One-step synthesis of carbon functionalized with sulfonic acid groups using hydrothermal carbonization

Carbon functionalized with sulfonic acid groups has been synthesized using the one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid aqueous solution at 180 °C for 4 h. The carbon exhibited high acidity and comparable activities to sulfuric acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for environment-friendly processes. The copolymerization method provides an efficient procedure for the synthesis of various functionalized carbons by one-step hydrothermal carbonization.     

Valorization of galactose into levulinic acid via acid catalysis

We applied methanesulfonic acid (MSA) as a green catalyst to produce levulinic acid (LA) from monomeric sugars. To optimize reaction factors and assess the effect of reciprocal interactions, a statistical experimental design was applied. Optimized result of 40.7% LA yield was obtained under the following conditions: 60 g/L galactose, 0.4M MSA at 188 °C for 26.7 min. On the other hand, 66.1% LA yield was achieved under 60 g/L fructose and 0.4M MSA at 188 °C for 36 min conditions. For the effect of combined severity factor on the LA yield from galactose, the LA yield showed a peaked pattern, which was linearly increased until a CSF 3.2 and then diminished with a high CSF. Moreover, it was closely fitted to a non-linear Gaussian peak pattern with a high regression value of 0.989. These results suggest that MSA and galactose, derived from marine red macro-algae, can potentially be applied for the conversion into platform chemicals.     

Methanesulfonic acid catalyzed addition of aromatic compounds to oleic acid

The addition of aromatic compounds to the double bond of oleic acid has been studied using methanesulfonic acid as the acid catalyst. When alkylbenzenes were reacted with oleic acid, the yield of addition product was dependent on the electron density of the benzene ring. For example, a 76% yield of addition product was obtained with toluene, whereas for benzene and monochlorobenzene, the yields of addition products were 60% and 2%. The addition of phenol to oleic acid gave 2 types of addition products, an ethertype (phenylether) product and a ring-substituted product (hydroxy-phenylstearic acid). The ratio of the 2 products varied with the reaction temperature and the amount of methanesulfonic acid. The ring-substituted product predominated at a high molar ratio of methanesulfonic acid to oleic acid (6:1) and elevated reaction temperature (50 C). Thiophenol was found to add to oleic acid to form a thioether derivative exclusively. Agricultural Research Service, US Department of Agriculture. Reference to a brand or firm name does not constitute endorsement by the USDA over others of a similar nature that are not mentioned.     

Methanesulfonic acid catalyzed additions to oleic acid and cyclohexene. III. Addition of acids and substituted phenols

Benzoic acid adds to oleic acid in methanesulfonic acid as catalyst-solvent to form an addition product in 30% yield. Saponification studies on the product reveal that the addition is made via the carboxyl group and no rearrangement of the initial product takes place. A number of substituted benzoic acids were also tried but the yield of addition product was nil. Data are included for the experiments with a number of phenols not previously reported. These include: o-chlorophenol,2,6-di-tert.-butylphenol, 2,4,6-trichlorophenol, resorcinol, 5-n-pentadecylresorcinol, hydroquinone, methyl salicylate, and 3-n-pentadecylphenol. Good yields of addition products of cyclohexene are obtained using methanesulfonic acid as catalyst-solvent and the same nucleophiles employed previously. Presented at the AOCS meeting in Toronto, Canada, 1962. A laboratory of the E. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Preparation and performance evaluation of a lignin-based solid acid from acid hydrolysis lignin

A new lignin-based solid acid was prepared by sulfonation of sulfuric acid lignin (a typical acid hydrolysis lignin). The solid acid has been characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), mercury injection apparatus, and elemental analysis. Structural analyses suggest that the material with high thermal and hydrothermal stability is composed of amorphous phenylpropane-based polymers with sulfonic acid groups. Catalytic tests in esterification of acetic acid with ethanol and hydration of 2, 3-dimethyl-2-butene show that the lignin-based solid acid exhibits high catalytic activities in acid-catalyzed reactions, which can be used as a replacement for the conventional solid acid catalysts. This may be attributed to good accessibility of reactants to sulfonic acid groups in the material structure.     

