16 



W. G. OVEREND AND M. STAGEY 



COOH 

 I 

 H-C-OH 



COOH 

 I 

 HO-C-H 



HOCH 



H-OH 



H-C-OH -»► H-C-OH 



I 



H-C-OH 

 I 

 CH2OH 



IV 



I 



H-C-OH 

 I 

 CH2OH 



V 



H AcOyH-OAc 



AcO 



H-Br 



COOH 

 I 

 HO-C-H 

 I 

 H-C-OH 



I 

 H-C-OH 



I 

 H-C-OH 



CH2OH 

 XI 



jj CH,— 



HO 



H 



HO 



C=0 



HOH 



H AcO 

 AcO Nj Y ' ^^^ 



AcO H AcO H HO H 



VIII IX X 



acid (V). Thereafter by reduction with sodium amalgam and purification 

 via the p-bromophenylhydrazone, a crystalline sample of D-ribose (I) 

 was obtained.^® This method of synthesis was reinvestigated thoroughly by 

 Steiger''" in 1936. D-Arabinose (III) \Yas oxidized electrolytically'^^ to D-ara- 

 bonic acid (IV). IV was partly epimerized through the action of boiling 

 aqueous pyridine and D-ribonic acid (V) was isolated as its cadmium salt 

 and converted into D-ribonolactone (VI). Controlled reduction of the 

 lactone with 2.5% sodium amalgam gave D-ribose (I). More product could 

 be obtained from the mother liquors as the p-bromophenylhydrazone. By 

 this method D-ribose was obtained from D-arabinose in 17% overall yield. 

 Alberda van Ekenstein and Blanksma''^ claimed that L-arabinose may be 

 partly converted directly to L-ribose through the Lobry de Bruyn rearrange- 

 ment, but the process has no preparative value. Austin et alP failed to 

 confirm the findings of van Ekenstein and Blanksma,^^ since they were 



'o Marguerite Steiger, Helv. Chim. Acta 19, 189 (1936). 



" H. S. Isbell and Harriet L. Frush, /. Research Natl. Bur. Standards 6, 1145 (1931). 

 " W. Alberda van Ekenstein and J. J. Blanksma, Chem. Weekblad 10, 213 (1913). 

 "W. C. Austin, C. J. Smalley, and M. I. Sankstone, /. Am. Chem. Soc. 54, 1933 

 (1932). 



