Chemistry of Essential Oils

482 THE CHEMISTEY OF ESSENTIAL OILS

The investigation showed that the first runnings of African copaiba

balsam oil contain a laevo-rotatory sesquiterpene, which, although differ-

ing materially from cadinene in regard to its physical properties,

Boiling-point.

246° to 251°

271° „ 273°

0*9077

0-9215

]a

• 13° 21'
  -105° 30'

nD20°.

1-48943

1-50647

Sesquiterpene.

Cadinene

yet affords cadinene hydrochloride. It is probably closely related to

cadinene.

So far, three sesquiterpenes are known which, when treated with

hydrochloric acid gas, afford laevo-rotatory cadinene hydrochloride;

namely:—•

1. ^-cadinene proper.

• 
  
  
  
  2. The d-sesquiterpeae of West Indian sandal wood oil and of African
     copaiba balsam oil.
  
  
  
  

3. The Z-S3squiterpene, boiling-point 246° to 251°, of African copaiba
   balsam oil.
   For the following reasons this result is considered by the investigators
   to be of considerable interest: in by far the great majority of instances
   the identification of cadinene in essential oils has not been achieved by
   isolating the body as such, but by preparing its hydrochloride from frac-
   tions of which the boiling-point usually lay between 250° and 270°, or
   frequently " from the sesquiterpene fraction ". It is therefore not im-
   possible that in many cases cadinene has been assumed to be a con-
   stituent of essential oils which possibly contained another sesquiterpene
   which yield cadinene hydrochloride. Hence, the isolation of cadinene
   hydrochloride by itself can no longer be regarded as proof of the presence
   of cadinene.
   The presence of gurjun balsam oil in copaiba oil may bs confirmed by
   the preparation of gurjene ketone semi-carbazone. The oil is fractionated
   under 10 to 12 mm. pressure. The portion boiling above 145° is rejected.
   The lower fractions are oxidised with potassium permanganate in acetone
   solution. The semi-carbazone melts at 234° C. and has a specific rotation

• 317° in chloral hydrate solution.
  Van Itallie and Nieuwland have identified a sesquiterpene alcohol,
  C 15 H 200 > melting at 113° to 115° in Surinam oil.
  Semmler and Stenzell have examined the laevo-rotatory sesquiterpene
  of African copaiba oil, which yields cadinene hydrochloride, and have
  named it copsene. By oxidation with potassium permanganate it yields a
  ketonic acid, which forms a ssmi-carbazone melting at 221°.

OIL OF AFRICAN COPAIBA.

The so-called African copaiba oil has been referred to somewhat fully

under oil of copaiba, so that only a few further details are necessary.

African balsam of copaiba is the product of a plant whose botanical origin

is not quite certain. It is probably Oxystigma Mannii, or Hardwickia

Mannii.

The balsam yields from 35 to 47 per cent, of essential oil having the

following characters:—

(^1) Berichte, 47 (1914), 2555.