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EIGHTH PACIFIC SCIENCE CONGRESS 



H2SO4 for an hour and has been named Agarobiose by one of the au- 

 thors. The same substance was subsequently obtained from agar-agar 

 as its dimethylacetal by partial methanolysis and as its diethylmercaptal 

 by partial mercaptolysis, from which free agarobiose has been isolated 

 respectively by the separation of methyl alcohol and ethylmercaptan. 



It reduces Fehling's solution and gives a-methyl-D-galactoside and 

 f»,,6-anhydro-L-galactose dimethylacetal by methanolysis with 2% HCl- 

 CH3OH. By preliminary treatment with 0.57o HCI-CH3OH and fur- 

 ther methylation with Purdie's reagents, agarobiose gives hexamethyl- 

 agarobiose dimethylacetal (b.p. 155-6° /0.052 mm., [aj^^ - 11° [H^O]). 

 When this methylated derivative is left in IN H2SO4 at ordinary 

 temperature for 182 hours, it is changed to hexamethyl agarobiose, 

 C,,H,,0, (OCH3)e, M^ - 4.4° (H^O). 



As hexamethyl-agarobiose dimethylacetal gives 2,3,4,6-tetramethyl- 

 methyl-D-galactoside and 2,5-dimethyl-3,6-anhydro-L-galactose dimethyl- 

 acetal by methanolysis with 2% HCI-CH3OH, it can be concluded that 

 the hexamethyl-agarobiose dimethylacetal is 4-2,3,4,6-tetra-methyl-D-ga- 

 lactoside< l,5>-2,5-dimethyl-3,6-anhydro-L-galactose dimethylacetal. Fur- 

 ther, from the fact that the specific rotatory power of the acetal is small, 

 it can be assumed that the sugar is a ^-galactoside. Therefore, the 

 chemical constitution of agarobiose is illustrated by Figure A: 



CHO 

 HO-C-H 



H-C 



iSo 



H-C- 



HO-C-H 



H2C 



CH — 



H-C-OH 

 HO-C-H 

 HO-C-H 

 H-C 



CH2OH 



Fig. a. — Agarobiose 



The constitution of agar-agar together with the mechanism of the 

 formation of 3,6-anhydro-L-galactose in marine algae was discussed (26). 

 Taking into consideration the isolation of 2,4,6-trimethyl-D-galactose 

 and 2-methyi-3,6-anhydro-L-galactose from the methylated agar by hydro- 

 lysis as well as the isolation of agarobiose from agar-agar by partial hy- 



