[Reprinted from The Journal of Analytical Chemistry, 
Vol, IV, Part i. January, 1890.] 
AN EXAMINATION OF FUSEL OIL. 
By J. H. Long and C. E. Linebarger. 
A few analyses of fusel oil are given in the literature, but of 
these none, as far as we know, have been made of samples of 
American origin. 
The analysis most frequently quoted is that by Rabuteau, while 
less complete results are given by others. We have attempted to 
determine, approximately, the composition of a sample of fusel oil 
obtained at a Chicago distillery, and give the results below. 
Most of our American distillers use corn as the chief substance 
to be converted into mash, with smaller amounts of other grains, 
and it would therefore naturally be expected that a somewhat 
different product would be obtained from that produced by a 
mash of potatoes or beets. 
For the purpose of our investigation, several gallons were 
secured and submitted to distillation, and the other tests given 
below. This oil had been separated from alcohol fermented dur- 
ing the spring season, by the longer or 72 hour period allowed by 
law. When brought to the laboratory, it was saturated with 
water and held some in suspension. This was allowed to settle 
out, leaving a perfectly clear liquid, of which the specific gravity 
was found to be .810 at 20° C. For one series of tests, two liters 
of this clear oil was dried as thoroughly as possible by shaking it 
with anhydrous copper sulphate. It was found that all of the 
water could not be removed in this way. The liquid poured from 
the sulphate was then treated with dry potassium carbonate, the 
mixture being kept at a temperature of 40-50° C. for two hours 
on several successive days. The supernatant liquid was then 
poured off and distilled nearly to dryness from a retort. Of the 2 
EXAMINATION OF FUSEL OIL. 
distillate thus freed from the water and purified, a liter was taken 
for a preliminary fractionation. After three complete fractiona- 
tions the following approximate results were obtained from this 
sample : 
80- 90° 17 cc. 
90- 95 8 " 
95-105 15 " 
105-115 30 " 
115-120 55 " 
120-125 95 " 
125-130 240 " 
130-133 515 " 
Loss and residue 25 " 
The general character of the liquid being shown in this way, 
larger quantities were operated upon, from which we finally 
secured several liters boiling above 130°, and correspondingly 
smaller amounts at the lower temperatures. 
Attention was first turned to the portions with higher boiling 
points, and at the outset the specific rotation was found for several 
different samples. For the fractions boiling at the given tempera- 
tures, we found in a 400 mm. tube (Schmidt & Haensch, large 
model instrument) at 250 C. 
Fraction. ao d25 [a] 
120-125° -3-37° -8075 -1-043 
125-128 -3.94 .8092 -1.217 
128-130 -3.86 .8110 -1.189 
130-133 -3'59 -8ii5 -1.106 
From this it is evident that notwithsanding all our precau- 
tions, a considerable portion of the active amyl alcohol passed 
over below 1250 C., with other portions, and this was observed 
in samples distilled at several different times. An attempt was 
made to separate the active and inactive alcohols in two of the 
portions. For this purpose, over a liter of the portion boiling 
above 130° was treated with sulphuric acid according to the Pas- 
teur method, the mixture of acid and alcohol being allowed to 
stand for a week, with an occasional gentle heating on the water 
bath. The barium amyl sulphate was formed in the usual manner, 
and crystallized repeatedly in fractions, the less soluble portion 
being finally reserved. This was converted into the sodium salt EXAMINATION OF FUSEE OIL. 
3 
by treatment with sodium carbonate. The sodium salt was 
distilled with sulphuric acid, producing an alcohol which after 
washing and drying showed a constant boiling point of 1310 and 
a specific gravity of .8116 at 250. Only 30 cubic centimeters of 
the alcohol was obtained in the process. When examined in a 
100 mm. polarization tube, it showed a rotation aD - -. 180, from 
which the specific rotation [a] = -.222°. This is a smaller value 
than usually given, suggesting, probably, comparative freedom 
from the active alcohol. An equal degree of success was not ob- 
tained in the separation of the latter in a state of purity. For 
this a liter boiling below 128° was treated in the same manner as 
before, but only a small amount of alcohol was secured from the 
more soluble barium amyl sulphate. When washed and dried, 
the volume amounted to about 20 cc., and showed a boiling 
point 128-129° C. In the 100 mm. tube this gave a rotation 
aD = -3.50°, which is a much smaller rotation than reported by 
Ley, LeBel, and others. 
The preparation of this alcohol from the more soluble barium amyl 
sulphate is practically a very tedious matter, and it is evident that 
in our experiments the crystallizations were not carried far enough. 
But enough was done to show that both alcohols were present in 
quantity in the fusel oil. From a preliminary examination of the 
oils obtained from other sources, it appears that the amount of 
the active alcohol present must in some cases be quite small, as 
the specific rotations of fractions boiling from 128-133° were often 
less than [a] =-.75°. 
In the distillation of the dried crude oil in quantity, numerous 
small fractions could be separated between 85-105°, and a con- 
siderable portion below 85°. 
