33 « 
Journal of Agricultural Research 
Vol. XXVI, No. 8 
products of phloroglucin; that, so far as could be determined by means 
of the spectroscope employed, the constituent of rancid fats responsible 
for the Kreis test forms the same condensation product with phloroglucin 
as does the compound that results from the interaction of acrolein and 
hydrogen peroxid; and that the Kreis test, when followed by a spectro¬ 
scopic examination, is a valid index of rancidity in cottonseed oils, 
although of doubtful significance in this connection when the spectro¬ 
scopic examination is omitted. 
It remains to determine the chemical constitution and physical prop¬ 
erties of this compound formed by interaction of acrolein and hydrogen 
peroxid, and whether or not it occurs as such in rancid fats or is first 
liberated under the influence of the concentrated hydrochloric acid used 
in making the Kreis test. In the interest of brevity, this substance, 
formed by interaction of acrolein and hydrogen peroxid and giving a 
red color in the Kreis test, will be referred to hereafter as Substance K. 
REACTION BETWEEN ACROLEIN AND HYDROGEN PEROXID 
The reaction between acrolein and hydrogen peroxid is apparently not 
described in the literature. In the study of this reaction it seemed 
important, first of all, to determine whether it is the double bond or the 
aldehyde group of the acrolein that is involved in the formation of sub¬ 
stance K. Oxidation of the aldehyde-group would be indicated by the 
loss of aldehydic functions, or the acquisition of acidic functions, and 
could probably be effected by oxidizing agents other than hydrogen 
peroxid. These questions were examined in the following experiments: 
(a) A small amount of acrolein solution in a test tube was treated 
with an excess of N/io potassium permanganate solution in presence 
of a small amount of dilute sulphuric acid. The pink color was dis¬ 
pelled by adding the required amount of dilute oxalic acid solution. 
On testing a few drops of the resulting solution with phloroglucin-hydro- 
chloric acid no red color was obtained. 
(b) According to Beilstein’s “ Handbuch der Organischen Chemie ’' (2, 
v . 2, p. 389 ), acrolein is oxidized to acrylic acid by the action of freshly 
prepared silver oxid in the presence of light. 
Ten gm. of freshly prepared silver oxid were suspended in a solution 
of 10 cc. of acrolein in 100 cc. of water, and the mixture was exposed in a 
west window for several days. Acid formation had occurred, as shown 
by the effervescence that took place when sodium bicarbonate was added. 
The acrylic acid was lost by accident at a subsequent stage of the experi¬ 
ment, however, and could not, therefore, be thoroughly identified. 
Absence of substance K was indicated by failure of the acid solution 
to respond to the Kreis test. Some unchanged acrolein remained in 
solution, as indicated by the odor and by a positive test for aldehydes 
with decolorized fuchsin. 
(c) A purchased sample of acrylic acid, bearing the Kahlbaum label, 
was tested with phloroglucin-hydrochloric acid, both with and without 
the previous addition of hydrogen peroxid, a negative test being obtained 
in each case. 
From the above-described experiments it would appear that substance 
K is not acrylic acid, and that the reaction leading to the formation of 
substance K is not brought about by oxidizing reagents in general, but 
depends upon the chemical nature of peroxid oxygen in particular. 
