TRANSACTIONS OF SECTION B. 681 



isomeric substances are very nearly the same, and equal to about half the constant 

 of camphoric acid, which is precisely what should be expected if camphoric acid 

 -were a dicarboxvl acid (compare WaUcer, ' Jour. Chem. Soc.,' 1892, p. 715). 



7. The Halogen Addition Products of Salts of Organic Bases. 

 By Leonakd Dobbin, Ph.D., and James Walker, D.Sc, Ph.D. 



In 1885 and 1886 one of us in conjunction with Dr. Orme Masson ' showed 

 that the haloid salts of trimethylsulphine and of tetramethylammonium were acted 

 upon by the halogens and by iodine monochloride with formation of compoimds, 

 the composition of which is represented by the general formula RX3, where R 

 stands for the group SMe3 or NMe^, and X for one atom of a halogen. 



The products obtained in both cases differed very greatly in the readiness with 

 which they underwent decomposition by themselves and on treatment with water 

 or alcohol. The compounds containing three atoms of the same halogen were by 

 far the most easily decomposed, and, indeed, the formation of definite compounds 

 of this kind was never clearly proved, but only somewhat vaguely indicated. The 

 only compounds which remained unchanged on exposure to the air, and whicli 

 were further almost unattacked by boiling alcohol, were the dibromiodides pre- 

 pared by the action of bromine upon the monoiodides. The corresponding 

 dichloriodides, obtained from the monoiodides and chlorine, or from the mono- 

 chlorides and iodine monochloride, decomposed slowly on exposure to the air, 

 giving off chlorine and iodine. They were decomposed with moderate rapidity by 

 boiling alcohol, with formation of the monochlorides of the organic bases, alcoholic 

 solution of iodine, and products of the action of chlorine upon alcohol. Water 

 attacked all the compounds, but while trimethylsidphine trichloride was instantly 

 decomposed with liberation of torrents of chlorine, the dibrom- and dichloriodides 

 of both bases were only decomposed after prolonged contact. The dichloriodides 

 and dibromiodides were found to be very stable when heated, melting at tempera- 

 tures ranging from 94° to 216°, some almost and others entirely without decom- 

 position. 



More recently the dibrom- and dichloriodides of methyl-pyridium have been 

 prepared by us by the action of bromine and chlorine respectively on methyl- 

 pyridium iodide. The dichloriodide has also been obtained by Ostermayer - from 

 niethylpyridium chloride and iodine monochloride. These substances both crystal- 

 lise from alcohol, and were found to possess properties resembling in general those 

 of the corresponding trimethylsulphine and tetramethylammonium compounds, 

 being, however, more stable than these. The melting-point of the chloriue com- 

 pound is 88°, that of the bromine compound being 63°. 



In view of the serial character exhibited by these various substances with 

 respect to their stability in alcoholic solution, it seemed to us that the determina- 

 tion of the molecular weights of the most stable of tlie compounds by observing 

 with Beckmann's apparatus ^ the elevation of the boiling-point of alcohol in which 

 they were dissolved might yield results of interest in regard to the so-called 

 molecular compounds. 



The results of the determinations showed that methylpyridium and tetra- 

 methylammonium dibromiodides are not decomposed to any appreciable extent by 

 several minutes' boiling in alcoholic solution, while the trimethylsulphine analogue 

 is undoubtedly attacked, and that the dichloriodides are all decomposed, some to 

 a considerable degree, by the same treatment. The following table exhibits the 

 molecular weights calculated from the formula IIX3 and from the elevation of the 

 boiling-point respectively. Where there is no decomposition the values should be 

 identical, and the more widely they diverge, the greater is the amount of decom- 

 position. 



1 Dobbin and Masson, J<mrn. Chem. Soc, 47, 56 (188.5), and 49, 846 (1886). 



2 Bcrichtr, 18, 592. 



3 Zeit. Phydltal. Chem., 8, 223 (1891). 