Grafting of poly(3‐hydroxyalkanoate) and linoleic acid onto chitosan

Poly(3‐hydroxy octanoate) (PHO), poly(3‐hydroxy butyrate‐co‐3‐hydroxyvalerate) (PHBV), and linoleic acid were grafted onto chitosan via condensation reactions between carboxylic acids and amine groups. Unreacted PHAs and linoleic acid were eliminated via chloroform extraction and for elimination of unreacted chitosan were used 2 wt % of HOAc solution. The pure chitosan graft copolymers were isolated and then characterized by FTIR, ¹³C‐NMR (in solid state), DSC, and TGA. Microbial polyester percentage grafted onto chitosan backbone was varying from 7 to 52 wt % as a function of molecular weight of PHAs, namely as a function of steric effect. Solubility tests were also performed. Graft copolymers were soluble, partially soluble or insoluble in 2 wt % of HOAc depending on the amount of free primary amine groups on chitosan backbone or degree of grafting percent. Thermal analysis of PHO‐g‐Chitosan graft copolymers indicated that the plastizer effect of PHO by means that they showed melting transitions T_ms at 80, 100, and 113°C or a broad T_ms between 60.5–124.5°C and 75–125°C while pure chitosan showed a sharp T_m at 123°C. In comparison of the solubility and thermal properties of graft copolymers, linoleic acid derivatives of chitosan were used. Thus, the grafting of poly(3‐hydroxyalkanoate) and linoleic acid onto chitosan decrease the thermal stability of chitosan backbone. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:81–89, 2007     

Further studies on methanesulfonic acid catalyzed additions to oleic acid

Infrared study of the products of the addition of m-cresol to oleic acid in methanesulfonic acid, revealed the presence of both the m-creasoxy and hydroxytolyl substituted stearic acids. By employing a modified extractive procedure to recover the products of the reaction, followed by chromatography on a Florisil column, a separation of the two types of addition products was effected. The methanesulfonic acid catalyzed addition reaction was extended to include aryl thiols. Among the sulfur analogues of the previously used phenols that were added are: benzenethiol, p-t-butyl-benzenthiol, 2-naphthalenethiol, o-, m-, and p-toluenethiol. The yields of addition products (which were unobtainable in sulfuric acid media) ranged from 37–70%. In contrast with the results obtained when phenolic nuleophiles were employed no evidence for the formation of rearranged addition products has been found. Thioethers were the only products identified. Presented at the A.O.C.S. meeting, Chicago, 1961. Eastern Utilization Research and Development Division, U.S.D.A.     

Chemical functionalization of chitosan biopolymer and chitosan-magnetite nanocomposite with sulfonic acid for acid-catalyzed reactions

Chemical functionalization of chitosan biopolymer and chitosan-magnetite nanocomposite was performed with sulfonic acid functional groups to achieve new solid acid materials. The sulfonic acid functional groups were created through the ring opening nucleophilic reaction of amine groups of chitosan with 1,4-butane sultone. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopies (XPS) verified the successful sulfonic acid functionalization of chitosan. The obtained sulfonic acid functionalized chitosan-magnetite nanocomposite showed superparamagnetic properties according to the vibrating sample magnetometry analysis and exhibited magnetic separation feature from dispersed mixtures. Nitrogen adsorption-desorption analysis indicated the increase in surface area after formation of chitosan-magnetite nanocomposite and functionalization with sulfonic acid. Both of the prepared solid acids exhibited high catalytic activities in the acid-catalyzed acetic acid esterification with n-butanol and benzaldehyde acetalization with ethylene glycol as model reactions. Furthermore, they can be reused several times without considerable loss of their activities.     

