In the cold geraniol is scarcely acted upon by alkalies. When heated with concentrated alcoholic potassa to 150°, there is formed, according to Barbier,9) a tertiary alcohol C9H180 while carbon dioxide is being split off. However, this statement is based on an error since the resulting alcohol is methyl heptenol

1) Bouchardat, Compt. rend. 116 (1893), 1253; Tiemann and Semmler, Berl. Berichte 26 (1893), 2714; Stephan, Journ. f. prakt. Chem. II. 58 (1898), 111.

2) Report of Schimmel & Co. April 1898, 27.

3) Tiemann, Berl. Berichte 31 (1898), 832; Dupont and Labaune, Berichte von Roure-Bertrand Fils October 1909, 27.

4) Tiemann and Schmidt, Berl. Berichte 28 (1895), 2138. 5) Semmler, Berl. Berichte 24 (1891), 683.

6) Bertram and Gildemeister, journ. f. prakt. Chem. II. 49 (1894), 195; 53 (1896), 236; Stephan, Journ. f. prakt. Chem. II. 60 (1899), 244.

7) Berl. Berichte 41 (1908), 1475.

8) Ibidem 2083.

9) Compt. rend. 126 (1898), 1423.

The addition products of bromine and hydrohalogen are mostly liquid and readily decomposible. However, a crystalline tetrabromide of geraniol, melting at 70 to 71°, can be prepared.2)

As already pointed out on p. 358 geraniol yields upon oxidation with chromic acid mixture first an aldehyde, citral, C10H16O.3) Under special conditions, however, methylheptenone can also be obtained.4) Other "Abbau" products are likewise obtained, so that the reaction is by no means a quantitative one. When shaken with very dilute permanganate solution polyatomic alcohols are presumably first formed. With chromic acid mixture these are oxidized to acetone, lasvulinic acid and oxalic acid.5) In as much as geraniol is optically inactive and a primary alcohol, the above oxidation products have lead to the adoption of the following formula, viz., that of dimethyl-2,6-octadiene-2,6-0I-8.

CH3 • C (CH3): CH • CH2 • CH2 • C (CH3): CH • CH2 OH.6)

The isomeric formula given above, however, appears to have some points in its favor. Like citronellol, geraniol can add sodium acid sulphite, namely two molecules since it has two double bonds.7) The occurrence of esters of geraniol in volatile oils has already been mentioned. In as much as geraniol is relatively stable toward acids, its esters can be obtained either by the action of acid anhydrides on geraniol, or by the action of acid chlorides on geraniol in the presence of pyridine.8) The esters of the fatty acids are all liquid and their odor becomes fainter with the increase of the radicle of the acid introduced. The formate and the acetate are described among the esters.

1) Report of Schimmel & Co. October 1898, 27; Tiemann, Berl. Berichte 31 (1898), 2991.

2) v. Soden and Treff, Berl. Berichte 39 (1906), 913.

3) Semmler, Bed. Berichte 23 (1890), 2965; 24 (1891), 203.

4) Semmler, Bed. Berichte 26 (1893), 2720.

5) Tiemann and Semmler, Bed. Berichte 28 (1895), 2130.

6) Ibidem 2132.

7) Labbe, Bull. Soc. chim. III. 21 (1898), 1079.

8) H. and E. Erdmann, Journ. f. prakt. Chem. II. 56 (1897), 14; Bed. Berichte 31 (1898), 356.

Of the other esters of geraniol the diphenylcarbaminic acid ester and the acid phthalic acid ester should be mentioned. Both are crystalline. The former may well be used for the identification of geraniol (see p. 362) whereas the latter (m. p. 47°)1) may be employed in the preparation of pure geraniol. It should be noted, however, that geranylphthalate of sodium is partly converted into linalool when subjected to distillation with steam.2) A tetrabromide of the geranylphthalic acid is also known which melts at 114 to 115°. The silver salt melts at 133°. When preparing this acid it is best to work in benzene solution for the purpose of avoiding higher temperatures, for otherwise the geraniol is completely destroyed. The following derivatives remain to be mentioned, viz., geranyl-a-naphthylurethane (m. p. 47 to 48°), geranyl-di-B-naphthylurethane (m. p. 105 to 107°), and the geranyl-urethane (m. p. 124°).

For the purpose of separating geraniol from a geraniol-containing oil one can proceed, according to Bertram and Gilde-meister,3) in the following manner: Equal parts of the oil and finely powdered calcium chloride are carefully mixed in a mortar. The mixture, which as a result of the reaction has heated itself to 30 to 40°, is set acide for several hours in a desiccator in a cool place. The solid mass is pulverized and triturated with anhydrous ether, benzene or low boiling petroleum ether, transferred to a force filter and washed with ether, respectively benzene or petroleum ether. To the mixture of geraniol-calcium chloride with the excess of calcium chloride, water is added thus causing the geraniol to be regenerated. The separated oil is washed repeatedly with warm water and finally distilled with steam.

The separation of geraniol from its mixtures according to this method is not quantitative. Moreover, the oil to be thus treated should contain at least 25 percent, of geraniol. If only small amounts of material are available, it is best to use for characterization the diphenylurethane of geraniol

(C6H5)2NCOOC10H17, first recommended by Erdmann and Huth.4) For its preparation the following directions are given:1) 1 g. of oil, 1,5 g. diphenyl-carbamine chloride and 1,35 g. pyridine are heated for two hours on a water bath. The reaction product is subjected to steam distillation and the residue, which solidifies upon cooling, crystallized from alcohol. If much citronellol is present with the geraniol, it is difficult to obtain a pure product, since citronellol yields also a diphenylurethane which, however, remains liquid. In such a case, urethanes with a low melting point (40 to 50°) are first obtained which after repeated recrystallization from alcohol may show the melting point of the diphenylurethane of geraniol, viz., 82,2°.

1) Flatau and Labbe, Compt. rend. 126 (1898), 1725. 2) Stephan, Journ. f. prakt. Chem. II. 60 (1899), 252. 3) Journ. f. prakt. Chem. II. 53 (1896), 233; 56 (1897), 507. 4) Journ. f. prakt. Chem. II. 53 (1896), 45.

If geraniol is to be further characterized, it can be oxidized to citral and this converted into the citryl-i-naphthocinchoninic acid (see Citral). For this purpose, however, the alcohol must be fairly pure and not contain linalool, since this likewise yields citral with chromic acid mixture. If citral is present with geraniol the former must first be removed which removal may be accomplished by treatment with sulphurous acid.

A conversion of geraniol to citronellol is possible through the geranic acid. This is reduced to citronellic acid and the latter to citronellol.2) Thus the proof is established that citronellol is dihydrogeraniol.