4-2 Proceedings of the Royal Irish Academy. 



general molecular pattern of the flavones and anthocyanidins, all of which are 

 derivatives of ay-diphenylpropane. In fact, the latter worker (Ber. d. Deutsch. 

 Chem. Ges., 1922, Iv, 1938) regards the phlorogliieinol tannins as being pro- 

 duced in plants from the catechins. 



St. von Kostanecki and Y. Lampe, however, could not reconcile Perkin's 

 formula (i) with the fact that catechin on bromination forms only a 

 monobromo derivative. Moreover, catechin does not readily split off water, 

 forming a simple anhydride, as the grouping 



)CH— COH 

 / \ 



would seem to require. For these reasons the latter workers (Ber. d. Deutsch. 

 Chem. Ges., 1906, xxxi.K, 1007) replaced the chromane formula (i) by the 

 coumarane formula (ii), which represents catechin as a derivative of 

 diphenylmethane. 



II. 



Latterly Perkiu and Everest also have adopted the coumarane formula 

 {vide Text-book ou the Natural Organic Colouring Matters, p. 466). 



Freudenberg (Ber. d. Deutsch. Chem. Ges., 1920, liii, 1420), however, has 

 pointed out that the earlier work of Perkin and his collaborators (Jour. 

 Chem. Soc, 1902, Ixxxi, p. 1164) somewhat annuls the force of the first 

 arguments used by von Kostanecki against the chromane formula (i) — 

 catechin readily forms a disazobenzene derivative. Too niuch emphasis, 

 therefore, should not be placed on the fact that catechin forms only a mono- 

 bromo derivative on bromination. 



From what follows in the present paper it will be seen Uiat the second of 

 the reasons advanced against the chromane formula also loses its significance ; 

 for although a direct elimination of the elements of water from the catechin 

 molecule is not readily accomplished, still this elimination can be achieved 

 by mdirect methods in such a way as to yield a simple anhydride containing, 

 in fact, an ethylene linking 



liencea coumarane formula, which represents catechin as a derivative 

 of diplienyl carbinol, is not necessarily the only formula to be considered, 

 von Kostanecki (Ber. d. Deutsch. Chem. Ges., 1907, xl, 720) by the 