Molecular stability of chitosan in acid solutions stored at various conditions

The stability of chitosan with a degree of deacetylation (DD) of 88 and 81% was investigated in solution during storage for 60 days at various temperatures (60, 28, and 5°C) and acid concentrations (0.8M, 0.2M, and 0.1M). The first‐order rate constant of chain hydrolysis of 88%DD chitosan at 60°C was about 1.4 times higher than that of the 81%DD sample. At 28°C, the rates of hydrolysis for both chitosan samples were four to five times lower than those at 60°C and are similar. At 5°C, chain degradation was not significant. Although acetic acid caused significantly higher (P ≤ 0.05) chain scission than formic acid, no significant difference of rate change was observed among three different acid concentrations. Reprecipitation of dissolved chitosan was applied for its purification and to transfer dissolved chitosan to the solvent used to measure its molecular weight. Reprecipitation resulted in slightly lower molecular weight (P ≤ 0.05) for both 88%DD and 81%DD samples. The molecular weight of chitosan before and after reprecipitation had good linear relationship (r² > 0.9). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

In situ chemically crosslinked chitosan membrane by adipic acid

Adipic acid, which is nontoxic, was used to dissolve chitosan. The chitosan/adipic acid solution was used to prepare chitosan membrane. After being heated at 80–100°C, the membrane was in situ chemically crosslinked by adipic acid, as verified by Fourier transform infrared and wide‐angle X‐ray diffractometer analysis. The crosslinked membrane did not collapse even without treatment in alkaline solution. In addition, the in situ crosslinking reaction was studied. The crosslinking degree (CLD) was quantitatively calculated based on the mass of water produced. The results showed that CLD was positively related to both heating temperature and time. Results of kinetic of crosslinking reaction suggested that the amidation was in agreement with the first‐order rate equation and that the temperature effect could be described with the Arrhenius equation. The results of weight loss of chitosan membrane in phosphate‐buffered solution (pH = 7.4) indicated that the best water resistance of chitosan membrane was obtained at 90°C. In brief, a straightforward, nontoxic, environment‐friendly, and economical chemically crosslinking approach has been developed for chitosan materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Studies on the cure kinetics of chitosan‐glutamic acid using glutaraldehyde as crosslinker through differential scanning calorimeter

The curing of chitosan‐glutamic acid with glutaraldehyde as curing agent in the presence of chlorpheniramine maleate (CPM) is carried out with the help of differential scanning calorimeter (DSC). The effect of concentration of chitosan and percentage of crosslinker on the curing of chitosan‐glutamic acid is studied at a heating rate of 5°C/min. Cure kinetics are measured by the DSC using scans from 25 to 220°C at four different heating rates (3, 5, 7, and 10°C/min) and it is observed that the crosslinking of chitosan‐glutamic acid is an exothermic process which results in a positive peak in the DSC thermograms. The activation energy (E_α) is determined by Flynn, Wall, and Ozawa method for curing of the samples. An increase in activation energy (E_α) is observed with the extent of conversion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Liquid‐crystalline behavior of chitosan in malic acid

This report describes how the degree of deacetylation and molecular weight of chitosan and the concentrations of sodium chloride and malic acid affect the formation of lyotropic chitosan liquid crystals. Chitosan samples of various degrees of deacetylation were prepared from β‐chitin that was isolated from squid pens. They were degraded by ultrasonic irradiation to various molecular weights. The critical concentrations forming chitosan liquid crystals were determined with a polarized microscope. A chitosan sample with a degree of deacetylation of 67.2–83.6% formed cholesteric lyotropic liquid crystals when it was dissolved in 0.37–2.59M malic acid. The critical concentrations increased with increasing degrees of deacetylation of chitosan. They decreased with increasing molecular weights or increasing concentrations of sodium chloride and malic acid. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Use of trifluoromethanesulfonic acid as catalyst for the cyclization of polyisoprene

In this study, trifluoromethanesulfonic acid was employed as catalyst for the cyclization of polyisoprene. From ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography investigations, cyclization was confirmed, and the molecular structure variation of polyisoprene during cyclization reaction was determined. With the comparison to that catalyzed by other strong acids (methanesulfonic acid), polyisoprene was cyclized with much higher efficiency, using trifluoromethanesulfonic acid as catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3666–3669, 2006     

