490 On the Action of Heat and Pressure upon Paraffins. [June 20, 



Boiling-point. Sp. gr. 



o o 



Pentane 37 



Hexane 67- 68 0*6631 at 18 C. 



Heptane 97- 99 0*6913 „ 18*5 



Octane 122-125 0*7165 „ 15*6 



Nonane.. ...... 147-148 0*7279 „ 3*5 



From their specific gravities and boiling-points these hydrides in all pro- 

 bability belong to the series of normal paraffins. 



CH 3 — CH 2 (n CH 2 )— CH 3 . 



The authors have established the existence of the defines, not only by 

 the action of bromine, but also by the preparation of a number of bromi- 

 nated derivatives. They have obtained : — 



Boiling-point. Sp. gr. 



C 5 H 10 Br 2 184-188 



C 6 H 12 Br 2 195-200 1*5967 at 20 



C 7 H u Br 2 decomposes 1*5146 „ 18*5 



cX 5 Br 185-190 



C 8 H 16 C1 2 about 235° with decomposition. 



C 9 H 17 Br 208-212 



They have also prepared a few derivatives from the hydrides, and studied 

 the action of nitrogen tetroxide upon the mixture boiling at 122-125°. 



The mode of decomposition of the paraffins under the influence of heat 

 and pressure appears to be general for the higher terms of the series of 

 normal hydrocarbons. 



If the paraffins be represented constitutionally, by linking together the 

 carbon atoms in a single chain, the simultaneous formation of hydride and 

 define obviously arises from the loosening of the affinities of the CH 2 

 groups. Under the influence of heat, these groups become disassociated, 

 and recombine to form saturated hydrocarbons. Assuming, for the sake of 

 simplicity, that this decomposition may occur so low down in the series as 

 in the case of butane, it might be thus represented : — 



HHHH H H HH 



I I I I II II 



H— C—C— C—C— H = H— C— C— H + C = C 



I I I I II II 



HHHH HH HH 



The authors have but little direct evidence to offer as to the exact 

 manner of this decomposition — whether it is attended by the gradual 

 elimination of ethylene, a hydride containing a greater number of carbon 

 atoms being left behind, or whether the paraffin is at once split up into 



