Abstract:
The field of the present invention is the synthesis of a manganese-containing organometallic compound—methylcyclopentadienyl manganese tricarbonyl. More specifically, a key raw material in the synthesis process is treated to reduce the amount of protic side products in the material, thereby improving the yield of the overall synthesis.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This patent application is a continuation-in-part of patent application Ser. No. 10/800,784 filed Mar. 15, 2004, which is hereby incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The field of the present invention is the synthesis of a manganese-containing organometallic compound—methylcyclopentadienyl manganese tricarbonyl. More specifically, a key raw material in the synthesis process is treated to reduce the amount of protic side products in the material, thereby improving the yield of the overall synthesis.  
       BACKGROUND OF THE INVENTION  
       [0003]     Methylcyclopentadiene (“MCP”) is a key raw material in the synthesis of methylcyclopentadienyl manganese tricarbonyl (“MMT”). The first step of the reaction sequence involves reacting excess MCP with sodium metal in an ether solvent to generate a process intermediate complex, MCP-Na. For economic reasons, the excess MCP is recovered in the product distillation step, blended with fresh MCP, and finally recycled back to the initial reaction step.  
         [0004]     The ether solvent used in this first step in a MMT synthesis process is a dimethyl carbitol (“DMC”) solvent. This solvent, commonly known as “diglyme” or diethylene glycol dimethylether belongs to a class of solvents capable of sufficiently solubilizing alkali metals, metal compounds, and their salts. One way to make “glymes” is by a controlled polymerization of ethylene epoxide with sodium methoxide and then capping the desired chain product with methyl halide. This solvent is thought to be the source of the alcohol contaminants in the MMT crude that end up distilling over with the unreacted MCP. At the elevated reaction temperature stages of generating the MCP-Na the sodium is thought to cleave a small amount of the DMC solvent to give the alkoxides of methanol and 2-methoxyethanol. These alcohols are reconstituted further down the MMT synthesis steps at the stage where the MMT crude is washed with an aqueous solution to remove the salts before feeding this crude to the distillation columns. This is how the water is introduced into the MMT crude, and the water together with the alcohols end up distilling over with the MCP stream.  
         [0005]     In the MMT synthesis process, the water- and alcohol-laden MCP stream is recycled back and reacted with sodium metal in the DMC solvent to give the MCP nucleophile, MCP-Na. At the same time the sodium will react with the alcohol contaminants methanol and 2-methoxyethanol to give the corresponding sodium alkoxides, and with the contaminant water to give sodium hydroxide. These alkoxides and hydroxide will compete with MCP-Na chemistry further down the process for making MMT, hence compromising overall MMT yield. Finally they will be reconstituted back to their original methanol, 2-methoxyethanol, and water form at the aqueous wash of the MMT crude before being sent to the columns. These contaminants then recycle back into the MMT synthesis process as part of the MCP recycle stream. The kind of cycle these contaminants are exhibiting in this MMT process can be termed as a catalytic cycle of destroying the reactant sodium metal. If allowed to continue, this can become expensive because the levels of these contaminants in the process are being boosted as more are generated from DMC cleavage each cycle. Therefore, there is a need for a purification process that efficiently removes the contaminants from the MCP recycle stream.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     One aspect of the invention relates to a method of extracting water and alcohol from a mixture comprising methylcyclopentadiene, water and alcohol, comprising (a) providing an organic material comprising methylcyclopentadiene, water and alcohol; (b) adding water to the organic material to create organic and aqueous fractions; and (c) separating the organic and aqueous fractions; wherein the separated organic fraction comprises less water or alcohol than in the organic material before the addition of water and separation of fractions. In one embodiment of the invention, the method further comprises processing the separated organic fraction by contacting a bed of molecular sieve, such as a bed of activated alumina. In another embodiment of the invention, the organic and aqueous fractions are separated using a liquid/liquid extraction, optionally utilizing centrifugation.  
