— 167 — 



Barbier and Grignard 1 ) have continued their investigations into the 

 hydration of pinene. The process already described 2 ) was modified 

 to this extent that to 1 kilo of pinene from French oil of turpentine 

 (b. p. 155 to 160 ) there were added 1 kilo of glacial acetic acid, 

 100 cc. of a 5O°/ benzene - sulphonic acid, and 100 cc. acetic acid 

 anhydride. After mixing the temperature rises to 70 . Instead of 

 leaving the mass to stand for 12 hours, as in the older process, it 

 was worked up after i 1 ^ hours. The subsequent treatment is the 

 same. The hydrocarbons were separated from the esters by fraction- 

 ation. The same reaction was continued each time with the recovered 

 hydrocarbon until no further hydration took place. This point was 

 reached after five or six repetitions. 



The examination of the products of reaction was carried out se- 

 parately. It was shown that /J-pinene (nopinene) was first attacked 

 and converted into fenchyl alcohol. /?-pinene therefore, appears to be 

 the starting-point in the formation of fenchyl alcohol. This hydration 

 renders an analysis of French turpentine oil possible. The pinene 

 which remains behind after elimination of the /?-pinene is much purer. 



a-Pinene is chiefly converted into a-terpineol in the course of the 

 hydration process referred to. In addition to it small quantities of 

 terpadiene are formed, but these will also disappear as soon as it 

 becomes possible still further to reduce the temperature. The hydro- 

 carbons which hydratise less readily consist of a hydrocarbon which when 

 impure boils at 150 to 15 2°, a camphene (m. p. 4 2°) which is con- 

 verted by the hydration into borneol and zsobomeol, and a liquid 

 saturated hydrocarbon C 10 H 18 (b. p. 157 to 160 ). 



As we have already mentioned 3 ) Balbiano and Paolini, when oxid- 

 ising pinene with mercuric acetate, obtained a ketone-alcohol C 10 H 16 O 2 , 

 which they afterwards 4 ) described as zl 6 -6-hydroxymenthenone-2. But 

 from a recent paper by G. G. Henderson and J. W. Agnew 5 ) it appears 

 that this alcohol is not zl 6 -6-hydroxymenthenone-2 but zl 6 -8-hydroxy- 

 menthenone-2. The formation of this body proceeds as follows: First, 

 i-pinol hydrate is formed from the pinene and from this, by further 

 oxidation a hydroxyketone, m. p. 154 (10 mm.). By acting upon this 

 ketone with anhydrous oxalic acid there results a mixture of carvone 

 and carvacrol; reduction with sodium in moist etherial solution regener- 

 ates pinolhydrate ; reduction with hydriodic acid at ordinary temper- 

 ature yields carvacrol; oxidation with permanganate of potassium, 



1 ) Bull. Soc. Chim. IV. 5 (1Q09), 512, 519. 



2 ) Comp. Report April 1908, 178. 



3 ) Berl. Berichte 35 (1902), 2995; Report April 1903, 83. 

 *) Berl. Berichte 36 (1903), 3575; Report April 1904, 100. 

 5 ) Journ. chem. Soc. 95 (1909), 289. 



