306 MM. Friedel and Oppenheim on Allylene. 



have the composition C 4 H 2 I 4 , and are thus formed by the union 

 of two molecules of acetylene. It has a very unpleasant odour, 

 is volatile at ordinary temperatures, but decomposes when 

 melted. By treatment with various agents it furnishes acety- 

 lene. Treated with reducing agents it furnishes a very volatile 

 oil, which is probably iodated acetylene, C 2 H 4 1, corresponding 

 to the brominated acetylene of Sawitzsch and of Reboul. 



The author is engaged on the further investigation of this 

 and of other substances. 



Semenoff * recommends for the preparation of ethylene gas a 

 mixture of 1 part by weight of absolute alcohol and 5 parts by 

 weight of sulphuric acid. With such proportions the addition 

 of sand is unnecessary ; for with careful heating in the sand- 

 bath there is no frothing up, and the disengagement of gas, 

 which commences at 100°, is quite regular. 



For the preparation of monobrominated ethylene, C 2 H 3 Br, 

 the same author recommends the following method. In a retort 

 connected with a Liebig's condenser is placed a mixture of bro- 

 mide of ethylene, G 2 H 4 Br 2 , with an equivalent quantity of 

 aqueous potash ; alcohol is then dropped in from a burette until 

 two layers are no longer perceptible. At the temperature of 

 40° to 50°, the monobrominated ethylene is then distilled off 

 mixed with alcohol. It is obtained in almost the theoretical 

 quantity. 



Friedel f has described a new method of preparing allylene J. 

 In the year 1857 he described two compounds obtained by the 

 action of chloride of phosphorus on acetone, methylchloracetole } 

 G 3 H 6 CI 2 , and chlorpropylene, G 3 H 5 CI. The latter he has found 

 is readily converted into allylene. It was enclosed in a sealed 

 tube with sodium-alcohol, and heated for about 16 hours to a 

 temperature of 120°. The tube was then provided with a vul- 

 canized tube and carefully opened. A quantity of gas escaped, 

 which was collected over brine, in which it is less soluble than 

 in water. Its properties were found to agree in all respects with 

 those of allylene. 



Oppenheim § has investigated the action of bromine and of 

 iodine on allylene-gas. The method used by him is that of its 

 discoverer Sawitzsch ||, that is, the action of sodium-alcohol on 



* Zeitschriftfur Chemie, No. 5, 1864. 

 t Bull. Soc. Chim. Paris, vol. ii, p. 96. 

 t Phil. Mag. vol. xxi. p. 359. 

 § Repertoire de Chimie, July 1864. 

 || Phil. Mag. S. 4. vol. xxi. p. 359. 



