Crystalline fructose

Crystalline fructose Crystalline nylons Crystalline platelets Crystalline polymers Crystalline polypropyL Crystalline Si Crystalline silica... 

Another mono-isopropylidene-D-fructose, crystalline and non-reducing, was made by Zervas and Sessler86 by debenzoylation of the product obtained by condensing D-fructofuranose 1,6-dibenzoate (see page 63) with acetone. From the method of preparation this must be 2,3-iso-... 

The Structure of Normal Fructose Crystalline Tetramethyl /8-Methyl-fructoside and Crystalline Tetramethyl Fructose (1 3 4 5), W. N. Haworth, E. L. Hirst, and A. Learner, /. Chem. Soc., 1040 (1927). 

In a 50-100 ml. conical flask place a solution of 0 -5 g. of glucose in 5 ml. of water, 12-15 ml. of 10 per cent, sodium hydroxide solution and 1 ml. of benzoyl chloride, cork tightly, and shake until the odour of benzoyl chloride has disappeared and a crystalline (frequently sticky) soUd has separated. Filter oflF the solid, wash it with a Uttle water, and recrystaUise it from ethyl or n-butyl alcohol. (If the product is sticky, it should be removed, and spread on a porous tile before recrystaUisation.) Glucose pentabenzoate has m.p. 179°. Fructose pentabenzoate, m.p. 78-79°, may be similarly prepared. 

Early applications of crystalline fructose focused on foods for special dietary applications, primarily calorie reduction and diabetes control. The latter application sought to capitalize on a signiftcandy lower serum glucose level and insulin response in subjects with noninsulin-dependent diabetes melUtus (21,22) and insulin-dependent diabetes (23). However, because fmctose is a nutritive sweetener and because dietary fmctose conversion to glucose in the hver requires insulin in the same way as dietary glucose or sucrose, recommendations for its use are the same as for other nutritive sugars (24). Review of the health effects of dietary fmctose is available (25). 

Simple sugars undergo reaction with phenylhydrazine, PhNHNH2, to yield crystalline derivatives called osazones. The reaction is a bit complex, however, as shown by the fact that glucose and fructose yield the same osazone. 

With the experimental results accumulated during his stay in Berlin, Garcia Gonzalez prepared two doctoral dissertations, entitled New Crystalline Phosphoric Esters of o-Fructose and Tests on Some Assumed Phases of Alcoholic Fermentation, which he presented in order to receive his doctorates in Chemistry and in Pharmacy, respectively, at the University of Madrid in 1932. Armed with these two degrees, he decided to pursue an academic career in his own country. His early training in a provincial... 

The taste of D-fructose has been widely studied, and numerous relativesweetness intensity-scores have been assigned to it. Shallenberger and Acree reported that the crystalline solid is 1.8 times as sweet as sucrose. Verstraeten claimed that it is 8 times as sweet, but this must have been a misinterpretation of a statement made by E. G. V. Percival. ... 

The structure of the levan synthesized by the action of B. subtilis on sucrose was determined by Hibbert and Brauns.89 Levan, in a yield of 60-65% calculated on the D-fructose part of the sucrose, was obtained by precipitation of the concentrated culture into methanol, and purified by reprecipitation and electrodialysis. Hydrolysis of purified levan with 0.5% aqueous oxalic acid for one hour at 100° gave a 99% yield of crystalline D-fructose. Triacetyllevan was prepared by treatment with acetic anhydride in pyridine, and deacetylation with alcoholic alkali yielded material identical with the original levan.940... 

Two methylations of levan by means of dimethyl sulfate and potassium hydroxide (not sodium hydroxide) followed by one inethylation with methyl iodide and silver oxide yielded trimethyllevan in 88% yield. This was purified by solvent fractionation over-all yield 75%, m. p. 145-146°, OCHs 45.9%. Trimethyllevan, hydrolyzed by heating at 95° for twenty-four hours with a dilute solution of sulfuric acid gave a 98.5% yield of a crystalline trimethyl-D-fructose. The trimethyl-D-fructose was proved940 to be 1,3,4-trimethyl-D-fructofuranose since oxidation with nitric acid gave a 97% yield of a dimethyl-2-keto-D-gluco-saccharic acid which was identified as the crystalline diamide (95% yield). 

Upon hydrolysis an equal amount of tetramethyl-D-fructose and dimethyl-D-fructose was obtained. The first of these was identified as 1,3,4,6-tetramethyl-D-fructose by conversion to the characteristic crystalline acid amide obtained by Haworth, Hirst and Nicholson.66 The dimethyl-D-fructose was obtained as a thick brown sirup having [oT]d20 = + 20.0° (c = 1.82, chloroform). 

The structure of difructose anhydride II has not yet been determined. McDonald and Jackson76 prepared its hexamethyl ether, which proved to be a crystalline compound melting at 73°. The behavior of the product from the acid hydrolysis of this hexamethyl derivative toward phenylhydrazine suggests that two different trimethyl-D-fructoses are present, the identification of which remains to be accomplished. Lately some evidence concerning the structure of this anhydride has been obtained by the use of per-iodic acid oxidation, as described on page 275. 

A compound represented by XVIII would yield 1,3,4-trimethyI-D-fructose, a crystalline substance with [aJD20 = — 51.4° (water), and 1,3,6-trimethyl-D-fructose (now unknown), upon hydrolysis of its hexa-methyl derivative. No evidence has been obtained to indicate the presence of this negatively rotating trimethyl-D-fructose and it is established that the mixture of trimethyl-D-fructoses from hexamethyl-di-D-fructose anhydride II rotates in the positive range of 25 to 30°. Unless the 1,3,6-trimethyl-D-fructose should prove to possess the unusually high rotation of about + 100°, which seems at least improbable, structure XVIII can be excluded. 

The reaction with ethyl acetoacetate has been extended to glycolaldehyde, and to carbohydrates other than n-glucose, by employing different experimental conditions it is probably applicable to aldoses in general. With d-fructose, yields are lower, but two molar proportions of water are liberated and a crystalline product results. This has a constitution similar to that of II but with the D-omhfno-tetrahydroxybutyl chain at the /3-position on the furan ring. The reaction has been applied successfully to other ketoses and... 

The reaction of ethyl acetoacetate with simple hydroxy ketones has been compared with the corresponding reactions of the ketoses. The results obtained with l-hydroxy-2-propanone and 3-hydroxy-2-butanone, under the same experimental conditions as with D-fructose, establish a parallel between these reactions. However, as in the case of the aldoses, the yield is greater for these simpler hydroxy ketones than for the ketoses.9 The resultant esters, (XV and XVI), were obtained in the form of sirups, but the free acids, (XVII and XVIII), and their phenacyl esters are crystalline. The acids were shown to be identical with those of known structure described in the literature.9... 

The second mechanism (B) likewise does not agree with the results of recent experiments, as compound XI, from the reaction of D-fructose with ethyl acetoacetate, cannot be formed from either of the enolic forms of D-fructose. The structure of the crystalline compound isolated shows that the substituents at Cl and C2 of D-fructose also take part in the condensa-... 

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