Of Lobry de Bruyn and Alberda van

Mathews and Jackson did not carry out fermentation experiments nor did they discuss the possible relation between D-fructose anhydrides and the glutose of Lobry de Bruyn and Alberda van Ekenstein. They merely concluded that the well-known reversion products in cane molasses probably consist of these same anhydrides. The term reversion product was first introduced by WohP to describe the sugar anhydrides formed when highly concentrated D-fructose or invert sugar solutions are heated in the presence of acid. He anticipated Mathews and Jackson s... 

The collaboration of Lobry de Bruyn and Alberda van Ekenstein appears to have been occasioned by Lobry de Bruyn s interest in those reactions of the sugars brought about by alkalis. It is interesting to note, however, that their joint efforts were not limited to this investigation, which terminated in 1899, and that they continued to publish other work throughout the remainder of de Bruyn s life. 

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. 

Reducing glycose units of polysaccharide chains will be transformed, in part, to their C2-epimers in alkaline solution. The classical transformation of Lobry de Bruyn and Alberda van Ekenstein is a base-catalyzed enolization giving an enediol (II) which may either revert to the starting aldose or be converted to epimers of the original aldose (see Fig. 1) they showed that the main product is the ketose. However, the ions (I and III) may also be in equilibrium by prototropy, without transition through an enediol (II). 

The complex reactions of alkalies with reducing sugars have been described extensively. The origin of the initial products that are obtained is usually explained by the classical Lobry de Bruyn and Alberda van Ekenstein transformation,80 in which an enediol (XLVI) is proposed as the key intermediate. In recent studies Sowden and Schaffer61 used D-glucose-l-C14, D-fructose-l-C14, and D-glucose in D20 to... 

It has been postulated (37) that lactulose is formed from lactose by the Lobry de Bruyn and Alberda van Ekenstein transformation, whereby glucose is isomerized to fructose via an enol intermediate. In turn, two mechanisms have been proposed for the degradation of this intermediate (38)- One involves the addition of a proton to the enediol resulting in epimeric aldoses and the original ketose, while the other involves 8-elimination to yield galactose and saccharinic acids. The authors experimental data would tend to better support the second pathway. 

The situation was clarified by the isolation of a, )8, and y isomers of D-glucose by Tanret in 1895. He showed that the a and y isomers mutarotate in opposite directions and, at equilibrium, each have the same rotation as the y3 form. The isomers were also found to have the same molecular weight. Tanret s three isomers of D-glucose were considered to be ring and free aldehyde forms by Lobry de Bruyn and Alberda van Ekenstein in 1895, von Lipp-mann in 1896, and Simon in 1901. Fischer in 1893, and von Lipp-mann pointed out that ring formation would produce a new asymmetric carbon atom, and thus the existence of isomeric sugars, glycosides, and acetates was clarified. 

Before going into a detailed study of the nature of glutose, it will be helpful to quote (in translation) Lobry de Bruyn and Alberda van Ekenstein. We shall then have before us the original source of the misconceptions which have given body and substance to a mere inference and have misled subsequent workers. 

It will be recalled that Lobry de Bruyn and Alberda van Ekenstein claimed that pseudofructose (n-psicose) was one of the products formed as a result of a transformation of D-fructose and n-glucose in mildly alkaline solution. The doubt that one can have about its presence in the glutose mixture rests on their observation that D-psicose is fermentable. Synthetic D-psicose prepared by Steiger and Reichstein is... 

It is of interest that, in 1882, lime-water treatment of lactose was found to yield the insoluble calcium a -D-isosaccharinate, a rearrangement product of the n-glucose component, and, in 1896 and 1899, Lobry de Bruyn and Alberda van Ekenstein" observed that treatment of lactose with either lead hydroxide or potassium hydroxide liberated n-galactose. Kiliani established the structure of the saccharinate as that of a 3-deoxy-2-C-(hydroxymethyl)pentonic acid and, had the mechanism of its formation been understood (see p. 188), this would have been sufficient evidence... 

The Lobry de Bruyn-Alberda van Ekenstein transformation has usually been considered to embrace both epimerization of aldoses and ketoses and aldose-ketose isomerization. Actually, Lobry de Bruyn and Alberda van Ekenstein observed all three reactions, so that an experimental basis for defining the transformation has existed from almost the time of its first recognition. 

A number of hydroxides and carbonates of the alkali and alkaline-earth metals have been used as catalysts for these reactions. Lobry de Bruyn and Alberda van Ekenstein considered the hydroxide ion to be responsible for their effect. Michaelis and Rona examined the transformation of D-glucose in several alkaline buffers and found that the re-... 

The history of the mechanism of the Lobry de Bruyn-Alberda van Ekenstein transformation begins with the first description of its reactions. Thus, Lobry de Bruyn and Alberda van Ekenstein proposed that the transformation might take place by intramolecular transfer of hydrogen in... 

Fig. 1.— The Classical Base-catalyzed Transformation of an Aldose (Lobry de Bruyn and Alberda van Ekenstein).

