Methanesulfonic Acid Solution Research Articles

Determination of the S Isotope Composition of Methanesulfonic Acid

Sulfur (S) isotopes have been used to apportion the amount of biogenic and anthropogenic sulfate in remote environments, an important parameter that is used to model the global radiation budget. A key assumption in the apportionment calculations is that there is little isotope selectivity as reduced compounds such as dimethyl sulfide (DMS) are oxidized. This paper describes a method to determine, for the first time, the S isotope composition of methanesulfonic acid (MSA), the product of DMS oxidation. The isotope composition of MSA was measured directly by EA-IRMS and was used as an isotope reference for the method. Synthetic mixtures approximating the conditions expected for aerosol MSA samples were prepared to test this method. First, MSA solutions were measured alone and then in combination with MSA and SO4(2-). In synthetic mixtures, SO4(2-) was separated from MSA by precipitating it as BaSO4 prior to preparation of MSA for isotope analysis. The delta 34S value for MSA solutions was -2.6 per thousand (SD +/- 0.4 per thousand), which is not different from the delta 34S obtained from MSA filtrate after precipitating SO4(2-) from the mixture (-2.7 +/- 0.3 per thousand). However, these values are offset from direct EA-IRMS analysis of MSA used as the isotope reference by -1.1 +/- 0.2 per thousand, and this must be accounted for in reporting MSA measurements. The S isotope measurements using this method approach a limiting value above 300 microg of MSA. This is approximately equal to the MSA found in 20,000 m3 of air, assuming ambient concentrations of approximately 15 ng m(-3). Three samples of MSA from the Pacific Ocean measured using this technique have an average delta 34S value of +17.4 +/- 0.7 per thousand.

Synthesis of High Molecular Weight Polybenzoxazoles in Polyphosphoric Acid and Investigation of their Hydrolytic Stability under Acidic Conditions

Studies on the synthesis of high molecular weight polybenzoxazoles (PBOs) in polyphosphoric acid (PPA) and investigations of their hydrolytic stability in aqueous methanesulfonic acid are described. The polymerization of PBOs based upon 2,2′-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP) and 4,4′-oxydibenzoic acid (ODBA) was investigated as a function of the percentage of P2 O5 content in PPA, polymerization temperature, percentage monomer (total weight of monomers/weight of monomers plus PPA), and reaction time. It was found that the percentage of P2 O5 content was the most important polymerization variable and that PPA with more than 85% P2 O5 content was required to achieve high molecular weight PBOs. Hydrolytic stability of PBOs prepared from selecting 6FAP and either ODBA, isophthalic acid (IA), or terephthalic acid (TA) was investigated by solution viscosity measurements, 1 HNMR and FTIR spectroscopy. The hydrolysis experiments were conducted in aqueous methanesulfonic acid solutions at room temperature, 50, and 80° C. The 6FAP/ODBA PBO showed improved stability over time with respect to the 6FAP-IA and 6FAP-TA PBOs, which may be due to the decreased electrophilicity of the carbon atom of the oxazole ring. But, the inherent viscosities of all the PBOs decreased over time and 1 H-NMR and FTIR spectroscopic evidence for chain scission was obtained. Benzoxazole model compounds, 2,2′-Bis(2-phenylbenzoxazol-6-yl)hexafluoropropane, 2,2′-bis[2-(4-phenoxyphenyl)benzoxazol6-yl]hexafluoropropane, were synthesized from selecting 6FAP and ether 4-phenoxybenzoic acid or benzoic acid in N -cyclohexylpyrrolidinone. Nuclear magnetic resonance spectroscopic data provided direct evidence of hydrolysis of oxazole functional groups.

Inhibitory activity of phosphorylated chitooligosaccharides on the formation of calcium phosphate

Chitooligosaccharides (COSs) were successfully prepared using an ultrafiltration membrane bioreactor system, and named as COS-I (10–5 kDa), COS-II (5–3 kDa), COS-III (3–1 kDa), and COS-IV (below 1 kDa), respectively. In addition, their phosphorylated derivatives were prepared by a P 2O 5 in methanesulfonic acid solution, and inhibitory activity on the formation of insoluble calcium phosphate of phosphorylated chitooligosaccharides. Phosphorylated COS-IV exhibited the highest inhibitory activity of calcium phosphate precipitation among tested chitooligosaccharides. Its inhibitory activity, especially at the concentration more than 4 mg/ml, was similar to that of CPP, which is widely used as a calcium fortifying agent increasing calcium absorbability. Therefore, phosphorylated chitooligosaccharides may be potential inhibitors of calcium phosphate precipitation.

