182 A GENERAL REVIEW OF 



simultaneously, and from these results it would appear that 

 the method might prove to be useful for the esterification of 

 acids which give unstable silver salts. 



The possibility of utilising the reaction as a means of 

 determining constitution and configuration will be discussed 

 later. 



RANGE or APPLICATION OF THE REACTION 



It may at once be stated that all stable compounds con- 

 taining primary or secondary alcoholic hydroxyl groups or 

 carboxyl groups invariably give positive results with the 

 reaction if the compounds are soluble in the alkyl iodides or 

 other neutral solvent ; no cases have yet been encountered 

 in which substances of the nature described have escaped 

 alkylation by this process. Tertiary alcoholic groups, exclud- 

 ing those formed in tautomeric compounds by the keto-enol 

 change, appear to entirely resist the action of the alkylating 

 mixture. Lander (4) found, for instance, that triphenyl 

 carbinol showed no change either when boiled for twelve hours 

 with silver oxide and ethyl or isopropyl iodides, or even when 

 heated with silver oxide and ethyl iodide in a sealed tube at 

 160 C. for four hours. The point is well illustrated by the 

 experience of McKenzie and Wren (53), who subjected i-tri- 

 phenylethylene glycol to two alkylations with silver oxide 

 and methyl iodide, and obtained a monomethyl ether as the 

 sole product. This product they proved to be y8-hydroxy-a- 

 methoxy-a/3y8-triphenylethaneC 6 H 5 .CH(OCH 3 ).C(OH).(C 6 H 5 ) 2 

 and not the isomeric a-hydroxy-/3-methoxy-a/3/3-triphenyl- 

 ethane, since they obtained a substance identical with this 

 product by the action of magnesium phenyl bromide on 

 either ^-benzoin methyl ether or z-methyl phenylmethoxy- 

 acetate. It is clear, therefore, that only the secondary 

 alcoholic hydroxyl group of triphenylethylene glycol is 

 methylated by the alkylating mixture ; the tertiary hydroxyl 

 group remains unattacked despite the excess of alkylating 



