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.
10/16 page 1885
![To 7-3 grams of the acid, dissolved in 300 c.c. of boiling 96 per cent, alcohol, the calculated quantity of quinine base, dissolved in 100 c.c. of alcohol, was added, and the solution left standing for four days, when it had deposited 14 grams of quinine salt. The latter was then recrystallised from 96 per cent, alcohol until the specific rotation became constant at about —128° and the melting point at 227°. About 10 grams of material of this quality were accumulated by repeatedly working through the middle fractions. The acid regenerated from this, and recrystallised, gave a sodium salt having [a]D -f 3*53°, but on repeating the separation it was found that the constancy in melting point and rotation of the quinine salt was only apparent, and with other conditions other results were obtained, sometimes higher and sometimes low’er. Recourse wTas then had to cinchonine, and after various trials it was found that crystallisation of the acid cinchonine salt, C19H22ON2,C10H18OG, from 96 per cent, alcohol gave much better results, a fraction melting constantly at 174° and having [a]D -{- 116° being ready separable. From 23 grams of the crude salt, 7-5 grams of the pure salt of the dextro- acid having [oc]D -j- 115-2° were obtained (aD = + 4-6° in alcohol; c = 2-11; l = 1-894). This salt crystallises in prismatic plates, sparingly soluble in alcohol and scarcely soluble in water. It was suspended in fine powder in hot water and the calculated quantity of 2A7-soda added, the cinchonine filtered off, washed twice in a mortar with water, and the washings and filtrate concentrated to low bulk under reduced pressure, again filtered, and the clear solution acidified, when it deposited 3-0 grams of well-crystal¬ lised acid melting at 214°. This was converted into sodium salt, which had a specific rotation [a]D -j- 5-1° (a -f- 1-94° in water, c = 19*02). A second determination gave [a]D -f- 5-36° for the same conditions. The acid regenerated from the sodium salt and recrystallised gave in alcoholic solution [a]£5 -f- 7-37° (c = 0-6 to 1-25), but owing to the difficulty of reading such small rotations no great stress is laid on the quantitative value of this result. The quinine salt made by neutralising the pure d-anti-acid with quinine and recrystallising from 96 per cent, alcohol had m. p. 231°, and [a]D - 127-2° in alcohol (a - 1-79°, c = 0-7454, l = 1-894). The quinidine salt of the d-acid, made similarly, crystallises from 30 per cent, alcohol, and has m. p. 144° and [a]D -f- 154-4° in alcohol (a + 15-84°, c = 5-417, l = 1-894). The more soluble cinchonine salt could only be obtained as an oil for some time, but eventually a portion of this was induced to crystallise from a syrupy solution in 10 per cent, alcohol. Yield 5-5 grams = 24 per cent. The acid regenerated from this was](https://iiif.wellcomecollection.org/image/b30624058_0010.jp2/full/800%2C/0/default.jpg)
