DERIVATIVES OF CHLOROPHYLL 233 



These two series of magnesium containing and magnesium 

 free compounds are respectively obtained by the action of 

 alkali or of acid upon chlorophyll and its derivatives. 



THE ACTION OF ALKALI. 



By shaking an alcoholic or an ethereal solution of chloro- 

 phyll with the calculated quantity of concentrated methyl 

 alcoholic potash, the chlorophyll is saponified and converted 

 into the potassium salt of the tribasic acid chlorophyllin. 



The latter substance if heated at 100-200° in an auto- 

 clave with concentrated methyl alcoholic potash, loses carbon 

 dioxide to give two isomeric dicarboxylic acids, Rhodophyllin 

 and Glaucophyllin, Cg^Hg^N^MgCCOOH^. 



At the higher temperature, 200°, a certain amount of a 

 monocarboxylic acid is formed by the loss of two molecules 

 of carbon dioxide. This substance, which is known as Phyllo- 

 phyllin, has the formula C3iH3,N4MgCOOH. If heated to 

 225-250° with alcoholic potash rhodophyllin gives a second 

 isomeric monocarboxylic acid known as pyrrophyllin.* 



THE ACTION OF ACID. 



By the careful addition of a strong solution of crystallized 

 oxalic acid in 96 per cent alcohol to an alcoholic solution of 

 chlorophyll, the magnesium is precipitated as oxalate, and a 

 compound formerly known as Phaeophytin, but now called 

 Phytylphaeophorbide,! is formed — 



/COOH 

 CyiH.jiN^— COOCH3 



\cOOC,oH33 

 This substance differs from phytyl chlorophyllide by having 

 two atoms of hydrogen in place of one atom of magnesium. 



Similarly if crystalline or ethyl chlorophyllide is treated as 

 above with oxalic acid, the magnesium free compound, known 

 as ethyl phaeophorbide, is produced. This substance when 

 first prepared was called phaeophorbin | ; the latter name is, 

 however, reserved for the magnesium free tricarboxylic acid, 

 C3iH3jN4(COOH)3, the analogue of chlorophyllin. 



*Cf. Willstatter and Pfannenstiel : " Annalen," 1908,358,205; Willstatter 

 and Fritzsche: id., 1910, 371, 33. 



t Willstatter and Hocheder : id., 1907, 354, 265. 

 J Willstatter and Benz : id., 1908, 358, 267. 