         [0007]     A second aspect of the invention relates to a method of improving the purity of methylcyclopentadiene to be added to a methylcyclopentadienyl manganese tricarbonyl synthesis reaction by removing water and/or alcohol contaminants therein, said method comprising (a) adding to methylcyclopentadiene contaminated with water and/or alcohol an amount of water sufficient to create methylcyclopentadiene and aqueous fractions; and (b) separating the methylcyclopentadiene and aqueous fractions; wherein the separated methylcyclopentadiene comprises less water and/or alcohol than the initial methylcyclopentadiene. In one embodiment, the methylcyclopentadiene and aqueous fractions are separated using a liquid/liquid extraction, optionally utilizing centrifugation.  
         [0008]     A third aspect of the invention relates to methylcyclopentadiene purified by the method comprising (a) providing an organic material comprising methylcyclopentadiene, water and alcohol; (b) adding water to the organic material to create organic and aqueous fractions; and (c) separating the organic and aqueous fractions; wherein the separated organic fraction comprises less water or alcohol than in the organic material before the addition of water and separation of fractions. In one embodiment of the invention, the method further comprises processing the separated organic fraction by contacting a bed of molecular sieve, such as a bed of activated alumina. In another embodiment of the invention, the organic and aqueous fractions are separated using a liquid/liquid extraction, optionally utilizing centrifugation.  
         [0009]     A fourth aspect of the invention relates to methylcyclopentadienyl manganese tricarbonyl produced by the method comprising providing methylcyclopentadiene that had been purified by a method involving (a) providing an organic material comprising methylcyclopentadiene, water and alcohol; (b) adding water to the organic material to create organic and aqueous fractions; and (c) separating the organic and aqueous fractions; wherein the separated organic fraction comprises less water or alcohol than in the organic material before the addition of water and separation of fractions. In one embodiment of the invention, the method of purifying the methylcyclopentadiene further comprises processing the separated organic fraction by contacting a bed of molecular sieve, such as a bed of activated alumina. In another embodiment of the invention, methylcyclopentadiene is further purifying by separating the organic and aqueous fractions using a liquid/liquid extraction, optionally utilizing centrifugation.  
         [0010]     A fifth aspect of the invention relates to a hydrocarbon composition comprising methylcyclopentadienyl manganese tricarbonyl produced by the method comprising providing methylcyclopentadiene that had been purified by a method involving (a) providing an organic material comprising methylcyclopentadiene, water and alcohol; (b) adding water to the organic material to create organic and aqueous fractions; and (c) separating the organic and aqueous fractions; wherein the separated organic fraction comprises less water or alcohol than in the organic material before the addition of water and separation of fractions. In one embodiment of the invention, the method of purifying the methylcyclopentadiene further comprises processing the separated organic fraction by contacting a bed of molecular sieve, such as a bed of activated alumina. In another embodiment of the invention, methylcyclopentadiene is further purifying by separating the organic and aqueous fractions using a liquid/liquid extraction, optionally utilizing centrifugation.  
         [0011]     Further embodiments, features, and advantages of the present invention, as well as the structure and operation of the various embodiments of the present invention, are described in detail below with reference to the accompanying figure. 
     
    
     BRIEF DESCRIPTION OF THE FIGURE  
       [0012]     The accompanying figure, which is incorporated herein and forms a part of the specification, illustrates one of the embodiments of the present invention and, together with the description, further serves to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.  
         [0013]      FIG. 1  illustrates the amounts of DMC (diamonds), 2-methoxyethanol (“2MeEthOH”) (circles), water (squares), and methanol (triangles) in the MCP recycle stream following a liquid/liquid extraction utilizing centrifugation. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     The disclosed process is directed to removing protic contaminants that inevitably result during the processes and synthesis of methylcyclopentadienyl manganese tricarbonyl (“MMT”). Specifically, as noted earlier herein, the intermediate product methylcyclopentadiene (“MCP”), when reacted with sodium metal in an ether solvent, generates protic contaminant side products including methanol, water and 2-methoxyethanol. Treatment of the recycle crude MCP with a water wash and optionally a molecular sieve bed removes most of the contaminants. Alternatively, a liquid/liquid extraction, optionally utilizing an ultracentrifugation step, may be utilized during the MCP recycling process to remove most of the contaminants.  
