1911 Encyclopædia Britannica/Saccharin

SACCHARIN, the name given to several distinct chemical substances. The saccharin of commerce, so named from its excessively sweet taste, is a coal-tar product, being the imide of orthosulphobenzoic acid, CJ-L<g82>NH. It may be prepared by the oxidation of ortho-toluenesulphonamide CH3fC¢H4-SO2NH¢, with potassium permanganate (C. Fahlberg and I. Remsen, Bef., 1879, 12, p. 469); by the electrolytic oxidation of the above sulphonamide (German patent 3 5211); by the action of concentrated sulphuric acid on ortho-sulphamidobenzoic acid, NH;-SO, -C¢H¢-CO2H (German patent 113720); by warming the chloride of ortho-sulphobenzoic acid phenyl ester (SO2Cl-C¢, H4-CO, C¢H5) with excess of aqueous ammonia (R. List and M. Stein, Bef., 1898, 31, p. 1662); and from benzaldehyde orthosulphonic acid by conversion into its acid chloride, which with ammonia yields the corresponding acid-amide, which gives saccharin on oxidation with atmospheric oxygen (German patent 94948). It is a crystalline powder which melts at 220° C. with partial decomposition. It is soluble with difficulty in cold Water, but is moderately soluble in hot water and readily soluble in alcohol. By the action of concentrated hydrochloric acid at 1 50° C. it is decomposed into ammonia and ortho-sulphobenzoic acid. With phosphorus pentachloride above 200° C. it yields orthochlornitrobenzene. Sodium saccharin, C¢H4(CO)-(SO2)-N~Na, 2H-, O, is used under the name of “ soluble saccharin ” or “crystalIose, ” and is readily soluble in hot water. The ammonium salt is named “ sucramine.” Saccharin is» largely used for sweetening purposes, pure saccharin being 500 times sweeter than sugar. Until 1891 the commercial product contained about 40 % of the tasteless para compound and was only 300 times as sweet as sugar; the mixture, however, is now separated by dissolving out the saccharin with xylene, in which solvent the para compound is insoluble. Saccharin is used as a sugar substitute for diabetic patients. It is interesting to note that o-sulphobenzoic acid has an acid taste, and the sulphamide is tasteless; the sweetness of saccharin therefore appears to be connected with the formation of a cyclic an hydride. In the United Kingdom there is an import duty of rs. 3d. per oz. on saccharin and similar products, and manufacturers have to take out a licence. In the United States the import duty is $1- 50+ IO% ad valorem per lb. Austria-Hungary, France, Belgium and Germany prohibit the importation. On the estimation of saccharin in commercial samples and for its detection in foods and beverages see J. H. Kastle, Jour. Chem. Soc., 1905, 87, p. 503; E. M'K. Chace, Jour. Amer. Chem. Soc., 1904, 39, p. 1627. The lactones of the saccharin acids are also known as “ saccharin's." By boiling dextrin or laevulose with milk of lime the so-called “ sacCH¢OH~CH-CHOH~C(OH)-CH; o- co is obtained (E. Péligot, Bef., 1880, 13, p. 196; H. Kiliani, Bef., 1882, 15, p. 2954). It crystallizes in large prisms, has a bitter taste, and is easily soluble in hot water. Potassium perrnanganate oxidizes it to carbonic and acetic acids. Heatin with caustic potash to 200 °C. gives formic and lactic acids, and when reduced by hydriodic acid and phos horus it is converted into any-dimethylbutyrolactone. " Iso-saccharin " and “ meta-saccharin " are, formed by the action of lime on milk sugar (H. Kiliani, Bef., 1885, 18, p. 631). The former melts at 95 C., and on reduction by hydriodic acid and phosphorus is converted into ary-dimethylvalerolactone. Metasaccharin melts at 141-142° C. and is easily soluble in water.