Chemistry of Essential Oils

292 THE CHBMISTEY OF ESSENTIAL OILS

Artemisia frigida, submitted in the fresh state to distillation with
steam, yields about 0*4 per cent, of a greenish oil with a cineol-like odour,
and having the following characters :—
Specific gravity 0-927 to 0-933
Optical rotation - 23
°
40' to - 25° 10'
Acid value ........ 1 to 4
Ester „,, 31 „ 45
„ „ (after acetylation) .... 139 „ 143
The dried herb gave on distillation a yield of only 0

• 07 per cent, oil
  of a darker colour; d22o 0'930; acid number, 47; ester number, 40;
  saponification number, 447. From the distillation-water of this second
  distillation an oil could still be obtained with petroleum ether, which
  was also darker than the oil from the fresh herb. Eabak^1 gives for the
  extracted oil d22o 0916; acid number 53 ; ester number 25; saponi-
  fication number 30'3. The oil has the following composition :—
  Free borneol ........ 35-8 per cent.
  Borneol combined as .heptoic ester .... 6-8 ,,
  Gineol (eucalyptol) 18 to 20 „
  Fenchone.8 ,, 10 „
  From the fresh herb of Artemisia leudoviciana 0


• 
  

  38 per cent, greenish-
  yellow oil is obtained, having a strong aromatic odour. Its characters
  are as follows :—
  Specific gravity...... 0'924 to 0'926
  Optical rotation......- 13° to - 17° 20'
  Acid value........ 0 to 4-5
  Ester „.....10 „ 26
  „ „ (after acetylation).... 116
  The fresh.herb of Artemisia caudata yielded 024 per cent, yellow
  oil with a sweetish odour, which points to the presence of methyl
  chavicol or anethol. Its characters are as follows :—
  Specific gravity 0-842 to 0'920
  Optical rotation.0° to - 24° 20'
  Acid value 0 to 20
  Ester ,,,17 „ 73
  Artemisia arborescens yields about 06 per cent, of a deep blue
  essential oil of specific gravity about 0946, acid value 98, and ester
  value 19*5. According to Jona
  2
  it contains 13

  
  


• 
  

  9 per cent, of alcohols,
  of which borneol and thujyl alcohol have been identified, and about 13
  per cent, of thujone. As constituents of the esters there were found
  formic, acetic, isovalerianic, pelargonic, palmitic, and stearic acids.
  Artemisia vulgaris yields an oil which has the following characters :—
  Specific gravity. 0-907 to 0*939

  
  

• 8° „ - 19°
  1-4776 to 1-4855 (Indian oil
  1 to 2
  16 „ 103
  50 „ 206

1-4620)

Optical rotation.

Retractive index

Acid value.

Ester „.

„ „ (after acetylation)

The oil contains a-thujone.

Artemisia Dracunculus yields the well-known estragon or tarragon

oil. This is a pale yellowish-green oil of characteristic odour and taste

of the tarragon herb, and having the following characters :—

~ - • 0-900 to 0'946

**J UVV1I4U B^W T »»* J * t •

Optical rotationRefractive index.

Acid value ....

Ester „

+ 2°

. 1-5028

0

1

°, + 10°

„ 1-5138

„ 2

1 , 10

(^1) Pharm Review, 23 (1905), 86. *Ann. Chim. Appl., 1 (1914), ii. 63.