By the action of dilute sulphuric acid on terpin hydrate (see p. 384) the liquid terpineol of commerce results. This, however, is not a chemical unit, but a mixture of isomeric compounds C10H18O, among which the a-terpineol, m. p. 35°, predominates. The presence of B-terpineol, m. p. 32°1) and the liquid terpineol-12) has likewise been established.
In nature there apparently occurs only the a-terpineol, either optically active or inactive, the constitution of which has been established by the researches of Wallach,3) Wagner,4) Semmler and Tiemann.5) Although liquid terpineols have been isolated, it seems highly probable that they can be otained in the solid condition.
Solid d-a-terpineol has been observed in the oils of Malabar cardamom, sweet oranges, petit-grain, neroli, in Cayenne- and the lsevogyrate Mexican lignaloe oils, also in oil from lovage-root. In Malabar cardamom oil it occurs probably for the most part as acetate. As ester only, namely as acetate and valerianate (?), it occurs in cypress oil. In liquid form it has been isolated from marjoran oil.
1) Stephan and Helle, Berl. Berichte 35 (1902), 2147.
2) Wallach, Liebig's Annalen 356 (1907), 218; 362 (1908), 269.
3) Liebig's Annalen 275 (1893), 103, 150; 277 (1893), 110; 291 (1896), 342; Berl. Berichte 28 (1895), 1773.
4) Berl. Berichte 27 (1894), 1652, 2273.
5) Semmler, Berl. Berichte 28 (1895), 2189; Tiemann and Semmler, ibidem 28(1895), 1778; Tiemann and Schmidt, ibidem 1781; Tiemann, ibidem 29 (1896), 2616.
Solid /-a-terpineol has been found in the wood turpentine oil from Pinus palustris, in camphor oil, in the oil from the leaves of Laurus Camphora, in the dextrogyrate Mexican lignaloe oil, in limette oil and niaouli oil, in the last mentioned also as valerianate. As a liquid it has been isolated from Canada snakeroot oil, the bark oil from Ocotea usambarensis and both free and as ester in European wormseed oil.
Without reference as to angle of rotation, the presence of terpineol has been recorded for the following oils: kuromoji oil, lemon oil, oil of Melaleuca uncinata (?), gardenia oil, valerian oil (?). kesso root oil and erigeron oil. Probably the acetate also occurs in the German oil of Pinus sylvestris.
According to the statement of Bouchardat and Voiry,1) solid inactive terpineol m. p. 30 to 32° is formed by the action of very dilute sulphuric acid on terpin. However, it has not yet been definitely settled whether this is a- or B-terpineol. The solid, optically active modifications of a-terpineol can be obtained either, according to the method of Semmler,2) by boiling the d- or /-limonene monobromhydrate with the oxides of silver or lead; or, according to Wallach3) by shaking limonene monochlorhydrate with dilute potassium hydroxide solution, or by shaking homono-pinol with dilute sulphuric acid.4) The simplest method is to prepare them as acetates by the simultaneous action of glacial acetic acid (comp. under camphene, p. 305) and sulphuric acid on limonene, or by the action of glacial acetic acid and zinc chloride on pinene.5) Note-worthy is also the formation of optically active stolid terpineols from linalool by the action of acetic acid anhydride or formic acid,1) also of solid inactive terpineol from geraniol and formic acid.-)
1) Compt. rend. 104 (1887), 996. 2) Berl. Berichte 28 (1895), 2189. 3) Liebig's Annalen 350 (1906), 154. 4) Liebig's Annalen 360 (1908), 98.
5) Ertschikowsky, Journ. russ. phys chem. Ges. 28 (1896), 132. According to Bull. Soc. chim. III. 16 (1896), 1584.
The solid inactive a-terpineol possesses the elder-blossom-like odor of the liquid to a slight degree only. It is very readily soluble in organic solvents and possesses the following properties:
M.p. 35°3); b. p. 217 to 218° (760 mm.), 104 to 105° (10 mm.); d16o0,935 to 0,940; nD20o 1,48084.4)
The following constants were observed in the laboratory of Schimmel & Co.:
M. p. 35°; b. p. 85° (3 mm.); d15o (supercooled) 0,9386; nD20o 1,48268.
In connection with a strongly active a-terpineol, obtained by shaking homonopinol with dilute sulphuric acid, Wallach5) observed the following constants:
M.p. 37 to 38°; b. p. 218 to 219°; [a]D - 106° in 16,34 p. c. ethereal solution.
The optical activity is variable. The highest deviation observed in connection with a natural terpineol is [a]D + 95° 9' for the d-terpineol from oil of orange,6) and [a]D - 27°20' for the /-terpineol from lignaloe oil.7) The highest deviation has been revealed by an artificially prepared /-terpineol, namely [a]D-117,50.8)
In connection with the commercial liquid products of their own manufacture, which consist only in part of a-terpineol and contain someB-terpineol and terpinenol-1, Schimmel & Co. observed the following constants:
B. p. 217 to 219°; d15o0,935 to 0,940; aD + 0°; nD20o1,481 to 1,484; soluble in about 9 vols. 50 p. c. alcohol, in 3 to 5 vols, of
1) Stephan, Journ. f. prakt. Chem. II. 58 (1898), 109.
2) Stephan, ibidem 60 (1899), 244.
3) Wallach, Liebig's Annalen 275 (1893), 104.
4) Stephan, Journ. f. prakt. Chem. II. 58 (1898), 110; 60 (1899), 244.
5) Liebig's Annalen 360 (1908), 89.
6) Stephan, Journ. f. prakt. Chem. II. 62 (1900)530.
7) Report of Schimmel & Co. October 1905, 48.
8) Ertschikowsky, Journ. russ. phys. chem. Ges. 28 (1896), 132. According to Bull. Soc. chim. III. 16 (1896), 1584.
60 p. c. alcohol, and in abt. 2 vols, of 70 p. c. alcohol. With petroleum ether it should be miscible in all proportions, /'. e. it should be free from water.
As to their chemical properties the inactive and both active modifications of a-terpineol behave alike. The derivatives, however, differ in part: