SACCHARIN  , the name given to several distinct chemical sub-stances . The saccharin of

commerce, so named from its excessively sweet taste, is a coal-tar product, being the imide of orthosulphobenzoic acid, CeH4< CO >NH . It may be prepared by the oxidation of ortho-toluenesulphonamide CH3•C6H4•SO2NH2, with potassium permanganate (C . Fahlberg and I . Remsen, Ber., 1879, 12, p . 469); by the electrolytic oxidation of the above sulphonamide (German patent 35211); by the action of concentrated sulphuric acid on ortho-sulphamidobenzoic acid, NH2•SO2•C6H4•CO2H (German patent 113720); by warming the chloride of ortho-sulphobenzoic acid phenyl ester (SO2C1•C4H4• CO2C.H6) with excess of aqueous ammonia (R . List and M . Stein, Ber., 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 15o° C. it is decomposed into ammonia and ortho-sulphobenzoic acid .

With

phosphorus pentachloride above 200° C. it yields ortho= chlornitrobenzene . Sodium saccharin, C6H4(CO)•(SO2)•N•Na, 2H2O, is used under the name of " soluble saccharin " or "crystallose," 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 anhydride . In the United Kingdom there is an import duty of Is . 3d. per oz. on saccharin and similar products, and manufacturers have to take out a licence . In the United States the import duty is $1.5o+to% 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 . 5o3; E . M'K . Chace, Jour . Amer . Chem . Soc., 1904, 39, p . 1627 . The lactones of the saccharic acids are also known as " saccharins." By boiling dextrin or laevulose with milk of lime the so-called " sac- CH2OH•CH•CHOH•Q(OH)•CH2 charin," a lactone of the formula, 0 CO is obtained (E . Pefigot, Ber., 188o, 13, p .

196; H . Kiliani, Ber., 1882, 15, p . 2954) . It crystallizes in large prisms, has a

bitter taste, and is easily soluble in hot water . Potassium permanganate oxidizes it to carbonic and acetic acids . Heating with caustic potash to 200 °C. gives formic and lactic acids, and when reduced by h vdriodic acid and phosphorus it is converted into ay-dimethylbutyrolactone . Iso-saccharin " and " meta-saccharin " are formed by the action of lime on milk sugar (H . Kiliani, Ber., 1885, 18, p . 631) . The former melts at 95 C., and on reduction by hydriodic acid and phosphorus is converted into ay-dimethylvalerolactone . Meta-saccharin melts at 141-142° C. and is easily soluble in water .