16. A-MenthenoneS (m.p. of semicarbazone 224 to 226°; of oxaminooxime 166°)1). The same substance has been found by Schimmel & Co.4) in Japanese peppermint oil.
17. Carvacrol. When the oil is shaken with a solution of sodium hydroxide, there is obtained, in addition to the acids referred to below, a mixture of several phenols, one of which is carvacrol (m.p. of phenylurethane 136°). In addition, there is present a second phenol with a somewhat higher boiling point, the phenylurethane of which melts between 85 and 95° 5).
18. Cuminic alcohol. When the higher boiling fractions of camphor oil are heated with phthalic acid anhydride and the resulting compound is saponified, an alcohol is obtained (b.p. 240 to 248°; d15o0,9634; nD20o1,49038) which has the odor of cuminic alcohol. That the substance in question is in reality cuminic alcohol was demonstrated by its oxidation to cuminic aldehyde by means of chromic acid and glacial acetic acid. The aldehyde thus obtained yielded a semicarbazone melting at 210 to 212°. Upon oxidation with silver oxide cuminic acid melting at 111 to 113° resulted1).
19. Eugenol is the oldest of the known phenols in camphor oil. It was discovered in 1886 6).
1) Observation made in the laboratory of Schimmel & Co. 2) Schimmel's Bericht April 1888, 9; April 1889, 8; Report of Schimmel & Co. October 1903, 15.
3) Schimmel's Bericht September 1885, 7.
4) Report of Schimmel & Co. October 1910, 97.
5) Ibidem October 1902, 21.
6) Schimmel's Bericht April 1886, 5.
20. Bisabolene. The trichlorhydrate of this sesquiterpene, which melted at 79 to 80°, is obtained by saturating fraction 97 to 116° (5 to 6 mm.) with hydrogen chloride after it has been deprived of its phenols1).
21. Cadinene. By passing hydrogen chloride into fraction 260 to 270° a good yield of cadinene dichlorhydrate, melting at 117°, has been obtained2).
22. Caprylic acid. During an examination of the phenols found in camphor oil, small amounts of acids of the fatty series were isolated. Among these caprylic acid (congealing point + 15°; b.p. 113 to 114° under 4 mm. pressure; analysis of calcium and silver salts)3) was identified.
23. The acid CeH1802 can be separated from caprylic acid by means of its calcium salt. It boils at 114 to 115° (4 mm.), is liquid at ordinary temperature and apparently belongs to the olefinic acid series3).
24. Blue oil. The last fraction that comes over between 280 and 300° (142 to 155° at 6 mm.; sp.gr. 0,95 to 0,96; aD + 32°) consists in the main of a substance alcoholic in character4). When heated with acetic acid anhydride the resulting product has a fairly high ester value. When heated with concentrated formic acid, the alcohol loses water and yields a hydrocarbon (d15o about 0,918; aD about - 22°; nD20o about 1,512) which boils principally between 265 and 268°. It adds hydrogen chloride, however, without yielding a solid derivative4).
A few words should be said about the so-called camphor-ogenol, which boils between 212 and 213° and to which the formula C10HlsO2 has been assigned. According to Yoshida5), it polymerizes when heated for a prolonged time, at the same time separating camphor. When acted on by dilute nitric acid, acetic acid anhydride or benzoic acid, it is said to yield camphor, and when heated with sodium and alcohol to be converted into borneol.
1) Report of Schimmel & Co. October 1909, 31.
2) Schimmel's Bericht April 1889, 9.
3) Report of Schimmel & Co. October 1902, 22.
4) Ibidem October 1902, 18.
5) Footnote 4 on p. 461.
As a matter of fact, no substance with these properties occurs in camphor oil. "Camphorogenol" is nothing more than a fraction consisting principally of camphor and terpineol and behaving toward reagents as "camphorogenol" is reported to behave1). When boiled, a portion of the terpineol decomposes into terpenes and water and the camphor, which is less soluble in the terpenes, crystallizes out in part. If the terpineol is removed by oxidation with nitric acid the camphor, which is not readily attacked, remains behind. Sodium reduces the camphor, already present, to borneol.
Properties. Normal camphor oil, i.e. an oil with all of its constituents such as is produced upon the distillation of camphor wood, constitutes a soft mass, or is a liquid more or less permeated with camphor. As a rule, however, the designation camphor oil is applied to the oil that results after the removal of the camphor by filtration and pressure. Such a product was placed upon the market about the middle of the eighties. It contained considerable quantities of camphor in solution, which could be separated by fractionation and cooling. At the present time these operations are carried on in Japan, for the oil now exported is almost free from camphor.
Camphor oil is classed in three kinds which differ materially from each other in their composition. Their valuation is based on specific gravity.
1. Crude camphor oil2). This is the oil that remains after the removal of the crystallized camphor. It is a light yellow to brownish-yellow liquid. Sp. gr. 0,95 to 0,995. It is fractionated in Japan and resolved into white oil, red oil and camphor.
2. White camphor oil. It consists of the lowest boiling portions and is composed almost entirely of terpenes and small quantities of cineol. d15o0,87 to 0,91.
3. Red or black camphor oil. It is the portion of the oil which boils higher than camphor and contains safrol, phenols and sesquiterpenes. d15o mostly between 1,000 and 1,035.
1) Schimmel's Bericht April 1888, 9.
2) Nakazo Sugiyama, Journ. pharm. Soc. of Japan 1902, Mo. 242; Report of Schimmel & Co. October 1902, 17.
The normal oil as well as the several fractions are dextrogyrate. All fractions have the odor of camphor, but in the so-called black oil it is greatly obscured by that of safrol.