September 14, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
201 
MONOBROMATED CAMPHOR. 
BY JOHN M. MAISCH. 
Monobromated camphor was discovered by Tli. 
Swarts, in .1801,* who obtained it by heating j 
Laurent’s bibromide of camphor (C 20 H J6 d 2 Br 2 ), in a 
sealed tube, to 100° C. After several hours, the 
colour of bromine disappears, hydrobromic acid is 
formed, and a brownish oil, which gradually becomes 
crystalline, and contains the new compound. If 
bromine and camphor, in the proper proportions, are 
heated in a sealed tube for three hours, in the water- 
bath, the same compounds are formed. The crystal¬ 
line mass is washed with water, recrystallized from 
alcohol after treatment with animal charcoal, washed 
with an alcoholic solution of potassa, to free it from 
hydrobromic acid, then with much water, and finally 
recrystallized from a mixture of alcohol and ether. 
After the publication of Professor Deneffe’s ac¬ 
count! of the medicinal properties of this compound, 
I attempted to prepare it, at the request of Professor 
Wm. A. Hammond, of New York, and followed at 
first the above process, not being aware at the time 
of the researches of W. H. Perkin, to which I shall 
presently refer. 
Laurent prepared bibromide of camphor by dis¬ 
solving camphor in cold bromine, and freeing the 
crystals, which form after some time, by rapid 
expression between bibulous paper. Gerliardt states 
that these crystals decompose on the application of 
heat into bromine and camphor, which, however, 
has been refuted by Perkin. I can confirm this ob¬ 
servation of the latter, and have also satisfied myself 
that Laurent’s statement, that camphor crystallizes 
unaltered from its warm solution in bromine, is in¬ 
correct, as the copious evolution of hydrobromic acid 
proves. 
Monobromated camphor is formed according to 
the following equationC 20 H 16 O 2 +2Br= C 20 H l5 BrO 2 
-|-HBr. If prepared in a closed tube, it is evident 
that at all stages of the process the pressure must be 
very considerable; at first, in consequence of the 
volatile nature of both camphor and bromine, and 
subsequently on account of the presence of the 
gaseous hydrobromic acid. When operating on a 
small scale, with suitable precautions, there was 
little difficulty in obtaining the compound. But 
when using several ounces of bromine at once, the 
tubes were usually shattered, and it became evident 
that this process could not be used with advantage on 
a large scale.. The observation that on slightly 
heating the mixed camphor and bromine, the heat 
increases after the withdrawal of the fire, and the 
vessel contains considerable quantities of hydro¬ 
bromic acid, suggested the idea that the camphor 
might be bromated without using closed tubes, 
simply by digesting the bibromide at an elevated 
temperature, or by allowing bromine to act upon 
camphor at a higher temperature, with the precau¬ 
tion to return into the retort any bromine and bro¬ 
mide of camphor which might be volatilized, while 
the disengaged hydrobromic acid might be absorbed 
by a solution of an alkali. 
The neck of the retort was raised and connected 
with a reversed Liebig’s condenser, which being 
found unnecessary, was afterwards substituted by a 
1862 ’ 46 o 1S ^ U * : ’ 18(32-63. Kopp and Will’s ‘ Jahresbericht/ 
t American Journal of Pharmacy, 1872, 84. 
Third Series, No. 116. 
glass tube.. If the reaction was not allowed to be¬ 
come too violent in the beginning, no bromine vola¬ 
tilized, but a yellowish-brown substance condensed 
in the neck, flowing back into the retort like oil; 
gradually this became lighter in colour, and golden- 
yellow needles were observed in the upper part and 
neck of the retort after cooling. Whether these 
needles are a bromide of camphor or a hydrobromate 
of monobromated camphor has not been determined. 
The heat was raised after the first reaction was 
over to a temperature varying in the different ex¬ 
periments between 100° and 132° C. (2128 and 270° 
F.). The higher temperatures were' found better 
adapted for rapidly generating the monobromated 
camphor; but in all cases a considerable quantity of 
an oily compound was found in the mother-liquor 
from which the monobromated camphor had crys¬ 
tallized. This oil contained more or less of the latter 
compound in solution, which was obtained by re¬ 
ducing it to a low temperature. The mother-liquors 
containing the oil, in consequence of the frequent ap¬ 
plication of heat, turned black and left, after the 
evaporation of the menstruum, a black oil, which, in 
the course of several weeks, became granular; the 
oil still present in the magma could not be removed 
by different solvents which would also dissolve the 
crystallized granules. On being expressed between 
bibulous paper a grey solid mass was left behind, 
which was permanent in a temperature of 32° C. 
(90° F.), but became soft and oily when exposed to 
the direct heat of the sun, which was above 38° C. 
(100° F.) . This compound is not monobromated 
camphor; its composition lias not yet been inves¬ 
tigated. 
Attempts to separate the whole of the monobro¬ 
mated camphor from this oily substance by sublima¬ 
tion were not successful; the whole mass, after a 
slight white sublimate had been obtained, near 132° 
C. (270° F.), turned black, and after cooling some¬ 
times did not separate any crystals, but remained 
liquid and oily, while at other times dark blackisli- 
grey crystals were obtained. 
It was noticed that the mother-liquors of the first 
crystallizations of monobromated camphor contained 
considerable hydrobromic acid, which also adhered 
to the crystals. The endeavour to remove it by 
washing with hot water was not entirely successful, 
and necessitated the drying of the solid portion pre¬ 
vious to recrystallization from alcoholic solvents. To 
avoid these difficulties, the removal of the acid by 
means of a weak alkali (carbonate of lime) suggested 
itself, and, instead of alcohol, petroleum benzine was 
experimented with as a suitable menstruum for re- 
crystallization. 
The first crystallizations, whether obtained from 
alcohol or from petroleum benzine, contained notable 
quantities of the oily matter mentioned above, in 
consequence of which bromine was liberated on ex¬ 
posure to the light. The greatest portion of this oil 
could be removed by pressure between bibulous 
paper, and the remainder by subsequent recrystal¬ 
lization ; but the loss of monobromated camphor was 
considerable, owing to its being partly absorbed by the 
paper with the oil, and to its remaining to some extent 
in the mother-liquor with that portiomof the oil not 
absorbed by the paper. Gasoline or petroleum 
naphtha was found to be a good solvent for this oil, 
and to dissolve at the same time much less of the 
monobromated camphor than alcohol, ether, or pe¬ 
troleum benzine. Accordingly, when the crystals as 
