Diosphenol 197

Diosphenol (buchu camphor), C10H16O2, is a constituent of the oil of buchu leaves, in which it was first found by Fliickiger.1) Since then it has been subjected to investigation repeatedly. Its chemical constitution was revealed by Semmler and Mc Kenzie,2) who regard it as a cyclic reduced ketophenol of the above formula.

The diosphenol content of buchu oils varies with their botanical source. From some oils it separates as a crystalline mass upon standing at ordinary temperature, whereas other oils contain but little of this phenol. It is obtained from the oils either by freezing out, or by shaking out with dilute caustic alkali. If the latter method be followed, it should be remembered that a part of the diosphenol is removed when the alkaline solution is shaken out with ether.

Synthetically diosphenol is obtained by the oxidation of oxy-methylene-menthone, C11H1802. A diketone C10H16O2 results which is inverted to diosphenol by means of acids or alkalies.3)

Diosphenol has a peculiar minty odor, is optically inactive, and crystallizes in monoclinic crystals that melt at 83°. It boils at 109 to 110° under 10 mm. pressure and with partial decomposition at 232° under atmospheric pressure. With ferric chloride it produces a dark green color.

With acetic acid anhydride and benzoylchloride, diosphenol yields the respective esters, with carbanil a phenylurethane melting at 41°. On account of the neighboring hydroxy group, the ketone group possess but little capacity for reaction. However, an oxime is known, which melts at 156° according to Kondakow and Bjalobrzeski,4)

1) Pharmaceutical Journ. III. 11 (1880), 174, 219.

2) Berl. Berichte 39 (1906), 1158.

3) Semmler and Mc Kenzie, ibidem 1169.

4) Journ. f. prakt. Chem. II. 54 (1896), 437.

but Semmler and Mc Kenzie (loc. cit.) record the melting point as 125°. When reduced in alkaline solution with sodium amalgam a diol alcohol, C10H18O21) results which melts at 159°. Reduction with sodium and alcohol yields /-menthol and a glycol C10H20O2. Upon oxidation with potassium permanganate, the latter yields a-Isopropyl-a'-methyladipinic acid, which melts at 104°.2)

Characteristic for diosphenol is its ready oxidation which property explains its capacity to reduce Fehling's solution, also ammoniacal silver solution.

Upon oxidation with ozone Semmler and Mc Kenzie (loc. cit.) obtained a-Isopropyl-/-acetyl-/7-butyric acid, m. p. 41°, whereas with potassium permanganate they obtained a ketoacid, C10H14O3 which melts at 104 to 105° and yields an oxime melting at 182°. As an intermediate product an acid C10H16O4 is formed from which the keto acid results by splitting off a molecule of water.

When diosphenol is heated with concentrated hydrochloric acid in a sealed tube to 150 to 180°, thymol, together with little carvacrol, results quantitatively.

When heated with alcoholic potassa in a sealed tube to 150 to 160°, it yields an alcohol acid C10H18O3, which can readily be recrystallized from water in needles that melt at 94°.

Diosphenol is readily recognized by its properties. For its identification its behavior toward Fehling's solution and ammonia-cal silver solution can be utilized. Of its derivatives the phenyl-urethane and the alcohol acid mentioned may also be used.

Phloracetophenone dimethyl ether.

Diosphenol 198

Brief mention may be accorded to the phloracetophenone dimethyl ether, which was recently found by Jonas3) in the oil of

1) Shimoyama, Arch, der Pharm. 226 (1888), 413.

2) Kondakow and Bachtschiew, Journ. f. prakt. Chem. II. 63 (1901), 61; Semmler and Mc Kenzie, Berl. Berichte 39 (1906), 1162.

3) Report of Schimmel & Co. April 1909, 150.

Blumea balsamifera. This compound can be shaken out of the oil with the aid of caustic soda solution. From this alkaline solution, acids precipitate it as a solid, yellowish substance which after repeated recrystallization from benzene or light petroleum ether is obtained colorless and melts at 82 to 83°.

Phloracetophenone dimethyl ether had previously been obtained synthetically by Friedlander and Schnell1) and was later made the subject of careful study by v. Kostanecki and Tambor.2)

Of its derivatives the oxime melts at 108 to 110°, the acetyl compound at 106 to 107°, the methyl ether at 103°, and a yellow crystalline monobromide at 187°.

Condensed with benzaldehyde it yields 2-hydroxy-4,6-di-methoxychalcone (m. p. 91 to 92°).