Methanesulphonic acid

Gollnick and Stracke176 investigated the very complex mechanism involved in the photolysis of dimethyl sulphoxide and concluded that disproportionation is probably the route for the major sulphone-producing reaction. Other oxidized species such as methanesulphonic acid are also produced and are also probably formed by a series of disproportionation reactions, for example equation (62). Thus photolysis of dimethyl sulphoxide is not a synthetically useful reaction due to the large number of compounds produced. 

The base catalysed autoxidation of dimethyl sulphoxide and methyl phenyl sulphoxide at 80 °C produces low quantities of methanesulphonic acid in both cases and benzenesul-phonic acid in the latter case189 (equation 71 and 72). There is no evidence of sulphone formation in either reaction. Dimethyl sulphoxide oxidation to methanesulphonic acid also occurs in the presence of trace quantities of acid and oxygen. Again the reaction would not be synthetically useful190. 

Transformation of bromocriptine free base 2 into water soluble salt -mesylate, is the only way to obtain a suitable therapeutical form. Crystallization of mesylate using alcohol as a solvent in the presence of excess of strong acid, e.g. methanesulphonic acid can induce formation of 12 -0-alkyl-derivative 2. Until now this derivatisation of ergot molecule has been practically unknown. In continuation we developed the preparative method for obtaining these compounds, (using tetrafluoroboric acid as a catalyst) (ref. 20). 

Although methanesulphonic acid was found, it was assumed that the above... 

The acidic properties of methanesulphonic acid that have just been mentioned have been responsible for two other accidents. When this acid is contact with methyl and vinyl oxide, this caused the latter to polymerise violently. The electrolysis of methanesulphonic acid with an aqueous solution of hydrogen fluoride gives rise to a violent detonation that was put down to the formation of oxygen difluoride that is explosive. 

The ultraviolet spectrum of bromocriptine mesilate was recorded on a Philips 1700 uv spectrophotometer in 0.1 M me-thanolic methanesulphonic acid solution. It is given in fig. 

Figure 2. Ultraviolet Spectrum of Bromocriptine Mesilate in 0.1 M Methanolic Methanesulphonic Acid.

The mesilate is then formed by addition of methanesulphonic acid. The salt is recrystallized from butanone-2 (s. fig. 10) (2,3,11). 

The methanesulphonic acid content of bromocriptine mesilate is usually determined by titration with 0.1 N methanolic potassium hydroxide. The endpoint may be detected potentiometrically using a glass/calomel electrode system. 

Spectrophotometrie analysis of bromocriptine mesilate is carried out directly using the uv maximum at about 305 nm in methanolic methanesulphonic acid. However, the method is not very specific. 

It was preferred to first separate the impurities from bromocriptine by thin layer chromatography and then to isolate the substance by elution from the silica gel of the plate with methanol. The intact active ingredient is measured in 0.01 M methanolic methanesulphonic acid (26). 

The identity of methanesulphonic acid may be determined by tic on cellulose plates, Merck no. 5728, with ethanol/ water/conc. ammonia 80 16 4 (v/v/v) as a mobile phase. Detection is achieved by spraying with acid-base indicators, e.g. bromocresol green or similar species. Rf of methanesulphonic acid is 0.5 (that of bromocriptine base = 0.9). 

In the course of our polarographic studies on organic cations we determined the half-wave potentials, 1/2, for various arylmethylium ions [1-11]. The aim of the present work is to extract from these values some new information concerning the relative magnitude of their solvation enthalpies in three very different solvents. A comparison of our results [obtained in methanesulphonic acid (MSA) and dichloromethane (DCM)] with those of Volz and Lotsch [12] [obtained in cyanomethane (CM) solutions] yields some useful conclusions. 

Polarography of Organic Cations in Acid Solution, Part II, Various Aralkyl Ions in Sulphuric and Methanesulphonic Acids, P.H. Plesch and I. Sestakova, Journal of the Chemical Society, (B), 1971, 1337-1342. 

Busulphan is first hydrolyzed by refluxing it with water and two moles methanesulphonic acid (from one mole of Busulphan) thus generated, titrated with 0.1 N sodium hydroxide employing phenolphthalein as indicator. Hence, the equivalent weight of busulphan is 123.145 g. Therefore, each millilitre of 0.1 N sodium hydroxide is equivalent to 0.01232 g of busulphan. 

The Beckmann rearrangement of oximes to produce amides is promoted by perrhenate ions under phase-transfer catalytic conditions, in the presence of trifluoro-methanesulphonic acid in nitromethane [6]. Under these conditions, the rearrangement reaction is frequently accompanied by the solvolysis of the oxime to the ketone. This can be obviated by the addition of hydroxylamine hydrochloride. No reaction occurs in the absence of the ammonium catalyst or with the O-acetyl oximes. 

Typical procedure for the cyclization of f-(aryltelluro)propenoyl acids with P2O . 7-Methoxy-4-oxo-4H-l-benzotellurinP 2-Carboxyethenyl 3-methoxyphenyl tellurium (1.20 g, 3.92 mmol) is added to a solution of 1 g of phosphorus pentoxide in 10 mL of distilled methanesulphonic acid and the resultant mixture is stirred at 20°C for 4 h. Saturated aqueous sodium hydrogen carbonate solution (250 mL) is then added dropwise, the mixture is extracted with three 50 mL portions of dichloromethane and the combined extracts are dried with anhydrous sodium sulphate, fdtered and concentrated. The residue is recrystallized from methanol. Tield 0.76 g (67%) m.p.l03°C. 

C(l) in 355 is in the oxidation state of an aldehyde or a ketone in 1-alkylated products. The necessary solvolytic attack of the enol carbamate double bond requires substoichio-metric amounts of a catalyst such as mercuric acetate or palladium chloride and one equivalent of acid (e.g. methanesulphonic acid) for binding the liberated diisopropylamine. 

The addition of phosphine to olefins is accelerated by acidic and basic catalysts. Under the influence of non-oxidising acids or Lewis acid such as, for example, methanesulphonic acid, benzenesulphonic acid, trifluoro-acetic acid or boron trifluoride phosphine is quickly added to olefins at pressures of 20-40 at, and temperatures of 30-60 °C. It is assumed that the reaction proceeds via a carbonium ion which is first formed thus ... 

Parallel work by Penczek and his co-workers (134) using esters of fluoro-methanesulphonic acid, e.g. Et-0S02CF3, to polymerise THF has shown that these initiators are more complex, polymerisations being characterised by a relatively slow initiation process. Rather interestingly, both kinetic data and independent 1HNMR studies indicate a further complication in that during polymerisation a polymeric ester species exists in equilibrium with a fully developed macroion. 

The work reported so far has concerned fibres spun from solutions of either (a) 5-6% polymer in PPA or (b) 10 % polymer in a mixture of 97,5 % methanesulphonic acid (MSA)/2.5% chlorosulphonic acid. The processing of PBT fibres from PBT/PPA dopes has however two advantages over spinning from PBT/MSA dopes. The... 

In both cases a dry-jet wet-spinning process is used employing coagulation baths of water or water/methanesulphonic acid. 

A convenient general method for the conversion of aliphatic and aromatic carboxylic acids into the corresponding peroxyacids involves reaction with 70 per cent hydrogen peroxide in the presence of methanesulphonic acid.33... 

Sodium borohydride with methanesulphonic acid is also a convenient and effective reductant for amides,208 and a general procedure is included in Expt 5.195. 

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