September 21, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
221 
MONOBROMATED CAMPHOR. 
BY JOHN M. MAISCH. 
(Concluded from paejc 202.) 
To recapitulate tlie results of these experiments, 
before giving the process which, in my experience, 
is best adapted to obtain monobromated camphor on 
a more extensive scale for medicinal purposes, it may 
be stated that the process is divided into three dis¬ 
tinct operations: 1, the combination of bromine 
with camphor (bibromide of camphor), which takes 
place at the ordinary or slightly elevated tempera¬ 
ture, particularly in the presence of a trace of al¬ 
cohol ; 2, the formation of the substitution compound 
(monobromated camphor), which may be effected at 
a temperature of 100° C. (212° F.), or in a much 
shorter time at 132° C. (270° F.) ; and 3, the utili¬ 
zation of the oily residue, the greatest part of which 
is converted into the substitution compound at 260° 
C. (500° F.). The product of the second part is at 
once white, requiring, if decomposition has been 
avoided, no filtration, but simply recrystallization. 
The use of the cheap petroleum benzine and naphtha, 
in preference to alcohol and ether, will also com¬ 
mend itself for the sake of economy. The yield is 
probably larger than by Perkin’s process, and the 
entire absence of all danger by the bursting of appa¬ 
ratus recommends this method as more practical 
than that of Swarts. Although more time is re¬ 
quired for finishing the process completely, the dif¬ 
ferent reactions will not require much supervision, 
except the careful attention to the temperatures. 
Tlie combining weight of camphor C 20 H 16 O 2 is 
152; that of 2Br=160; equal weights of the two 
substances, therefore, give a slight excess of cam¬ 
phor. I have found it advisable to use about one- 
twelfth more of camphor, the excess of which re¬ 
mains in the mother-liquor, and very likely serves 
to prevent the formation of bibromated camphor 
(C 2 oH 14 Br 2 0 2 ), if the oily residue previous to its final 
treatment has liberated bromine on exposure to the 
light. A greater increase of camphor is unnecessary, 
since even in the proportion of two to one bromine, 
the formation of the oily compound and the libera¬ 
tion of bromine on subsequent exposure is not pre¬ 
vented, while the difficulty of obtaining the substitu¬ 
tion compound free from camphor is considerably 
increased. 
In regard to the quantity that may be conveniently 
worked up at. a time, the manipulation described 
below renders it possible to use 12 oz. of bromine in 
a retort of the capacity of a quart, in which even 
14 oz. have been operated upon by me at once. 
Regarding the necessary apparatus, I have found 
the following most serviceable, and well adapted for 
the purpose. 
A quart retort is placed in such a position that, 
the neck being sufficiently raised, any liquid con¬ 
densing therein may readily flow back into the re¬ 
tort. lo the neck is joined a glass tube, eighteen 
inches to two feet in length, bent downwards at the 
further end, and by means of india-rubber and glass 
tubing connected with a bottle of about 8 oz. or more 
capacity; the glass tube is cut off immediately be¬ 
neath the cork, while another glass tube, running 
nearly to the bottom of the bottle, is bent twice at 
right angles, and dips with the other end into an 
open bottle containing about 8 oz. of water and an 
alkali for the absorption of the liydrobromic acid. 
Third Series, No. 117. 
The intervenient bottle, which is empty, serves 
merely as a receptacle for the bromide solution, 
which is drawn over on the cooling of the contents 
of the retort, and pressed back again into the last 
bottle on the reapplication of heat; the liquid is 
thereby prevented from running into the retort, but 
the bottle maybe replaced by a Welter’s safety-tube 
inserted into the tubulure. Since, theoretically, one 
half of the bromine employed is converted into hy- 
drobromic acid, its saving is a matter of some im¬ 
portance ; it may be collected in water, or combined 
with any salifiable base or its carbonate. I have 
found the employment of white marble very conve¬ 
nient ; the resulting solution of bromide of calcium 
is nearly pure ; traces of iron present are removed 
by hydrosulphate of ammonia, after which the solu¬ 
tion will, on evaporation, yield the pure salt. 
The retort is charged with 13 oz. of camphor 
broken into pieces of convenient size, with which 
the neck is completely filled, while the balance is 
given into the retort. For this quantity, 12 oz. of 
bromine are used, which is introduced in four or 
five portions in quantities ranging from 2 to 4 oz. 
at a time, the larger quantity being used in the be¬ 
ginning, the smaller afterwards. If a funnel tube 
is used for this purpose, and the last drops of the 
bromine are washed down with a small quantity 
of alcohol (about J drachm), the reaction usually 
commences in from 15 to 20 minutes, or it may be 
brought on by the careful application of heat, 
which should be at once withdrawn as soon as gas 
bubbles commence to rise in the retort; the 
reaction will then proceed without any further at¬ 
tention, the heat increases, some bromine and bro¬ 
mine compounds volatilize, the latter being mostly 
condensed in the upper part of the retort, while 
the former condenses in the neck, forming with 
the camphor an oily liquid which returns to the 
retort. The next addition of the bromine should not 
be made until the contents of the retort have cooled 
down almost or quite to the ordinary temperature : 
and this precaution should be particularly observed, 
if, perhaps, in consequence of too violent reaction, 
all the camphor has run into the retort. The con¬ 
tents of the latter will usually solidify when cool¬ 
ing, after such a reaction: but sometimes they 
remain quite fluid, and congeal on the subsequent 
addition of the requisite bromine. If the bromine 
is added in too large quantities, the heat will be¬ 
come so high, and the reaction so violent, that a 
large quantity of bromine may distil over uncon¬ 
densed ; if added in fractions, with the precautions 
stated, the temperature rises generally to from G0° 
to 65° C. (140° to 150° F.), with at first slow, but gra¬ 
dually brisk extrication of liydrobromic acid gas. 
It follows from the latter phenomenon, that the 
mass must contain some monobromated camphor, or 
perhaps combinations of it with liydrobromic acid 
and bromine. 
Up to this stage the tubulure of the retort may 
be kept closed with the glass stopper; now a ther¬ 
mometer is inserted, and the retort slowly heated ; 
a rapid, but regular evolution of lijulrobromic 
acid gas takes place as the temperature increases; 
the golden yellow needles, mostly condensed in the 
neck, fuse and run back, and when the temperature 
has gradually reached about 120° C. (241° F.), the 
liquid boils somewhat and the evolution of gas 
slackens. From and above 90° C. (194° F.), the 
deep red colour of the liquid becomes much lighter, 
