INOSITOL 



4. PROPERTIES OF INOSITOL 



weso-Inositol has m.p. 225 to 226° C. and forms a dihydrate, m.p. 

 218° C.^ It is very soluble in water, i part dissolving in 57 parts at 

 24° C, slightly soluble in alcohol but insoluble in ether and other 

 organic solvents. It has a sweet taste. 



It is best characterised as the hexa-acetate, m.p. 213° C. meso- 

 Inositol is often referred to as ^-inositol. 



Reference to Section 4 

 I. D. W. WooUey, /. Biol. Chem., 1941, 139, 29. 



5. ESTI2V1ATION OF INOSITOL 



Biological Methods 



D. W. Woolley ^ devised a biological method for the assay of 

 inositol, based on the development of alopecia in mice. In the original 

 diet yeast extract was used, but better results were subsequently 

 obtained by ref)lacing this with a mixture of synthetic vitamins. 



Chemical Methods 



The earliest chemical method for the estimation of inositol was 

 the extremely laborious one of isolating the substance and either 

 weighing it,^ or determining the carbon content of the isolated material 

 by a micro-combustion method.^ 



A simpler method was used by P. Fleury and J. Marque * for the 

 estimation of polyhydric alcohols, in which the test solution is heated 

 with potassium mercuric iodide and sodiimi hydroxide in presence of 

 a suspension of barium sulphate. As the alcohol is oxidised, metallic 

 mercury is formed as a finely-divided powder. This is dissolved by 

 the addition of iodine, the excess of which is titrated with sodium 

 thiosulphate solution. The method was improved by L. Young ^ to 

 give a greater degree of accuracy with smaller amounts of inositol 

 (i to 5 mg.) and further modified by R. A. Gregory ^ mainly by 

 simplifying the extraction procedure. The tissues were heated with 

 10 % potassium hydroxide solution and the alkali and, incidentally, 

 unwanted impurities were removed by the addition of a zinc salt ; 

 the filtrate was then clarified by means of acid mercuric sulphate 

 solution. After removal of mercury by hydrogen sulphide, the 

 inositol was precipitated with alcoholic baryta and bariimi removed 

 from the precipitate. The purified inositol was then oxidised by 

 potassium mercuric iodide. 



A better chemical method of assay was developed by B. S. Piatt 



568 



