860 



METHYL L^VO INOSITOL IN A POISONOUS PLANT, 



mirror-images. Tliis condition, arising from a certain degree of 

 molecular symmetry, is accompanied by inactivity towards polar- 

 ised light. Tliese seven forms having their asymmetric carbon 

 atoms internally compensated, are, therefore, optically inactive 

 in the polarimeter. One form alone is found to possess an 

 entirely asymmetric molecule, and, in consequence, this arrange- 

 ment can exist as active dextro and lt«vo compounds, and, in 

 addition, their (f/- or racemic inactive combination may also exist. 



Constifution of the methyl psters. — As has just been stated, the 

 active forms of inositol are the result of one particular arrange- 

 ment of the hydroxy 1 groups. This arrangement, which may Ije 

 readily discovered in the models, is that where the six hydroxyl 

 groups occupy the positions 1, 2, 4, on each side of the ring. 

 This form (Fig. 2) and its mirror-image (Fig. 3) constitute the 

 dextro- and l?evo-inositols. 



Fig. 1. Fig.2, Fig.3. Fig. 4. 



H H OH OCH, 



and 



inositol. 



Text-fig. 2. 



methyl leevo- 

 inositol . 



The methyl ester, C^H,(OH)- (OCH..^) is obtained by sub- 

 stitution of a methyl group in one of the hydroxyl groups, and 

 again from the models it can be proved that substitution in tlie 

 hydroxyl 1, 2, or 4 results in three possible and different com- 

 pounds being obtained. The first of these is represented by 

 Fig. 4. The corresponding three positions in the mirror-image 

 (Fig. 3) — which are identical with the alternate three positions 

 below^ in the other form (Fig. 2) — produce their optical anti- 



