Fructose from glucose + hydroxide

Whether these alkaline-earth metal ions are capable of directing the course of the transformation is at present unclear. Kusin reported that, when D-glucose reacts in calcium hydroxide solution at 25°, no D-fructose appears, whereas sodium hydroxide brings about formation of D-fructose under the same conditions of time and temperature. However, this claim is contrary to the findings of Lobry de Bruyn and Alberda van Ekenstein, Sowden and Schaffer, and Topper and Stetten, all of whom isolated D-fructose from the reaction of D-glucose with calcium hydroxide under comparable conditions. 

On the other hand, the product from glucose is an exceedingly complex mixture, the composition of which varies with the conditions of treatment. D-Psicose (from treatment with ammonia) (55) and (dl + n)-sorbose (from treatment with a strong base resin) 90) have been identified definitely in the mixture. D-Glucose is readily converted to D-fructose. From the latter has been isolated after treatment with potassium hydroxide (dl + D)-sor-... 

Some workers have reported a cation dependence and others an independence. Any differences, if noted, were attributed usually to the strength of the base. Thus, Lobry de Bruyn and Alberda van Ekenstein (78) reported the reaction products of lead hydroxide to be different from those of numerous other bases which they studied. Notably, with lead hydroxide the ketose of the 1,2-enediol equilibrium was missing. This was attributed to its very rapid conversion to the supposed 3-ketose. Kusin (97) recorded a similar observation with calcium hydroxide as compared to sodium hydroxide, but he believed the ketose was never formed. Under the conditions studied, lime acting on glucose gave mannose but no detectable amounts of fructose, whereas sodium hydroxide gave a measurable amount of fructose but only a trace of mannose. Sowden and Schaffer (81) found no differences in the initial mutarotation of D-mannose in the presence of 0.035 N sodium and calcium hydroxides at 35°, but differences in the direction of... 

In the long history of the LdB-AvE transformation [8], the suggestion has appeared several times that the reaction is catalyzed by calcium ions, but the proof has often been inconclusive. There are several points on which different authors disagree. Let us examine some of them. Kusin reported [46] that when D-glucose reacted in calcium hydroxide solution at 25 °C no fructose was formed whereas, in a solution of sodium hydroxide, fructose was detected under the same conditions. This is contrary to the observations of LdB and AvE [4], Sowden and Schaffer [47] and Topper and Stetten [48], who all isolated fructose from the reaction in calcium hydroxide solutions. 

Kusin s results were recently confirmed, by chance and unexpectedly. During studies on the nickel-amine catalyzed epimerization (see Osanai, this voL), calcium hydroxide plus amine was also tried [50] and proved successful. However, calcium cations do not form complexes with amines and when calcium hydroxide was tried without the amine, mannose was still formed from glucose but not fructose [51 ]. It was found that the reaction did not proceed through an ene-diol but by carbon-carbon bond migration within a calcium complex. 

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. 

Some examples will illustrate the applicability of this generalization in so far as it concerns alkaline scission. 5,6-Anhydro-l,2-isopropylidene-D-glucofuranose with alcoholic sodium hydroxide gives a mixture of isopropylidene-D-glucose and isopropylidene-L-idose. The latter results from inversion on C5, the former presumably by inversion on the non-asymmetric C6.7 3,4-Anhydro-l,2-isopropylidene-D-psicose (or allu-lose17) (XX) when treated with sodium hydroxide yields a mixture of products among which 1,2-isopropylidene-D-fructose (XIX) was detected (in the representations inversions are denoted by circles above the arrows and the carbons inverted are noted below the arrows). With sodium methoxide, however, l,2-isopropylidene-4-methyl-D-sorbose (XXI) is the chief product and results from inversion on C4.1S... 

Removal of the a-hydrogen in o-glucose leads to enolization (we have omitted the enolate anion in the mechanism). Reversal of this process allows epimerization at C-2, since the enol function is planar, and a proton can be acquired from either face, giving D-mannose as well as o-glucose. Alternatively, we can get isomerization to o-fmctose. This is because the intermediate enol is actually an enediol restoration of the carbonyl function can, therefore, provide either a C-1 carbonyl or a C-2 carbonyl. The equilibrium mixture using dilute aqueous sodium hydroxide at room temperature consists mainly of o-glucose and o-fructose, with smaller amounts of D-mannose. The same mixture would be obtained... 

Figure 6.12 Amperometric detection of a mixture of 15 different carbohydrates (80-150 fiM). Conditions electrolyte, 100 mM sodium hydroxide capillary, 73 cm X 50 /xm I.D. fused silica injection, gravity, 10 cm for 10 sec voltage, 11 kV. Peaks a, trehalose b, stachyose c, raffinose d, sucrose e, lactose f, lactulose g, cellobiose h, galactose i, glucose j, rhamnose k, mannose 1, fructose m, xylose n, talose o, ribose. (Reprinted from Ref. 65 with permission.)...

D-glucose yields 67 g of D-fructose and 10 g of D-glucose. After isomerization, the pH of the solution is so adjusted as to cause precipitation of aluminum hydroxide, and the D-fructose is isolated by precipitation as its calcium complex, from which a solution of pure D-fructose is obtained by treatment of a slurry of the complex27 in water with carbon dioxide. 

The first really definitive work on glutose was carried out by Benedict, Dakin and West. They showed that glutose in vitro resembles D-fructose in that it is converted by sodium hydroxide into hydroxy acids (principally optically inactive lactic acid) to about the same extent as D-glucose. In slightly alkaline solution phenylhydrazine reacts to form the phenylosazone of methylglyoxal, and zinc ammonium hydroxide converts glutose into methylimidazole in yield comparable to that obtained from fermentable hexoses. But in vivo glutose ... 

Clean five test tubes by adding a few milliliters of 10% sodium hydroxide to each and heating them in a water bath and then empty and rinse with distilled water. In each tube place one micro drop of a 0.1 M solution of a sugar or of n-butyralde-hyde and 1 ml. of the test solution. Let the reaction proceed first at room temperature and note the order of reactivity, as judged both from the color and by the time of first appearance of silver. After a few minutes put the tubes in the heating bath. The test shows the order of reactivity to be fructose > glucose > lactose > maltose > n-butyraldehyde. 

Topper and Stetten s work involved (1) the reaction of n-glucose-l-d in ordinary water saturated with calcium hydroxide, and (2) the reaction of D-glucose in deuterium oxide saturated with calcium hydroxide-d2. These isomerizations were carried out at both 25° and 35°. In the experiments with D-glucose-l-d at 35°, the n-mannose isolated (as the phenylhydrazone) contained 44 % of the deuterium in the starting substance, all of which was retained at Cl, whereas the n-fructose isolated (as the phenylosazone) retained 94% of the deuterium. A similar result (100% retention of deuterium) was reported for the n-fructose isolated from the reaction at 25°. These figures for n-fructose were based on the assumption that 50 % of the... 

Mannitol can also be obtained from o-glucose when the hydrogenation is performed under conditions which enable its isomerization to o-fructose [26-29]. The use of calcium hydroxide or sodium bicarbonate-sodium hydroxide as alkaline agents for the isomerization of D-glucose, in the presence of Raney nickel as the hydrogenation catalyst, yielded 27 % mannitol [29]. 

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