QUININE ESTERS OF PHENYLARSINIC ACID DERIVATIVES. 33 



precipitate of quinine. The solubilit}'^ in organic solvents corresponds 

 exactly with that of the other ar}'larsinic acid qninine esters. In order 

 to prove whether any reduction of the arsinic group had taken place 

 0.5 gram of the compound was dissolved in 5 cubic centimeters of dilute 

 hydrochloric acid ; the titanic acid test was negative, but became positive 

 and remained so on the addition of two drops of a 2 per cent hydrogen- 

 peroxide solution.^® 



Amongst the other drugs which were tested the following may be mentioned: 

 1. An extract of the stem of Tinospora reticulata Miers, macahuhay}'' Although 

 the plant has an exceedingly bitter taste and is used for various medicinal 

 purposes, neither Bacon nor others who worked with it have been able to find 

 any physiologically active substances. There were 170 grams at my disposition; a 

 few tests with the material proved that whilst the sap of a fresh cut is exceedingly 

 bitter, the latter taste disappears entirely in ten to twenty minutes when a 

 relatively thin slice is exposed to the air. This change is due to a rapid oxidation 

 which the very unstable bitter substance undergoes, since a test proved that it 

 does not take place, or at least takes place much more slowly in an atmosphere of 

 carbon dioxide. This fact is not mentioned in the former note" on macabuhay, 

 and it may have been overlooked during the preparation of the extracts. "If drying 

 did not effect the bitter taste," it probably was done in a specific way, instead 

 of crushing the material and boiling it with water. In my work the stems 

 were cut in slices under water, both were filled in a bottle up to the neck and 

 warmed for several hours on the water bath. The solution was then filtered and 

 evaporated in an atmosphere of carbon dioxide with a reduced pressure of 30 

 millimeters. A few drops of the solution added to dilute mercury potassiiun- 



" Since the yield of this ester, calculated upon the weight of pamidopheny- 

 larsinic acid, is so poor and the materials so expensive, the following method 

 [Ber. d. deutschen chem. Ges. (1884), 17, 2661), for preparing a corresponding 

 ester is under way: 



from (a) CfiHs-N (CH3) ^- and CI -CHj-COOCaHg 

 or (6) CgHs NH • CH3 and CI • CH^ ' COOH. 



2. It is expected that CgHj •ISr< CH^ -COOC H '^^'^^^ ^^^^^ ^^*^ arsenic chloride, 

 as dimethyl and diethyl amidobenzol very easily do without heating and with a 

 good yield, forming AsClz • CeH^ • N < ^g^ ^^^^ ^ This ester can be saponi- 

 fied, and then esterified with quinine. 



Preliminary experiments showed that the first intermediate product, methylphe- 

 nylglycin ethylester is formed in very good yield when the two compounds are 

 heated in a xylol bath to 136° for eight to nine hours; no carbon dioxide whatever 

 is given off at this temperature. 



0.2685 gram substance gave 0.0634 gram MgoAsjOj. 



Calculated for CgHasNaOeAs t?^„„a 



(CsoHosNoO . CO2 . CH3 . HN . C6H4 . ASO3H2) J? ppnt 



Per cent. I"^'^ ceui. 



As=12.00 ^ 11.4 



"Bacon, This Journal (1906), 1, 1030. 



" Ibid. 



101334 3 



