Synthesis 



grade. In either case, the adequately purified product melted 

 at 167" to i68°C. (corr.), with the evolution of carbon dioxide, 

 and this melting point was not lowered when the material was 

 admixed with a specimen prepared from indolyl acetonitrile 

 or one synthetized by the method to be detailed later [i.e., from 

 the cyanopropionacetal mentioned above; not otherwise 

 reproduced here — H.N.], The yield of indolyl-acetic acid was 

 12 gm. and that of the diacetic 1-2 gm." 



Indylene-i : 3 -diacetic acid and the other two acids des- 

 cribed in this paper (3 -methyl-indolyl-i -acetic and indolyl-3- 

 succinic acid) are much less effective physiologically than is 

 indole-3 -acetic acid. The very effective indole-3 -propionic 

 acid can, however, be obtained by heating the 3 -succinic acid. 

 Another synthesis of indole-3 -acetic acid, and syntheses of 

 other indole compounds, were recorded by King and L'Ecuyer 

 (1934). Several of these compounds had carboxy in the 2- 

 position. King and L'Ecuyer prepared the first 2-acetic com- 

 pound (2-carboxy-i-methyl-indole-2-acetic acid). The simple 

 indole-2-acetic acid is not known. Still another synthesis of 

 indole-3 -acetic ^^^^ ^^ mentioned on p. 113. 



Microbiological Preparation 



Biological methods of preparation are suggested by the 

 work of Ehrlich (1912). In presence of a yeast and much sugar, 

 tyrosine gives tyrosol (^ -hydroxy phenyl-ethyl alcohol), and 

 Ehrlich discovered that tryptophan similarly gave the analo- 

 gous alcohol (named by him tryptophol) : in absence of other 

 sources of nitrogen, the yeast deaminized the tryptophan. In 

 the hands of Jackson, (1929) Ehrlich's "elegant biological 

 method" gave a yield of over 90 per cent, of crude crystalline 

 tryptophol, but Jackson did not say whether he used the 

 sugar or alcohol technique. Jackson (1930) has prepared 

 tryptophol artificially by reduction of methyl (or, ethyl) 

 indole-acetate. As tryptophol is 3-indole-ethyl alcohol, it is 

 curious that no laboratory oxidation of it to indoie-acetic acid 

 has been recorded, though its phenyl ether has been prepared 

 by Manske (193 1). A physiological oxidation of tryptophol to 

 indoie-acetic acid has been recorded by Ward (1923). 



107 