150 cc. of this was converted into bromine compounds in the 
usual manner, by treatment with red phosphorus and bromine, 
and the product obtained, amounting to nearly 100 cc., was 
washed, dried, and carefully fractioned. We found in this way 
over 50 cc. boiling near 40° C. This fraction by subsequent tests 
was found to consist essentially of ethyl bromide. 
35 cc. was obtained boiling from 61-62° C., which pointed to 
the presence of isopropyl alcohol in the liquid brominated. Prac- 
tically nothing was found boiling above these limits. 4 
EXAMINATION OF FUSEL OIL. 
From the boiling points of the alcohols taken, it would be pos- 
sible for butyl alcohol to be present, and this has been re- 
ported as a constituent of fusel oils. But we did not succeed in 
isolating a bromide fraction corresponding to it. The bromide is 
said to boil at 72° C., but only a very minute quantity was ob- 
tained about 62°. 
It appears, therefore, that the lower alcohol fractions consist 
essentially of the ethyl and isopropyl compounds. 
It was stated above that no large fraction of alcohol was ob- 
tained between 85° and 105°. We took the fraction boiling be- 
tween 95-105°, and converted it into bromide as before. If nor- 
mal propyl alcohol existed in the oil, it should be found in the 
fraction taken, and as it is readily converted into a bromide, we 
should expect to find some of the latter compound boiling about 
71°. In the distillation of the mixed bromides resulting from the 
reaction, it at first sight appeared that only a trace boiled as low 
as 710, but after some little difficulty, we found that the mixture 
could be resolved into two portions, boiling between 70-73° and 
90-94°. That the lower portion actually consisted of normal 
propyl alcohol, was shown by the behavior of the product on 
saponification. 
The presence of a product boiling between 90-94°, would sug- 
gest that in the alcohol fraction brominated, along with the propyl 
compound, some isobutyl alcohol boiling normally at 108-109° 
must have been present. In order to gain more accurate informa- 
tion regarding the isobutyl alcohol apparently present, 150 cc. of 
the fraction boiling at 105-110° was taken and brominated. 
The product obtained after washing and drying amounted to 
60 cc., of which over 50 cc. boiled at 90-93°. An abundance of 
the isobutyl alcohol was therefore present in this fraction. It was 
suspected that the higher fractions, 110-120°, might also contain a 
not inconsiderable portion. They were subjected to treatment 
with phosphorus and iodine, the latter being added very gradu- 
ally, so as to avoid the loss complained of by Chapman and Smith 
{Joiirn. Ghent. Soc. 22, 153). 100 cc. boiling at 110-120°, and 
100 cc. boiling at 120-125°, were treated in this way. The yield 
was satisfactory. On purifying and fractionating the products, 
we found 65 cc. boiling at 121-122°, 20 cc. boiling at 128-130°, EXAMINATION OF FUSEE OIE. 
5 
and over 50 cc. boiling between 140° and 1450 C. Below 120° 
and between 1220 and 128° only very small amounts were found. 
On further fractionating the portion boiling at 140-145°, we found 
that most of it boiled at 143°, while a little boiled continually 
higher. It would appear, therefore, judging from the boiling 
points alone, that the fractions converted into iodides consisted 
chiefly of active amyl alcohol and primary iso-butyl alcohol with 
a smaller amount of normal butyl alcohol. 
It may appear singular that so large an amount of iodide with 
high boiling point was obtained from the alcohol boiling below 
125°, but it must be remembered that this fraction showed also a 
marked rotary polarization ; in fact, almost as great as with the 
fraction 125-130°. It is also possible that methyl propylcarbinol 
was present in the fraction 120-125°, as its boiling point is only 
slightly below 120°, and the boiling point of the iodide 145-146°, 
but no attempt was made to separate it. 
The alcohols of high boiling point seem to pass over readily 
with those of lower, but from an experiment carried out by us, it 
appears plain that the fractions boiling above 1250 are but slightly, 
if at all, mixed with lower alcohols. We converted about 200 cc. 
of the fraction 125-130° into iodides, and found that of the puri- 
fied product, only a very inconsiderable portion passed over below 
140°. 
We have made no attempt to find alcohols or other bodies, 
present in minute quantity only, in the fusel oil examined, but 
have sought, rather, to show the characteristic features of the oil. 
From the foregoing, it appears that it consists chiefly of the active 
and inactive amyl alcohols, probably three-fourths being made up 
of these bodies. The next most important substance appears to be 
isobutyl alcohol, and after that isopropyl and ethyl alcohols, with 
traces of normal propyl and normal butyl alcohols. 
Only a very inconsiderable portion of the original fusel oil 
possessed a higher boiling point than 133°. Part of this residue 
consisted of alcohols, and a part of bodies of an ethereal nature, 
as shown by simple saponification tests, but the amounts con- 
cerned were too small for identification. 
Chicago, Nov., 1889.