Five different crystalline products were separated and characterized from the reaction mixture obtained from the condensation of L-rhamnose with paraformaldehyde. None of the products isolated corresponded to the acetal isolated earlier by Lobry de Bruyn and Alberda van Ekenstein. The expected 1,2 3,5-di-0-methylene-a-L-rhamnofuranose was identified on graded hydrolysis, this gave the 3,5-0-methylene acetal. However, the possibility of the 3,4-0-methylene-L-rhamnopyranose structure was not eliminated. The main product was 3,4-0-(oxidodimethylene)-L-rhamnose a smaller yield of 2,3-0-(oxidodimethylene)-a-L-rhamnose was obtained. 

Lobry de Bruyn and Alberda van Ekenstein obtained a di-O-meth-ylene-D-fructose by treating a mixture of D-fructose and paraformaldehyde with either 50% sulfuric acid or 75% phosphoric acid. The diacetal, which melted at 92° and had [aJi, -34.9° in water, did not reduce Fehling solution nor react with phenylhydrazine, but it did form a monoacetate, from which the parent diacetal could be recovered by saponification. By analogy with 2,3 4,5-di-0-isopropyli-dene-)8-D- ctopyranose (2) ([a]o —33.7°), the dimethylene acetal may be formulated as 2,3 4,5-di-0-methylene-j8-D-fructopyranose (95). 

This reaction was first reported by Lobry de Bruyn in 1895, and explored extensively by Lobry de Bruyn and Alberda van Ekenstein. It is the reciprocal interconversion of carbohydrates into their isomers in an alkaline solution through the enediolic intermediate. The name of reaction given here is probably the only one time the full name of the people who discovered such reaction. It is known as the Lobry de Bruyn-Alberda van Ekenstein rearrangement, Lobry de Bruyn-Alberda van Ekenstein transformation, Lobry de Bruyn-Albreda van Ekenstein C-2 epimerization, or Lobry de Bruyn-van Ekenstein transformation. ... 

The simplest isomerization reaction of the reducing sugars is the Lobry de Bruyn and Alberda van Ekenstein transformation (78). Thus, when glucose is treated with dilute alkalies at room temperature, the optical rotation decreases, and from the products of reaction, glucose, mannose, and fructose can be separated. The treatment of sugars with alkalies has considerable value for preparatory purposes, particularly for obtaining ketoses. 

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... 

Two Dutch chemists, Lobry de Bruyn and Alberda van Eckenstein, collaborated in the study of the effects of alkali on carbohydrates. The reaction with alkali produces epimerization of aldoses and ketoses and aldose-ketose isomerization [2]. At pH values of 11-13 and 20°C, alkali catalyzes the transformation of D-glucose into D-fructose and o-mannose. The transformation most probably takes place by the formation of two enediols, although the enolic forms of the sugars have never... 

Nearly all of the investigations of the kinetics of Lobry de Bruyn-Alberda van Ekenstein reactions have failed because of the complications imposed by side-reactions. It has only recently been found that good kinetic data can be obtained for the DL-glycerose-l,3-dihydroxy-2-propanone interconversion. This Section mainly concerns the work with this simple system, which contains implications for the mechanisms of all Lobry de Bruyn-Alberda van Ekenstein reactions, and the attempts to extend it to the higher sugars. 

Albrecht M (2004) Supramolecular Templating in the Formation of Helicates. 248 105-139 Ando T, Inomata S-I, Yamamoto M (2004) Lepidopteran Sex Pheromones. 239 51-96 Angyal SJ (2001) The Lobry de Bruyn-Alberda van Ekenstein Transformation and Related Reactions. 215 1-14... 

For the preparation of 2 by aqueous, alkaline hydrolysis of the lactone ring in 4, precautions against Lobry de Bruyn-Alberda van Ekenstein rearrangements,100 and even against decomposition101 of... 

Aldoses generally undergo benzilic acid-type rearrangements to produce saccharinic acids, as well as reverse aldol (retro-aldol) reactions with j3-elimination, to afford a-dicarbonyl compounds. The products of these reactions are in considerable evidence at elevated temperatures. The conversions of ketoses and alduronic acids, however, are also of definite interest and will be emphasized as well. Furthermore, aldoses undergo anomerization and aldose-ketose isomerization (the Lobry de Bruyn-Alberda van Ekenstein transformation ) in aqueous base. However, both of these isomerizations are more appropriately studied at room temperature, and will be considered only in the context of other mechanisms. 

The reaction of carbohydrates in alkaline or acidic aqueous solutions results in a myriad of products, many of which have been recognized for well over a century. The number of identified products has greatly increased in recent years, owing to the development of sophisticated techniques for separation and identification. With the exception of anhydro sugars and oligosaccharides, found as concentration-dependent, equilibrium constituents (reversion products) in acidic solutions, all of the products result from reactions of intermediates present in the Lobry de Bruyn-Alberda van Ekenstein transformation. 

Lobry de Bruyn-Alberda van Ekenstein transformation 693 Lock and key theory 478 Log phase of growth 470 Lon protease 628 Loricin 439... 

Speck, John C., Jr., The Lobry de Bruyn-Alberda van Ekenstein Transformation, 13, 63-103 Spedding, H., Infrared Spectroscopy and Carbohydrate Chemistry, 19, 23-49 Sprinson, D. B., The Biosynthesis of Aromatic Compounds from d-G1u-cose, 16, 235-270... 

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