In the preparation of malic acid from mountain ash berries, the fruits of Sorbus Aucuparia, Gsertn. (Ger. Vogelbeere, family Rosaceae), a pungent odor is noticed that is due to a substance volatile with steam. If the vapors are condensed a colorless oil results, which, when diluted, has a not unpleasant odor and which has the following properties: b. p. 221° (755 mm.)2); 136° (30 mm.)3); d15o1,0682); d21o1,06283); [a]J + 40,8°.
1) Journ. f. prakt. Chem. II. 84 (1911), 247; 87 (1913), 142.
2) Liebig's Annalen 110 (1859), 129.
3) Bed. Berichte 27 (1894), 344 and 33 (1900), 2140.
The volatile oil of the mountain ash berry was first investigated by A.W. Hofmann1) and designated by him as parasorbinic acid. According to O. Dcebner-) it is a lactone of the formula C6H802, more particularly that of y-or d-hydroxyhydrosorbinic acid.
According to Doebner, the mature or nearly mature mountain ash berries are the most suitable material for the preparation of the oil. Whereas the immature berries contain malic acid only, the ripening berries contain sorbin oil and the malic acid disappears. At the same time sorbinose (Ger. Sorbinzucker), C6H12O6 and sorbite C6H14O6 result.