Methane sulfonic acid MSA

Methane Sulfonic Acid (MSA), Properties, Reactions and Applications, Technical Bulletin PB-70-1A, Elf Atochem North America, Philadelphia, Pa., 1993. 

Solutions of poly(l,4-phenylene-2,6-benzobisthiazole), PBT, exhibit an isotropic to nematic phase transition in a variety of solvents including methane sulfonic acid, MSA, chlorosulfonic acid, CSA, and poly phosphoric acid, PPA (1-4). In the latter case the transition occurs over a range of water -P2O5 compositions. In these acids the polymer, with repeating unit... 

In the reactive crystallization of an API, methane sulfonic acid (MSA) is reacted with the free base of the previous intermediate. Due to the highly compressible nature of the resulting crystals on filtration, caused by fines from the crystallization, it is desirable to minimize the level of secondary nucleation by reducing the degree of supersaturation and allowing a slower release of supersaturation during the reactive crystallization. 

On the other hand, DMS oxidation by the OH -radical is postulated to explain the occurrence of methane sulfonic acid (MSA), DMSO, and dimethyl sulfone (DMSO2) in marine air. The MSA and SO2 formed act as condensation nuclei during cloud formation. 

Once the importance of DMS to the global sulfur cycle was established, numerous measurements of DMS concentrations in the marine atmosphere have been conducted. The average DMS mixing ratio in the marine boundary layer (MBL) is in the range of 80-1 lOppt but can reach values as high as 1 ppb over entrophic (e.g., coastal, upwelling) waters. DMS mixing ratios fall rapidly with altitude to a few parts per trillion in the free troposphere. After transfer across the air-sea interface into the atmosphere, DMS reacts predominantly with the hydroxyl radical and also with the nitrate (N03) radical. Oxidation of DMS is the exclusive source of methane sulfonic acid (MSA) in the atmosphere, and the dominant source of S02 in the marine atmosphere. We will return to the atmospheric chemistry of DMS in Chapter 6. 

Solutions of the rodlike macroion were prepared by dissolution in methane sulfonic acid (MSA) of deuterated poly(l,4-phenylene-2,6-benzobisthiazole)(d-PBT), which was supplied by Dr. J. R. Wolfe, SRI International. Solutions were prepared in a glove box with air circulated over drierite. The solvent MSA was distilled under vacuum. The solutions were filtered several times with a teflon millipore filter into the light scattering cells in a glove box filled with dry nitrogen. Cells were sealed with flame under vacuum and then centrifuged for 24 hours before measurements. 

Fig. 6.4 Schematic illustration of the key pathways in the atmospheric cycle of S involving (7) the natural emissions of reduced S compounds such as H2S frran terrestrial biota and dimethyl sulfide (CH3SCH3) from oceanic biota (2) anthropogenic emissions of S compounds, principally SO2 (3) the oxidation of reduced S compounds by OH and other photochemical oxidants leading to the production of intermediate oxidation state S compotmds such as SO2 and methane sulfonic acid (MSA) (4) the oxidation of these mtermediate oxidation state compounds within the gas phase by OH-producing H2SO4 vapor (5) the conversion of intermediate oxidation state compounds within liquid could droplets, which upon evaporation yield sulfate-containing particles (6) the conversion of H2SO4 to sulfate-containing particles and (7) the ultimate removal of S fiom the atmosphere by wet and dry deposition (Chameides and Perdue 1997)...

Methane sulfonic acid (MSA) is a relatively expensive acid used to strip (remove) solder (tin/lead) and copper metals. This acid is also used to condition metal surfaces prior to fluo-borate free-solder electroplating when applying a final etch resist of solder onto multilayer printed circuit boards. By continuously recirculating the acid bath through a diffusion dialysis unit, a 95 percent reduction of chemical purchases (required by the process steps indicated in the first paragraph of this section) may result, producing less than a six-month return on the initial capital investment (ROI).Typically, 80 to 90 percent of the acid is recovered with 70 to 90 percent of the metals removed in an equal volume of dilute acid. 

Dimethyl disulfide (DMDS), CH3SSCH3, is released mainly from marine biology and biomass burning. The rate constant of the OH reactimi is very fast, 2.3 X 10 ° cm molecule s at 298 K, and the atmospheric lifetime is very short within a few hours. The reaction is thought to give methane sulfonic acid (MSA) directly (Barnes et al. 1994) as. 

Asensio et al. [71] also developed a method for producing acid-doped membranes by direct casting from an AB-PBI/phosphoric acid (PA)/methane-sulfonic acid (MSA) solution. The methanesulfonic acid was evaporated to produce a very homogenous, nearly transparent film with controlled composition and up to 3 moles PA/BI. This method of preparation was much more convenient than the typical multi-step, organic solvent based process. 

Ion chromatography detected these primary anion residues chloride (C1-), bromide (Br-) and WOAs (typical for PWBs and assemblies). The following substances also were tested for (and found below detectable levels) nitrates (NO3-), phosphates (PO42-), methane sulfonic acid (MSA), sulfates (SO42-), WOAs and conductive organic-element residues. 

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