CHEMISTRY OF CHLOROPHYLL: THE CAROTINOIDS 47 



with an acid R — COOH, water is split off and the resulting product 

 is an ester. 



R— OH+R— COOH = R— C— OR+H2O 



II 

 O 



Chlorophyll A has the structural formula 



/COOCH3 

 (C 3 iH 29 N 3 Mg)— COOCaoHa, 



\co 



NH 



and B 



/COOCH3 



(C32H 28 2 N 4 Mg) 



^COOC 20 H 39 



They are both thus seen to be esters of methyl alcohol (CH 3 OH) 

 and another alcohol (C 2 oH 39 OH) called phytyl alcohol. Chloro- 

 phyll A in addition contains a ring formation known as a lactam 

 ring. 



Phytol. — The phytyl alcohol or phytol, which makes up a third 

 of the chlorophyll molecule, is thought to have the following 

 construction : 



HHHHHHHH H 



H — C — C — C — C — C — C — C — C — C = C — C — OH 



H CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 H 



It is a colorless, oily liquid which is found nowhere else in nature. 

 When the leaves are treated with ethyl alcohol in the ordinary 

 methods of extracting chlorophyll from leaves, the phytyl alco- 

 hol is replaced by the ethyl so that what one obtains is ethyl 

 chlorophyllide. Methyl alcohol may be used in the same way. 

 These chlorophyllides are crystalline while the original phytyl 

 chlorophyllide or chlorophyll is amorphous. 



The Acid.— The acid in the ester has been called chlorophyllin. 

 It is a tri- or di-carboxylic acid, as shown by the formula, in which 

 only two of the acid groups are effective. One of these is joined to 



