Oxides have been found in volatile oils in isolated cases only, those of the aliphatic series having not yet been observed. Of synthetic products, however, several are known. Of special importance is the pinol, C10H16O, which is closely related to to pinene.

It is obtained as a by-product in the preparation of pinene nitrosochloride. It is also formed when pinolhydrate (sobrerol) is heated with dilute sulphuric acid1) or terpineol dibromide with sodium alcoholate.2)

According to Wagner and Slawinsky,3) an optically active pinol can be obtained when hypochlorous acid is allowed to act on pinene and subsequent reduction of the c/s-pinolglycol-2-chlorhydrin, in alcoholic solution, with zinc dust.

Pinol is a liquid which boils at 183 to 184° and possesses an odor resembling that of cineol and camphor. d20o 0,9455; nD20o 1,47096. It is very stable toward reducing agents and can be distilled over sodium without decomposition. When oxidized with permanganate or dilute nitric acid it is converted into terebic acid (m. p. 175 to 176°). Inorganic acids react with pinol forming cineol. Bromine is added forming a dibromide which melts at 94° and which is suited to its identification.

Another artificially prepared oxide is the /, 4-Cineol which, together with terpineol, is formed when 1,4-terpin is heated with oxalic acid. It is a liquid which boils at 172 to 173° and which, unlike cineol, does not congeal when cooled, d 0,987; n1,4485.4)

Prileschajew5) has succeeded in preparing the oxides of a number of so-called terpene alcohols, and other terpene compounds the properties of which are indicated in the following table:

1) Wallach, Liebig's Annalen 259 (1890), 315. 2) Wallach, Ibidem 277 (1893), 115.

3) Berl. Berichte 32 (1899), 2070.

4) Wallach, Liebig's Annalen 356 (1907), 205. 5) Berl. Berichte 42 (1909), 4811.

boil. point

d 0o/0o

d 16o/16o

nD16°

Geraniol monoxyde

157 to 168° (25 mm.)

0,9716

0,9610

1,4681

When hydrated, a glycerol, b. p. 205 to 207° (20 mm.) results

Geraniol dioxyde

180 to 183° (25 mm.)

1,0587

1,0472

1,4653

When hydrated, a glycerol oxyde, b. p. 220 ° (15 mm.), m. p. 137 to 138° results

Linalool monoxyde

95° (25 mm.)

0,9660

0,9507

1,4554

[a]o - 4,98°. Hydration yields a two- fold unsaturated aldehyde

, b. p. 120 to 122 ° (25 mm.), m. p. of the semicarbazone 138,5°.

Linalool dioxyde

131 to 133° (25 mm.)

1,0552

1,0423

1,4616

When hydrated, there results a glycerol oxyde, b. p. 210 to 212°

(25 mm.)

Citral oxyde

146 to 148° (20 mm.)

1,0091

0,9740

1,4604

When hydrated, there results a glycol aldehyde, b. p. 141 to 142°

(24 mm.)

Citronellal oxyde

130 to 131° (25 mm.)

0,9437

0,9344

1,4421

Upon hydration there results a glycol aldehyde, b.p. 180 to 182°

(18 mm.)

Limonene monoxyde

113 to 114° (50 mm.)

0,9435

0,9303

1,4693

[a]D - 6,76°. Upon hydration there results a glycol, m. p. 66,5 to 67,5°.

Limonene dioxyde

146,5 to

147° (50 mm.)

1,0471

1,0338

1,4702

[a]D + 52,23°. Upon hydration there results an amorphous erythrol, b. p. 220° (23 mm.)

Pinene oxyde

102 to 103° (50 mm.)

0,9812

0,9689

1,4708

[a]D - 92°. Upon hydration pinol hydrate results.

Wellnigh the only oxide which occurs in volatile oils is cineol.