SU577997A3 - Method of preparing pantolactone optical antipodes - Google Patents

Description

or tahiti carbonate, a molten L-pangoate piti is subjected to racemization in a poprotic solution at 12 ° -18 ° C in the presence of basic catapnaators.

As the main salts, piti carbonate piti, and as basic catapizators, aiphatic amines or hydroxides, or Jiap6oHaTU alkaline metaps, are used as the main salts.

Usage 1), 1g-pantoat piti dp

splitting into optical antipodes allows one to shorten the formation of the coli to 1.5 hours, to increase the optical purity of the target product to 87-98%, to racemize the-C-pantoate piti within 4 hours. In addition, it is possible to use raw pantopakton when good purity is achieved at the same time as 1) | “Pantoate Piti on the high-temperature coefficient of solubility and thermal stability.

Obtained as a by-product, an undesirable optically active form {, Pant zantoate is dissolved in a vapor solvent, preferably in a lower alcohol, or suspended in this one; the case in the presence of basic kagapizator, for example, apifatic amines, hydroxides of alkaline metaps ipi. alkali metal carbonates, at elevated temperatures, mostly at 12O-18OT, BDjIrnaHToaT piti is racemized.

This product without processing can be used again dp splitting.

Lithium pantoate, obtained by; cristaplaadium on polar solvents; as a racemic mixture, you can; also cleaved into optical isomers by conventional, ultra-macrostatic separation methods.

Example 1. In a vessel with a skewer and reverse cholipnik for 1.5 hours, 1, OO kg1), L-pantopactone, 1.5 pp of water and 0.3 kg of carbonate are boiled. After the formation of the GOj is completed, the hot reaction mixture is filtered, and 0.025 K of carbonate is recovered. From the filtrate, after cooling with stirring, 0.77 to 11 is obtained, and lithium-pantoate with 1 mol of cristappization water (53.0% of the theoretical), m.p. 107-1. By evaporation of the mother liquor, 3), 1-pantolactone is obtained as D1-panthoate piti.

Example 2. When mixing and

After boiling for 2.5 hours, 1, O kgV, 1-lactopactone, 2.5O p of methanol and 0.34 kg of piti hydroxide monohydrate are reacted. After that, skip carbon dioxide, set the pH to 7, and hot

the lithium carbonate formed is filtered off.

620 gT}, b-iantoate of piti (5.2% of the theoretical), etc. 18О-182 С.

After evaporation of the mother liquor, an additional 43% of the used D, li pantolactone is obtained in the form of monohydrate B, b panthoate peti, etc. 1O7-BUT ° C.

EXAMPLE 3: 334 gB of b-panthoate drip 102 g of oxalate piti and 6OO g of water are heated with stirring for 4 hours with reverse hodipnic until boiling. The mixture was filtered hot and the calcium calcium alkalate was washed three times with 70 ml of hot water. The filtrate and the washings are evaporated in a vacuum evaporator to a volume of 4OO MP. 254 g1, lpanthoate lithium (74% of the theoretical), etc. are exhausted. 1O7-BUT

From the mother liquor, another 20% of the used VD-pantopatone as V, 1-pantoate of piti is evaporated.

Example 8: 4. 431 gM-pantoate bari, 128 g of suphateted piti monohydryate and iOOO ml of water are boiled with stirring for 6 hours with reverse chopipnic. The barium sulphate formed is filtered off hot and washed three times with a VO of hot water. The filtrate and washings are evaporated twice in a vacuum evaporator.

Just get 320 g of monohydrate B, L-pantoate Piti (93% of theoretical), t. PP, 107-11O ° C

Example 5. 50 g of racemic panthoate piti and 1O gt) piti panthoate are dissolved in HO of methanol, heating to 60 ° C, after which the solution is seeded with 0.1 g lbit antoate. After 60 hours of stirring - and the subsequent 3 hours of gentle settling, the precipitated crystals are isolated by means of filtration and dried, and 19 g of B-pantot are obtained. lithium with optical purity (., h: 10 (, 0, water).

Example 1OO g of racemic pantoate piti and B g1-lithium panthoate are dissolved in 1.1 l of ethanol, heated to 62 C. Then, seed crystals of L-pantoate lithium are placed in the solution, cooled down to 2 C with stirring days at this temperature. Kristappa precipitates are filtered, washed with 10 ml of ethanop and 5 ml of acetone and dried. 1 7 g of L - lithium pantoate with an optical purity of 87%, 9, (, O, water) will be released.

Example 7. 895 g of D L pantoate lithium are dissolved in a 1BOO mp meganop by stirring and heating to 65 ° C. Next, this saturated solution is seeded with a crygaplam (up to 1 g) of pure D () -) pant