The resolution of benzoyloscine / by Frank Tutin.

  • Tutin, Frank.
Date:
[1910?]
Catalogue details

Licence: In copyright

Credit: The resolution of benzoyloscine / by Frank Tutin. Source: Wellcome Collection.

    6/10 (page 1796)
    It was again crystallised as before, when it seemed much less soluble, and melted at 238—244°. 0-3982, made up to 20 c.c. with water, gave aD + 2°4; in a 2-dcm. tube, whence [a]D +51'9°; [M]D +295'8°. When recrystallised a third time, this salt yielded handsome, glistening needles, which melted sharply at 246—2465°. 0'4092, made up to 20 c.c. with water, gave aD + 2°8/ in a 2-dcm. tube, whence [o]D +52'1°; [M]D + 297-0°. This salt was evidently that of the dextrorotatory component of the racemic base, and since, as shown below, it yielded d-oscine on hydrolysis, it must be designated benzoyl-d-oseine d-bromocamphor- sulphonate. Repeated crystallisation caused no further change in its melting point or rotatory power: 0-1437 gave 0-2767 C02 and 0’0800 H20. C = 52’5; H = 6’2. C15H]703N,Cloni504BrS requires C = 526; H — 5'7 per cent. The molecular rotation of benzoyl-d-oscine, calculated from that of its d-bromocamphorsulphonate, is [M]D +26*0°, whence the basic ion has [a]D + 10'0°. A small quantity of the above-described salt of benzoyl-^-oscine was treated with sodium carbonate, the base extracted with chloro¬ form, and examined polarimetrically, wrhen a reading of + 0°25'r was obtained. It was evident, therefore, that the base could be obtained in the free state without suffering complete racemisation. A larger quantity of the salt was then decomposed, and the resulting base dissolved in 20 c.c. of 50 per cent, alcohol, when it had aD + 0°49/ in a 2-dcm. tube. Ten c.c. of the solution were subsequently found, on titration, to contain 0*1172 of base, whence [a]D +3*5°; [M]d + 9'75°. The fact that the value thus obtained for the rotation of benzoyl-<Aoscine is lower than that previously calculated for the basic ion of benzoyl-d-oscine d-bromocamphor- sulphonate ([a]D + 10*0°) may be due, in part, to racemisation, but it is probably largely owing to the fact that the free base is incom¬ pletely ionised when dissolved in 50 per cent, alcohol (compare Carr and Reynolds, this vol., p. 1328). Attempts were made to isolate b enzoyl-l-o seine d-b romo camphor- sulphonate, but without success. A fraction of salt, melting at 219—227°, was, however, obtained, the basic ion of which had LM]d-4-7°. Benzoyl-d-oseine hydrochloride was prepared from the correspond¬ ing d-bromocamphorsulphonate by double decomposition. It formed colourless needles, melting at 283—284°. Benzoyl-d-oscine nitrate was similarly prepared. It was very sparingly soluble in water, and crystallised in irregular prisms,