180 A GENERAL REVIEW OF 



a general means of synthesising alkyl derivatives of compounds 

 of more or less well-defined acid character, possessing hydrogen 

 atoms replaceable by alkyl radicles. 



ADVANTAGES OF THE PROCESS 



There are many advantages attending the use of this 

 method of alkylation. The products are generally obtained 

 pure, in good yield, and there is no difficulty in separating 

 the inorganic by-products. If an alkyl iodide has been em- 

 ployed in the alkylation, these by-products are silver iodide 

 and water. The latter can in some cases be removed by 

 employing a sufficient excess of the alkylating materials ; 

 in any case the insolubility of water in alkyl halides renders 

 it of little effect on the course of the main reaction if no 

 extraneous solvent is being used. The insolubility and 

 stability of the remaining inorganic by-product, silver iodide, 

 obviate any difficulty in the extraction of the organic product. 

 The reaction is generally smooth and rapid in its course, and 

 it can be very readily controlled. Alkyl iodides are, for the 

 purpose of this reaction, more conveniently used than other 

 halides. This is, possibly, simply a manifestation of the 

 well-known fact that the elimination of silver iodide in organic 

 synthesis occurs with great readiness. It is further possible 

 that the iodides are more suitable than other halides by reason 

 of their inferior stability. Alkylation proceeds most readily 

 in the case of those compounds which are soluble in alkyl 

 iodides, and in such cases no further addition of a solvent is 

 necessary. It should be noted that the reaction is carried 

 out in a neutral medium, and is therefore advantageously 

 employed in the etherification of substances which readily 

 undergo hydrolysis. 



A further advantage of this method of alkylation is that 

 it can be applied to optically active compounds without the 

 occurrence of racemisation or inversion. In fact, up to the 



