THE MONOSACCHARIDES 5 



Glycuronic acid. If saccharic acid is heated five or six hours in the 

 water bath, it is changed into saccharo-lactonic acid, C 6 H 8 7 . If this is 

 reduced by means of sodium amalgam, one obtains ylycuronic acid ; * this 

 substance is of considerable interest because it is sometimes found in the 

 body, and when it passes into the urine is apt to be mistaken for sugar, 

 many of the tests for which it gives. 



Its composition is 



COOH (CH.OH) 4 CHO = C 6 H 10 7 



It is soluble in water and alcohol, is dextro-rotatory, reduces alkaline 

 solutions of metallic salts, and yields saccharic acid on oxidation with 

 bromine. It does not undergo the alcoholic fermentation. Though 

 related in its composition so nearly to the carbohydrates, it yields with 

 urea decomposition products which are aromatic, such as orthonitro- 

 benzyl alcohol (Jaffe). 2 It occurs in the urine in the form of the 

 potassium salt (C 6 H 9 7 K) after the administration of chloral and 

 butylchloral, 3 nitrobenzol, 4 orthonitrotoluol, 5 camphor, 6 etc. It also 

 occurs in the urine after chloroform narcosis, and in the paralytic 

 secretion that takes place on section of the renal nerves. 7 Occasion- 

 ally it is found without any apparent cause, as a result of disordered 

 metabolism. 



Levulose on oxidation always yields acids containing less carbon 

 atoms than itself, namely, trioxybutyric (CH 2 OH(CH.OH) 2 COOH), 

 formic (H.COOH), and glycollic (CH 2 .OH.COOH) acids. But different 

 acids are yielded by different methods of oxidation; thus chlorine or 

 bromine and silver oxide oxidise levulose to glycollic acid ; 8 nitric acid 

 yields oxalic, tartaric, glycollic, acetic, and other acids. 9 



Synthesis of sugars. The first step towards the synthesis of the sugars 

 was made by Butlerow. 10 He obtained a sugar-like substance by adding lime 

 water to a solution of dioxymethylene ; this he termed metliylenitan, 

 and gave its formula as C 7 H 14 6 . Loew n next obtained a condensation 

 product of formaldehyde (CH 2 0) by means of lime water ; to this substance 

 he attributed the formula (C 6 H 12 ( .), and called it formose. 



Neither methylenitan nor formose ferment with yeast. Fischer 12 

 investigated these substances, and found that they were mixtures of two 

 sugars, one of which is formose (C 6 H 12 6 ), and another a-acrose 13 (C 6 H 12 6 ), 

 both of which yield crystalline osazones. 



From the osazone which is yielded by a-acrose the sugar can be again 



1 H. Thicvfelder, Ztschr. f.phi/sioL Chem. , Strassburg, 1887, Bd. xi. S. 388; 1891, Bd. xv. 

 S. 71 ; Ber. d. dentsch. chem. G-esellsch. , Berlin, 1886, Bd. xix. S. 3148; E. Fischer and 

 0. Piloty, ibid., 1891, Bd. xxiv. S. 521. 



Ztschr. f. pliysiol. Chem., Strassburg, Bd. ii. S. 47. 



Musculus and v. Mering, Arch. f. d. gcs. Phijsiol., Bonn, Bd. xx. S. 64. 



v. Mering, Centralbl. f. d. med. Wissensch., Berlin, 1875, No. 55. 



Jaffe, loc. cit. 



Schmiedeberg and Meyer, Ztschr. f. pliysiol. Chem., Strassburg, Bd. iii. S. 422. 



Aahdown, Brit. Med. Journ., London, 1890, vol. i. p. 171. 



8 Hlasiwetz and Habermann, Ann. d. Chem., Leipzig, Bd. civ. ; Kiliani, ibid., Bd. 

 civ. S. 175. 



9 Kiliani, ibid., S. 162 ; Hornemann. Journ. f. prakt. Chem., Leipzig, Bd. Ixxxix. S. 283. 



10 Ann. d. Chem., Leipzig, Bd. cxx. S. 295 *; Compt. rend. Acad. d. sc., Paris, tome Hi. 

 p. 145. 



11 Journ. f. prakt. Chem., Leipzig, Bd. xxxiii. S. 321. 



12 .Ber. d^deutsch. chem. Gesellsch., Berlin, Bd. xix. S. 2133. 



13 Acrose is a sugar obtained by Fischer, ibid., Bd. xx. S. 1093 and 2566, by acting on 

 acrolein bromide with bases (2C 3 H 4 OBr., + (2Ba(OH)., = C 6 H 12 6 +2BaBr., ; two isomeric 

 sugars, - and /3-acrose are thus produced. " 



