The Sodium Nitroprusside Reagent Il-A
Solvent Modification
Recently, we reported an improved classification test for aliphatic and my1 amines utilizing the sodium nitroprusside reagent.' The solvent system for the reagent was 80%DMS0/20% water-a combination which dissolved the amines, the nitroprusside, and the zinc chloride catalyst quite well, hut which presented other prohlems in terms of the unique physiological properties of DMSO and its so1utions.z We have been testing a large number of solvent systems to circumvent this situation; unfortunately, no simple two solvent system (one of which must he water, present in 20% hy volume) gave the same favorable solubility characteristics as DMSO. In examining various combinations of three solvents, we have found a system with solvent properties at least as good as DMSO, but without the detrimental side effects. This combination, 60% tetrahydrofuranl20% ethanol/20% water, has two additional benefits: first, the solution may he made 0.15 M in sodium nitroprusside, which gives more intense colors mare rapidly than a 0.13 M solution; and the second, the reagent seems to decompose much more slowly than when DMSO is used. with 2ffilr catalyst
Without catalyst Rimini Test deep red Allphatlc Z0 deep red 3 O . m mlor change 1-
lo grwn or no color
change Aromatic Z0 no color change 3O no colw change
Simon Test
Rimini Test
Simon Test
red-nge deep blue no color change or pale red red or no colw change
... ...
... . ..
no color change ppt forms deep red
no color change ppt forms deep red
no colw change a pale
deep red
blue or purple
orange no color change
orange to green
mange to green
Srastr ww Mm m l h l p L M M sample. CDmmerciai m e s dtadary aliphatic a m i m contah nmficant qwrnies d prinrvy an6 semndary amlnes and onen give mioieading coiao due m me asnsltlvny of me tart.
Experimental Sufficient sodium nitroprusside is dissolved in a mirturp of6Oso tetrahydn,furan/209o ethanol 20% n,ater to make the final solutim 0.15 M in nirroprusuide.'l'he reagent should beatored in the refrigerator to prevent dsumnpositicm, usin[: small amounts hum a dropping hotrlpai needed. Betawe 01 the enhanced soluhilitier of high molrcular weight ammes in rhe solvent system, we now recommend all tests he run utilizing the modified nitroprusside reagent. The tests are run as previously descrihed1; first, without the ZnC12 catalyst; then, if no positive results are obtained, with the catalyst. The following colors are observed, generally within one minute (see table). ---...m-.~~..,~..-.,-~-m..~..,,-...~.,-..-..~.~~~~.-.,-.,~.~..-....--~-.,~~,~~~
~
%Seefor example: "Dimethyl Sulfoxide Technical Bulletin," Crown Zellerhach Corporation, Camas, Washington, 1966, p. 23; Brown et al., J. Pharm. Pharmacol., 15,688 (1963); Wilson et al., Toxical. Appl. Pharmacol., 7,104 (1965). Herbert A. Lehman College City University of New York Bronx, New Yark 10468
Charles M. Dougherty Reuben L. Baumgarten Maria Markowska York C. Battey
Volume 55, Number 5, May 1978 / 341
