1. Agar-agar after suitable preliminary treatment
can be acetylated easily with pyridine and acetic
2. The Agar acetate obtained can be simultaneously
deacetylated and methylated to give methylated agar
3. Hydrolysis of the methylated agar with dilute
mineral acid, followed by esterification, gives
methyl laevulate, 2:4:6-trimethyl methylcgalactosid
and a substance behaving as a methylated ketoside
4. The 2:4:6-trimethyl methyl^galactoside on hydrolysis gives 2:4:6-trimethyl a-d-galactose, the
structure of which is proved by
(a) Complete methylation which gives 2:3-4:6-tetramethyl
(b) The isolation of a crystalline dimethyl galactose phenyl osazone.
(c) Oxidation with bromine water forming a trimethl-galactonolactone, which gave a crystalline
(d) Oxidation with nitric acid, followed by esterification
and amide formation which gave product
of indefinite composition, neither trimethyl
mucic acid nor dimethoxy succinic acid being
It would appear therefore that the galactose
units are of the ß-form and linked at positions 1
Methylated agar can also be hydrolysed with
1.2% methyl alcoholic hydrogen chloride to give a
trace of methyl laevulate, 2:4:6-trimethyl methyl-
galactoside and the substance behaving as a methylated ketose.
7. Extensive examination of the latter fraction
has been hindered for lack of material. Complete
methylation yielded a crystalline "Trimethyl anhydr
ketose" C₉H₁₆O₅ but oxidative degradation has so far
been unsuccessful in determining the structure of
this fragment. The original "dimethyl methyl≃ketoside"
appears to be a mixture but oxidation with
nitric acid failed to produce any dimethoxy succinii
acid which is taken as evidence that the two rnethoxyl
residues apparently present are not adjacent.