Oleum Cochlearia?. - Loffelkrautol. - Essence de Cochlearia.
Origin. Spoonwort, Cochlearia officinalis, L, family Cruci-ferae, flourishes in the wild state in the proximity of the sea coasts of the northern continents, also in isolated high areas of the Central European Alps. It is also successfully1) cultivated as an economic plant.
1) Comp. oil of Tropaeolum majus.
2) Steudel, Dissert, de Acredine nonnull. Vegetabil. Tubingen 1805.
3) Liebig's Annalen 58 (1846), 36.
4) Ibidem 51 (1844), 298.
5) Arch, der Pharm. 230 (1892), 434.
Production. In order to obtain good yields, it is absolutely necessary to mix the well comminuted herb with water and to allow it to stand over night. This must be done in order to give the enzyme an opportunity to come into contact with the glucoside which is to be hydrolyzed and which is located in different cells2). Dry herb as well as fresh herb may be used. In the former case, however, some powdered white mustard should be added, since the enzyme of the herb becomes inactive upon drying. When fresh herb is used such addition is unnecessary, for Schimmel & Co.8) have shown that the yield of oil is not increased thereby. The yield from dry herb amounts to 0.1753) to 0,305 p.c.2) (computed for fresh herb this amounts to 0,0173 and 0,030 p.c. respectively). The yield from fresh, non-flowering herb amounts to 0,03 to 0,04 p.c, from fresh flowering herb up to 0,048 p.c.
From the seeds an oil can also be obtained upon the addition of white mustard4). In its composition this oil is identical with the one obtained from the herb.
Properties. Spoonwort oil has a pungent but not unpleasant odor, similar to that of mustard oil. d15o0,933 to 0,950; aD + 52 to -f-56°; soluble in 3 to 10 vol. of 80 p.c. alcohol, occasionally with slight opalescence, also in 1 vol. or more of 90 p.c. alcohol. It contains from 87 to 98 p.c. of butyl mustard oil. (For method of analysis see below.)
Upon fractionation of 42,8 g. the following results were obtained: between 150 and 154° 6,3 g., between 154 and 156° 12,2 g., between 156 and 158° 10,0 g., between 158 and 162° 12,0 g., residue 2 g. The specific gravity of these fractions fluctuated between 0,941 and 0,943, the angle of rotation between + 51,41° and + 62,78 ° 5).
l) E. Lucker, Apotheker Ztg. 21 (1906), 1006. *) J. Gadamer, Arch, der Pharm. 237 (1899), 92. 3) Report of Schimmel & Co. April 1900, 16. 4) W. Urban, Arch, der Pharm. 241 (1903), 691. 8) Gadamer, loc. cit.
Composition. Simon1) records the boiling point of the oil as being 156 to 159°. He found that it contains sulphur and that with ammonia it yields a substance similar to thiosinamine.
Geiseler2) believed the oil to be free from nitrogen and to contain oxygen, hence regarded it as an hydroxysulphide of allyl.
A. W. Hofmann3) ascertained the composition of spoonwort oil. Upon the distillation of the fresh herb, pounded to a pulp and mixed with water, 0,034 p.c. of an oil boiling between 158 and 165° were obtained. Fraction 161 to 163, obtained after several fractionations, yielded upon analysis results that agreed with butyl mustard oil.
Comparison between the natural oil and the synthetic product enabled Hofmann to establish the identity of spoonwort oil with the isothiocyanate of secondary butyl alcohol having the structural formula CH-N: C:S. It is a colorless liquid (d12o0,944; b. p. 159,5°) with the characteristic odor of the oil of spoonwort. When heated with ammonia to 100° it yields an optically active thiourea which melts at 136 to 137°.
As demonstrated by Gadamer4), spoonwort oil contains small amounts of several other constituents. Whereas the two lower fractions, viz., up to 156° (see under Properties) consist quantitatively of pure benzyl mustard oil, the higher fractions are admixed with a substance which has a lower specific gravity and a higher angle of rotation. Its odor reminds one of that of Curacao peels, and Gadamer supposes it to be limonene.
According to Moreigne5), oil of spoonwort contains raphanol.
For the preparation of spirit of spoonwort 0,7 g. of the natural oil are dissolved in one litre of dilute alcohol.
For the preparation of this spirit from the dry herb, Gadamer gives the following directions: four parts of dry spoonwort6), one part of coarsely comminuted white mustard, forty parts of water, and fifteen parts of alcohol (90 p.c.). The finely cut herb and the white mustard are covered with water in a glass retort and set aside for 3 hours. The alcohol is then added and 20 parts of spirit are distilled over.
1) Poggend. Annalen 50 (1840), 377.
2) Otto Geiseler, De Cochlearia officinali ejusque oleo dissertatio. Berol. 1857.
3) Berl. Berichte 2 (1869), 102; 7 (1874), 508. 4) Loc. cit.
5) See Spanish radish oil, p. 529.
6) For its preparation from fresh herb comp. E. Lucker, Apotheker Ztg. 21 (1906), 1006.
For the analysis, Gadamer1) gives the following directions:
To 50 g. of spirit of spoonwort, contained in a measuring flask of 100 cc. capacity, 10 cc. of 1/10-N-silver nitrate solution and 5 cc. of ammonia water are added, the flask is well stoppered and set aside for 24 hours. Enough water is then added to fill the flask to the 100 cc. mark. 50 cc. of the filtrate, to which 4 cc. of nitric acid and a few drops of ferric sulphate have been added, should not require more than 2,5 cc. of 1/10-N-ammonium sulphocyanate solution to produce a red color.
According to these directions, the mustard oil contained in 50 g. of spirit of spoonwort should convert the silver nitrate of at least 5 cc. of the 1/10 normal solution into silver sulphide. According to the equation C4 H9 Ncs + 3Nh3 + 2AgNO3 + g2S -h N:C-NHC4H9(NH4N03)2, one molecule of butyl mustard oil (= 115) corresponds to two molecules of silver nitrate (= 340), hence 1 cc. of 1/10-N-silver nitrate (= 0,017 g. AgN03) is the equivalent of 0,00575 g. butyl mustard oil. Therefore 0,00575 x 5 will yield the butyl mustard oil content of 50 g. of spirit of spoonwort, or 0,00575 x 1.0, the percentage content. According to this a minimum content of 0,0575 p.c. is required.
According to W. Urban2), spirit of spoonwort can also be prepared from the seed.