Solvents methanesulfonic acid

Physical Properties. Methanesulfonic acid [75-75-2] (MSA), CH SO H, is a clear, colorless, strong organic acid available in bulk quantities from Elf Atochem North America as a 70% solution and on an anhydrous basis (100%). MSA is soluble in water and in many organic solvents. Its physical properties ate described in Table 10. 

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esteri nf methanesulfonic acid, p-toluenesidfonic acid, and especially trifluoromethane-sulfonic acid (tnflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

A variety of media have been used for the Wallach fluorination reaction anhydrous hydrogen fluoride alone or with cosolvents such as methylene chloride, benzene, or tetrahydrofuran and hydrogen fluoride-pyridine alone or with co solvents such as benzene, glyme, or acetic acid [42,43, 46 50] Solutions of cesium fluoride, tetraethylammonium fluoride, or tetrabutylammonium fluoride in strong acids such as methanesulfonic acid or trifiuoroacetic acid with numerous cosolvents have also been studied [48, 49]... 

Malonic acid, amino-, diethyl ester, HYDROCHLORIDE, 40, 24 Malonic acid, bts(hydroxymethyl)-, DIETHYL ETHER, 40, 27 Malonitrile, condensation with tetra-cyanoethylene, 41, 99 2-Mercaptopyrimidine, 43, 6S hydrochloride of, 43, 68 Mercuric oxide in preparation of bromo-cyclopropane, 43, 9 Mesityl isocyanide, 41,103 5-Methallyl-l,2,3,4,5-pentachlorocyclo-pentadiene, 43, 92 Methane, dimesityl-, 43, 57 Methanesiileinyl chloride, 40, 62 Methanesulfonic acid, solvent for making peroxybenzoic acid from benzoic acid, 43, 93... 

DCC has also been used. The most common catalyst for aliphatic R is concentrated sulfuric acid. The reaction is an equilibrium and is driven to the right by removal of water or by the use of excess reagents. For aromatic R the best catalyst is methanesulfonic acid, which is also used as the solvent. 

In the preparation of anhydrous DMSO by a literature method [1], an explosion occurred during distillation from anhydrous magnesium perchlorate [2], This may have been due to the presence of some free methanesulfonic acid as an impurity in the solvent, which could liberate traces of perchloric acid. It is known that sulfoxides react explosively with 70% perchloric acid, (but several metal perchlorates also form unstable solvates with DMSO) The alternative procedure for drying DMSO with calcium hydride [3] seems preferable, as this would also remove any acidic impurities. 

This reaction has been studied in mote detail, and a study of the cyclization of thiobenzamide using DMSO as oxidant led to the following conclusions. There must be an oxygen donor oxidant present and it is essential to use a solvent of high polarity such as dimethyl formanide (DMF). An acid catalyst is essential and the counterion is also important HCl and HBr are good catalysts but sulfuric acid, methanesulfonic acid, and trifluoroacetic acid do not give... 

The freezing point depression of a solvent is proportional to the concentration of solute particles and may be used to measure the extent of ionization once the new particles have been identified qualitatively as ions. The method has the obvious disadvantage of not allowing measurements over a range of temperatures in a single solvent. It is almost certainly not worth while to compute an enthalpy of ionization from ionization constants at two different temperatures in two different solvents. Usable solvents are limited not only by the requirement that the melting point be at a convenient temperature but also by the requirement that the solvent be capable of producing ions yet not be sufficiently nucleophilic to react irreversibly with them once they are formed. For this reason most cryoscopic work has been done in sulfuric acid or methanesulfonic acid.170... 

A powerful and efficient method for the preparation of poly(ketone)s is the direct polycondensation of dicarboxylic acids with aromatic compounds or of aromatic carboxylic acids using phosphorus pentoxide/methanesulfonic acid (PPMA)16 or polyphosphoric acid (PPA)17 as the condensing agent and solvent. By applying both of these reagents to the synthesis of hexafluoroisopropylidene-unit-containing aromatic poly(ketone)s, various types of poly(ketone)s such as poly(ether ketone) (11), poly(ketone) (12), poly(sulfide ketone) (13), and poly-... 

Poly(benzimidazole)s possess excellent thermal stability, flame resistance, and outstanding chemical resistance. The solubility of hexafluoroisopropyli-dene-unit-containing poly(benzimidazole)s is remarkably improved.24 They are readily soluble in strong acids such as formic acid, concentrated sulfuric acid, and methanesulfonic acid and in aprotic polar solvents such as DMAc and NMP. The polymer from tetramine (23) is soluble even in m-cresol and pyridine. 

