Chemistry of Essential Oils

28 THE CHEMISTEY OF ESSENTIAL OILS

These facts are recognised in the turpentine market, and users are
.content to accept the fractionated oil as Eussian turpentine. But it is
considered necessary that it should be in a reasonably good condition and
as what is known as of good merchantable quality. The difficulty of fix-
ing empirical standards under these conditions is obvious, but as the re-
sult of considerable experience in disputes on shipments of this oil the
author is able to say that the points to which objection is taken are (1)
the presence of phenoloid bodies (absorbed by caustic potash); (2) the
presence of much oil boiling over 180° which renders the oil unremunera-
tive to refine, as these fractions are useless for most purposes; (3) the
presence of impurities distilling below 155°. As a result of this experi-
ence, the following values may be laid down as representing what is ac-
cepted on the London markets as Eussian turpentine of fair merchantable
quality. The figures relate to four typical samples:—

Initial boiling-point.

Distils below 155°

„ 155° to 160°

„ 160° „ 165°

„ 165° „ 170°

„ 170° „ 180°

,, „ above 180°

Specific gravity at 15°

Refractive index at 20°

Optical rotation

Absorbed by 5 per cent. KOH

1.

157°

none

1 per cent.

(^44) „
37 „
15 „
3 „
0-863
1-4730

• 4° 28'
  nil

2. 156°
   none
   1 per cent.
   45 ,,
   35 „
   16 „
   3
   0-8635
   1-4726

• 4° 30'
  nil

3. 157°
   none
   5 per cent.
   40 „
   42 „
   10 „
   3 „
   0-863
   1-4725

• 9°
  nil

4. 158°
   none
   11 per cent.
   18 „
   48 „
   19 „
   4
   0-868^4
   1-4748

• 8°
  nil
  A very large number of samples, however, have been even more
  largely deprived of their middle runnings, and contain a considerable
  amount of hydrocarbons boiling over 180°, and also a considerable
  amount of acid bodies, which are absorbed by caustic potash. Such
  samples are quite useless to the rectifier, as their redistillation must en-
  sure the removal of the acid bodies and also of the bodies boiling over
  180°, with a resulting loss which, as mentioned above, causes the rectifi-
  cation to be unremunerative.
  The following are typical samples of this kind which represent
  numerous deliveries on the London market:—

1. 
   
   
   
   2. 
      
      
      
      3. 148° 146° 146°
         per cent. 3 per cent. 5-5 per cent.
         3 5
      
      
      
      
   
   
   
   

Initial boiling-point..

Distils below 155°

155° to 160°

160° „ 165°\

165° „ 170°J '

170° ,, 180°

above 180°

Specific gravity at 15 °

Refractive index at 20°

Optical rotation.

Absorbed by KOH.

Finnish turpentine oil closely resembles Eussian oil. Aschan l has

identified it in the following compounds; diacetyl, furane, methyl-furane,

methyl-isobutyrate, benzene and its homologues, pinene, sylvestrene,

^-limonene, and dipentene. He has also recently isolated a new terpene

from this oil, boiling at 163° to 165°, specific gravity 0-8628 at 20°, and speci-

fic rotation + 7* 7 °. It is a saturated bicyclic terpene, closely related to

2

3

35

48

12

0-863

1-4762

8 (

34

50

10

0-8665

1-4756

+ 9'

22

46

21-5

0-878

1-4^780

+ 11°

4.

153°

1 per cent.

3 „

36 „

50 „

10 „

0-869

1-4792

+ 8° +9° + 11° + 12° 45'+ 12° 45'

6 per cent. 8-5 per cent. 7 per cent. 3 per cent,

(^1) Farm. Notisblad., 1907, 93, and Chem. Zeit. (1919), 1, 284.