Year: 1899

page_text: Date of Application, 30th Dec.. 1899
Complete Specification Left, 17th Aug., 1900-Accepted, 22 Sept., 1900
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Buildings, in
the County of London, Consulting Engineer and Chartered Patent Agent, do hereby
declare the nature of this invention (as communicated to me from abroad by Actien
Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire of Germany, Chemical
Manufacturers) to be as follows:-
The salicylic esters heretofore employed in therapeutics are almost without excep-
tion solid crystalline substances. They are consequently more fit for internal use,
but cannot so well be employed as external remedies. Only methyl salicylate-the
so-called Gaultheria-oil-is an oily product which has proved to be a powerful external
remedy. The intense smell, however, of this compound-which is known to be a
valuable perfume-renders it little fit for medical use.
My foreign correspondents have now found that another ester of salicylic acid,
honzul salicylate:
which has not hitherto been described, possesses all properties necessary for a good
external remedy, forming at ordinary temperature a colourless liquid and being free
from smell.
They have found that the benzyl group can be readily introduced into the carboxyl
group of salicylic acid by allowing benzyl chloride to act upon salicylates. The re-
action is performed slowly at about 100° C. but in order to render it complete
and to bring it more quickly to an end the temperature must be raised to 1300
-140° C. At higher temperatures, above 170° C., by-reactions take place, large
quantities of resinous matters and products which boil at high temperatures being
formed. It is most probable that the hydroxyl group has been attacked at this
temperature.
Pure benzyl salicylate is a colourless liquid without any smell, hardly soluble in
water, more easily soluble in alcohol and ether. By the action of soda or potash lye,
the ester is converted into the corresponding alkali-salt, which is almost insoluble in
water. By heating the ester with alcoholic potash-lye it is readily saponified, benzyl
alcohol and salicylic acid being formed. It boils in vacuo under a pressure of 26 m/in
at about 208° C.
The following example illustrates the invention.
12.6 kilos. of anhydrous potassium salicylate and 12.6 kilos. of benzyl chloride are
heated up to 130°-140° C. in a vessel standing in an oil-bath and provided with a
In order to
reflux-condenser. This temperature is maintained for about 24 hours.

page_text: solate the benzyl salicylate thus formed, the product is gently heated with dilute
sodium carbonate, whereupon the ester separates in the form of an oil. This oil is
washed with water, and distilled with steam in order to remove the last traces of
benzyl chloride. The oily product thus obtained is subjected to fractional distillation
in vacuo. Pure benzyl salicylate distils over at 208° C. (uncorrected) under a pressure
of 26 m. m.
which has not hitherto been described," possesses all properties necessary for a good
external remedy, being at ordinary temperature a colourless liquid free from smell.
They have found that the benzyl group can be readily introduced into the carboxyl
group of salicylic acid by allowing benzyl chloride to act upon salicylates. The reaction
is performed slowly at about 100° C. ; but in order to render it complete and to bring
it more quickly to an end the temperature must be raised to 130°-140° C. At
higher temperatures, above 170° C., by-reactions take place, large quantities of
resinous matters and products which boil at high temperatures being formed. It is
most probable that the hydroxyl group has been attacked at this temperature.
Pure benzyl salicylate is a colourless liquid without any smell, hardly soluble in
water, more easily soluble in alcohol and ether. By the action of soda or potash lye,
the ester is converted into the corresponding alkali-salt, which almost insoluble
in water. By heating the ester with alcoholic potash lye it is readily saponified,
benzyl alcohol and salicylic acid being formed. It boils in vacuo under a pressure of
26 m. m. at about 208° C.
The following example illustrates the invention.
12.6 kilos. of anhydrous potassium salicylate and 126 kilos. of benzyl chloride are
heated up to 130° to 140° C. in a vessel standing in an oil-bath and provided with a
reflux-condenser. This temperature is maintained for about 24 hours. In order to
isolate the benzyl salicylate thus formed, the product is gently heated with dilute

page_text: Pure
sodium carbonate, whereupon the ester separates as an oil. This oil is washed with
water, and distilled with steam in order to remove the last traces of benzyl chloride.
The oily product thus obtained is subjected to fractional distillation in vacuo.
benzyl salicylate distils at 208° C. (uncorrected) under a pressure of 26 m. m.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. The herein described manufacture of benzyl salicylate by causing benzyl
chloride to react with a metallic salt of salicylic acid at a temperature of 130° to
140° C.