Methyl salicylate (salicylic acid methyl ester, artificial oil of wintergreen) is one of the most important perfumes and is also highly esteemed on account of its antiseptic properties. It has been known for a long time, and, as has been demonstrated in the course of years, is very widely distributed in the vegetable kingdom. Neither is its occurrence restricted to a certain part of the plant, but is found in all organs from the root to the flower. It constitutes the bulk of the oils of gaultheria and sweet birch. It has also been found in the oils of tuberose (from pomade), ylang-ylang, beech seedlings, in Roman and French cassie flowers, rue, tea, cloves, Viola tricolor, likewise in the following plants:1) Podocarpus chinensis, P. Nageia, Gnetum Gnemon B ovalifolium, Castanopsis javanica, C.j. var., C. Tun-gurrut, C. spec, Quercus spec, div., Q. bancana, Q. glandulifera, Q. Junghuhnii, Q. pseudomoluccana, Q. spicata, Q. Teysmannii, Cecropia Schiedeana, Cinocephalus ovatus, C. suaveolens, C. spec, Urostygma acamptophyllum, Ficus elastica, F. Benjamina, F. B. var. crassinerve, F. annulata, F. geniculata, F pilosa, F. p. var. chrysocannia, F. retusa var. nit/da, F xylophylla, Sleetia Sideroxylon, Streblus mauritianus, Gironn/era subee-qualis, Nyristica intermedia, Lindera Benzoin, Parinarium l) Compare: van Romburgh, Vers/ag van 's lands plantentuin te Buiten-zorg 1897, 37; 1898, 29; 1901, 58; Kremers and James, Pharm. Review 16 (1898), 100; Report of Schimmel & Co. Oct. 1899, 56; Tailleur, Compt. rend. 132 (1901), 1235.
spec, Photinia serrata, Rubus sundaicus, Spiraea Ulmaria, Acacia Intsia, A. pluricapitata, A. sarmentosa, A. tenerrima, Bauhinia pyrrhaneura, Caesalpinia Bonducella, Guilandina spec, Mucuna gigantea, Erythroxylon Coca, E. bolivianum, Canarium spec, Garuga spec, Poly gala Senega, P. S. var. latifolia, P. Baldwin i, P. variabilis, P. /a van a, P. oleifera, P. serpyllacea, P. calcarea, P. vulgaris, Epirixanthes elongata, E. cylindrica, Adenocrepis javanica, Antidesma diandrum, Agy-neia multiflora, A. spec, Baccaurea spec, Cyclostemon macro-phyllus, Bridelia tomentosa, Elateriospermum Tokbrai, Clu-ytia oblongifolia, Leiocarpus arboreus, L spec, Pierardia dul-cis, P. spec div., Phyllanthus zeylanicus, Rottlera dispar, Sphenodesme Wallichiana, Trewia spec, Mangifera spec, Seme-carpus spec, Turpinia sphaerocarpa, T. spec, Capura alata, Harpullia imbricata, H. spec, Meliosma pendula, Mischocarpus fuscescens, Elaeocarpus resinosus, Wormia triquetra, Thea chinensis, T. cochinchinensis, Calpandria lanceolata, Hydno-carpus Wightiana, H. alpina, H. venenata, Scolopia Roxburghii, Taraktogenos Blumei, Alsodeia cymulosa, Viola tricolor, fioma-lium tomentosum, H. javanicum, Carallia symmetria, Meme-cylon spec, Nania vera, Barringtonia rubra, B. spicata, B. spec div., Monotropa Hypopithys, Gaultheria fragrantissima, G. leu-coca r pa, Ardisia hum His, A. lurida, A. fuliginosa, A. macro-phylla, A. purpurea, A. reclinata, A. sanguinolenta, A. speciosa, A. spec, Sideroxylon obovatum, Diospyros aurea, D. cauli-flora, D. acuminata, D. Gardneri, Maba spec, Symplocos spec div., S. fasciculata, Chionanthus elliptica, C. latifolia, C. montana, C. ramiflora, C. spec, Allamanda Hendersoni, Chilo-carpus densiflorus, C. denudatus, C. spec, Melodinus laevigatus, M. oriental is, Landolphia Watson ii, Alston ia an