407 



Pyrans and Related Substances 



Another bacterial species, Gluconoacetobacter roseum, 

 studied by the Japanese, produces kojic and isokojic acids 

 and only from a fructose, sucrose or mannitol substrate. 

 The two products are always found together. The pro- 

 posed route by which these two pyrones are formed from 

 fructose by Gluconoacetobacter roseum is shown below :^ 



CH:OH CH2OH CHOH CHO 



HOCH 



HOCH 



j 



HCOH 



HCOH 



CH.OH 

 Mannitol 



CO 



2H HOCH 



HCOH 



HCOH 



CH2OH 

 Fructose 



COH CO 



I I 



HOCH — 2H HOCH 



HCOH HCOH 



HCOH 



CH2OH 

 Enol Form 



HCOH 



CHjOH 

 Glucosone 



CHOH 



I 

 COH 



II 

 COH 



I 

 HCOH 



HC 



CH2OH 



CH2OH 



CH2OH CH2OH 



Kojic Acid Isokojic Acid 



Kojic acid is potentially an inexpensive chemical be- 

 cause of high yields from aspergilH. 



862 Rubiginol, C5H4O4, colorless plates, m.p. 203.5°. 



O 



HO 



OH 



^O 



Gluconoacetobacter liquefaciens 



A yield of 1.2 g. of rubiginol from 140 g. of glucose sub- 

 strate was reported. 



Ko Aida, /. Gen. and Appl. Microbiol. (Japan) 1 30 (1955). 



^ Ko Aida, Mitsuko Fujii and Toshinobu Asai, Proc. Japan Acad. 

 32 595 (1956). 



