UNSYMMETRICAL ADDITION TO THE DOUBLE BOND, I: 
A THEORY OF THE REACTION MECHANISM 
OF THE DIRECT UNION? 
By GRANVILLE A, PERKINS 
Chemist, Bureau of Science, Manila 
SIX TEXT FIGURES 
Certain difficult problems in organic chemistry, such as those 
of the chemical changes in living organisms, cannot be solved 
without much more definite knowledge of the mechanism of 
chemical reactions than is available at present. Remarkable ad- 
vances have been made recently in the theory of valence and the 
nature of the binding forces between atoms, but it does not 
appear that any organic chemist has applied these new concep- 
tions toward revising the older theories of the mechanism of 
reactions. 
The theories of Thiele,” Vorlander,? Michael, and Nef,° 
Were founded on Kekulé’s hypothesis of “affinity units.” Ac- 
cording to this hypothesis in its simple form, a reaction involvy- 
ing the main uniting forces between atoms can take place only 
when preceded or accompanied by a rupture of the bonds of the 
original compounds. This was supposed to take place sym- 
metrically, as follow: 
A—B gives A— + —B. 
Observing, however, that A—B in general reacts quite unsym- 
metrically, these investigators merely amended the hypothesis, 
the favorite amended form being: 
A-—B* gives A-— + —B*. 
Even with all possible amendments, the hypothesis proved 
entirely inadequate * for the formation of any definite and con- 
* Received for publication March 15, 1921. 
* Thiele, J., Ann. d. Chem. 306 (1899) 87 et al. 
* Vorlainder, D., Ann. d. Chem. 341 (1905) 1 et al. 
* Michael, A., Ber. deut. chem. Ges. 39 (1906) 21388 et al. 
* Nef, J. U. Ann. d. Chem. 298 (1897) 202 et al. 
*Cf. Vorlander, D., Ber. deut. chem. Ges. 36 (1903) 3529, “Der Kérper x 
hat an und fiir sich weder eine bestimmte Wertigkeit noch eigne Valenzen.” 
183013—~2 645 
