C6 H5 • CH2 • CH2 OH.
Phenylethyl alcohol, which is used in the preparation of artificial volatile oils, has been observed as constituent of the leaf oil of Pinus halepensis, of oil of rose (especially that distilled from dried rose leaves) and of neroli oil. In the,oils of rose and neroli, the alcohol appears also to be combined as ester with benzoic acid and phenylacetic acid.
1) Liebig's Annalen 96 (1855), 246.
2) Meisenheimer, Berl. Berichte 41 (1908), 1420.
3) Report of Schimmel & Co. April 1899, 28, footnote.
4) Ibidem October 1903, 19.
5) Masson, Compt. rend. 149 (1909), 630.
Artificially it can be prepared from phenyl acetaldehyde by reduction with sodium amalgam;1) likewise from phenylacetic acid esters by reduction with sodium and absolute alcohol, a method patented by Bouveault and Blanc.2) In connection with a preparation, made in the laboratory of Schimmel & Co. according to the latter method and purified by means of the calcium chloride compound, the following constants were observed:
B. p. 220 to 222° (740 mm.), abt. 104° (12 mm.), 93° (6 mm.); d15o 1,0242; nD20o 1,53212.
According to observations thus far made the latter two constants for technical products fall within the following limits: d15o 1,023 to 1,024; nD20o 1,532 to 1,533.
Phenylethyl alcohol is a colorless liquid that is optically inactive and possesses a very mild and faint odor. As a result of its partial oxidation to phenyl acetaldehyde it becomes honey-like in consistency in the course of time. It is readily soluble in all of the common organic solvents. It is soluble in 2 vols. of 50 p. c. alcohol and in 18 vols. of 30 p. c. alcohol. Even in water it is soluble in the ratio of 1:60. Because of this appreciable solubility in water, rose oil contains only a small fraction of the phenylethyl alcohol found in the leaves. The larger part of the alcohol remains in the aqueous distillate from which it cannot be separated by cohobation because of its great dilution.
With anhydrous calcium chloride phenylethyl alcohol forms a solid compound which can be used for its purification. Oxidation with chromic acid mixture yields phenyl acetaldehyde and phenylacetic acid, at times also its phenylacetic acid ester which melts at 28°. For the identification of phenylethyl alcohol its phenylurethane (m. p. 80°), its diphenylurethane (m. p. 99 to 100°) and acid phthalic acid ester (m. p. 188 to 189°) are used.
1) Radziszewski, Berl. Berichte 9 (1876), 372.
2) G. I. P. 164294. Comp. also Compt. rend. 136 (1903), 1676 and 137 (1903), 60.