IQQ J. SAKURAI. 



the metallic aumlo-acctatc theory (HojST.CHg.COOM) ; it is this reaction 

 which has led many eminent chemists to regard metallic derivatives 

 of glycocoll as MHX.CH..COOH, and to represent the formation of 

 hippuric acid accordingly : 



COOH.CH,.^H!Äg + CliC0C«H5 = COOH.CH,.NH.COCeH, + AgCl. 



As already pointed out, however, there are reasons to believe 

 that hippuric acid is benzoyl-glycocoll, and its formation is, therefore, 

 no more easily expressed Ijy the scheme above given than by 



H,C-NH..iAg + Ci;COC,H, H2C-XH..C0C,H, 



I I ■" ■ -- i I +AgCl. 



OC-0 OC-0 



It must be observed that an opening of the ring, as in the case of the 

 action of alkyl iodides upon silver-giycocoll, could not occur here, 

 because both the radicals, CI and COCJi^, are negative. 



The metallic amido-acetate theory can furnish no satisfactory 

 explanation of the formation of hippuric acid by the action of benzoyl 

 chloride upon silver-giycocoll, nor can the metallamido-acetic acid 

 theory that of the production of amido-acetic esters by the action of 

 alkyl iodides upon silver-giycocoll. Both theories are imperfect, in- 

 asmuch as each considers only one set of facts ; the metalkuiinioniLtin 

 theonj, on the contrary, takes complete account of the reactions of the 

 derivatives under consideration and, at the same time, meets the 

 objections and requirements of the other two theories. 



With regard to other metallic derivatives, such as those contain- 

 ing iiicrcunj, cadinii))!. :inc. iiHKjnc.^imii, and lead, they are no doul)t 

 constituted like the copper or the silver derivative. Those containing 

 the metals of the alkaline earths — barium, slruntiiim, and calcium — have 

 only Ijeen recently obtained in definite and crystalline states (Kraut: 



