The irritant constituent of anti-leprotic oils / by H. Paget, J.W. Trevan and A.M.P. Attwood.

  • Paget, Humphrey.
Date:
[1934]
Catalogue details

Licence: Public Domain Mark

Credit: The irritant constituent of anti-leprotic oils / by H. Paget, J.W. Trevan and A.M.P. Attwood. Source: Wellcome Collection.

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    acid number of 260. On esterification with ethyl alcohol it yields two products with the following characters: (A) Insoluble in light petroleum; acid number about 37; sap¬ onification number about 252; ethoxyl about 12.3 per cent. (B) Soluble in light petroleum; acid number about 19; sapon¬ ification number about 249; ethoxyl about 18.1 per cent. These data can be explained if it may be assumed that the tarry acid is essentially a mixture of a hydroxy-dibasic acid of molecular weight about 418, with the corresponding lactone acid. The first will have two free carboxyl groups (acid number, calc. 268) ; the lactone acid will contain one free carboxyl group (acid number, calc. 140) and one lactone group (apparent saponification number 280). Further, that on esterification the free carboxyl group is first esterified yielding the petroleum-insoluble product (A), which is a monoethyl ester (ethoxyl, calc. 10.5 per cent) still containing the lactone group (apparent saponification number, calc. 262), and the petroleum-soluble product (B), in which both carboxyl groups have been esterified giving rise to a diethyl ester of a hydroxy-acid (ethoxyl, calc. 19.0 per cent, saponification number, calc, 236). For comparison with the tarry acid the only satisfactory “ex¬ posed product” yet available is that from the ethyl esters of the mixed crystalline acids (Fraction A, p. 151) after exposure to light and air during the summer of 1933. This should correspond approxi¬ mately with the petroleum-insoluble monoethyl ester (A) referred to above. The two are compared in Table 2. Table 2.—Constants of ethyl esters of (1) crystalline acids before and after ex¬ posure, and (2) tarry acids, petroleum insoluble and soluble fractions. Constant Ethyl esters of crystalline acids Ethyl esters of tarry acids Before exposure After exposure Petroleum insoluble Petroleum soluble Acid value . 0.7 40.3 37 19 Saponification value. 189.0 274.0 252 249 Ethoxyl, per cent. 14.9 8.3 12.3 18.1 Iodine value, per cent. 88.0 15.0 40 43 Specific rotation [a] 1I^0 . + 59.0 + 0.3 a + 1.5 Specific gravity D.18/18 . 0.9093 1.032 — 1.0180 ‘Too dark to read. Having regard to the intractable character of these products and the difficulty of bringing two such materials, isolated in dif-
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