Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-04-04
2003-04-22
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C585S612000, C260S66500B
Reexamination Certificate
active
06552237
ABSTRACT:
The present invention relates to a Grignard-type process for the preparation of unsaturated organic compounds. The process comprises contacting an unsaturated organic halide with magnesium metal in a mixture of ether and a polar halogenated hydrocarbon co-solvent, filtering the reaction product from the reaction step and thereafter, treating the reaction product filtrate from the filtration step to obtain the desired unsaturated organic compounds.
The inventors of the present invention have found that the use of halogenated solvents in conjunction with ethers, the traditional Grignard reaction solvents, results in lower reaction temperatures, the ability to separate the desired unsaturated organic compounds from the by-produced magnesium halides with ease which results in higher yields of purer unsaturated organic compounds.
BACKGROUND OF THE INVENTION
The reaction of organic halides with magnesium metal in the presence of oxygenated solvents such as dialkyl ethers to form reactive complexes typically referred to as Grignard reagents is well known. The production and reactions of Grignard reagents has been the subject of books and numerous review articles. Such reviews are provided, for example, in Coates, et al., ORGANOMETALLIC COMPOUNDS, Vol. 1, pp. 76-103, (1967), Methuen and Co. Ltd, London, U.K.; and in Kirk/Othmer, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Vol. 10, 721-734 (1966), The Interscience Encyclopedia, Inc., NY, N.Y. The structure of the Grignard reagent has not been determined with certainty, however it is generally believed that the Grignard reagent exists as a complex in solution and that solvent can play a critical role in such complex formation. The unpredictable effect of solvent on the formation and reactivity of Grignard reagents is discussed in the above cited review articles, and the inventors herein believe, but should not be held to such a theory, that the following reaction equations may be the actual mechanisms, using allyl chloride as the organic halide reactant example:
The preparation of unsaturated organic compounds such as 1,5-hexadiene by a process using a Grignard reagent as an intermediate is known. For example, Turk, et al., Organic Synthesis, Vol. 27, 7-8, 1947, teach a process for preparing 1,5-Hexadiene by the reaction of allyl chloride in anhydrous ether with magnesium turnings. Turk et al. teach that this reaction results in the formation of a thick slurry that becomes unstirrable. This unstirrable slurry is then treated with a hydrochloric acid solution until enough of the chloride by-product is in solution and then the slurry becomes sufficiently fluid to be stirred.
Such processes as taught by Turk et al. are not generally acceptable as a commercial process. The formation of the unstirrable slurry during the reaction can cause reduced mass transfer and heat transfer and therefore reduced yields. Furthermore, the nature of the slurry makes it necessary to treat the slurry in an additional step with a reagent to solubilize the slurry to allow isolation of the product. Typically, a major portion of the product is trapped with the unstirrable slurry. In addition, the non-flowable nature of the slurry does not allow for the reaction to be run as a large scale or continuous process.
A further disclosure regarding the use of the Grignard technology to prepare unsaturated organic compounds can be found in U.S. Pat. No. 5,596,120, that issued to Bank, et al., on Jan. 21, 1997 in which an attempt is made to overcome the drawbacks of the Turk, et al. process. Therein, Bank et al. teach that organosilanes can be prepared using magnesium metal with a mixture comprising an organic halide and a halosilane in a co-solvent comprising about one to 15 mole of a dialkyl ether comprising less than seven carbon atoms, per mole of allyl chloride, and about 0.05 to less than two mole of a liquid aromatic hydrocarbon solvent per mole of the dialkyl ether, at a temperature within a range of about 5° C. to 200° C. The taught hydrocarbon solvent is toluene. No mention is made in this disclosure about the use of chlorinated hydrocarbon solvents and the benefits achieved by their use in the Grignard technology.
Another disclosure is that found in European Patent Specification EP 0 729 931 to Hayes II, et al., in which there is disclosed a one-step Grignard-type process for the preparation of 1,5-Hexadiene. The process comprises contacting magnesium metal with a mixture comprising allyl chloride; one to 15 mole of a dialkyl ether comprising less than seven carbon atoms, per mole of the allyl chloride; and 0.05 to less than two mole of a liquid aromatic hydrocarbon solvent per mole of the dialkyl ether at a temperature within a range of 5° C. to 200° C. The liquid aromatic hydrocarbon solvent is disclosed as toluene and there is no mention in this disclosure with regard to the use of chlorinated hydrocarbon solvents for use in preparing unsaturated organic compounds. It is alleged that this process provides easily stirred slurries which improve mass transfer and heat transfer during the process and allows for easier separation of the unsaturated organic compound from the product slurry. Furthermore, it is noted therein, that the method allows for the process to be run as a continuous process.
THE INVENTION
The present invention thus deals with a process of preparing unsaturated organic compounds using a Grignard-type reaction technology wherein magnesium metal is contacted with an unsaturated organic halide in the presence of an ether and a polar halogenated hydrocarbon co-solvent or a mixture of ether and a mixture of polar halogenated hydrocarbon co-solvents.
Thus, what is disclosed and claimed herein is a method for the preparation of unsaturated organic compounds wherein the method comprises contacting an unsaturated organic halide with magnesium metal in a mixture of ether and a polar halogenated hydrocarbon co-solvent or a mixture of ether and a mixture of polar halogenated hydrocarbon co-solvents to produce the unsaturated organic compound. Thereafter, filtering the reaction product and treating the reaction product filtrate to obtain the desired unsaturated organic compounds.
A further embodiment of this invention is a method for the preparation of unsaturated organic compounds wherein the method comprises contacting an unsaturated organic halide with magnesium metal in a mixture of ether and a polar halogenated hydrocarbon co-solvent or a mixture of ether and a mixture of polar halogenated hydrocarbon co-solvents wherein the temperature is in the range of from 5° C. to 200° C. and most preferred range is from 50° C. 100° C., and the pressure is in the range of from ambient pressure to about 200 psig wherein the most preferred range is from 0 psig to about 125 psig.
Both of these embodiments are known as “one-step” processes for the preparation of unsaturated organic compounds because it is not necessary to isolate an intermediate Grignard-type reagent in the process and then further react this Grignard-type reagent with the unsaturated organic halide to form the unsaturated organic compounds. Further, it is not necessary to conduct a separate solubilization step on the resulting product slurry to facilitate recovery of the unsaturated organic compound.
The magnesium metal used in this invention can be any of the known forms of the metal that are currently used for Grignard-type reactions. For example, the metal can be any of those known in the art that are in the form of powder, flakes, granules, chips, lumps, and shavings, and the like.
Contact of the magnesium metal with the unsaturated organic halide can be undertaken in standard type reactors suitable for running Grignard type reactions. The reactor can be a batch, semi-batch, or continuous type of reactor. A preferred reactor is a continuous reactor. The environment in which the present method is carried out should be inert for best results. Therefore, in a preferred method, the reactor is purged and blanketed with an inert gas such as, for example, nitrogen or argon.
Generally, the magnesium metal is
Bedbury Curtis J.
Nguyen Binh T.
Dow Corning Corporation
McKellar Robert L.
Shippen Michael L.
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