1010
NOTES
added and the mixture agitated with hydrogen chloride gas until it becomes homogeneous. From this solution thorium chloride octahydrate precipitates as pure white crystals, which are filtered off, washed with ether and dried. A sample of the salt when dissolved in water gives a negative thiocyanate test for iron.
Vol. 64
The Mutarotation of arD-Glucose in DioxaneWater Mixtures at 25' BY H. H. ROWLEY~ AND WARDN. HWBARD
The mutarotation of a-D-ghCOSe has been an object of study for many years by numerous inDEPARTMENT OF CHEMISTRY vestigators. Though the majority of the experiTHE CITYCOLLEGE RECEIVED JANUARY 6, 1942 NEWYORK,N. Y. ments concerned this phenomenon in aqueous solution both with and without catalysts, a few have been studied in mixed aqueous solvents. The Action of Monoethanolamine on Ethyl Worley and Andrews' studied the mutarotation Bromomalonate in methanol-water mixtures; Richards, Faulkner BY CHESTERB. KRIWER,M. MELTSNER -D H. HWDIN and L0wry3 in both methanol-water mixtures and ethanol-water mixtures; Lowry and FaulkIn the course of work being carried out in these ner4 in pyridine-water mixtures; and more reLaboratories dealing with the synthesis of cently Rowley" in ethanol-water mixtures at 25". diureides, the condensation of monoethanolamine The mutarotation of glucose in solution is bewith ethyl bromomalonate was attempted. As lieved by many to be catalyzed by acids and ordinarily carried out, we find condensation does bases and since water is a complete catalyst, havnot result; rather the bromine atom in the ester ing both acidic and basic properties, the reaction is replaced by hydrogen. This reaction is analo- is fairly rapid in pure water. Absolute methanol gous to the action of alkaline reagents and halogen is amphiprotic and apparently a complete cataacids on similar compounds containing active lyst but much inferior to pure water6as is absolute halogen atoms. ethanol.6 On the other hand, pyridine is not The ethyl bromomalonate was prepared by the amphiprotic but is a fairly strong base so mixtures action of bromine on ethyl malonate dissolved of this solvent and water should be a fair catalyst in carbon tetrachloride. The product was care- for the mutarotation. fully purified by several distillations through a In continuing the studies of the mutarotation column under reduced pressure. The fraction of a-D-glucose in mixed aqueous solvents, it was boiling a t 126-127' under 18 mm. pressure was decided to use an inert organic solvent which used. probably does riot itself catalyze the reaction. Forty-six grams of monoethanolamine (0.752 Unlike the alcohols, which have been used in premole) and 90 g. of the ethyl bromomalonate vious studies, dioxane has no apparent acid group (0.376 mole) were refluxed together for six hours. and its basic properties are probably relatively On cooling, the mixture separated into two layers, weak. Thus it might be assumed that its catathe lower one eventually solidifying. The solid lytic effect on the mutarotation will be exceedingly material was identified as monoethanolamine small. This appears to be justified by subsehydrobromide. The liquid upper layer was ex- quent experimental work. Since a-D-glucose is tracted with diethyl ether, thus effecting separa- fairly soluble in mixtures up to ninety weight per tion from any excess monoethanolamine, and the cent. of dioxane, the mutarotation of this sugar was ether extract dried over anhydrous magnesium studied in dioxane-water mixtures at 25'. sulfate. The ether was distilled off and the resulting liquid fractionated. A low-boiling fracDiscussion of Results tion, b. p. 58-60' (2 mm.), was shown to be ethyl The solutions were made by dissolving a 1.4144) and weighed amount of pure anhydrous a-D-glucose malonate by its refractive index (TL~OD density (dz04 1.055). The yield was 11 g. A in dioxane-water mixtures of known composition. higher boiling fraction (36 g.), b. p. 92-93' (2 The concentration ranged from 4.0 g. of sugar/ mm.), was identified by its boiling point and (1) Present address: Department of Chemistry, Lawrence Coldensity (dPo*1.426) as unchanged ethyl bromo- lege, Appleton, Wisconsin. (2) Worley and Andrews, J . Pkys. Chcm., 81,742, 1880 (1927). malonate. DEPARTMENT OF CHEMISTRY THECITYCOLLEGE NEWYORE,N Y. RECEIVED JANUARY 6, 1942
(3) (4) (5) (6)
Richards, Faulkner and Lowry,J . Chcm. Soc.. 1733 (1927). Lowry and Faulkner, ibid., 197,2883 (1926). Rowley, Tms JOURNAL, 69, 2663 (1940). Rowley and Bailey, ibid.. 62,2562 (1940).
