Resolution of the alpha-beta-dihydroxy-alpha-methyl-beta-isopropyladipic acids / by T.A. Henry and H. Paget.
- Thomas Anderson Henry
- Date:
- [1923.]
Licence: Public Domain Mark
Credit: Resolution of the alpha-beta-dihydroxy-alpha-methyl-beta-isopropyladipic acids / by T.A. Henry and H. Paget. Source: Wellcome Collection.
11/16 page 1886
![converted into the sodium salt, as already described, and gave in successive readings, the acid being recrystallised each time, [a]D — 5-71°, — 5*78°, — 5*62° in water (c = 17-94 to 18-03). The acid itself, regenerated as described in the case of the d-acid, melted at 214°, and in alcoholic solution gave as a mean of three determin¬ ations [a]D — 7-20° (c = 0-76 to 1-42), but for the reason given in the case of the d-acid great accuracy is not claimed for this result. The pure cinchonine salt of the l-acid was made by adding the calculated quantity of base to the acid, dissolved in water, and distilling off the excess of solvent. On cooling, the salt crystallised in colourless, triangular plates, which began to soften at 178° and melted completely at about 190°. This salt is abnormal and appears to have approximately the composition 3C19H22ON2,2C10H18O6. It is soluble in little more than its own weight of 96 per cent, alcohol. [a]D -f- 145-7° in alcohol (a -f- 6-96°, c — 2-521, l = 1-S94). The quinine salt, similarly prepared, crystallises from 50 per cent, alcohol in warty masses of colourless needles, m. p. 225°, [a]D — 135-6° in alcohol (aD — 2-72°, c = 1-057, l = 1-894). The quinidine salt of the £-acid, similarly made, crystallises from 30 per cent, alcohol in warty masses of needles closely resembling the quinine salt in appearance. It melts at 154° and has [a]D -f- 162-4° in alcohol (a -j- 17-37°, c = 5-645, l — 1-894). The quinidine salts of both the d- and the l- acid separate from hot solution in dilute alcohol as oils, which slowly crystallise on standing, and are to some extent soluble in water. para-Acid, m. p. 198°.—Five grams of this acid were converted into the neutral quinine salt, and the crude salt recrystallised from 96 per cent, alcohol in the usual manner until a constant product, m. p. 212°, [a]D — 111-9° in alcohol (aD — 3-18°, c = 1-420), was obtained. The yield was 2-5 grams. A repetition of this separation, using 8-3 grams of acid and crystallising from dilute alcohol (30 to 50 per cent.), gave 6-8 grams of pure quinine salt, m. p. 213°, [a]D — 111-4° in alcohol (aD — 4-62°, c = 2-074), but the use of weaker alcohol, involving a higher temperature on con¬ centration, leads to gradual darkening of the solution and makes it more difficult to recover the more soluble quinine salt. The acid regenerated from the pure less soluble quinine salt melted at 208°, re-solidified on cooling, and then re-melted at 74°, owing to conversion into the dilactone. The sodium salt in aqueous solution gave [a]D -j- 4-25°, + 4-41° (a -f- 1-49°, 1-62°; c = 17-54, 18-36). The free acid had [*}%-’ - 10-96° in water (a - 0-22°, c = 1-004) and — 9-55° in 96 per cent, alcohol ([a]D — 0-<4°, c = 4-091, l = 1-894). The more soluble quinine salt was difficult to obtain in satisfactory](https://iiif.wellcomecollection.org/image/b30624058_0011.jp2/full/800%2C/0/default.jpg)