Hybrid proton-conducting membranes for polymer electrolyte fuel cells: Phosphomolybdic acid doped poly(2,5-benzimidazole)—(ABPBI-H 3PMo 12O 40)

The synthesis and characterization of a novel hybrid organic–inorganic material formed by phosphomolybdic acid H 3PMo 12O 40 (PMo 12) and poly(2,5-benzimidazole) (ABPBI) is reported. This material, composed of two proton-conducting components, can be cast in the form of membranes from methanesulfonic acid (MSA) solutions. Upon impregnation with phosphoric acid, the hybrid membranes present higher conductivity than the best ABPBI polymer membranes impregnated in the same conditions. These electrolyte membranes are stable up to 200 °C, and have a proton conductivity of 3 × 10 −2 S cm −1 at 185 °C without humidification. These properties make them very good candidates as membranes for polymer electrolyte membrane fuel cells (PEMFC) at temperatures of 100–200 °C.

Ionizing properties of complexes with strong symmetrical hydrogen bonds in acid solutions in aprotic solvents

The acidity functions H0 of solutions of trifluoroacetic acid (TFA) in DMF and methanesulfonic acid (MSA) in 2-pyrrolidone over an acid (HA) concentration range of 0–100% and of H2SO4 solutions in 2-pyrrolidone (66.7–100 mol % HA) at 25°C were determined using the indicator method. Data were obtained on the relative ionizing powers of the quasi-ion pairs S⋯H⋯A (S is a solvent molecule) formed by DMF with acids (HCl, MSA, and TFA) and by MSA with DMF and 2-pyrrolidone. The effects of the acid anion (with MSA and H2SO4 solutions in 2-pyrrolidone acting as examples) and the counterion SH+ (with MSA solutions in DMF and 2-pyrrolidone acting as examples) on the ionizing power of (A⋯;H⋯A)− ions with strong symmetrical H-bonds were studied. It was found that, under comparable conditions, the replacement of a 2-pyrrolidone molecule by a DMF molecule in the SH+ cation insignificantly decreased the acidity of solution, whereas the (A⋯;H⋯A)− ions in H2SO4 solutions exhibited a much higher ionizing power than that of structurally similar anions in MSA solutions.

Joint theoretical and experimental study of the UV absorption spectra of polybenzoxazoles

A series of conjugated rigid-rod polymers, poly( p-phenylene benzobisoxazole) (PBO), poly(benzobisoxazole-2,6-diylvinylene) (PBOV), poly(benzobisoxazole-2,6-diyldivinylene) (PBODV) have been synthesized. UV absorption spectroscopy has been used to investigate the optical properties of these polymers in methanesulfonic acid (MSA) or in films. The results show that the introduction of vinyl segments into the poly(benzobisoxazole)s backbone narrowed the optical bandgap of this class of polymers. The UV spectra of the polybenzoxazole can be well predicted with the polybenzoxazole models by the semiempirical method AM1/ZINDO (Austin Method 1/Zerner's intermediate neglect of differential overlap), coupled to single configuration interaction. The UV spectra of polymers in MSA solution were red-shifted from that of the thin films and the theoretical UV spectra. The AM1/ZINDO-CI calculations of protonated PBO at N heteroatom suggest that the red shift is due to the protonation effect.

Surface modification and interfacial adhesion of rigid rod PBO fibre by methanesulfonic acid treatment

PBO is a rigid rod polymeric material with potential applications as reinforcement fibres for advanced composites. The adhesion between fibre and matrix in a composite system is a primary factor for stress transfer from matrix to fibre. In this report, we investigated the surface modification of PBO fibres by acid treatments under various treatment conditions, using methanesulfonic acid solution. Both commercially available as-spun and high-modulus type PBO fibres were studied. The experimental effects on the changes in the surface morphology, mechanical strengths, and surface free energies of the fibres were carefully evaluated. In addition, the interfacial adhesion properties of the epoxy-based composites were studied by microbond pull-out tests. The results showed that the surface free energy could be significantly increased up to 62 mJ/m2 or by 34%, while the interfacial shear strength was improved to 40 MPa or by 22% with the proposed treatment process. The failure mode also changed from fibre/matrix interface adhesive failure to partly cohesive failure mode. On the other hand, the corresponding reduction in fibre tensile strength has been only 1–5% for the same treatment process.

