, orthogonal experiment design method was applied combining three levels coupled with four factors. From this study, it is concluded that 550w, 3min, 30°C with an indigo-fuming sulfuric acid concentration ratio of 0.02:1 is the best condition to synthesize indigotindisulfonate lithium.

Development of TiO2-Carbon Composite Acid Catalyst for Dehydration of Fructose to 5-Hydroxymethylfurfural

A TiO2-Carbon (TiO2C) composite was prepared using the microwave-assisted method and sulfonated using fuming sulfuric acid to produce a TiO2C solid acid catalyst. The prepared solid acid catalyst was characterised using scanning electron microscopy, Brunauer-Emmett-Teller analysis, Fourier transform infrared spectroscopy, and X-ray diffraction. Crystallinity analysis confirmed that TiO2C has an anatase structure, while analysis of its morphology showed a combination of spheres and particles with a diameter of 50 nm. The TiO2C solid acid catalyst was tested for use in the catalytic dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The effect of reaction time, reaction temperature, catalyst dosage, and solvent were investigated against the 5-HMF yield. The 5-HMF yield was found to be 90% under optimum conditions. The solid acid catalyst is very stable and can be reused for four catalytic cycles. Hence, the material has great potential for use in industrial applications and can be used for the direct conversion of fructose to 5-HMF because of its high activity and high reusability.

Surface and Interfacial Properties of Mono and Didodecyl Diphenyl Ether Disulfonates

Abstract In this paper, monododecyl diphenyl ether disulfonate (C12-MADS) and didodecyl diphenyl ether disulfonate (C12-DADS) are Friedel-Craft reaction product of 1-dodecene and diphenyl oxide using sulfated zirconium as a catalyst, followed by sulfonation with fuming sulfuric acid in 1,2-dichloroethane and neutralization with aqueous sodium hydroxide solution. The relationship between the structures of the surfactants C12-DADS, C12-MADS and linear alkylbenzene sulfonate (C12-LAS) and their surface and interfacial properties was studied by measuring equilibrium surface tensions, dynamic surface tensions and dynamic interfacial tensions (IFT). The results show that the surface and interfacial activity of C12-MADS is better than that of C12-DADS and C12-LAS. The gemini surfactant C12-DADS shows most unfavorable surface and interfacial activity due to the fact that the cross-linked hydrophobic carbon chains decreases the number of exposed methyl in molecule. The dynamic surface tensions results show that the diffusion coefficients values of C12-MADS and C12-DADS are lower than that of C12-LAS, and the adsorption process of surfactants at air/water interface is a mixed diffusion-kinetic adsorption mechanism. The data of dynamic ITF between aqueous surfactants solutions and dodecane indicate that the NaCl and CaCl2 concentration has a weak effect on the stable value of dynamic IFT for C12-DADS. With increasing the NaCl and CaCl2 concentration, the stable values of dynamic ITF for the three surfactants mostly passes through a minimum at an optimum concentration, and the C12-MADS and C12-LAS can reduce the IFT to the 10−2 mN/m order of magnitude.

Initial stage of C60 cation formation in superacids

While superacids are solvents for individualizing carbon nanotubes, the behavior of insulating C60 is different. The final ionization state depends on the superacid used. With chlorosulfonic acid, chlorination is observed while with fuming sulfuric acid, sulfonation has been reported. Both reactions are fast and it is important to characterize the first step to understand the involved reaction mechanisms. Employing Raman spectroscopy and first-principles calculations, we show that C60+ is present with chlorosulfonic acid and surprisingly C602+ ions are predominantly formed during the first seconds after immersion in fuming sulfuric acid.

Acidic activated carbons as catalysts of biodiesel formation

Biodiesel is recognized as one of the most attractive motor vehicle fuels of the future. Therefore, technologies of its production are continuously improved and optimized. The research work reported concerns the process of biodiesel production via transesterification of vegetable oil over modified carbon catalysts obtained from waste material. In order to introduce strongly acidic groups into the carbon structure, the initial sample was treated with concentrated or fuming sulfuric acid, sodium sulfide, 4-aminobenzenesulfonic acid, phosphoric acid, or H2SO4/HNO3 mixture. The carbon materials prepared in this way were thoroughly characterized (elemental and textural analysis, potentiometric titration, TG, NMR, SEM, and XPS measurements) and then used in transesterification of rapeseed oil in the presence of methanol at 130 °C under elevated pressure. The results obtained revealed that not only sulfonic groups are capable of catalyzing transesterification reaction (FAME yield up to 60% for the best SO3H bearing sample), but also materials containing phosphate groups can successfully catalyze this process (FAME yield 43%). It was established that the carboxyl functionalities, which can be generated on the catalyst surface upon its reaction with some modification agents (e.g., H2SO4 or H2SO4/HNO3 mixture), block the active sites of the process and reduce the reaction effectiveness. The stability of the catalysts was rather poor, as they underwent deactivation in subsequent reaction cycles (mainly due to neutralization of —SO3H groups but also by their leaching); however, the catalyst regeneration was possible.

Rupturing Cotton Microfibers into Mesoporous Nitrogen-Doped Carbon Nanosheets as Metal-Free Catalysts for Efficient Oxygen Electroreduction

Mechanical grinding is exploited to effectively rupture biomass cotton microfibers into metal-free, nitrogen-doped carbon nanosheets with a large number of mesoporous textures. Experimentally, raw microfibers of absorbent cotton are presoaked with fuming sulfuric acid to generate plenty of hierarchical pores/cavities, which sufficiently expose the inner parts of cotton microfibers to nitrogen source for efficient incorporation of nitrogen dopants onto carbon skeletons in subsequent thermal annealing process. Mechanical grinding of these thermally annealed carbon microfibers leads to exfoliated nitrogen-doped thin carbon nanosheets with a high surface area of 912.1 m2/g as well as abundant mesopores and a considerable nitrogen content of 8.5 at. %. These characteristics contribute to an excellent electrocatalyst with marked catalytic activities toward oxygen reduction reaction in an alkaline electrolyte solution, including a more positive half-wave potential, much higher diffusion-limiting current, remarka...

Solventless esterification of fatty acids with trimethylolpropane using sulfonated amorphous carbons derived from wood powder

Polyolesters synthesized by an esterification between polyols and fatty acids are value-added oleochemicals widely used as lubricants, cosmetics, and food additives among other applications. However, homogeneous acid catalysts are still preferred in their industrial production, despite their associated energy cost and the environmental issues that they present. In this paper, we describe lignocellulose-derived amorphous carbons with a high loading level of SO3H and their application to the synthesis of polyolesters as a biobased heterogeneous acid catalyst. These sulfonated amorphous carbons could be readily prepared via (i) heat treatment at 400°C for 1h and (ii) sulfonation with chlorosulfuric acid. XRD and BET analyses demonstrated that these carbonaceous materials were not crystalline but were amorphous structures with a low surface area. The attachment of SO3H groups was confirmed by FT-IR and XPS, and the loading level of SO3H was determined by CHNS elemental analysis. Chlorosulfuric acid gave a higher loading level of SO3H than other sulfating agents, such as conc. sulfuric acid and fuming sulfuric acid. The higher SO3H-loaded amorphous carbons exhibited a greater catalytic activity for esterification between trimethylolpropane and fatty acids under solventless conditions. Esterification of oleic acid derived from vegetable oil with trimethylolpropane using this catalyst afforded the desired biolubricant at over 93% yield in 3h. The sulfonated amorphous carbons could be reused three times without any significant loss of catalytic activity.