Saccharinic acids, from lactose

In support of his contention that /3 -D-isosaccharinic acid is present in the hexose-alkali reaction mixture, Nef also cited certain observations of Kiliani and Eisenlohr, who oxidized (with nitric acid) the residue obtained, after substantial removal of a -D-isosaccharinic acid and the meta-saccharinic acids, from the lactose-alkali reaction mixture. Among the products identified was the tribasic acid, (H02C)2C(0H)—CHj—CHOH— CO2H, previously obtained by a similar oxidation of a -D-isosaccharinic acid (see page 50). Nef concluded that the tribasic acid must in this instance have arisen from j3 -D-isosaccharinic acid. This conclusion ignores, however, the experimental demonstration by Kiliani and Eisenlohr that the residue subjected to oxidation had still contained a small proportion of a -D-isosaccharinic acid, isolable as the slightly soluble calcium salt. 

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. 

Earlier investigators of the alkaline-degradation products of lactose found succinic acid, formic acid, and a crystalline lactone, later identified by Kiliani as a -D-isosaccharinic lactone. This lactone was obtained in about 20% yield from the action of lime-water on lactose also detected as products of this reaction were D-galactose, lactic acid, pyruvaldehyde, formaldehyde, and other saccharinic acids. The... 

Biamperometric titration of cyclamate was exploited by Fatibello-Fiho et al. [84,85]. These investigators developed an inexpensive laboratory-built selectable voltage source specially constructed for use in biamperometric titrations. It was made of very simple electronic components and its performance was tested and compared with a potentiostat/galvanostat equipment. The titrant-reagent system was sodium nitrite in 1.0 M phosphoric acid and there was no interference from glucose, fructose, sucrose, lactose, sorbitol, saccharin, benzoic acid, salicylic acid, fumaric acid. Sunset Yellow, and Bordeaux-S. 

---