Compositions and Structures of Methanesulfonic Acid Complexes with Acetonitrile According to IR Spectroscopic Data

IR spectra of solutions of methanesulfonic acid in acetonitrile are recorded and analyzed at 30°C at methanesulfonic acid concentrations ranging from 0 to 100%. Molecular 1 : 1 complexes with the coordination of the acid proton at the nitrogen atom of the acetonitrile molecule are formed over a wide range of acid concentrations. When the base is in excess, the whole amount of the acid is bound in these complexes. In solutions with excess acid, the solvation of the 1 : 1 complexes by several methanesulfonic acid molecules produces associates containing a structure fragment in which the acetonitrile molecule acts as both the donor and acceptor of hydrogen bonds. Hydrogen bonds involving CH3 groups of acetonitrile can be formed when the 1 : 1 complexes are solvated by several acid molecules.

Surface Modification of Reinforcement Fibers for Composites by Acid Treatments

In this study, we investigated the surface modification of reinforcement fibers for composites by acid treatments, including PBO fiber, Kevlar fiber and carbon fiber. The corresponding changes in the surface free energy components were carefully evaluated using a Cahn dynamic contact angle analysis system. In addition, the fiber's surface elemental composition and topography were studied using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the surface nitrogen-to-carbon (N/C) and oxygen-to-carbon (O/C) ratios were significantly increased after the treatments. The surface free energy γ of PBO fiber was increased from 43.3 mJ/m2 to 58.5 mJ/m2 or by 35% with 60 wt% methanesulfonic acid solution treatment for 36 h. However, the increase with 60 wt% nitric acid solution was only by 14% (to 49.5 mJ/m2) for the same treatment time.

Phase‐separated, conducting composites from polyaniline and benzobisthiazole rigid‐rod polymer

AbstractAs an alternative method for processing polyaniline (PANI) from its conducting (protonated) state, vacuum casting of PANI from a methanesulfonic acid (MSA) solution provided films with electrical conductivity values of about 130–150 S/cm. In addition, we similarly prepared blended films of PANI · MSA and poly(p‐phenylene benzobisthiazole) (PBZT). This process eliminated the need for a subsequent protonation step and had the additional advantage that the conjugated PBZT may provide alternative conducting pathways. Conductivity values of the composite films ranged from 100 pS/cm to 124 S/cm, and the films displayed critical concentration behavior with a PANI threshold concentration of 2.75% and a critical exponent of 4. Transmission electron micrographs displayed phase‐separated regions with PANI forming a continuous network at high concentrations. Thermogravimetric analysis results demonstrated the thermal and thermooxidative stability advantage of the blends due to the PBZT component. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2539–2548, 2001

Acidity function of methanesulfonic acid solutions in ethyl acetate

The acidity function of solutions of methanesulfonic acid (MSA) in ethyl acetate (EA) was measured by the indicator method at 25 °C in the 0.4—100% concentration range. Molecular complexes formed by MSA and EA show a higher ionizing activity than H5O2+ ions. The relative ionizing activity of the MSA·EA complexes and ion pairs formed by MSA and DMF was determined.

Solvation of complexes with strong symmetric H bonds in the methanesulfonic acid—2-pyrrolidone system

Multiple Attenuated Total Reflectance (MATR) IR spectra of solutions of methanesulfonic acid (MSA) in 2-pyrrolidone (Pyr) (0—100 % MSA) were examined at 30 °C. Depending on the ratio of components, two types of species with strong symmetric H bonds are formed: uncharged quasi-ion pairs of 1 : 1 composition and anions (AHA)–. The solvation of quasi-ion pairs by base molecules and of the (AHA)– anions by acid molecules was detected. The data on the influence of the hydrogen bond donor and acceptor on the IR spectra of the quasi-ion pairs and (AHA)– anions are presented.

