M. Wertheim on Piperidine. 113 



cylie acids. These acids lie names paramidobenzoic and paroxy- 

 benzoic acids ; and the interesting result was obtained, that the 

 paroxybenzoic acid formed was identical with that obtained in 

 another way by Saytzeff (vide supra). 



The method by which the base piperidine has hitherto been pre- 

 pared, by the decomposition of piperine by potash, is so unproduc- 

 tive as to make investigation of the former base very expensive. 

 Wertheim has now* found that when the alcoholic solution of 

 pepper is directly treated with potash, the whole of the piperine 

 which it contains is converted into piperidine ; after distilling off 

 the alcohol, adding water and again distilling, an alkaline dis- 

 tillate is obtained containing, besides a large quantity of ammonia, 

 piperidine and a small quantity of etherial oil of pepper. When 

 this distillate, neutralized with acid, is evaporated to dryness 

 and exhausted with absolute alcohol, the piperidine salt is dis- 

 solved out along with the oil. This latter is removed by eva- 

 porating again, dissolving in the smallest quantity of water, 

 and filtering through a moistened filter. The small quantity of 

 oil which passes through is finally got rid of by repeatedly eva- 

 porating the solution to dryness in the water-bath with addition 

 of water. On subsequently treating the salt with potash, the 

 base is separated as an oily layer, which is rectified. 28 kilo- 

 grammes of pepper thus treated gave 350 grms. pure piperidine. 



Nitrous acid acts energetically on piperidine ; it is absorbed 

 with such rapidity that the delivery-tube of the gas must not dip 

 in the liquid, and during the whole operation the liquid must be 

 carefully cooled. When the excess of nitrous acid is removed by 

 passing carbonic acid through at a temperature of 30° to 40° C, 

 a clear yellow oily liquid of an acid aromatic odour is left. 



This liquid was purified by several methods, one of which was 

 the following. It was dissolved in water, and potash gradually 

 added, by which an oil was separated. This was washed with 

 very dilute hydrochloric acid, dried over chloride of calcium and 

 rectified. This substance was distilled below its boiling-point, at 

 160° to 180° C. ; and as the distillate was still somewhat alkaline, 

 the same process was repeated. 



The substance thus purified is neutral, tolerably soluble in 

 water, more so in dilute acids, and very much so in strong acids, 

 from which it is precipitated by the addition of water. It rapidly 

 evaporates at 160° to 180° C. ; at 205° C. the body passes over 

 almost to the last drop. At 240° it begins to boil, but at the 

 same time gradually decomposes. Its composition is expressed 

 by the formula € 5 H 10 N 2 9, which was confirmed by a vapour- 

 density determination. 



* Liebig's Annal^n, July 1863. 



Phil Mag. S. 4. Vol. 27. No. 180. Feb. 1864. I 