         [0015]     A method of extracting water and alcohol from a mixture comprising methylcyclopentadiene, water and alcohol, comprises providing an organic material comprising methylcyclopentadiene, water and alcohol; adding water to the organic material to create organic and aqueous fractions; and separating the organic and aqueous fractions; wherein the separated organic fraction comprises less water or alcohol than the organic material before the addition of water and separation of fractions. In one embodiment of the invention, the method further comprises processing the separated organic fraction over, through, or otherwise contacting a bed of molecular sieve, such as a bed of activated alumina. In another embodiment of the invention, the organic and aqueous fractions are separated using a liquid/liquid extraction, optionally utilizing centrifugation.  
         [0016]     The MCP recycle stream may contain in one embodiment one or more of the following contaminants: about 0.1 to about 0.8% methanol, about 0.1 to about 0.8% water, and about 0.1 to about 1.1% 2-methoxyethanol. The amount of any of these contaminants may be decreased utilizing the method of the present invention. Optimally, the amount of methanol may be decreased by about 50 to about 85%, the amount of water may be decreased by about 0 to about 60%, and the amount of 2-methoxyethanol may be decreased by about 50 to about 90%. In one embodiment, the water or any alcohol contaminant in the purified MCP recycle stream is present in an amount less than about 1%, by weight. In another embodiment, the water or any alcohol contaminant in the purified MCP recycle stream is present in an amount less than about 0.5%, by weight. In a third embodiment, the water or any alcohol contaminant in the purified MCP recycle stream is present in an amount less than about 0.1%, by weight.  
         [0017]     One method of decontaminating the MCP recycle stream from methanol, 2-methoxyethanol, and water side product contaminants of the MMT synthesis process is to include a step consisting either of a water wash or a molecular sieve bed in the MCP purification process. If lower levels of these protic contaminants are required than what can be achieved by either one of the two individual methods above, then the two purification methods may be installed together in series, first the water wash followed by the molecular sieve bed.  
         [0018]     In one embodiment of the present disclosure, the MCP recycle stream being recovered from the crude product by column distillation and recycled back into the MMT synthesis process contains at least the three detrimental protic components methanol, water and 2-methoxyethanol in levels of about 0.361, 0.39, and 1.087 wt % respectively. On washing the MCP organic layer with 2.5% vol/vol water, these contaminants are pulled into the aqueous phase and their levels are lowered in the organic phase by 82.8, 55.9, and 64.7% respectively. An even higher level of purification is achieved by running this same organic layer over, through or otherwise contacting UOP AZ molecular Sieve. In one example the three contaminants are lowered by 79.4, 97.1, and 77.2% for methanol, water, and 2-methoxyethanol, respectively. Recycled MCP thus purified results in significant process savings and improved MMT yield.  
         [0019]     The amount of water that is added to the MCP recycle stream may vary. It has been determined that relatively small amounts of water are effective to wash the contaminants from the MCP recycle stream. In one example, the addition of about one to about ten volume percent of water may be added to the organic MCP recycle stream and then separated from it. In another example, about 2.5 volume percent may be added. For processing efficiencies, the less water that can be added to remove the contaminant side products, the better.  
         [0020]     In some examples, the MCP recycle stream may be further treated by passing it over, through, or otherwise contacting a molecular sieve bed or over activated alumina to remove still further water and other protic side products from the stream. This step is performed alone on an MCP recycle stream, or in one example, is performed in series after the washing step described otherwise herein. For best processing efficiency, this step is done after the washing step, because then there is less water to remove. The result is that the sieve bed or the activated alumina will not need to be regenerated as often than if it was used to extract higher volumes of water and protic side products.  
