ON ABSORPTION SPECTRA AND CHEMICAL CONSTITUTION, 99 



Absorption Spectra and Chemical Constitution of Organic Substances. — 

 Fourth Interim Eeport of the Committee, consisting of Professor 

 W. Noel Hartley (Chairman ayid Secretary), Professor F. E. 

 Japp, Professor J. J. Dobbie, and Mr. Alexander Lauder, 

 appointed to investigate the Relation between the Absorption Spectra 

 and Chemical Constitution of Organic Substances. 



The Committee has been occupied with two distinct branches of its work, 

 each of which has demanded a large share of attention. First, the spectra 

 and constitution of phloroglucinol and of substances derived therefrom, as 

 being intimately connected with tautomerism. Secondly, the absorption 

 curve of quinone and substances of a like nature, as being connected with 

 the view that quijione has a special structure, and that all organic colour- 

 ing matters are constructed on the same type. 



Part I. — The Absorption Spectra of Phloroglucinol and some of its Deri- 

 vatives. By W. N. Hartley, D.Sc, F.R.S., James J. Dobbie, D.Sc, 

 M.A., and Alexander Lauder, B.Sc} 



Phloroglucinol reacts with some reagents as a phenol, with others as a 

 ketone. When heated with phenyl-isocyanate in benzene solution it yields 

 a tricarbanilide derivative, C6H3(0-CO-NH-C6H.,)3, and when alkyl- 

 ated under certain conditions it gives derivatives which are re<^arded as 

 true ethers, since their alkyl groups are split off by heating with hydrogen 

 iodide. On the other hand, it reacts with hydroxylamine with formation 

 of a trioxime, and forms alkylated derivatives, from which the alkyl 

 groups are not split oflf by boiling with hydrogen iodide. It is impossible, 

 therefore, from its chemical behaviour to decide whether the oxygen atoms 

 of phloroglucinol are present in enolic or ketonic groups ; that is to say, 

 whether it possesses the structure (I.) or (IL) — 



C(OH) CO 



HC^'^CH HaC/^CHj 



(HO)C^^C . (OH) OC . 



CH CH 



CO 



IT. 



If it possesses the structure represented by (I.) its absorption spectra 

 should closely resemble the spectra of the trimethyl ether, M.P. 52° which 

 is decomposed by boiling with hydrogen iodide. If, on the other hand it 

 possesses the structure represented by (TL), its spectra should resemble 

 those of the alkyl derivatives which are not decomposed under this treat- 

 ment. 



Before comparing the absorption spectra of phloroglucinol and its alkyl 

 derivatives we deemed it advisable to examine specimens of phloroglucinol 

 from as many different sources as possible, and for this purpose specimens 

 were prepared from (1) kino, (2) maclurin, (3) resorcinol, (4) phenol, and 



' Chem. Soc. Trans., August 1903. 



