Weerman test

Both XVIII and its methyl ester (XXI) readily furnish a crystalline amide (XX) which gives a positive Weerman test for a-hydroxy acids... 

The crystalline 0-form of the sugar was first isolated17 by the hydrolysis of the mixture of products obtained by the methylation with methyl iodide of the thallium derivatives of methyl xylopyranosides (aft mixture) in which the 2,4-dimethyl-D-xylose was the principal component. Since the corresponding acid gave a pyranolactone, the amide gave a negative Weerman test and the derivatives in question were different from those of 2,3-dimethyl-D-xylose, the constitution was established. 

Pentamethyl-D-glucoascorbic acid on ozonolysis and hydrolysis gives 3,4,5-trimethyl-D-arabonic acid.88 The ester and the amide are also described, the constitution of the latter following from the fact that it gave a positive Weerman test. 

The constitution of the product followed from the facts that the derived amide gave a positive Weerman test and that the crystalline lactone underwent the characteristically slow hydrolysis of a furanolactone. 

The 2,3-dimethyl-L-arabinose so prepared gave on oxidation a crystalline lactone having the characteristically slow rate of hydrolysis of a furanolactone, the crystalline amide from this lactone gave a negative Weerman test, and the free sugar gave 3-methyl-L-arabinosazone when... 

The constitution of the product was proved by methylation to give methyl 2,3,4-trimethyl-/3-L-rhamnopyranoside, from which trimethyl-L-rhamnopyranose and the crystalline 2,3,4-trimethyl-L-rhamnonolactone, rapidly hydrolyzed in water, were obtained. The 3,4-dimethyl-L-rhamnonolactone was also shown to undergo hydrolysis in water with the characteristic rapidity of a pyranolactone, and the derived amide gave a positive Weerman test.65... 

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