ON THE APPLICATIONS OF GRIGNARD’S REACTION. 295 
be used. Occasionally the temperature at which the reaction is con- 
ducted is maintained below 0°.! Sometimes ammonium chloride solution 
is used in place of mineral acid after the addition of ice ;* thus in the 
preparation of phenylmethyltriazene by the action of magnesium methyl 
iodide the action of acid must be avoided, otherwise the very labile 
diazoamino-compound undergoes decomposition. 
A perusal of the literature shows that it is often by no means 
immaterial whether the Grignard reagent is added to the compound to be 
acted on, or vice versd. This is especially true when one deals with a 
compound presenting several points of attack for the Grignard reagent 
This aspect does not appear to have been fully recognised by a consider- 
able number of investigators in this field. Further, the heating of the 
product obtained after mixing the Grignard reagent and substance acted 
on often has an important bearing on the result. 
Srcrion ITI. 
Theoretical. 
The formation of Grignard’s reagent was first represented + by an 
equation such as CH,1 + Mg=CH.MglI, and it is convenient to interpret 
the various reactions as being due to the type R.MgX. The fact, 
however, that the reaction takes place with such ease in the presence of 
absolute ether suggested to Grignard himself ® and to Blaise ® that the 
ether is not simply a solvent in the ordinary sense, but is one of the 
necessary materials for the action. If the reaction product obtained 
from magnesium, ethyl iodide, and ether is heated under diminished 
pressure in a current of hydrogen, the residue contains the compound 
C,H;MglI,(C,H;),0, in which the ether is so firmly bound that it is only 
partially eliminated when the compound is heated under diminished 
pressure at 100°-125°. The compound C,H;MgBr,(C-H,),O exhibits 
a similar stability towards heat. 
Whereas Grignard and Blaise at the time regarded the ether in these 
compounds as playing the réle of ether of crystallisation, Baeyer and 
Villiger 7 formulate the compounds in question on the basis of the quadri- 
valency of oxygen, thus : 
CH | Mer 
OH \x 
where R represents the alkyl or aryl group, and X the halogen atom, 
The existence of oxonium compounds, such as 
CH | SnCl, 
Cue ol 
and 
OH 7 ot o)s 
(Gomberg) 
CH \O(CH,)s 
' Kohler and Heritage, « AE Chem. J., 1905, 88, 21. nt 
* Tilden and Stokes, Trans. Chem. Soc., 1905, 87, 837. 
* Dimroth, Ber., 1903, 36, 909; 1905, 88, 670. Compare also Klages, idid., 1905, 
38, 2219. ‘ Grignard, Compt. rend., 1901, 182, 558. 
5 Theses sur les combinaisons organomagnésiennes miates et leurs applications a des 
syntheses (Lyon, 1901). & Compt. rend., 1901, 182, 839. 
7 Ber., 1902, 35, 1201. 
