DIPENTENE 



37 



(Gildemeister and Hoffmann, p. 869) ; 

 in oils from the Spanish Satureia thymbra 

 (Schimmel's Ber. Oct. 1889) and Thymus 

 capitatus (Ibid.} ; in oil of frankincense 

 from Boswellia carteri, &c. (Wallach, 

 Ann. 252, 100) ; in wartara oil, probably 

 from the seeds of Xanthoxylum alatum 

 and X. acanthopodium (Schimmel's Ber. 

 April, 1900). 



Dipentene and d-limonene are con- 

 tained in the ethereal oil from the 

 bucco-leaf, Barosmd betulina and . 

 serratifolia (Kondakoff and Bachtschieff, 

 Journ. pr. Ch. [2] 63, 49). Dipentene 

 is contained (with d-limonene) in man- 

 darin oil (Schimrnel's Ber. Oct. 1901 ; 

 Ch.Centr. 1901,2, 1007), and (probably) 

 in oil of pennyroyal from Mentha 

 pulegium (Tetry, Bull. Soc. [3] 27, 186). 

 "White camphor oil, ne*roli oil (Cannes), 

 and oil of petit-grain contain dipentene 

 (Schimmel's Ber. Oct. 1902 ; Ch. Centr. 

 1902, 2, 1207). 



NOTE : The question of the existence of di- 

 pentene as such in plant oils is complicated by 

 the fact that many compounds of the terpene 

 group give this hydrocarbon when acted upon 

 by heat or chemical reagents. 



Dipentene is racemic limonene or 

 (possibly) a pseudo-form of limonene 

 (Semmler, Ber. 83, 1455). d-Limonene 

 = hesperidene, carvene or citrene. The 

 synthetical product is inactive ( = di- 

 pentene), but the occurrence of the active 

 limonenes is here included in anticipation 

 of some method of resolution of the 

 racemic form being discovered. The 

 dipentene found in some ethereal oils 

 may arise from limonene by the action 

 of the heat applied for distillation. 



d-Limonene occurs in oil of sweet 

 orange, Portugal (Wright, Ch. News, 

 27, 260; Wallach, Ann. 227, 287 : see 

 also Wright and Piesse, Ch. News, 24, 

 147 ; Flatau and Labbe, Bull. Soc. [3] 

 19, 361 ; Fabris, Journ. Soc. Ch. 

 Ind. 19, 771), and in the ne"roli oil from 

 the flowers (Theulier, Ch. Zeit. 26, 1 26) ; 

 in oil of mandarin orange from Citrus 

 madurensis (Gildemeister and Stephan, 

 Arch. Pharm. 235, 583 ; Flatau and 

 Labbe, loc. cit. 364 ; Fabris, loc. cit. : for 

 references to botanical source of man- 

 darin oil see Gildemeister and Hoffmann, 

 p. 626, note) ; in Italian limetto oil 



from Citrus limetta (Gildemeister, Arch. 

 Pharm. 233, 1 74) ; in oil from the peel 

 of Citrus medico, (possibly with dipen- 

 tene : Burgess, 'Analyst/ 26, 260) ; in 

 Chinese neroli oil from Citrus triptera 

 (Umney and Bennett, Pharm. Journ. 

 [4] 15, 146) ; in oil of lemon (Wallach, 

 Ann. 227, 290) ; in oil of bergamot 

 (Ibid.; also Charabot, Comp. Rend. 129, 

 728; Fabris, loc. cit. 772); in oil of 

 caraway from Carum carui (Schweizer, 

 Ann. 40, 333 ; Journ. pr. Ch. 24, 257 ; 

 Sauer and Griinling, Ann. 208, 75; 

 Wallach, loc. cit. 291) ; and in oil of 

 dill from Peucedamim graveolens (Nietzki, 

 Arch. Pharm. 204, 317; Wallach, loc. 

 cit. 292). 



d-Limonene occurs also in oil of fleabane 

 from Erigeron canadensis (Beilstein and 

 Wiegand, Ber. 15, 2854); in kuromoji oil 

 (see above under dipentene) ; in ne"roli oil 

 from orange flowers, CVfrw* bigaradia (Tie- 

 mann and Semmler, Ber. 26, 2711 ; E. 

 and H. Erdmann, Ber. 32, 1214) ; in oil 

 of petit-grain from the youngfruit of the 

 same plant (Paraguay oil : Semmler and 

 Tiemann, Ber. 25, 1 186 ; Charabot and 

 Fillet, Bull. Soc. [3] 21, 74) ; in oil of 

 Massoia bark (see above under dipen- 

 tene) ; possibly in small quantity in oil 

 of spoonwort from Cochlearia ojficinalis 

 (Gadamer, Arch. Pharm. 237, 92). 



d-Limonene occurs also in oils of 

 American horse-mint from Monarda 

 punctata and wild bergamot from M. 

 fistulosa (Kremers and Hendricks,Pharm. 

 Arch. 2, 73 ; 76 ; Brandel and Kremers, 

 Pharm. Rev. 19, 200 : the hydrocarbon 

 from the latter plant is entered simply 

 as limonene) ; in oil of Malabar carda- 

 mom from Elettaria cardamomum (Parry, 

 Pharm. Journ. [4] 9, 105); in oil of 

 Macedonian fennel (Schimmel & Co. ; 

 Gildemeister and Hoffmann, p. 741); 

 in oil of celery from herb and seeds of 

 Apium graveolens (SchimmeFs Ber. April, 

 3892); in Ceylon citronella oil (Lana 

 Batu) from Andropogon nardus and vars. 

 (SchimmeFs Ber. Oct. 1 899). Limonene 

 probably exists in the oleo-resin of 

 Dacryodes Alexandra, Montserrat, W. 

 Indies (More, Trans. Ch. Soc. 75, 718). 



1- Limonene occurs in oil from the 

 needles and cones of Pinus picea = Abies 

 alba (Wallach, Ann. 227, 287; 246, 



