RESINOUS CONTENTS OF PINE. 335 



The position of tUN particular terpene, pinene, will be best seen from the general classifica- 

 tion of terpenes taken from Wallach. 1 



I. Hemiterpems or penteius of the formula CUH V 

 IT. Terpens 01 dipenfenes of the foimuli dolln. 



(1) Pinene, obt*tmed fiom maii5^ varieties of tuipentme. 



(2) famphene, obtained aitifieially from camphor. 



(3) Fmchene, obtained artificially from feuchone, a < onstituent of many fennel oils. 



(4) Lemonene occurs in orange-peel oil, in oils of lemon, bergamot, cummin, etc. 



(5) Bipenlene, obtained artificially from pinene. Occuis in Russian and Swedish turpentine. 



(6) Syhtbtrene occurs m Russian and Swedish turpentine. 



(7) PheJandrene occurs in the oils of bitter fennel and water fennel, elemi, eucalyptus. 



(8) To pinene occurs in oil of cardamom 



(9) Terpinolene, only slightly known. 



III. — Poh/terpous, at the foimula (0 Hgjn, as codrenos Ci TI„, caoutchouc (CrH s )„, etc. 



The hydrocarbon of the American and French oils of turpentine is pinene. It is dextro- 

 rotatory when obtained from the American turpentine oil, and is known as austro-terebinthene 

 or australene; hevo-rotatory when obtained from the French turpentine oil, and is known as 

 terebinthene. Otherwise the two hydrocarbons agree entirely in specific gravity, boiling point, 

 and behavior toward chemical reagents. 



The hydrocarbon of the Eussian oil of turpentine is sylvestrene. It is dextio-rotatory, and 

 has a higher boiling point than pinene. The latter boils at 155° to 150° 0., the former at 175° to 

 178° o. 



But even the turpentine oils of high grade as found on the market do not consist of pure 

 pinene; especially is this true of ordinary oil of turpentine, which is obtained from the cruder 

 turpentine by a single distillation with steam. Different samples vary from one another 

 considerably in their specific rotatory power as well as their boiling point. 



American oil of turpentine has a density of 0.864° to 0.870°. According to Allen 2 it begins 

 to boil at a temperature between 156° and 160° C, and fully passes over below 170° 0. "A good 

 sample of rectified American oil will give 90 to 93 per cent of distillate below 165°, the greater 

 part of which will pass over between 158° and 160° r , 3 while in the experience of J. H. Long/ 

 "In the examination of a large number of pure commercial samples of turpentine oil it was 

 observed that the boiling point was uniformly at 155° to 156°, and that 85 per cent of the samples 

 distilled between 135° and 163°. The distillation is practically complete below 185° O." 



Then, again, as found by Long, the vapor densities of many samples of oil are too high to 

 allow the formula K ,Hj b for the entire oil. Fractions of different boiling points show different 

 degrees of specific rotation. All this would indicate that ordinary turpentine oil contains 

 hydrocarbons heavier than pure pinene, Ci H lh . They are probably either isomeric with pinene, 

 but of a higher boiling point, or may belong to the polyterpeues. 



Still less do we know of the source of these hydrocarbons. Whether they are produced by 

 the tree simultaneously with pinene, and are therefore to be found in the oleoresin or whether 

 they are all or in part produced by external agencies after the turpentine has been dipped can not 

 be answered. Probably the formation of these other hydrocarbons takes place in both ways 

 spontaneously in the tree and by some influences outside the tree. 



Indeed, all terpenes have this £>roperty in common that they easily undergo change, from 

 optically active to inactive, from hemiterpenes to terpenes and polyterpeues. The change can be 

 brought about either by heat alone, or by heating the terpenes with salts or acids. So, when a 

 sample of American turpentine oil of +18.6° was heated to 200° 0. for two hours it showed an 

 opposite rotation of — 9.9°. r> Pinene heated to 250° to 300° 0. is converted into dipentene OH, 

 boiling at 175°, and a hydrocarbon OH, boiling at 260° O. 



These illustrations will suffice to show that the transformation of pinene into isomeric and 

 heavier hydrocarbons may occur, at least partially, after the turpentine has been removed from 

 the tree. 



1 Ann. Chem. (Liebig), 227, 300; Ber. d. Chem. Ges., 24, 1527. 3 Allen, Com. Org. Anal., 2, 441. 



2 Allen, Com. Org. Anal., 2, 437. 4 Jour. Anal, and Appl. Chem., 6, 5, 



fi Mnspratfc's Chemie, 4th ed. ; 1, 153. 



