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Chemical Library
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Chemical Library
RS
43
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BULLETIN OF THE UNIVERSITY OF WISCONSIN
Serial No. 991; General Series No. 775
CIRCULAR 7, SEPTEMBER, 1919 º:
WATER-SOLUBLE VOLATILE PRODUCTS
FROM PEPPERMINT
EMERSON R. MILLER ‘. . .9
The University of Wisconsin
Pharmaceutical Experiment Station
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Issued monthly by the University of Wisconsin at Madison. Wisconsin.
Entered as second-class matter July 11, 1916, at the post office at Madison, Wisconsin,
under the Act of August 24, 1912.
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s PREFATORY NOTE
At the request of the Office of Drug-Plant and Poisonous.
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Plant Investigations of the Bureau of Plant Industry, Depart-
ment of Agriculture, the Pharmaceutical Experiment Station
in 1917 began operations on an acre scale. In order to make.
such experiments possible, the Board of Regents of the Uni-
versity allotted the Station a tract of land known as the “Olin
forty” for the new Pharmaceutical Garden.
While the prime object of the Government was to enable its
expert to learn important economic lessons that fail to reveal
themselves when experimenting on the smaller scale hereto-
fore practiced, the Station Chemist availed himself of the op-
portunity to attack chemical, and more particularly, biochemical
problems that were impractical heretofore. Thus, the cultiva-
tion of an acre of American peppermint, and the distillation
of the crop toward the close of the season, made available suf-
ficient material for experimentation along new lines. The in-
teresting results of this first attempt are herewith reported by
the former chemist of the station. $
The scientific or biochemical significance of these results is in
no way marred by their possible economic importance. As will
be shown in a subsequent circular, the aqueous distillate of the
peppermint crop yielded an amount of cohobated oil about
equal to ten per cent of the oil originally separated; in addi-
tion, a liter of water-soluble material was obtained, and ex-
amined by Professor Miller. Inasmuch as the material har-
vested represents the first crop, (hence a smaller yield than may
be expected later), it becomes apparent that the oil yield per
acre can be materially increased. The yield of about a liter of
water soluble material shows that for a thousand acres of pepper-
mint a thousand liters or more of chemicals may be secured
which, heretofore, have been wasted.
— 4–
As already indicated, this preliminary study is but the be-
ginning of new lines of phytochemical research that are made
possible by cultivation on a larger scale. That still other sub-
stances than those reported in this preliminary survey are be-
ing lost in the ordinary steam distillation there can be little
doubt. As soon as time permits, their study will be begun.
As previously indicated the results recorded are those of the
cooperation between the office of Drug-Plant and Poisonous-
Plant Investigations, U. S. Department of Agriculture, and
the Pharmaceutical Experiment Station of the University of
Wisconsin.
THE DIRECTOR.
WATER-SOLI IBLE VOLATILE PRODUCTS
FROM PEPPERMINT
A large part of the aqueous distillate resulting from the
distillation of about 5,500 pounds of the fresh herb was re-
distilled as follows. The original distillate which separated
from the oil was distilled in a steam-jacketed still, the process
being continued until the new distillate measured about one-
fourth the volume of the original distillate. The portion re-
maining in the still was rejected. This process was repeated
several times as in the earlier cohobations the first part of the
distillate was decidedly milky, and an oily layer separated from
it.
A point was finally reached, however, when the first part
of the distillate was no longer milky, as before, but was clear
and formed no separate layer of oil. This was due to the fact
that the proportion of alcohol in the first runnings had in-
creased to such an extent as to make it a solvent for any oil
still present. But if the distillation was continued longer the dis-
tillate gradually became turbid as more and more water dis-
tilled. Usually any oil which now separated differed in odor
from the oil obtained earlier in the process.
Fractionation was now continued in a distilling flask over a
Bunsen burner. In each operation the distillation was stopped
when the residual liquid in the flask had become turbid and
separated a small amount of oil, but while the contents of the
receiver were still clear. By repeating the distillation a great
many times most of the water was separated and a small amount
of a reddish brown oil, having a “fusel oil” odor, was obtained.