         [0021]     Another method of decontaminating the MCP recycle stream from methanol, 2-methoxyethanol, and water side product contaminants of the MMT synthesis process is by a liquid/liquid extraction. A liquid/liquid extraction is a process that allows the separation of two or more components due to their unequal solubilities in two immiscible liquid phases, such as an organic and an aqueous fraction. Optionally, the liquid/liquid extraction utilizes centrifugation to separate the two immiscible liquid phases.  
         [0022]     In an embodiment of the invention, the liquid/liquid extraction utilizes a liquid/liquid Separator to remove the methanol, 2-methoxyethanol, and water side product contaminants from the MCP recycle stream. In this embodiment, the liquid/liquid Separator may be installed across the MCP recycle stream coming off of the distillation column. The MCP recycle stream coming off the distillation column may be mixed with an immiscible solvent, e.g. water that has a different density than the MCP recycle stream to yield a liquid/liquid dispersion. The liquid/liquid dispersion may then be separated by centrifugal force using a liquid/liquid Separator. Optionally, the liquid/liquid extraction steps may be repeated one or more times to increase the purity of the isolated MCP.  
         [0023]     Any amount of immiscible solvent may be added to the MCP recycle stream to form the liquid/liquid dispersion. If the immiscible solvent is water, then, optimally, the amount added will be minimized to decrease the amount of water that may later be processed to remove any extracted DMC. In one embodiment, the amount of water added to the MCP recycle stream is about 0 to about 10%, by weight. In another embodiment, the amount of water added to the MCP recycle stream is about 2 to about 8%, by weight. In a third embodiment, the amount of water added to the MCP recycle stream is about 4%, by weight.  
         [0024]     The MCP purified by the method of the present invention may then be utilized in synthesizing MMT. The synthesized MMT may then be incorporated into a hydrocarbonaceous fuel, such as gasoline, diesel fuel, fuel oil, biofuels, and synfuels or into hydrocarbon containing wastes and coals. In one embodiment, the synthesized MMT is incorporated into a hydrocarbon composition that is gasoline or diesel to be utilized in an internal combustion engine, such as an internal combustion engine of an automobile. In another embodiment, the synthesized MMT is incorporated into home heating equipment burning fuel oil, an industrial furnace, or utility power furnaces burning fuel oil or stationary burners. In a third embodiment, the synthesized MMT is used in waste incinerators.  
         [0025]     The following examples are illustrative, but not limiting, of the methods of the present invention. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which are obvious to those skilled in the art, are within the spirit and scope of the invention.  
         [0026]     All patents and publications cited herein are fully incorporated by reference herein in their entirety.  
       EXAMPLES  
     Example 1  
       [0027]     An MCP recycle stream from a MMT purification system was found to contain 0.361 wt % methanol, 0.39 wt % water and 1.078 wt % 2-methoxyethanol. To an aliquot of this organic material was added 2.5 vol % water. The resulting biphasic product was agitated to extract the three protic impurities into the aqueous layer. The liquid mixture was allowed to settle and the organic layer separated from the aqueous layer. Analysis of the organic layer showed a dramatic decrease in methanol of 82.8%, water of 55.9%, and 2-methoxyethanol of 64.7%. The process was repeated on a fresh aliquot of recycle MCP, but this time the wash was carried out with 5 vol % water. This doubling of the water layer did not significantly improve on the purification process (see Table 1).  
                                                                   TABLE 1                           Removal of protic contaminants methanol, water, and 2-methoxyethanol       from MCP recycle stream in a commercial scale MMT production       process by washing the organic material with water            Impurity   Initial   2.5% H 2 O   Impurity   5.0% H 2 O   Impurity       Component   wt %   Wash   Removed (%)   Wash   Removed (%)                    Methanol   0.361   0.062   82.8   0.054   85       Water   0.39   0.172   55.9   0.146   62.6       2-Methoxyethanol   1.078   0.38   64.7   0.264   75.5                  
 
       Example 2  
       [0028]     An MCP recycle stream from one of the MMT purification systems was found to contain 0.68 wt % methanol, 0.69 wt % water and 1.62 wt % 2-methoxyethanol. This material was contacted with a bed of UOP AZ molecular sieve. Subsequent analysis of the sieve treated MCP recycle showed a significant decrease in methanol of 79.4%, water of 97.1%, and 2-methoxyethanol of 77.2%. (see Table 2).  