gusti'folia, A. Hoedti, A. macrophylla, A. villosa, A. spec, Hunteria corymbosa, Rauwolfia spectabilis, Cryptolepis laxiflora, Marsdenia tenacis-sima, Cordia asperrima, Bignonia Chamberlaynii, B. exoleta, Tecoma mexicana, Hexacentris coccinea, Nyctocalos brunfelsiae-florus, Thunbergia grand/flora, Canthium palembanicum, C. spec, Gardenia Fitzalani, G. Schoemannii, Nauclea fagifolia, N. poly-cephala, N. spec, Pavetta angustifolia, P. arborea, P. barbata, P. grand/flora, P. g. var. lutea, P. g. var. aurantiaca, P. littorea, P. longiflora, P. rosea, P. paludosa, P. Iongipes, P. spec,
Petunga variabilis, P. spec, Psychotria celastroides, P. robus-ta, P. undata, Wendlandia spec, Anthocephalus Cadamba, Coffea densiflora, C. lepidophloia, C. liberica, C. stenophylla, Griffithia acuminata, G. eucantha, Mussaenda frondosa, M. offi-cinalis, M. rufinervia, Polyphragmon spec, Randia densiflora, R. dumetorum, R. uliginosa, Sarcocephalus subditus, Scyphos-tachys coffeoides, Viburnum sundaicum, Stifftia chrysantha and Vernonia arborea.
As a rule, methyl salicylate does not occur as such in the vegetable kingdom, but in the form of a glucoside. Thus in the leaves of Gaultheria procumbens and in sweet birch bark it occurs as gaultherin from which it is set free by ferment action. Hence the yield of methyl salicylate from these sources is greatly increased if the material is moistened and set aside for several hours. In the case of many of the above mentioned plants the distillate from fresh material contains no methyl salicylate whatever.
As to the nature of the methyl salicylate-yielding glucosides little is as yet known. In addition to the gaultherin already mentioned primverin and primulaverin yield methyl salicylate. Both glucosides occur in the Primulaceee and are hydrolysed by primverase, the accompanying ferment.1)
Artificially methyl salicylate is obtained by heating methyl alcohol and salicylic acid in the presence of sulphuric acid. On a large scale this ester has been manufactured by Schimmel & Co. since 1886 and is placed upon the market as artificial oil of wintergreen.
Methyl salicylate is a colorless liquid, which is optically inactive and possesses an intense, peculiar odor. As to its other properties, the following data have been recorded:
B. p. 217° (730 mm.);2)
B. p. 223,7° (corr.), d0o 1,1969, dl6o 1.1819;3)
M. p. - 8,3°;4)
B. p. 222,2° (corr.), d4o1,1992, d15o1,1890.5)
1) Goris and Mascre, Compt. rend. 149 (1909), 947.
2) Schreiner, Liebig's Annalen 197 (1879), 17.
3) Kopp, Ibidem 94 (1855), 301, 302.
4) v. Schneider, Zeitschr. f. physik. Chem. 22 (1897), 233.
5) Perkin, Journ. chem. Soc. 69 (1896), 1187.
In connection with technical products, Schimmel observed the following constants: dl5o 1,185 to 1,190; nD20o 1,536 to 1,538; soluble in 6 to 8 vol. of 70 p. c. alcohol.
Methyl salicylate dissolves in potassium hydroxide solution of medium concentration forming the readily soluble ester salt potassium methyl salicylate. From such a solution it can be recovered unchanged by means of dilute acids. Sodium hydroxide solution precipitates the difficultly soluble sodium methyl salicylate. When heated with an excess of alkali, both ester salts are saponified. From these saponified solutions, acid precipitates salicylic acid.
Characteristic for salicylates is the violet color produced by ferric chloride.