New polyamides with long alkane segments: nylon 6.24 and 6.34

A series of new amphiphilic, semi-crystalline polyamides based on hexamethylenediamine and long alkane carboxylic diacids has been synthesized and characterized, here exemplified by polyamide 6.24 (PA-6.24) and polyamide 6.34 (PA-6.34). The polymers were produced by melt polycondensation, which yielded materials of weight-average molecular weights in the range of 30,000–35,000 g/mol. The thermal properties of the polyamides were investigated by various thermo-analytical methods. PA-6.24 and PA-6.34 exhibit relatively high melting temperatures of 189 and 177°C, respectively. Both materials display rather poor solubility in solvents that are used for common polyamides, but by contrast, dissolve in, e.g. ethanesulfonic acid. PA-6.34 was found to aggregate in dilute methanesulfonic acid solutions and form thermo-reversible gels in H 2SO 4, which we attribute to its amphiphilic character. The latter enabled the use of PA-6.34 as a “compatibilizer” for blends of polyolefins and polyamides. Finally, the Young's moduli of isotropic films of PA-6.24 and PA-6.34 were determined to be 1.3 and 0.7 GPa, respectively, representing a stiffness that is intermediate between that of common polyamides and polyethylene.

Acidity function of methanesulfonic acid solutions in DMF

The acidity function of solutions of methanesulfonic acids (MSA) in DMF and H2O were measured by the indicator method at 25 °C in the 0–100% concentration range. A higher ionizing activity of HCl complexes with DMF as compared to that of similar MSA complexes was established. The relative ionizing activity of MSA molecules, H5O2+ ions, and ion pairs between MSA and DMF was determined.

Environmental benefits of methanesulfonic acid

This paper reviews some chemical and physical characteristics of methanesulfonic acid and the short-chain alkanesulfonic acids in general. The aqueous solubility of metal methanesulfonates, the conductivity of aqueous methanesulfonic acid (MSA) solutions and the low toxicity of MSA all make MSA(aq) an ideal electrolyte for many electrochemical processes, especially those involving tin and lead. Aspects of aqueous process effluent treatment, acid recovery and metal alkanesulfonate salt preparation are also environmentally favorable. Emphasis in this paper is given to rationalizing the rapidly growing commercial preference for MSA(aq) as an electrochemical electrolyte, especially with respect to the substitution of MSA for HBF4 in the electroplating of Sn/Pb solder. Economic aspects of MSA are also considered.

New aromatic benzazole polymers II: Synthesis and conductivity of benzobisthiazole-co-polymers incorporated with 4-N,N-dimethylaminotriphenylamine groups

New aromatic benzobisthiazole copolymers containing 10-70 mol % of 4-N,N-dimethylamino-triphenylamine functionality were prepared from the respective dinitrile or dicarboxylic acid monomers, terephthalic acid, and 2,5-diamino-1,4-benzene-dithiol dihydrochloride in polyphosphoric acid. At the first approximation, the copolymers containing 10 mol % or less of the triarylamino moieties in the polymer chains still preserve the capability to form anisotropic (nematic) solutions at 10 wt % polymer concentration. This is an important requirement for processing the copolymers into fibers and films with good to excellent mechanical properties. Films with good mechanical integrity were cast from the dilute methanesulfonic acid solutions of the copolymers under reduced pressure. They showed electrical conductivity values of the order of 10 -11 -10 -10 S/cm in pristine state, with four to seven orders of magnitude increase upon exposure to mild oxidizing agents such as iodine vapor. On the contrary, the parent polymer, poly(p-phenylene benzobisthiazole) is an insulator with conductivity of less than 10 -12 S/cm, and its conductivity does not improve at all with exposure to iodine vapor.

