7 o2 SCIENCE PROGRESS 



methyl iodide in the presence of dry ether behaved towards 

 certain ketones in the same way as zinc methyl. Grignard took 

 up the study of this reaction in 1900 and discovered the impor- 

 tant reagents which now bear his name. 



It is possible to obtain as white solids the so-called individual 

 magnesium compounds, composed only of magnesium and alkyl 

 groups. But in the presence of dry ether this solvent enters 

 into reaction and the Grignard reagents are additive compounds 

 of ether with the individual magnesium alkyl or aryl halide, 

 MgRI, (C 2 H 6 ) 2 0. 



V. Baeyer regards these compounds as derivatives of quadri- 

 valent oxygen (I.), and Grignard proposes the alternative 

 formula (II.) : 



CsHs^ /MgR CoHss^ /Mgl 



c 2 n/ ^1 C 2 H 5 / Nr 



1. 11. 



Whichever of these two configurations be accepted, it will be 

 seen that the same general principle is at work, namely the 

 grouping of four radicals round a central atom — in this case 

 oxygen — with possibly a development of tetrahedral symmetry. 



Similar compounds are known in the case of zinc, 

 Zn(CH 3 ) 2) (C 2 H 5 ) 2 0, and Tschelinzeff has isolated magnesium 

 compounds with two and four molecular proportions of ether 

 and this solvent may in certain cases be replaced by tertiary 

 amines, MgRI, NX 3 . 



These Grignard reagents are not spontaneously inflammable 

 in air, and being readily soluble in many anhydrous organic 

 solvents are much more easily handled than the inflammable 

 zinc alkyls. Accordingly, these reagents have already received 

 a very wide application, and in the hands of Acree, Behal, 

 W. H. Perkin, jun., Zelinsky and numerous other investigators 

 have facilitated many valuable syntheses which could not other- 

 wise have been effected. Perkins synthesis of terpineol may be 

 cited as a prominent example of the use of magnesium methiodide. 



In this paper attention will be confined to the use of the 

 Grignard reagents in preparing organo-metallic and metalloidal 

 derivatives. 



(d) The Alkali Metals 



In the first vertical series of the periodic table we find the 

 well-defined family of alkali metals which are typically univalent 