The distillate which now came over below 80° measured about
1140 cc. In reaction it was alkaline to litmus and possessed
an odor suggesting both ammonia and fish brine. With Schiff's
— 6 —
reagent for aldehydes a pink color was quickly produced. It
readily reduced ammoniacal silver nitrate solution. Some of
the lower boiling portion when treated by the hydrochloric
acid-milk test gave a slight reaction for formaldehyde.
The presence of a primary amine was shown by the car-
bylamine test. * . .
To remove the bases the liquid was neutralized with hydro-
chloric acid and again distilled. The residue in the flask was
reserved for examination for bases.
In order to make a fairly good separation of the constituents
the liquid was repeatedly fractionated, collecting the follow-
ing fractions:
I. b. p. 68°–70°; dzoo 0.801
II. b. p. 70°–74°; dzoo 0.798
III. b. p. 74°–79°; daoo 0.819
IV. Residue, turbid, from which a few drops of
oil separated, having a “fusel-oil” odor.
Fraction No. I when heated with salicylic acid and sulphuric
acid produced a substance with a pronounced wintergreen, odor.
When oxidized with a heated copper spiral the odor of for-
maldehyde became very perceptible, and the oxidized liquid
responded decidedly to the hydrochloric acid milk test for for-
maldehyde.
When treated with anhydrous oxalic acid in the usual way
there was obtained a white solid, which, after recrystallization
from dilute alcohol, melted at 53°–54°. The melting point of
methyl oxalate is usually given as 54°. With ammonia this
white solid, in alcoholic solution, gave a white precipitate show-
ing the properties of oxamide. With sodium nitroprusside this
fraction gave slight color reactions for acetone. -
Fraction No. III when heated with acetic acid and sulphuric
acid gave very distinctly the odor of ethyl acetate.
With benzoic acid and sulphuric acid it produced the char-
acteristic odor of ethyl benzoate. -
Heated with iodine and sodium carbonate it yielded a yellow
solid with a pronounced iodoform odor, which after recrystal-
—7 —
lization from alcohol melted at 121°. The melting point of
iodoform is given as 119°–120°.
When treated in the usual manner with iodine and red phos-
phorus there was obtained a liquid boiling at 72°–74° and hav-
ing a specific gravity 1.82 at 20° and with an ethereal odor sim-
ilar to that of ethyl iodide. The density of ethyl iodide at 0°
is given as 1.975. The low specific gravity in this case is un-
doubtedly due to the presence of a small amount of alcohol.
Fraction No. II appeared to be mainly a mixture of methyl
and ethyl alcohols. •
The reddish brown oil obtained by fractionation of the dis-
tillate gave a fine color reaction for furfural, as, when heated,
its vapor turned aniline acetate paper a bright pink. Al-
though the amount of this oil was very small an attempt was
made to distill it. Only a few drops passed over below 140°
and the temperature rose rapidly to 162°. Not enough was ob-
tained for any satisfactory test. The whole was, however, oxi-
dized with chromic acid mixture, in order to see if any valerianic
acid could be obtained, but no further indication of the presence
of an amyl alcohol was shown.
Identification of bases. The residue containing the bases in
the form of hydrochlorides was evaporated to dryness and the
Solid washed several times with alcohol. This would effect a
separation of ammonia from any methylamine or dimethylamine,
since ammonium chloride is sparingly soluble in alcohol and the
hydrochloride of dimethylamine is readily soluble in alcohol.
The residue remaining after washing with alcohol was con-
verted into the chloroplatinic salt. After drying and igniting
to constant weight, it yielded 43.55 per cent metallic Pt. The
double salt of ammonia contains 45.90 per cent Pt.
From the alcoholic solution a chloroplatinic salt was obtained
which yielded 42.2 per cent metallic Pt.
The double salt of methylamine contains 41.83 per cent Pt.
Summary. From the results of this investigation it follows
that the aqueous distillate from oil of peppermint contains the
following:
1. Traces of formaldehyde.
2. A small amount of acetone.
Methyl alcohol.
Ethyl alcohol.
Furfural.
Ammonia.
Methylamine.
A small amount of one or more of the constituents of
fusel oil.
i
More than half of the distillate boiling below 80° consists of
ethyl alcohol.