76 
CHEMISTRY: JOHNSON AND BROWN Proc. N. A. S. 
We have now inaugurated in the Sheffield Chemical Laboratory an 
extended research dealing with the application of catalytic methods of 
reduction and oxidation to pyrimidine, purine, hydantoin and glyoxaline 
compounds, and in this paper, the first of our series, we record the results 
obtained by direct reduction of the pyrimidine uracil with colloidal plat- 
inum. 
The process which we have applied successfully for the reduction of 
uracil is based on the method of reduction developed by Skita. 3 This 
investigator used both colloidal palladium and platinum in his work and 
utilized as a support for his colloidal metal gum arabic. He showed also 
that his colloidal metals were active in both acid and alkaline solutions. 
In our process we make use of a 10% solution of hydrochloroplatinic 
acid for preparation of our colloidal metal, and precipitate the activated 
metal in an aqueous solution of gum arabic by reduction with hydrogen 
gas without first introducing any colloidal metal to promote the reduc- 
tion of the platinum chloride solution. Skita used in many cases a pro- 
moter to stimulate the formation of colloidal metal (Impfmethode). 
This was prepared by reducing platinum solution with formaldehyde in 
alkaline solution. 
At a pressure of two atmospheres uracil III is reduced nearly quantita- 
tively in aqueous solution to hydrouracil IV by action of hydrogen gas 
in presence of colloidal platinum. For example, when six grams of this 
pyrimidine were agitated in the reductor at a temperature of 75-85° C. 
and at a pressure of two atmospheres the reduction was complete at the 
end of seven hours, and almost a theoretical amount of hydrogen had 
added to the pyrimidine. The reduced pyrimidine melted at 272° C. 
and corresponded in all its chemical and physical properties with hydro- 
uracil prepared by application of Hoffmann's reaction to succinimide. 4 
It did not respond to Wheeler and Johnson's test for uracil. 5 We are 
now engaged in determining whether hydrouracil can be reduced still 
further by our catalytic method to the cyclic urea derivative of syn- 
trimethylenediamine V. 
NH 
— CO 
NH 
— CO 
NH 
— CH 2 
1 
CO 
CH — > 
1 
CO 
1 
CH 2 
1 
— > CO 
CH 2 
1 
NH 
II 
— CH 
NH 
1 
— CH 2 
1 
NH 
— CH 2 
III IV V 
From both a biochemical and a synthetical point of view the synthesis of 
hydrogenated uracils by direct reduction of the pyrimidine ring is a re- 
action of considerable importance. These reduced uracils bear a similar 
relationship to /3-aminoacids as the hydantoins do to a-aminoacids. A 
practical method of reducing uracil combinations, therefore, opens up a 
new method of synthesizing representatives of this important class of 
