DicycZohexyl

For ethyl alcohol, two volumes of dicycZohexyl are mixed with one volume of the alcohol, a thermometer is introduced, and the mixture heated until it becomes clear. The solution is then slowly cooled, with constant stirring, and the temperature is determined at which the opalescent solution suddenly becomes turbid so that the immersed portion of the mercury thread of the thermometer is no longer clearly visible. This is the C.S.T. The water content may then be evaluated by reference to the following table. 

We carried out a great deal of work on the relationship between the above physiological effects and chemical constitution, and it was shown conclusively that the more potent compounds were those derived from secondary alcohols.3 Thus, for example, di-isopropyl phosphorofluoridate is very much more potent than diethyl phosphorofluoridate or di-ra-propyl phosphorofluoridate and the toxicity of the dicycZohexyl ester is of a high order (L.C. 50 for mice, rats and rabbits was 0-11 mg./l.). Din-butyl phosphorofluoridate had low toxicity and produced only feeble... 

Whereas diethyl phosphorofluoridate was hydrolysed in aqueous solution in about 4 hr., the di-isopropyl ester required 72 hr. for complete hydrolysis, and small quantities could be steam-distilled. DicycZohexyl phosphorofluoridate was very stable, and vigorous shaking with water did not produce any appreciable hydrolysis. It was hydrolysed by boiling water only after several hours. When stirred vigorously with 2 per cent sodium hydroxide solution at 28-5°, the time taken to bring about hydrolysis according to the equation... 

The compound was therefore much less toxic than the corresponding unsubstituted dicycZohexyl phosphorofluoridate. 

Although the pharmacologically important dicycZohexyl phosphorofluoridate is readily obtained by the action of phosphorus oxydichlorofluoride mentioned just above, it is not... 

An important application of the critical solution temperature is to the determination of the water content in such substances as methyl and ethyl alcohols. Here the system is usually the alcohol and a hydrocarbon, such as n-hexane or dicycZohexyl the water is, of course, insoluble in the hydrocarbon. Thus, the methyl alcohol - cyclohexane system has a C.S.T. of 45-5° and even 0-01 per cent, of water produces a rise of 0-15° in the C.S.T. The experimental details are given below. 

The writer would point out that the above conclusions were reached only with D.F.P., and it may well be that the physical properties of some other phosphorofluoridate might render it more suitable for this type of investigation. It may be noted, for example, that dicycZohexyl phosphorofluoridate, which is stable to hydrolysis (p. 52), has not yet been tried clinically. 

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