Chemistry of Essential Oils

220 THE CHEMISTEY OF ESSENTIAL OILS.

On fractional distillation, the following fractions were obtained :-

To 200°

200° to 205°

205° „ 210°

210°

215°

220°

225°

230°

215°

220°

225°

230°

235°

Residue

2 - 6 per <:ent.

2-4

8-6

18-8

24

19-6

9

3-6

12-2

The following compounds were identified in the oil:—

Acetic aldehyde CHS. GOH (about 0-044 per cent.).

„ acid CH?. COOH.

o-pinene (inactive) C 10 H 16.

Limonene (laevo) G 10 H 16.

Menthone C 1 0H 18 O.

Menthyl acetate G 10 H 19.

Gadinene C 15 H 24.

A menthyl est

Ilii

y ^u 8 ,,Oa.

Iso-valerianic aldehyde C 4 H 9. GOH (about 0*048 per cent.).

„ acid C 4 H 9. COOH.

Phellandrene CIOH 16.

Cineol G 10 H1 8 O.

Menthol C 10 H 19. OH.

Menthyl-iso-valerianate C 10 H 19. C 5 H 9 O 2.

A lactone C 10 H1 6 O 2 , melting at 23°.

Amyl acetate and dimethylsulphide have also been detected in traces.

Pure American peppermint oil has the following characters:—

Specific gravity at 15

°

Optical rotation.

Refractive index.

Menthol as esters

Total menthol

Menthone.

0-900 to 0-915 (rarely to 0'925)

• 18° to - 35° (rarely below - 18°).
  l-4600,to 1-4640
  5 to 14 per cent.
  50 „ 62 „
  9 to 19 per cent, (rarely to 25 per cent.)

An examination of nine samples by Kleber^1

menthone is usually lower as the menthol is higher.

hisvfigures:—

indicates that the

The following are

0-8995

0-8983

0-900

0-904

0-902

0-905

0-901

0-902

0-903

aD.

• 25° 27'


• 24° 20'


• 24° 14'


• 24° 28'


• 24° 30'


• 23° 18'


• 26° 12'


• 25° 30'


• 23° 49'

Total Menthol.

49-7 per cent.

48-4

51-7

50-2

50-2

53-5

56-1

55-8

56-4

Menthone.

18*8 per cent.

16-8

17-98 ,

16-98 ,

17-7

14-0

13-9

16-7

15-2

The following table is due to Power, and includes a few oils other

than American distillates. Samples No. II. and Ila. are so abnormal

that some suspicion as to their genuineness may well be forgiven :—

(^1) Schimmel's Report, April, 1914, 77.