Bell — Further OhservaUons on Pyrrol and its Derivatives. IGfJ* 



viously described by Liibawin.^ According to this chemist, when iodide 

 of ethyl acts upon potassium-pyrrol C4HiN'K, substitution of the group 

 C2H5 for potassium takes place, a body of the composition CgHgN = C^ 

 H4N(C2H5) being formed. This base was said to have a turpentine- 

 like odour, to boil between 155° and 175°C., and to turn brown rapidly 

 on exposure to air. The metal potassium acts with great vigour upon 

 pyrrol, expelling hydrogen and producing potassium-pyrrol ; but upon 

 ethyl-pyrrol from mucate of ethylamine it has little or no action. It 

 would be contrary to analogy to suppose that in Lubawin's base the 

 ethyl-group does not occupy the position of the potassium in potassium- 

 pyrrol, and it was hence difficult to resist the conclusion that the bases 

 prepared from potassium-pyrrol and from ethylammonium mucate must 

 be identical. On repeating Lubawin's experiment I have found thi& 

 to be the case. Potassium-pyrrol is most easily prepared in a state of 

 purity by adding to pyrrol, contained in a flask with inverted con- 

 denser through which a stream of dry hydrogen is passed, rather less 

 than the calculated quantity of bright metallic potassium. The action 

 is violent at first, and must be moderated by the application of cold ; 

 towards the close it must be assisted by a gentle heat. The contents 

 of the flask are finally heated to fusion, allowed to cool, the flask 

 broken, and the solid mass dropped into a mortar containing anhydrous 

 ether. It is then quickly powdered, the ether (which removes un- 

 altered pyrrol) quickly poured off, and the powder again transferred 

 to a flask provided with an inverted condenser. It is then covered 

 with rather more than the theoretical quantity of ethyl iodide, and the 

 mixture boiled for a couple of hours, a chloride of calcium tube being-^ 

 placed in connexion with the upper end of the condenser so as to pre- 

 vent ingress of moisture. Towards the close of the boiling, a not in- 

 considerable amount of ammonia is evolved, evidently due to secondary 

 decompositions. On fractionally distilling the contents of the flask, a 

 very large quantity of ethyl-pyrrol is obtained, boiling at 131°C., and 

 having all the other properties of the base from ethylammonium mu- 

 cate. Above 131°C. a quantity of secondary products of inconstant 

 boiling-point comes over, the thermometer rising to 180°. It is this 

 mixture that Lubawin evidently mistook for ethyl-pyrrol, no doubt 

 regarding the principal product of the reaction as unaltered pyrrol, 

 from which indeed it differs but little in odour or boiling-point. 

 (Pyrrol boils at 133°C.) 



It is thus clear that only one ethyl derivative of pyrrol is yet 

 known, no doubt having the constitution — 



H 



I >NC3H5. 



H 



» " Zeitschrift fiir Chemie," [2] v. 399. 



