B.— CHEMISTRY 



6S 



It was thus shown that the attachment of the group (C4H9)2N.(CH2)io 

 to a simple substituted amino group gave very high efficiency. • 



A long series of tetraalkyldiamino parafRns of the general formula 

 NRR'.(CH2),,.NRR' was then prepared, and the minimum amoebicidal 

 concentration under the optimum conditions for emetine determined. 



In the first place, derivatives of heptane and decane were examined ; 

 of the heptane series the tetraethyldiamino and tetra-«-butyldiamino 

 compounds were prepared and tested. The tetrabutyl member of the 

 series was superior as an amoebicide to the tetraethyl one, but neither 

 showed more than a fraction of the efficiency of the best harmol derivative. 

 More promising results were obtained with the corresponding decane 

 derivatives and ultimately the efficiency of dibutylaminoundecylharmol 

 was equalled or even, in some of our tests, surpassed. 



The following table shows the results of a test in which a number of 

 decane derivatives of the general formula, R2N.(CH2)ioNR2, were examined 

 simultaneously, so that the ' peak ' of the series could be ascertained. 

 This was found at ax-tetra-M-amyldiaminodecane, which was used as a 

 standard of comparison in later work. For brevity, it is referred to 

 below as T.A.D.D. 



Compound. 

 oLx-Decanes 



Tetra-n-propyldiamino 

 Tetra-n-butyldiamino 

 Tetra-«-amyldiamino 

 Tetra-«-hexyldiamino 



Minimum concentration lethal 

 to E. histolytica. 

 I in 250,000 not lethal 

 I in 1,500,000 

 I in 3,000,000 (or less) 

 I in 1,000,000 

 I in 250,000 not lethal 



Tetra-«-heptyldiamino 



A similar test indicated that the corresponding series of undecane 

 derivatives also showed the peak with the tetraamyldiamino member. 



Next, keeping a tetrabutyl or tetraamyl group constant, the hydrocarbon 

 residue was varied. The following table shows the results of two tests 

 on these series of compounds. 



