The constitution of pilocarpine / by Hooper Albert Dickinson Jowett.
- Jowett, H. A. D. (Hooper Albert Dickinson)
- Date:
- [1900-1905]
Licence: In copyright
Credit: The constitution of pilocarpine / by Hooper Albert Dickinson Jowett. Source: Wellcome Collection.
22/86 page 591
![The persistently low figures obtained for the carbon in these analyses cannot be explained, although it is possible that the large amount of bromine present may have some effect on the combustion. The acid is dextrorotatory, a determination of its specific rotation in alcoholic solution giving the following result : a}f = +1-6°; 1= 1 dcm.; c=6'544; [a]Jf = +24*4°. The determination of the basicity of this acid proved unexpectedly to be a most difficult problem. The first attempts were made by titration with cold and hot caustic alkali in the usual manner, and results were obtained indicating a tetrabasic acid. On examining the solution, it was found that the acid had been decomposed and sodium bromide formed. Attempts to prepare the barium salt were unsuccessful, as even with barium carbonate the acid was decomposed. The only way by which an approximate titration could be made was as follows: 0*2 gram of acid was dissolved in alcohol and 5 5 c.c. of deci- normal sodium carbonate were added; the liquid was found to be distinctly acid to litmus. Five c.c. of alkali were then added, and as the liquid was now distinctly alkaline, it was boiled and rapidly titrated back with decinormal acid ; the total amount of decinormal alkali required was thus found to be 7‘0 c.c. C11H1404N2Br2, if monobasic, requires 5*0 c.c. The acid is therefore certainly not dibasic, and, as it acts towards sodium carbonate as a monobasic acid, the excess of alkali used may be due either to slight decomposition of the acid, or to the effect of the lactonic grouping originally present in fsopilocarpine. Attempts to make the silver and ammonium salts were unsuccessful. The basicity was finally determined as follows. About 0*5 gram of acid was dissolved in slight excess of ammonia and then left in a partly ex¬ hausted desiccator over sulphuric acid for 18 hours. The solution,, which was perfectly neutral to litmus, was precipitated with platinic chloride, the mixture evaporated to a low bulk on the water-bath^ alcohol added, and the platinum salt ignited and weighed. 0-4838 acid gave 0-1192 Pt. Pt = 24-63. CnHi404N2Br2 requires Pt = .24’74 per cent. Dibromofsopilocarpinic acid is therefore monobasic. Action of Reducing Agents on Bibromoisopilocarpinie Acid. 0) With Sodium in Amyl Alcohol Solution.—This method having given good results with dibromofsopilocarpine, was first tried. One](https://iiif.wellcomecollection.org/image/b30598667_0022.jp2/full/800%2C/0/default.jpg)
