Researches on the constitution of physostigmine. Pt. I[-II] / by Arthur H. Salway.

  • Salway, Arthur Henry.
Date:
1912-1913
Catalogue details

Licence: In copyright

Credit: Researches on the constitution of physostigmine. Pt. I[-II] / by Arthur H. Salway. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    oxidation products, and accordingly these substances have now been investigated. Eseroline was found to be a strong base, which yields salts with only one equivalent of an acid. It contains one methyl group attached to nitrogen, and forms an additive product with one molecule only of methyl iodide, being therefore a tertiary base. Eseroline also possesses acidic properties, since it dissolves in aqueous sodium hydroxide without change in the absence of air. The state of combination of the oxygen atom in eseroline could not be determined with certainty, since the base did not react with semicarbazide or diazomethane, whilst attempts to prove the presence of a hydroxyl group by means of acetic anhydride led to indefinite products. Eseroline, in the presence of alkalis, was found to absorb 5 atoms of oxygen per molecule of the base. The first product of the oxidation, rubreserine, is formed by the rapid absorption of two atoms of oxygen. This compound, the formula of which has now been definitely established as C13Hlc02N2, pos- sesses both basic and acidic properties, and, unlike eseroline, readily reacts with diazomethane. If the oxidation is allowed to proceed further with free access of air or oxygen, the red colour of the rubreserine changes to yellowish-brown, with the formation of an indefinite mixture of degradation products. When the oxidation, on the other hand, proceeds slowly with a limited supply of air, the red solution gradually changes to an intense blue. This blue colour is due to the presence of a compound termed eserine blue, which has now been isolated in a pure state. It is a base which has the formula CjyH^OoNg, and yields salts with two equivalents of an acid. Its formation appears to be due to the condensation of eseroline with a degradation product of this base. In order to obtain further information regarding the structure of physostigmine, many attempts were made to resolve it into products having a less carbon content than that of eseroline and rubreserine. Hofmann’s method of degradation by exhaustive methylation was applied to eseroline, but found impracticable on account of the ease with which eseroline methiodide is oxidised in the presence of alkalis, whilst the vigorous oxidation of physo- stigmine aud eseroline under varied conditions yielded no definite compound. On the other hand, distillation of physostigmine with zinc dust gave a product which consisted of 2-methylindole, together with a small proportion of the isomeric 1-methylindole, C >CMe, The formation of indole derivatives by the
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