168 Proceedings of the Royal Irish Academy. 



XXYIII. — FiTRTHEE Obseetatioxs OX Ptkeol and its Deeivatiyes^ 

 By Chichestee A. Bell, M.B., University Dublin. 



[Eead, June 24, 1878]. 

 Synthesis of Pyrrol. 



Seveeal attempts which. I have made to effect the synthesis of pyrrol 

 have not been successful. The folloTring experiment is chiefly of in- 

 terest as suggesting a process by which bases of similar constitution 

 are likely to be obtained artificially. AVhen vapours of diethylamine 

 (CoHg), H^N", are passed through a heated tube packed with recently- 

 ignited pumice, they experience but little change if the temperature be 

 much below that of redness. On the other hand, a good red heat is 

 sufficient to decompose the base into a variety of products, amongst 

 which ethylene, free hydrogen, cyanogen, and hydrocyanic acid, are 

 easily recognised. If the tube be of sufficient length, the current of 

 vapour not too rapid, and the temperature that of incipient redness, a 

 liquid is obtained containing, besides much diethylamine, a considera- 

 ble quantity of pyiTol. The change probably consists in a direct 

 separation of hydi-ogen, thus — 



H 

 CH3 - CHo^ HC = C 



>XH= I >KE+3H, 

 CH3 - CH/ HC - C^ 



H 



I have not in this way prepared any large quantity of the base, but 

 in all cases have estimated the product by the rapidity and intensity 

 with which the vapours issuing fi^om the tube exhibited the fir-wood 

 reaction, the amount of precipitate yielded by the acidified distillate 

 with mercuric chloride, stannous chloride, etc., and by the quantity of 

 pyrrol-red obtained by boiling the liquid in the receiver with strong-^ 

 hydrochloric acid. 



I think it not unlikely that the conversion of diethylamine into 

 pyrrol may be effected in a more simple way. 



On the so-called ethyl-pyrrol of Luhaicin. 



In my previous communication on this subject (these Proceedings,. 

 2nd Series, vol. III., Science, page 33), I described a series of bases 

 derived from pyiTol by the substitution of various alcoholic radicles 

 for one atom of hydi'ogen. One of these, namely ethyl-pyrrol, CiB.i^ 

 ^{(CoIIs), differed widely in its properties from the similar base pre- 



