Phenyl salicylate

Phenyl salicylate, or salol, is the organic compound with the formula C6H5O2C6H4OH. It is a white solid. It is occasionally used in sunscreens and as an antiseptic.

Production and reactions
The title compound was synthesized first in 1883 by the Polish chemist and doctor Marceli Nencki (who didn't publish his findings) and then independently in 1885 by the German chemist Richard Seifert (de) (1861–1919) (who did publish his findings). It is synthesized by heating salicylic acid with phenol in the presence of phosphoryl chloride. It also arises from heating salicylic acid:
 * 2HOC6H4CO2H →  C6H5O2C6H4OH  +  CO2  +  H2O

The conversion entails dehydration and decarboxylation. Heating phenyl salicylate in turn gives xanthone.
 * 2C6H5O2C6H4OH →  2C6H5OH  +  O[C6H4]2CO +  CO2

In this conversion, phenol is produced as well as carbon dioxide.

Salol reaction
In the salol reaction, phenyl salicylate reacts with o-toluidine in 1,2,4-trichlorobenzene at elevated temperatures to the corresponding amide o-salicylotoluide. Salicylamides are a type of drug.

Medical
It has been used as an antiseptic based on the antibacterial activity upon hydrolysis in the small intestine.

It acts as a mild analgesic.

History
The Swiss physician Hermann Sahli (sometimes spelled "Saly") (1856–1933) sought a substitute for sodium salicylate, which was used as a treatment for rheumatoid arthritis but which wasn't tolerated by some patients. So Dr. Sahli asked the Polish chemist and doctor Marceli Nencki of Bern, Switzerland, if he knew of a salicylate compound that lacked sodium salicylate's side effects. See:
 * From column 524: "Das salicylsaure Natron ist zwar das verzüglichste Specificum … Dieser Körper, welchen N. "Salol" nannte, … " (Sodium salicylate is indeed the best remedy against acute rheumatoid arthritis; however, as is known, it's poorly tolerated by some patients who, after its use, suffer nausea, tinnitus, etc., occasionally even fainting spells.  These inconveniences caused Dr. Sahli (La Semaine Médicale [The Medical Week], no. 15, 14 April 1886 ; Allgemeine medizinische Central-Zeitung [General Medical Central Journal]) to inquire of Dr. Nencki whether he knew another salicylate compound that didn't have those drawbacks.  Soon thereafter he received from Nencki a communication that he had succeeded in producing a compound in which an ether (phenol) had been substituted [for one of salicylic acid's hydrogen atoms], instead of a base [i.e., metal alkali].  This substance, which Nencki named "Salol", … )
 * Reprinted in:
 * From pp.122–123: "Dans une communication faite à la Société de médecine et de pharmacie de Berne, le docteur Sahli a fait ressortir les effets funestes produits sur l'estomac par un usage prolongé du salicylate de soude.  Pour parer à cet inconvénient, il s'est adressé au professeur de Nencki, pour lui demander s'il n'y aurait pas possibilité de trouver une autre combinaison de l'acide salicylique.  Le professeur de Nencki ayant étudié, il y a trois ans, les propriétés chimiques, physiologiques et surtout antiseptiques de salicylate de phénol ou salol, conseilla immédiatement ce produit au docteur Sahli."  (In a communication [that he] made to the Berne Society of Medicine and Pharmacy, Dr. Sahli highlighted the harmful effects [that are] produced on the stomach by the prolonged use of sodium salicylate.  In order to deal with this drawback, he spoke to Prof. Nencki, in order to ask him if there wasn't a possibility of finding another compound of salicylic acid.  Prof. Nencki, having studied, three years ago, the chemical, physiological, and above all antiseptic properties of phenyl salicylate or salol, immediately recommended this product to Dr. Sahli.)  Nencki recommended phenyl salicylate, which he had synthesized circa 1883.   While Nencki had been investigating how phenyl salicylate behaved in the body, he hadn't published his findings.  Meanwhile, the German chemist Richard Seifert (de) (1861–1919), a student of the German chemist Rudolf Wilhelm Schmitt (de) (1830–1898), independently synthesized phenyl salicylate in 1885.  In 1885, Seifert accepted a position at the Heyden chemical corporation (de)  of Radebeul, Germany, which manufactured salicylic acid.  The United States granted to Nencki and Seifert a patent for the production of phenyl salicylate, whereas Germany granted a patent for its production to Nencki and the Heyden corporation.  The Heyden company subsequently sold phenyl salicylate as a pharmaceutical, under the commercial name "Salol", a contraction of "SALicylate of phenOL".  Among other applications, Salol was used as an orally administered antiseptic for the small intestine, where the compound is hydrolyzed into salicylic acid and phenol.