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sides in a discrete band, the center of which varies from Ri 0.33 to 0.40. Another band a t approximately Rr 0.57 corresponds to the free base and the sulfadiazine is a t 0.M;. The 0.40 fraction is eluted with water arid after lyophilizing rechromatographed on 2 sheets of filter paper with 60(+; npropanol in water in the presence of a beaker of 1 -If NH40H. The cornpound shows an Xi of approxiiiiately 0.65. X third chromatographing of tlie cornpound for 8.1 hr. a t room temperature with the organic phase of a mixture of n-l~utanol,acetic acid and water in the voluine proijcjrtioris of 4:1 : 5 allowing the solvent to run off the paper removes carbohydrate impurities. Assigning a migration value of 1.0 to D-ribose, the pentoside moves t o 1.19. ,-. 1 h e resulting cornpound rernains as a single orcinol-reacting, diazotizable, non-acetylatable amine through chromatography with a wide variety of solvents. In seven solvents the movement of the pentoside on paper is slower than that of the ca.rboxaniide. The movement of the conipouiid on paper and its analysis precludes its containing a phosphate ester. This carboxamide compound shows a niaxiniuin absorption a t about 267 mp a t p H 7 with a curve closely similar to that of the free base. Analysis of the imidazolecarboxarnide and pentose moieties of the riboside in terms of ultraviolet absorption maximum, diazotizable amine3 and orcinol reaction shows these relative molar ratios
a
Density 267 r n p
Diazotizable amine”
I’entoseb
1.17
1 . CJO
1 .oo
Standard: 4-NH4-j-iInidazolccarboxalnide hased
oii
of 1.27 X IO4. * Method of W. Mejbaurn,’O hcatiiig 4fl miii. ; standard, recrystallized D-ribose.ll mp
’14ie variation froin 1: 1 : 1 may be ascrihcd in part to the probable difference between the ultraviolet extinction coefficients of the free base and tlic riboside. Hydrolysis of carboxamide riboside with 0.3 AV hydrochloric acid 30 min. a t 100” liberates the free carboxamide as demonstrated by chroniatographiiig the hydrolysate with four solvents and coniparing the R1 values, ultraviolet absorption and diazotization reaction of the base which is formed with that of the authentic iiriidazolecarboxaiiiidr. Alcid hyclrolysis liberates an aldose-reacting sugar which tentatively may be considered to be ribose. Using papcr chromatography with four solvents, the sugar corresponds to D-ribose rather than arabinose, lyxose, or xylose and shows a pink color with aniline phthalate reagent. l 2 The absorption spectrum of the Bial orcinol reaction product of the riboside corresponds closely to that of the aldopentoses. ’The nature or positioii of the riboside linkage is not cvrtaiiily defincd. Sincc clilutc acid effccts hydrolysis o f tlie glycosidic linkugc and since the tiltra\ iolel ahsorptioii speclrurii oc thc riboside is silililar t o tha,t of the free basc, i t is assunicd that thc rilmsc ISattached to the nitrogen which mould correspond to the niiniher 9 position in the purine.13 l - X m . ,
I O ! 1%’. AIcjbaunt, L . phy.riol. L.,,c-~?I., 268, 117 !I939). ~,11)L. Berger, U. V. dolmbseu. 1:. i.eonarri, I.. Wrnis and J . Lee, J . O r # . Clicm., 11. Q 1 (1946). ‘12) ,i. 11. Partridge. A-iiturc, 164, 4 4 3 11049: :1.’
