Methanesulphonates

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). 

Kelly DP, SC Baker, J Trickett, M Davey, JC Murrell (1994) Methanesulphonate utilization by a novel methy-lotrophic bacterium involves an unusual monooxygenase. Microbiology (UK) 140 1419-1426. 

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 phenothiazines, chlorpromazine and promethazine, have been described as inhibitors of CCU-induced lipid peroxidation at relatively high concentrations in rat liver microsomes (Slater, 1968). Structural modifications of chlorpromazine were undertaken to try to increase antioxidant activity and maintain molecular lipophilicity. The 2-N-N-dimethyl ethanamine methanesulphonate-substituted phenothiazine (3) was found to be a potent inhibitor of iron-dependent lipid peroxidation. It was also found to block Cu -catalysed oxidation of LDL more effectively than probucol and to protect primary cultures of rat hippocampal neurons against hydrogen peroxide-induced toxicity in vitro (Yu et al., 1992). 

Bromocriptine mesilate is 2-bromo-a-ergocryptine methane-sulphonate or 2-bromo-12 -hydroxy-2,-(l-methylethyl)-5 -(2-methylpropyl-5 a-ergotaman-3, 6, 18-trione methanesulphonate or Bromocriptinum (INN). It is the active ingredient in Parlodel dosage forms. 

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). 

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