Definition
An important class of reagents used in synthetic organic chemistry, made
by union of metallic magnesium with an organic chloride, bromide, or iodide, usually in the presence
of an ether and in the complete absence of water. General formula RMgX, where R i
Hazard
Because the heat of decomposition of Grignard
reagents with water is great and the ether
in which they are dissolved is highly volatile and
flammable, they must be handled with extreme care.
Some, especially the solution of MeMgBr in ethyl
ether, may ignite spontaneously on contact with
water or even damp floors; nearly all will ignite
on a wet rag or similar material. Since all Grignard
reagents react rapidlywith bothwater and oxygen,
contact must be avoided. Ordinary materials of
construction are satisfactory for use with Grignard
reagents.