Compatible polynaphthimidazole blends with a benzophenone-based polyimide and their film properties

A series of new blends of the aromatic polynaphthimidazole (PNI) from 3,3′-diaminobenzidine (DAB) and dimethyl 2,6-naphthalenedicarboxylate, and the polyimide (PI) from 1,4-phenylenediamine and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride has been prepared by film casting from methanesulfonic acid solution mixture. The compatibility of PNI/PI blends is evidenced in the form of change in FTIR spectroscopy and single tan δ relaxation from dynamic mechanical analysis (DMA). The intermolecular interaction involving the N-H and carbonyl groups played an important role in the compatibility between polynaphthimidazole and polyimide. The tensile test in a series of PNI/PI blend films confirms that PNI/PI= 80/20 wt.% has the highest tensile strength and modulus.

Aromatic polyamides containing keto-benzocyclobutene pendants

A series of novel benzocyclobutene (BCB)-pendanted polyamides (inherent viscosities: 0.20–0.69 dL/g) was synthesized from 3,5-diaminophenyl-4-benzocyclobutenyl ketone, and terephthaloyl, isophthaloyl, 4,4′-oxydibenzoyl chlorides, as well as 4,4′-(o-phenylenedioxy)dibenzoyl chloride. The DSC studies demonstrated that the BCB crosslinking exothermic transition occurred at nearly the same temperature (max. ∼︁ 275°C) for all the four polyamides, and they were thermally stable up to 380°C in helium, where the weight loss started to occur. TGA and DSC studies in air indicated that the polymers, in contrast to the model compound, showed evidence of oxidation just prior to or occurring simultaneously with the BCB crosslinking reaction. This could be attributed to the oxidation of the reactive diene generated from the ring-opening of the BCB competing with the process of two BCB pendant units approaching each other for crosslinking reaction. Preliminary examination of the BCB-pendanted polyamide regenerated from a methanesulfonic acid solution indicates that the BCB ring is quite stable (DSC evidence) in the strong acid medium. © 1996 John Wiley & Sons, Inc.

Molecular composite fibers from rigid rod polymers and thermoset resin matrixes

AbstractFibers consisting of a rigid rod polymer and thermoset resin matrices were prepared. Poly(benzo‐[1,2‐d : 5,4‐d′]bisoxazole‐2,6‐diyl)‐1,4‐phenylene} (PBO) in polyphosphoric acid (PPA) was blended with isophthaloyl bis‐4‐benzocyclobutene (1) or 2,6‐bis‐4‐benzocyclobutene benzo[1,2‐d: 5,4‐d′]bisoxazole (2), and fibers were spun from these dopes. As‐spun fibers that did not show phase segregation between the two components as examined with an optical microscope, were soluble in methanesulfonic acid (MSA). After heat treat‐ment, the fibers swelled but did not dissolve in MSA. A fiber cross section of heat‐treated PBO‐1 fiber showed well‐dispersed benzocyclobutene polymer domains of 200–500 Å by transmission electron microscopy (TEM). Films cast from MSA solutions of PBO and 2 were homogeneous, and TEM of heat‐treated fiber showed only one phase. A molecular composite fiber was made. Some of these fibers showed 20–30% improvement in compressive strength over unmodified PBO fiber. © 1995 John Wiley & Sons, Inc.

Alloying of a Less Noble Metal in Electrodeposited Cu Through Underpotential Deposition

Underpotential deposition of Pb or Sn on Cu can be used to produce electroplated Cu‐Pb and Cu‐Sn alloys, with small amounts of alloyed Pb and Sn, from acid solutions that do not contain complexants. Such alloys are of interest as possible on‐chip wiring for very large scale integration; the content of alloying agent must be kept small in order to maintain a low resistivity. The primary requirement for the formation of the alloys is that the deposition process occur in the range of underpotential deposition (UPD); this requirement can be met in solutions of methane sulfonic acid (MSA). Both Pb(II) and Sn(II) depolarize Cu deposition from MSA; the Sn(II) is the weaker depolarizer. Thus, in the absence of other additions to the Cu(II)/MSA solution, electrodeposition proceeds in the UPD range in the presence of Pb(II), producing a Cu‐Pb alloy, but positive to the UPD range in the presence of Sn(II), producing pure Cu. The deposition potential can be manipulated by addition agents in solution. A direct relationship exists between the potential and the amount of incorporated Pb or Sn for all solution compositions and plating conditions, provided that the solution does not contain strongly adsorbing species that interfere with the UPD process. The minor component has been shown to be incorporated in the metallic state, even though the deposition potential is positive to its reversible potential.