18 



W. G. OVEREND AND M. STACEY 



calcium D-altronate see Richtmyer*^ into D-ribose (I) by the improved^^ 

 Ruff^' degradation method for converting hexonic acids into pentoses. 



Recently Sowden^ has introduced a method (cf. Fischer and Sowden*^) 

 whereby D-ribose can be obtained from D-glucose. 4,6-0-Benzylidene-D- 

 glucose (XII) was reduced catalytically to 4,6-0-benzylidene-D-glucitol 

 (XIII) which on oxidation with sodium metaperiodate yielded 2,4-0- 

 benzylidene-D-erythrose (XIV). Condensation of XIV with nitromethane 

 gave a mixture of epimeric, crystalline substituted C-nitro-alcohols, namely, 

 3,5-0-benzylidene-l-deoxy-l-nitro-D-arabitol (XV) and 3 , 5-0-benzylidene- 

 1-deoxy-l-nitro-D-ribitol (XVI). 



0-CH, 



HOH 



CH.OH 



I 

 H-C-OH 

 I 

 HO-C-H 



H-C-0 



H-C-OH 



CHaO 



XIII 



HO 



CH,NO, 

 -C-H 



;CHPh 



H-C-0. 



I \ 

 H-C-OH CHPh 



I y 



CHjO^ 

 XV 



CHO 



I 

 H-C-0. 



I \ 

 H-C-OH CHPh 



CHjO 



XIV 



CHjNO, 

 I 

 H-C-OH 



& H-C-0. 



H-C-OH XHPh 



I y 



CHjO 

 XVI 



Separation of XV and XVI was achieved by virtue of a remarkable dif- 

 ference in their solubility in chloroform: XVI was very soluble in this sol- 

 vent. Hydrolysis of XVI afforded amorphous 1-deoxy-l-nitro-D-ribitol, 

 which in the form of its sodium salt was decomposed directly to D-ribose. 

 The pentose was isolated as the benzylphenylhydrazone. The purification 

 of syrupy samples of ribose can be achieved by the tedious procedure of 

 forming the pure crystalline p-bromophenylhydrazone^^- '^' ^° or benzyl- 

 phenylhydrazone^-''^ or p-toluenesulfonylhydrazone.^* A more convenient 



81 N. K. Richtmyer, Advances in Carbohydrate Chem. 1, 37 (1945). 



8* R. C. Hockett and C. S. Hudson, J. Am. Chem. Soc. 56, 1632 (1934). 



83 O. Ruff, Ber. 32, 550 (1899) ; 35, 2360 (1902). 



8< J. C.SowdenandH. O.L.Fischer, J. ^m. Chem. Soc. 6S, 1048 (1947). 



80 D. G. Easterby, L. Hough, and J. K. N. Jones, J. Chem. Soc. 1951, 3416. 



