Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1999-01-05
2000-09-12
Vollano, Jean F
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
C07F 300, C07F 302
Patent
active
06117372&
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of Grignard compounds from organic halides and metallic magnesium in the presence of catalysts.
Grignard compounds are usually prepared by reacting organic halides with magnesium in an ether solvent; in certain cases, they may 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).
However, a wide variety of organic halogen compounds exist, including, in particular, aromatic and vinylic chlorine compounds, with which the Grignard reaction proceeds only hesitantly, has low yields, or hardly succeeds at all. To increase the reactivity of magnesium towards such halides, a number of methods is known which are based on physical (grinding, ultrasonic treatment, metal evaporation) or chemical (entrainment method, Rieke method, dehydrogenation of magnesium hydride, reversible formation of magnesium anthracene) activation of the magnesium (Active Metals--Preparation, Characterization, Applications, Ed. A. Furstner, VCH, 1996). Anthracene or magnesium anthracene and their derivatives are known as catalysts for the Gringnard reaction; however, they can be used only in the case of allyl, propargyl and benzyl halides (Chem. Ber. 1990, 123, 1507). The drawbacks of the mentioned methods are that they are either relatively cumbersome and expensive, or limited in their applicability or effects, or result in a higher consumption of magnesium (the 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, commercial magnesium types can be used.
Surprisingly, it has now been found that highly effective catalysts for the conversion of aromatic chlorine compounds, chlorine-containing polymers and other less reactive organic chlorine compounds to the corresponding Grignard compounds using commercial Mg powders or turnings can be produced using the so-called inorganic Grignard reagents of the transition metals (U.S. Pat. No. 5,385,716, Studiengesellschaft Kohle, 1995), optionally in combination with cocatalysts according to the invention. Those systems based on metals of groups 4 to 10 of the Periodic Table, especially Fe, Mn, Cr and Mo, are considered catalytically active, inter alia; of these, Fe and Mn catalysts are especially effective. The catalysts are preferably produced in situ by reacting the respective metal halides with excess Mg metal in tetrahydrofuran (THF), monoglyme or diglyme, in accordance with the preparation method for inorganic Grignard reagents (see above). As cocatalysts, there may be used, in particular, 9,10-diphenylanthracene (DA) and/or its magnesium adducts (Chem. Ber. 1990, 123, 1529) and magnesium halides. The system consisting of DA, FeCl.sub.2 or MnCl.sub.2, MgCl.sub.2 and excess Mg powder in THF, monoglyme or diglyme has proven to be particularly active as a catalyst. The reactions with organic chlorine compounds are preferably performed from room temperature to the boiling temperature of the solvent.
In one embodiment, the present invention relates to a process for preparing Grignard compounds comprising reacting an organic halide with magnesium metal in an ether solvent in the presence of an inorganic Grignard reagent catalyst of the formula [M(MgCl).sub.m (MgCl.sub.2).sub.n ], wherein M represents a transition metal of groups 4 to 10 of the Periodic Table, m represents 1, 2 or 3, and n represents 0 or 1, and optionally in the presence of a cocatalyst comprising anthracene or substituted anthracenes or their magnesium adducts and/or magnesium halides. The organic halide may be, for example, an aromatic compound or a chlorine-containing polymer. The ether solvent may be, for example, tetrahydrofuran, monoglyme or diglyme. The reaction may be per
REFERENCES:
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Bogdanovic Borislav
Schwickardi Manfred
Studiengesellschaft Kohle MBH
Vollano Jean F
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