Poly(acrylic acid)-grafted magnetic nanoparticle for conjugation with folic acid

Poly(acrylic acid) (poly(AA))-grafted magnetite nanoparticles (MNPs) prepared via surface-initiated atom transfer radical polymerization (ATRP) of t-butyl acrylate, followed by acid-catalyzed deprotection of t-butyl groups, is herein presented. In addition to serve as both steric and electrostatic stabilizers, poly(AA) grafted on MNP surface also served as a platform for conjugating folic acid, a cancer cell targeting agent. Fourier transform infrared spectroscopy (FTIR) was used to monitor the reaction progress in each step of the syntheses. The particle size was 8 nm in diameter without significant aggregation during the preparation process. Photocorrelation spectroscopy (PCS) indicated that, as increasing pH of the dispersions, their hydrodynamic diameter was decreased and negatively charge surface was obtained. According to thermogravimetric analysis (TGA), up to 14 wt% of folic acid (about 400 molecules of folic acid per particle) was bound to the surface-modified MNPs. This novel nanocomplex is hypothetically viable to efficiently graft other affinity molecules on their surfaces and thus might be suitable for use as an efficient drug delivery vehicle particularly for cancer treatment.     

二氧化硅负载甲烷磺酸催化酯交换制备生物柴油

通过溶胶-凝胶-包埋法制备的二氧化硅负载甲烷磺酸固体酸催化剂,用于大豆油与乙醇的酯交换制备生物柴油,考察了催化剂的处理温度、乙醇与大豆油物质的量比、催化剂用量、正庚烷用量和反应时间的影响。结果表明,二氧化硅负载的甲烷磺酸具有较高的酯交换反应活性。制备生物柴油的最佳条件为：催化剂焙烧温度130 ℃、醇油物质的量比6∶1、催化剂用量为大豆油质量的5.0%,溶剂正庚烷用量为大豆油质量的30.0%,反应时间6 h。在此条件下,产品收率可达98.33%。与固体碱催化剂相比,固体酸催化剂对原料的酸度有更强的适应性。     

Chitosan‐treated polypropylene matrix as immobilization support for lactic acid production using Lactobacillus plantarum NCIM 2084

Adsorption coupled with electrostatic interaction as an immobilization technique is an important microbial cell immobilization technique. Treatment of the polymer matrix with the cationic surface treating agent chitosan for lactic acid production has been studied. Cells of Lactobacillus plantarum NCIM 2084 were immobilized on a polypropylene (PP) matrix treated with different concentrations of chitosan. The biocatalyst adsorbed on the 1.0 g dm^?3 chitosan‐treated PP matrix proved to be most effective. Repeated batch fermentation experiments showed that the immobilized biocatalyst could be recycled effectively 11 times. Studies were also carried out in a packed bed reactor with media recirculation. A high productivity of 7.66 g dm^?3 h^?1 could be obtained with a conversion of 94% and a yield of 97% at an average residence time of 30 h. © 2001 Society of Chemical Industry     

Melt processing of biodegradable poly(lactic acid)/functionalized chitosan nanocomposite films: mechanical modeling with improved oxygen barrier and thermal properties

The present work demonstrates about the formulation of functionalized chitosan (CH-g-OLLA) through the transformation of hydrophilic nature of chitosan into hydrophobic by grafting with oligo(L-lactic acid) (OLLA). The developed CH-g-OLLA is easily soluble in poly(lactic acid) (PLA) matrix, which provides an opportunity towards producing industrially viable nanocomposite films for stringent food packaging and beverages applications. The grafting of OLLA chains is confirmed at NH₂ group of chitosan through the presence of two new peaks at 4.2 and 5.1 ppm in ¹H–NMR spectra. Various parameters like yield (%), grafting efficiency (%) and percent grafting (%) are calculated as ~51.6, ~40 and ~150%, respectively. Functionalized chitosan has been utilized as nano-filler in PLA matrix to fabricate PLA/CH-g-OLLA nanocomposite films which have compounded successfully by co-rotating twin screw compounder cum cast film extrusion technique (distinctly advantageous over conventional solution casting) at bench scale as well as semi-pilot scale and further demonstrated for its application in the area of food packaging with tailored oxygen barrier properties. Uniform dispersion of spherical aggregates of functionalized chitosan is observed in PLA/CH-g-OLLA nanocomposite films using TEM analysis. A significant reduction up to ~11 °C in glass transition temperature of PLA is observed by adding 5 wt% of nano-filler as a result of plasticization effect, which is an essential property in designing of flexible packages. Mechanical modeling of extruded PLA/CH-g-OLLA films has been performed to compare the experimental values with theoretical results using various mathematical models in which modified foam model, Nielsen model and modified Mitsuishi model demonstrate the best match for Young’s modulus (±0.08), tensile strength (±0.06) and percentage elongation (±0.03), respectively. This may be a significant contribution towards commercialization of such formulation where elegant melt extrusion process of PLA with functionalized chitosan is capable of reducing oxygen permeability up to ~10 folds due to a drastic reduction (~96%) in oxygen solubility.     

