The Limonene Group of Ter penes. 
339 
action of hydrochloric acid, which does not give a monochloride as 
might be expected if terpinol had the constitution expressed by C 10 H 17 
(O H) 
In the following year, however, a vapor density determination com¬ 
pels Tilden to accept the simple formula C 10 H 18 O. “It is somewhat 
remarkable that this chloride (i. e. dipentene dihydrochloride) thus 
formed from terpinol, corresponds in constitution not with that sub¬ 
stance but with terpin. 
although when decomposed by alkalis it yields terpinol and not terpin.” 
Tanret 6 (1885) states that the formula (C 20 H 16 ) 2 H 2 0 2 for terpinol 
ought to be rejected, that terpinol proper boils between 215-220° and is 
a monohydrate of terebenthene (C 20 H 16 f H 2 0 2 ; also that the product 
which results from the action of dilute acids upon the terpin, or of alco¬ 
holic potassa upon “ Terebenthen dichlorhydrat ” are but mixtures of a 
hydrocarbon C 20 H 16 with monohydrate. 
Since we shall have occasion to refer repeatedly to Wallach’s 8 (1885) 
researches on terpineol it may suffice here to mention the results of his 
dehydration experiments, which, as has already been mentioned served 
as a key to a better understanding of this part of the limonene literature. 
Hydrochloric and nitric acids were not employed as dehydrating agents 
on account of the byproducts to which they give rise: hydrochloric acid 
to chlorides, nitric acid to oxidation products. The products resulting 
upon treatment of terpin hydrate with 
sulphuric acid (1:2) are terpinene. 
terpinolene. 
terpineol. 
sulphuric acid (1:7) terpinene (largely), 
phosphoric acid [spec. gr. 1.12 = 20 p. c.] (1:4): terpineol and 
terpinene or 
dipentene. 
phosphoric acid [spec. gr. 1.12 = 20 p. c.] (1:2): terpineol (exclusively). 
glacial acetic acid terpineol (essentially), 
potassium bisulphate: terpineol. 
dipentene. 
Terpineol always results as intermediate product and upon further 
dehydration is converted into one or more of the above mentioned ter- 
penes. “ Bei der Zerlegung des Terpinhydrats durch Sduren od. durch 
wasserentziehende Mittel ensteht unter keirier Bedingung eine Verbindung 
von der Zusammensetzung C 20 IT 34 O und dem Siedepunkt 168 °. 
Thus far the terpineol under consideration, whether pure or impure 
as “ terpinol,” always showed itself to be optically inactive. 