                                     TABLE 2                           Removal of protic contaminants methanol, water,       and 2-methoxyethanol from MCP recycle stream in       a commercial scale MMT production process by treating       the organic with UOP AZ molecular sieve.                        UOP AZ               Impurity   Initial   Molecular   Impurity           Component   wt %   Sieve   Removed (%)                       Methanol   0.68   0.14   79.4           Water   0.69   0.02   97.1           2-Methoxyethanol   1.62   0.37   77.2                      
 
         [0029]     It is to be understood that the reactants and components referred to by chemical name anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., solvent, etc.). It matters not what chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution or reaction medium as such changes, transformations and/or reactions are the natural result of bringing the specified reactants and/or components together under the conditions called for pursuant to this disclosure. Thus the reactants and components are identified as ingredients to be brought together either in performing a desired chemical reaction (such as formation of the organometallic compound) or in forming a desired composition (such as an additive concentrate or additized fuel blend). Accordingly, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense (“comprises”, “is”, etc.), the reference is to the substance, components or ingredient as it existed at the time just before it was first blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure. The fact that the substance, components or ingredient may have lost its original identity through a chemical reaction or transformation during the course of such blending or mixing operations or immediately thereafter is thus wholly immaterial for an accurate understanding and appreciation of this disclosure and the claims thereof.  
         [0030]     Applicant does not intend to dedicate any disclosed embodiments to the public, and to the extent any disclosed modifications or alterations may not literally fall within the scope of the claims, they are considered to be part of the invention under the doctrine of equivalents.  
       Example 3  
     Optimization of Water Amount into the Liquid/Liquid Separator  
       [0031]     The LX 204 Liquid/Liquid Extractor (Rousselet Robatel, Annonay, France) was fed with a MCP stream contaminated with 2.87% DMC, 0.57% 2-methoxyethanol, 0.02% water, and 0.08% methanol. The LX 204 Liquid/Liquid Extractor was run with the water wash stream in batches of 0.0%, 0.75%, 2.00% and 4.00%, respectively. As the amount of water in the secondary stream into the Extractor increases, the level of contaminants in the MCP stream exiting the Extractor decreases, as shown in  FIG. 1 .  
       Example 4  
     Optimization of the Number of Stages Utilized in the Liquid/Liquid Separator  
       [0032]     The LX 204 Liquid/Liquid Extractor (Rousselet Robatel, Annonay, France) was utilized to optimize the number of stages required to yield highly purified MMT. The rotor speed of the Extractor used was 2700 rpm. The MCP stream was fed into the Extractor at a rate of 230 lbs/hr, with a corresponding secondary feed stream of water of 7.9%  
         [0033]     The purity of MCP from each successive liquid/liquid extraction stage was analyzed for the weight percent of each of methanol, 2-methoxyethanol, water, and DMC. The results are shown in Table 3 below.  
                                                           TABLE 3                           Liquid/Liquid Extractor use in removal of contaminants       from the MCP recycle stream in a MMT synthesis method.                Methanol   2-Methoxyethanol   Water   DMC           (%)   (%)   (%)   (%)                        Original Level   0.16   0.60   0.17   8.12       Stage 1   0.09   0.48   0.15   7.45       Stage 2   0.00   0.31   0.13   6.48       Stage 4 (Final)   0.00   0.22   0.13   6.38                  
 
         [0034]     As shown in Table 3, the levels of contaminants decrease with an increasing number of liquid/liquid extractions utilizing centrifugation to separate the two immiscible liquids. After four liquid/liquid extraction steps, the methanol had decreased by 100%, the methoxyethanol by 63%, and the water by 24%. The DMC level in the MCP stream being recycled was not an issue because DMC was the solvent used in the process.