ABSOEPTION SPECTRA AND CHEMICAL CONSTITUTION. 151 



Absorption Spectra and Ghemical Constitution of Organic Substances. — 

 Interim Report of the Committee, consisting of Professor W. Noel 

 Hartley (^Chairman and Secretary), Professor F. R. Japp, and 

 Professor J. J. Dobbie, appointed to investigate the Relation 

 between the Absorption Spectra and Ghemical Constitution of Organic 

 Substances. 



Four informal meetings have been held during the year, and, as 

 much work is still in progress, it has been considered desirable that an 

 interim report of that which has been completed should be presented. 

 This consists of five communications published by the Chemical Society 

 in their ' Transactions ' since March last. Two of these deal with the sub- 

 ject of tautomerism and one with stereo-isomerism. The fourth is a 

 study of ammonia and its derivatives, of hydroxylamine and oximes ; and 

 the fifth an examination of some closed-chain compounds one of which 

 contains two nitrogen atoms. Details of the measurements of the spectra 

 are omitted from this report for the sake of brevity. In connection with 

 the nitrogen compounds a brief abstract of a previous publication has 

 been included. It is of interest because it leads towards the conclusion 

 that there are two distinct classes of albuminoids, some of which have 

 long been known to act as enzymes or soluble ferments towards the 

 carbohydrates. 



SpectrograpMc Sttbdies in Tautomerism, 



I. Absorj)tion Curves of the Ethyl Esters of Dihenzoylsuccinic Acid.^ 



According to theory, thirteen isomerides of diethyl dibenzoylsuccinate 

 have a possible existence, but only three have so far been prepared and 

 studied. On chemical grounds Knorr "^ regards one of the three as an 

 enolic, and the other two as ketonic esters. He assigns to the enolic or 

 a-ester the constitutional formula 



CPh(OH):C-CO,Et 



I 

 CPh(OH):C-CO,Et 



without deciding which of the three possible stereo-isomeric modifica- 

 tions of this formula represents the substance examined by him. The 

 two ketonic esters are structurally identical but configuratively difi'erent. 

 To one of them, which he designates the para- or /5-ester, Knorr assigns 

 the formula (a), and to the other, which he designates the meso-, anti 

 or y-ester, the formula (6). 



H H 



I I 



CO,EtC-COPh COPh-C-CO^Et 



(«) 'I (6) I 



COPh-C-COaEt COPh-C-COaEt 



I I 



H H 



' Hartley and Dobbie, Trcms. Chem. Soc, vol. Ixxvii. 

 " Amialen, 1896, 293, 70. 



