Bell — On a Series of Bases clerked from Pi/rrol. 47 



What the precise nature of the relationship which subsists between 

 pyrrol and mucate of ammonia may be, is still obscure. Nevertheless, 

 I think the existence of the compound CjoHiglN'sOo is calculated to 

 throw some light upon it. Since this body on heating with alkalies 

 evolves ethyl-pyrrol, we must assume the pyrrol nucleus to exist in it 

 already formed. Its constitution is then most easily explained, if we 

 assume that it differs from diethyl-carbo-pyrrol-amide in containing the 

 group (COISTHCoIIs) twice instead of once. 



Ethyl-pyiTol. Diethyl-carbo-pyrrol-amide. New body. 



C4H4 NCCaHs) CiHs (CONHC2H5) N (C2H5) C4H0 (CONHC.Hs)^ N (C2H5) ; 



and since this view is quite in accordance with its chemical behaviour, 

 I propose for it, provisionally, the name triethyl-dicarbo-pyrrol-amide. 

 Further researches are needed before we can regard this relationship 

 as definitely established ; but I think I can show that at least great 

 probability is lent to it, when we collect the results of certain isolated 

 experiments on mucic acid, and endeavour to fit them together. 



Fittig,^ by the prolonged action of hydrobromic acid on mucic acid 

 in sealed tubes at 100° C, has obtained a bibasic acid which he terms 

 dehydromucic acid, and which bears to mucic acid the relation of an 

 anhydride : — 



CeHioOg - 3HoO = CsHiOs. 



The basicity of this acid compels us to write its formula C4H2O 

 (C00H)3, which formula is, moreover, in perfect accord with its be- 

 haviour when heated. When its temperature is rapidly raised it breaks 

 up at once, and quantitatively, into the monobasic pyromucic acid and 

 free carbonic anhydride, 



C4H2O (C00H)2 - C4H3O (COOH) + CO3. 



Some years ago, now, Limpricht^" showed that when this latter 

 (pyromucic) acid (which may also be obtained directly by heating 

 mucic acid) is heated with soda-lime, it again parts with CO2, and 

 yields a very volatile liquid, C4H4O, to which the inapt name tetra- 

 ph&nol has been applied. 



C4H3O (COOH) - C4TI4O + CO2. 

 The characters of this body are such as to show clearly that it does 

 not contain the grouping OH at all ; that it is, in fact, neither an 

 alcohol nor a phenol. Limpricht, therefore, assigns to it the formula 



H 

 HC =C 



I ^0. Pyromucic acid is then a mono-carboxyl, and Pittig's 

 HC = C 

 H 

 acid a di-carboxyl-derivative of this tetraphenol. 



^ " Bericbte der deutscben Chemiscben Gesellscbaft," ix. 1198. 

 lu " Aimaleu der Cbeiuic und der Pbarinacie," band clxv., 253. 