Considerable efforts have centered on carrying out the synthesis of polybenzimidazoles at more moderate temperatures. Polymerization of the isophthalic acid or its diphenyl ester have been successfully carried out in polyphosphoric acid or methanesulfonic acid-phosphorous pentoxide at 140-180°C, but the reaction is limited by the very low solubilities (<5%) of the reactants in that solvent. The lower reaction temperature is a consequence of activation of the carboxyl reactant via phosphorylation. Lower reaction temperatures are also achieved in hot molten nonsolvents such as sulfolane and diphenyl sulfone, but the need to remove such solvents by a filtration or solvent extraction is a disadvantage. 

Diphenyl ether undergoes cyclization to dibenzofuran in good yield on treatment with 1-2 mol equiv of palladium(II) acetate in boiling solvents such as acetic acid or trifluoroacetic acid or mixtures of acetic acid and methanesulfonic acid (15 The rate of reaction is greater in the more... 

The same mode of migration is found if the rc-bond needed for rearrangement is part of an aryl ring in the 2-position. Usually only the substituted C3 of cyclobutanones (Table 5)71 74,140 or cyclobutanols (Table 6)75 migrates on treatment with trifluoroaeetic acid,73 methanesulfonic acid,71 trifluoromethanesulfonie acid, 140/ -toluenesulfonic acid,74 phosphorus pentoxide,71-74 and tin(IV) chloride,72 generally with diethyl ether or benzene as the solvent. 

PPMA - solvent composed of methanesulfonic acid/P2Os (10 lw/w)... 

The benzobisazole family of rigid-rod polymers is soluble in acidic solvents such as PPA, methanesulfonic acid, chlorosulfonic acid, 100% sulfuric acid and Lewis acid salts such as antimony trichloride and bismuth trichloride. More recently, PBZT has been reported [22] to form liquid crystalline solutions in nitromethane containing aluminum trichloride or gallium trichloride. Since the glass transition temperature of these materials is above their decomposition temperature, they must be processed from solution. 

When s-oxepin oxide (155) is treated with a trace of methanesulfonic acid in an aprotic solvent, 4JF/-pyran-4-carbaldehyde (156) is rapidly produced. A quantitative yield is indi-... 

Hull and Conant in 1927 showed that weak organic bases (ketones and aldehydes) will form salts with perchloric acid in nonaqueous solvents. This results from the ability of perchlonc aad in nonaqueous systems to protonate these weak bases. These early investigators called such a system a superacid. Some authorities believe that any protic acid that is stronger than sulfunc aad (100%) should be typed as a superaad. Based upon this criterion, fluorosulfuric arid and trifluoro-methanesulfonic acid, among others, are so classified. Acidic oxides (silica and silica-aluminai have been used as solid acid catalysts for many years. Within the last few years, solid acid systems of considerably greater strength have been developed and can he classified as solid superacids. 

Only resinous products and methyl 6-acetamidopyridine-3-carboxylate were obtained when methyl 6-aminopyridine-3-carboxylate was reacted with ethyl 2-acetoxyacetoacetate by heating in phosphorus pentoxide, methanesulfonic acid, or polyphosphoric acid in the absence or presence of a solvent such as toluene, xylene, or methylene chloride. However the desired methyl 3-acetoxy-2-methyl-4-oxo-4//-pyrido[ 1,2-a]pyrimidine-7-carboxylate 93 was obtained when the above components were reacted in N, A-dimethylacetamide in the presence of polyphosphoric acid at 100°C for 48 hours (84FES837). 

To a suspension of 500 mg (1.74 mmoles) of the (S)-6-(2-oxo-l,3-oxazolidin-4-ylmethyl)-4,9-dihydro-3-pyrano-[3,4-b]indol-l-one in 10 ml of methanol were added 0.12 ml (1.9 mmoles) of methanesulfonic acid. The mixture was left under stirring at the reflux temperature for 3 hours. The solvent was evaporated to dryness under reduced pressure, the residue dissolved with 10 ml of a saturated bicarbonate solution and extracted three times with dichloromethane. The combined organic phases were dried and evaporated to dryness and the evaporated solid recrystallised from ethanol to give 517 mg (93%) of the title ester as a yellow crystalline solid. Melting point 178°-180°C. 

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