Of the aliphatic ketones only a few are found in volatile oils. They are mostly methyl ketones which can be isolated by means of their acid sulphite addition products. The lower members are water-soluble and hence are found either in the aqueous distillate or in the first portion of the oil which distils over.

Acetone, CH3CO-CH3. This ketone has been observed not infrequently during the distillation of volatile oils, more particularly of leaf oils. Presumably it is formed during the process of distillation, but the reaction by which it is produced is not known. It has been found in the Atlas cedar oil, coca leaf oil, clove oil and in the distillate of patchouli leaves. Together with hydrocyanic acid, it has been found in the distillate of numerous plants, thus in that of Triglochin maritima1), Thalic-trum aquilegifolium, Nandina domestica, Phaseolus lunatus, P. Mungo, Linum usitatissimum, L perenne, Hevea brasiliensis, H. Spruceana, Jatropha angustidens, Manihot bankens is, M. Glaziovii, M. palmata, M. utilissima, Passiflora alata, P. cosrulea, P. edul/s, P. foet/da, P. hybrida, P. laurifolia, P. maculata, P. princeps, P. quadrangularis, P. suberosa, Tacsonia spec, and T. van Volxemii.2)

Acetone boils at 56,5° and has the density d14o 0,79945. As characteristic derivatives the p-bromphenylhydrazone, m. p.94°, and the oxime, m. p. 59 to 60°, may be mentioned. With iodine-potassium iodide solution a precipitate of iodoform results.

1) Greshoff,Pharm.Weekblad45(1908), 1165; Chem.Zentralbl. 1908, II. 1446. 2) Greshoff, Arch. der Pharm. 244 (1906), 665.

Methyl-n-amyl ketone, CH3CO(CH.2)4CH3, is contained in the low boiling portions of clove oil and is of importance so far as the characteristic odor of this oil is concerned. Its presence in Ceylon cinnamon oil has also been demonstrated. B. p. 151 to 152°; d0o 0,8366. The semicarbazone melts at 122 to 123°.

Ethyl-n-amyl ketone, CH3CH2CO[CH2]4CH3, occurs in the first fraction of French lavender oil. B. p. 169,5 to 170°; d15o 0,8254; nD20o 1,41536; m. p. of semicarbazone 117 to 117,5°. It does not react with acid sulphite. Its oxidation with chromic acid yields /7-capronic acid.1)

Methyl-n-heptyl ketone, CH3 • CO • [CH2]6 • CH3, frequently constitutes the bulk of Algerian oil of rue. In small amounts it is also found in French and Spanish oils of rue and in oil of cloves. It is a colorless oil with an agreeable odor resembling that of rue.

For methyl heptyl ketone isolated from oil of rue, the following constants have been ascertained:

M. p. -17°; cong. p. -19°; b. p. 85 to 90° (7 mm.), 95,8 to 102° (24 mm.); d20o 0,83178.2)

Cong. p. -15°; b. p. 193 to 194° (740 mm.); d20o 0,821.3) B. p. 194,5 to 195,5° (763 mm.); d 14o/16o0,8296.4) B. p. 194 to 196°; 80 to 82° (15 mm.).5)

It reacts but slowly with acid sulphite solution. M. p. of the semicarbazone 118 to 119° or 119 to 120°. Oxidized with hypobromite it yields n-caprylic acid.

MethyLw-nonyl ketone, CH3CO[CH2]8CH3, has long been known as the principal constituent of the common oil of rue from France and Spain. In Algerian oil of rue it usually plays but a subordinate role as compared with methyl heptyl ketone. For its preparation the French oil is commonly used, the ketone being isolated either by freezing it out, or by means of the acid sulphite addition product.

1) Report of Schimmel & Co. April 1903, 47; October 1903, 44. 2) Thoms, Berichte d. deutsch. pharm. Ges. 11 (1901), 16. 3) v. Soden and Henle, Pharm. Ztg. 46 (1901), 277. 4) Power and Lees, Journ. chem. Soc. 81 (1902), 1588. 5) Houben, Berl. Berichte 35 (1902), 3588.

Methylnonyl ketone is a colorless liquid at room temperature and possesses an odor similar to that of methylheptyl ketone. Its constants, as determined by different investigators, are as follows:

B. p. 226° (766 mm.), 230,65° (corr.), 122 to 123° (24 mm., corr.).1)

M. p. + 13,5°; cong. p. + 12°; b. p. 223 to 224° (774 mm.), 99° (7 mm.); d20o 0,82623.2)

B. p. 230 to 231° (740 mm.).3)

B. p. 229 to 233° (759 mm.), after regeneration from the semi-carbazone 231,5 to 232,5° (761 mm.); d 20.5o/16o0,8263.4)

Cong. p. +13°; b. p. 228 to 230°, 120° (20 mm.), 118° (18 mm.); d15o 0,8295; d20o 0,8263.5)

In connection with a synthetically prepared product Gorup-Besanez and Grimm6) observed the following constants:

M. p.+ 15 to 16°; b.p.224°; d17.5o 0,8295.

The oxime melts at 46 to 47°, the semicarbazone at 123 to 124°. Hypobromite oxidizes it to caprinic acid.

Diacetyl, CH3COCOCH3. Like furfurol, this aliphatic diketone, which has been observed rather frequently in volatile oils, presumably owes its origin to the decomposition of certain plant constituents during the process of distillation. Inasmuch as it is rather water-soluble, it also is apt to concentrate in the cohobated aqueous distillate or in the first fractions. At times it even reveals its presence by means of its yellowish-green color and its quinone-like odor. In most instances, diacetyl is found together with methyl alcohol and furfurol. It has been observed in the first distillate of a pine tar oil from Finland, in the co-hobated aqueous distillate from the oils of cypress, savin, vetiver, orris, West Indian sandalwood, bay, and caraway.

B. p. 87,5 to 88°; density 0,9734 at 22°. Characteristic are its monophenylhydrazone, m. p. 133 to 134°; the oxime of the latter, viz. the diacetylhydrazoxime, m. p. 158°, and the osazone, m. p. 243°.

1) Carette, Journ. de Pharm. et Chim. II. 10 (1899), 256. 2) Thorns, loc. tit. 8.

3) v. Soden and Henle, loc. tit.

4) Power and Lees, loc. tit. 5) Houben, loc. tit. 3590.

6) Liebig's Annalen 157 (1871), 279.