Production of organomagnesium compounds using catalysts

Details Production of organomagnesium compounds using catalysts Production of organomagnesium compounds using catalysts

2000-06-19

2001-04-24

Nazario-Gonzalez, Porfirio (Department: 1621)

Chemistry of carbon compounds

Miscellaneous organic carbon compounds

C-metal

C502S150000, C502S167000, C556S001000, C556S045000, C556S113000, C556S146000

Reexamination Certificate

active

06221285

ABSTRACT:

The present invention relates to a process for the preparation of organomagnesium compounds from organohalides and magnesium metal in the presence of catalysts.
Grignard compounds are usually prepared by reacting organic halides with magnesium in an ethereal solvent; in certain cases, they can also be prepared in hydrocarbons (Comprehensive Organometallic Chemistry II, Vol. 1, 1995, p. 58-63; Comprehensive Organometallic Chemistry I, Vol. 1, 1982, p. 155; Chem. Ber. 1990, 123, 1507 and 1517; Houben-Weyl, Methoden der organischen Chemie, 1973, 13/2
a,
53-192).
However, there is a wide variety of organic halogen compounds, including, in particular, aromatic and vinylic chloro compounds, with which the Grignard reaction proceeds hesitantly, with low yields, poorly or not at all. For increasing the reactivity of magnesium towards such halides, numerous methods are known which are based on physical (grinding, ultrasonication, metal vaporization) or chemical (entrainment method, Rieke method, dehydrogenation of magnesium hydride, reversible binding of magnesium anthracene) activation of magnesium (Active Metals—Preparation, Characterization, Applications, Ed. A. Furstner, Verlag Chemie, 1996). As catalysts for the Grignard reaction, anthracene or magnesium anthracene and their derivatives are known; however, they can be employed only in the case of allyl, propargyl and benzyl halides (Chem. Ber. 1990, 123, 1507). There are drawbacks in the mentioned methods in that they are either relatively tedious and expensive or subjected to limitations in application or effectiveness, or result in an increased consumption of magnesium (entrainment method: J. Org. Chem. 1959, 24, 504). Therefore, there is still a need for effective and economical methods for the preparation of Grignard compounds from the above mentioned inert organic halogen compounds which are not subject to the mentioned drawbacks, and with the proviso that conventional, commercially available magnesium grades can be used.
Surprisingly, it has now been found that the addition of suitable metal compounds, optionally in combination with cocatalysts, results in a successful conversion of organic halogen compounds, especially of aromatic chloro compounds and chlorine-containing heterocycles, and other poorly reactive organic chloro compounds to the corresponding Grignard compounds using magnesium metal, e.g., in the form of commercially available Mg powders or turnings, in part with very high yields. Such systems are considered catalytically active when based on compounds of Periodic Table group
3
-
12
transition metals in which elements of groups
15
or
16
of the Periodic Table, preferably N or O, are bound to the metal. Particularly effective are catalysts containing Mn, Fe, Co or Cu with alkoxy, aryloxy, amido or phthalocyano groups. Useful cocatalysts include, in particular, magnesium halides and anthracenes or substituted anthracenes and their Mg adducts. The process is preferably performed in ethereal solvents, e.g., THF, diglyme and monoglyme. The reactions with organochlorine compounds are preferably performed at from room temperature to the boiling temperature of the solvent.


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