THE TERPENE GROUP 



317 



^-Limonene is found in numerous essential oils, in that of lemon, ber- 

 gamot, kummel, dill, celery. 



/-Limonene is present in pine-needle oil and Russian peppermint oil. 



Dipentene, or d, /-limonene, is present in Russian and Swedish turpentine 

 which has been heated to a high temperature. It is also formed by heating 

 other 'terpenes. It is contained in the distillate from rubber, having been 

 formed by the polymerisation of isoprene. 



a and y-Terpinenes are found in cardamom oil and other oils. They 

 have a smell of lemons. 



Phellandrene is present in fennel oil. Carvone is present in oil of 

 kummel and oil of dill. 



Sylvestrene is contained in Swedish and Russian turpentine and pine- 

 needle oil. It is dextrorotatory and also has a smell of lemons. 



P inane Group. 



CH 



CH 3 



d and /-Pinene. 



L 2 OH 



Myrtenol 



Camphane Group. 

 H 2 C 



H 2 C 



CHOH 



Borneol or 

 Borneo camphor. 



CH 



Camphor or 

 Japan camphor. 



= CH 2 



Camphene. Bornylene. 



</- Pinene is the chief constituent of American, Algerian and Greek tur- 

 pentine, /-pinene of French and Spanish turpentine ; both are prepared by 

 fractional distillation. 



Camphene is a solid terpene and is known in its optically active ' forms. 

 It is present in numerous essential oils ginger, Siberian pine-needle, 

 camphor. Bornylene is not a natural terpene, but borneol occurs as d- 

 borneol in Dryoba/anops Camphora, which is grown in Borneo and Sumatra, 

 as /-borneol in the oil of Blumta balsamifera. As ester with fatty acids it 

 occurs in pine-needle oil. It is very like Japan camphor, but has also a 

 peppermint smell. 



^/-Camphor, or Japan camphor, occurs in the camphor tree, Cin- 

 namomum camphora, and is obtained by distillation and sublimation. It is 

 made artificially from the pinene in turpentine. Pinene is converted into 