Zinc deposition and dissolution in methanesulfonic acid onto a carbon composite electrode as the negative electrode reactions in a hybrid redox flow battery

Electrodeposition and dissolution of zinc in methanesulfonic acid were studied as the negative electrode reactions in a hybrid redox flow battery. Cyclic voltammetry at a rotating disk electrode was used to characterize the electrochemistry and the effect of process conditions on the deposition and dissolution rate of zinc in aqueous methanesulfonic acid. At a sufficiently high current density, the deposition process became a mass transport controlled reaction. The diffusion coefficient of Zn²⁺ ions was 7.5 × 10⁻⁶ cm² s⁻¹. The performance of the zinc negative electrode in a parallel plate flow cell was also studied as a function of Zn²⁺ ion concentration, methanesulfonic acid concentration, current density, electrolyte flow rate, operating temperature and the addition of electrolytic additives, including potassium sodium tartarate, tetrabutylammonium hydroxide, and indium oxide. The current-, voltage- and energy efficiencies of the zinc-half cell reaction and the morphologies of the zinc deposits are also discussed. The energy efficiency improved from 62% in the absence of additives to 73% upon the addition of 2 × 10⁻³ mol dm⁻³ of indium oxide as a hydrogen suppressant. In aqueous methanesulfonic acid with or without additives, there was no significant dendrite formation after zinc electrodeposition for 4 h at 50 mA cm⁻².     

Improved yields in the acid catalyzed addition of phenols and phenyl ethers to oleic acid

Phenols may be added to oleic acid in methanesulfonic acid solution to give the corresponding hydroxyphenylstearates in good yield. With phenol not only is the yield (ca 80%) better than that reported previously using other reagents but considerably less color is developed also. Surprisingly good yields (35–60%) were obtained with such complex phenols asp-t-butylcatechol and 2-naphthol. Presented at the spring meeting, American Oil Chemists' Society, St. Louis, Missouri, May 1–3, 1961. Eastern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Preparation of poly(acrylic acid)–chitosan hydrogels by gamma irradiation and in vitro drug release

Biocompatible and biodegradable pH‐responsive hydrogels based on poly(acrylic acid) (AAc) and chitosan were prepared for controlled drug delivery. These interpolymeric hydrogels were synthesized by a gamma irradiation polymerization technique. The degree of gelation was over 96% and increased as the chitosan or acrylic acid content increased. The equilibrium swelling studies of hydrogels prepared in various conditions were carried out in an aqueous solution, and the pH sensitivity in the range of pH 1–12 was investigated. The AAc/chitosan hydrogels showed the highest water content when the 30 vol % AAc and 0.1 wt % chitosan were irradiated with a 30‐kGy radiation dose. Also, an increase of swelling degree with an increase in the pH was noticed and showed the highest value at pH 12. The drug, 5‐fluorouracil, was loaded into these hydrogels and the release studies were carried out in simulated gastric and intestinal fluids. The in vitro release profiles of the drugs showed that more than 90% of the loaded drugs were released in the first 1 h at the intestinal pH and the rest of the drug had been released slowly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3660–3667, 2003