Benzylmagnesium chloride
http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0471
In a dry 3-l. flask, fitted with a mercury-sealed stirrer, a 500-cc. dropping funnel, and a condenser provided at its upper end with a drying tube containing a mixture of calcium chloride and soda-lime (Note 1), is placed 48.6 g. (2 atoms) of magnesium turnings. There are then added 200 cc. of dry ether, a small crystal of iodine, and about 25 cc. of a solution of 253 g. (230 cc., 2 moles) of freshly distilled benzyl chloride in 1 l. of dry ether. If the reaction does not start at once, the flask is partially immersed in a bath containing water heated to about 40°. As soon as the ether begins to boil, and reaction sets in, the bath is removed and stirring is commenced. The remainder of the benzyl chloride in ether can be added during the course of one-half hour if the reaction is regulated by cooling the greater part of the flask by immersion in ice water (Note 2). The reaction will continue for about fifteen minutes after all the benzyl chloride has been added, and then the mixture is refluxed gently for about fifteen minutes.
1. The function of the calcium chloride and soda-lime is to absorb any moisture and carbon dioxide which might diffuse into the reaction flask.
The deleterious effect of another constituent of the atmosphere, oxygen, may be decreased by first sweeping out the flask with dry nitrogen or hydrogen. The initial use of a dry inert atmosphere may also be supplemented by the use of a trap1 to exclude the air, particularly in those operations requiring extensive periods.
