Ethyl alcohol (Ethanol), C2H6OH. Mol. wt. 46.05.

Occurrence Of Alcohol In Natural Products

Ethyl alcohol is present in a number of plants, chiefly combined with organic acids to form the ethyl esters of these acids. Thus ethyl acetate is contained in the flowers of Magnolia fuscala; ethyl butyrate in the oil from the fruits of Heracleum giganteum and H. sphondylium; ethyl valerate probably occurs in Algerian oil of rue; and ethyl cinnamate is present in liquid storax from Liquidambar orientalis and in the oil from Kaempferia galanga. This last oil contains also the ethyl ester of p-methoxycinnamic acid; whilst ethyl esters of hexoic, octoic, decoic, lauric, palmitic, and oleic acids are present in the juice from the fruits of the saw palmetto (Sabal serrulata).

Certain lichens also contain the ethyl esters of various acids: for these and others mentioned, see the references compiled by the late Prof. Meldola.1

The alcohol itself is found in many distillates obtained by distilling plants or parts of plants with water; but in most cases it is probably produced partly or wholly from the esters by hydrolysis during the distillation. Thus the aqueous distillates from the fruits of Heracleum sp., of Pastinacca saliva, and of Anthriscus cerefolium contain ethyl alcohol, as also do those from the oil of the leaves of Indigofera galegoides, from oil of storax, and from grass and leaves which have been macerated in very dilute sulphuric acid. The forerunnings obtained in the distillation of oil of Eucalyptus globulus likewise contain ethyl alcohol.

In the distillate from rose leaves alcohol is found, but is perhaps due to fermentation of carbohydrates, not to its production by the living petals.

According to Berthelot, however, alcohol is formed in the tissues of certain growing plants, e.g., wheat and hazel. It is produced in the cells of plants from carbohydrates by what has been called

1 "The Chemical Synthesis of Vital Products," p. 45.

" intracellular respration" when the cells have an insufficient supply of oxygen.

Besides the true yeasts (Saccharomyces sp.), other related micro. fungi, and certain moulds and bacteria, are capable of producing alcohol from sugars and other carbohydrates. Species of Torula, Mycoderma, Aspergillus, Mucor, Monilia, and Penicillium; Bacillus acidi lactici, B. eihaceticus, B. coli communis, B. typhosus, Saccharo. bacillus pastorianus, and Amylobacter butylicum are among the chief of these alcohol.producing organisms. A long list of the yeasts and these other ferments is given by Meldola.1

According to investigations carried out by A. R. Minenkoff,2 alcoholic fermentation can take place in the higher plants, both under aerobic and anaerobic conditions, and is directly related to the vital activity of the plant organism, particularly to its growth. In the presence of oxygen, the formation of alcohol is increased when growth is retarded either by high or low temperatures, or by changes in osmotic pressure due to dissolved organic or inorganic substances. Formation of acid diminishes with increasing production of alcohol, and ceases completely before the plant dies. When the retardation of growth is at a maximum, the ratio of carbon dioxide to alcohol approaches that observed in pure alcoholic fermentation. Absence of oxygen promotes the fermentation, owing to the growth of the plant being inhibited.

Properties of ethyl alcohol. . Anhydrous ethyl alcohol is a mobile, colourless liquid, possessing a slight but agreeable spirituous odour and a pungent taste, and burning with a pale.blue, non. luminous flame.

Boiling point. . This was found by Kopp3 to be 784°, and by Mendeleeff 783°, at 760 mm. pressure. Fuchs 4 gives it as ranging from 7636° at 710 mm. to 7931° at 790 mm.

R. W. Merriman5 gives the following as the boiling points of ethyl alcohol at pressures from 50 to 2000 mm.: -

Pressure in mm.

B.p.

Pressure in mm.

B.p.

50

22.20°

350

59.84o

100

34.35

400

62.87

150

42.06

450

65.59

200

47.83

500

68.06

250

52.47

550

70.33

300

56.41

600

72.43

1 Loc. cit., pp. 45.53.

2 Bull. Agric. Intell., 1915, 6, 1464; see J. Soc. Chem. Ind., 1916, 35, 135.

3 Annalen, 1854, 92, 9.

4 Zeitsch. angew. Chem., 1898, 870.

5 Trans. Chem. Soc, 1913, 103, 632.

Pressure in mm.

B.p.

650

74.39°

700

76.24

760

78.30

800

79.61

900

82.65

1,000

85.42

1,100

87.96

1,200

90.32

Pressure in mm.

B.p.

1,300

92.52o

1,400

94.58

1,500

96.53

1,600

98.37

1,700

100.12

1,800

101.78

1,900

103.37

2,000

104.89

According to Wroblewski and Olsewski,1 the solidifying point of ethyl alcohol is .130.5°; but a later determination by Ladenburg and Krugel2 gives the value .112.3°.

Vapour pressure. . Merriman gives the vapour pressures at various temperatures up to 25° and between 0° and 105° as follows: -

Vapour pressure of ethyl alcohol. 1. Temperatures from 0°; to 25°.

Temp.

Pressure in mm.

12.0

1

12.9

2

13.9

3

14.9

4

15.9

5

17.0

6

18.2

7

19.4

8

20.7

9

22.1

10

23.5

11

25.1

12

26.7

Temp.

Pressure in mm.

13°

28.4

14

30.3

15

32.2

16

34.3

17

36.4

18

38.7

19

41.2

20

43.8

21

46.5

22

49.4

23

52.4

24

55.6

25

59.0