Chemistry of hydrocarbon compounds – Purification – separation – or recovery – By plural serial diverse separations
Reexamination Certificate
2001-01-31
2002-06-18
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Purification, separation, or recovery
By plural serial diverse separations
C585S809000, C585S833000, C585S864000, C585S867000
Reexamination Certificate
active
06407304
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the isolation of high boilers, in particular C
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isomers, which are formed in the catalytic dimerization and trimerization of 1,3-butadiene.
2. Discussion of the Background
The reaction of 1,3-butadiene is carried out industrially over transition metal complexes or transition metal complex salts which are generally present as homogeneous solutions in a nonpolar organic phase. Suitable solvents are inert hydrocarbons such as benzene. The catalyst used is typically a transition metal of the 4th to 10th group of the Periodic Table in the oxidation state 0 and, if desired, a ligand such as a phosphine or a phosphite (W. Brenner, P. Heimbach, H. Hey, E. W. Muller, G. Wilke, Liebigs Ann. Chem. 727, 1969, 161-182; DE 12 83 836, Studiengesellschaft Kohle; DE 19 42 729, Mitsubishi Petrochemical Company Ltd.). Depending on the catalyst system, the main products formed are either the dimerization products cyclooctadiene (COD) and vinylcyclohexene (VCH) or the trimerization product cyclododecatriene (CDT). The selectivity of the reaction over the catalysts is high. It is generally over 90% in favor of the main component desired in each case.
After the reaction, the homogeneous catalyst is first decomposed and separated off. The decomposition is typically carried out by means of polar solvents such as monoalcohols having from 1 to 6 carbon atoms and water or by means of dilute acids. The reaction mixture (organic phase) is subsequently worked up by distillation. Here, unreacted 1,3-butadiene and solvent are returned to the reaction process; the various dimerization and trimerization products are subsequently separated from one another by distillation.
The bottoms from the column consist of a product mixture comprising oligomers and polymers of 1,3-butadiene as well as numerous high-boiling monomers having a defined molecular structure.
Typical monomers are compounds having from 12 to 30 carbon atoms, comprising a ring framework of from 6 to 24 carbon atoms and possibly one or more side chains. Important, nonlimiting representatives of such monomers are 3-(2-butenyl)-1,5,9-cyclododecatriene, 3-(3-butenyl)-1,5,9-cyclododecatriene and 3-(1-methylpropenyl)-1,5,9-cyclododecatriene as well as cyclohexedeca-1,5,9,13-tetraene.
Many of these macrocyclic monomers have been able to be isolated on a laboratory scale and their structure elucidated. Comprehensive descriptions may be found in DE 19 06 361 (Toyo Rayon Co.), GB 1 287 252 (Toray Industries), and in DE 20 63 348, US 3 658 926 and JP 48 019 304, cited according to CA 79:78229 (all Mitsubishi Petrochemical Co. Ltd.).
Difficulties generally occur in the selective synthesis of defined macrocycles. Studies have been carried out, for example, on the ring-opening metathesis of 1,5-cyclooctadiene over tungsten (E. A. Ofstead, Macromol. Synth. 1977, 6, 69), rhodium (K. Saito et al., Bull. Chem. Soc. Jpn. 1979, 52, 3192) or rhenium catalysts (US 3 865 888) and the oligomerization of 1,3-butadiene in which, if desired, linear dimers such as 1,3,7-n-octatriene may also be added (DE 20 63 348). All the methods give a product mixture comprising not only various macrocycles but also amounts of VCH, COD, CDT and polybutadienes. Only the selective syntheses of CDT and COD are used on an industrial scale.
In the selective synthesis of CDT or COD, a high-boiling, occasionally yellowish residue remains as bottoms from the distillation column in the customary form of work-up. At room temperature, this residue either remains a highly viscous liquid or solidifies to a wax-like solid, depending on composition. Distillation does not allow any further useful product to be isolated from this residue with a justifiable input of energy. The bottoms from the column are therefore generally incinerated as a waste product.
Extraction is a possible method of separating the high-boiling monomers and polymeric constituents. In GB 1 287 252, Example 1, this is carried out by addition of large amounts of acetone (500 g) relative to the reaction mixture (162 g of butadiene and 20 ml of toluene as solvent). In the other examples of GB 1 287 252, in which the reaction mixture is worked up and not only analyzed by gas chromatography, extraction with acetone as described in Example 1 is also employed.
In DE 19 06 361, not only toluene but also hexane, benzene, ether, i.e., diethyl ether, and tetrahydrofuran are mentioned as solvents. Here too, large amounts of acetone (500 g) relative to the solvent (in general from about 10 to 50 ml) are used as extractant. If larger volumes of solvent are used, viz., 200 ml of toluene (Example 10) or 250 ml of hexane (Example 15), the amount of solvent is reduced by distillation before acetone is added as extractant. However, in all cases the dimerization and trimerization products COD, VCH and CDT remain in the reaction mixture and are consequently also taken up in the acetone. JP 49 007 153 (cited according to CA 81:13184) also mentions acetone for the extraction.
However, application of the above-described extraction method to the selective synthesis of CDT or COD presents considerable difficulties. Thus, direct addition of acetone to the reaction mixture precipitates the polymeric or oligomeric components only very incompletely, if at all. It has also been found that the solvents described, in particular the aromatic and ether compounds, readily dissolve the oligomeric and polymeric components and thus make the extraction considerably more difficult.
Owing to the large amounts of CDT or COD which are also to be extracted in the selective synthesis of these compounds, the amount of acetone required for implementation of the prior art on an industrial scale would be tremendous.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a process for the isolation of high-boiling monomers from the distillation residue formed in the cyclodimerization and cyclotrimerization of 1,3-butadiene after the target products cyclooctadiene, vinylcyclohexene and/or cyclododecatriene have been separated off, which process does not have the abovementioned disadvantages.
It has now surprisingly been found that the high-boiling monomers can be readily extracted from the distillation residue using particular solvents without relatively large amounts of the oligomeric and polymeric components being dissolved at the same time. The insoluble oligomers and polymers can then be separated off predominantly in pulverulent, crystalline and surprisingly readily filterable form. With appropriate selection of the extractant, the extractant can easily be separated from the extracted monomers, preferably by distillation, and the monomers obtained in this way can then be isolated in pure form, preferably by means of vacuum distillation. (As used herein, the term “solvent” or “solvents” is intended to include solvent mixtures.)
The invention accordingly provides a process for the isolation of high boiling monomers from the distillation residue formed in the cyclodimerization and/or cyclotrimerization of 1,3-butadiene and separation of the target products, wherein
the low boilers and solvent are separated off,
the desired target products such as cyclooctadiene or cyclododecatriene are isolated by distillation,
the distillation residue is extracted with a nonpolar or slightly polar solvent or solvent mixture,
insoluble oligomers and polymers (partly) crystallize and are separated off by a mechanical separation operation,
the extractant is removed, and
the high-boiling monomers are isolated.
DETAILED DESCRIPTION OF THE INVENTION
The invention is a process for the isolation of high boiling monomers from the distillation residue formed in the cyclodimerization and/or cyclotrimerization of 1,3-butadiene and separation of the target products, wherein
the low boilers (e.g. unreacted 1,3-butadiene) and solvent are separated off,
the desired target products such as cyclooctadiene or cyclododecatriene are isolated by distillation,
the distillation residue is extracted with a
May Matthias
Oenbrink Georg
Schiffer Thomas
Wilczok Norbert
Degussa - AG
Griffin Walter D.
Nguyen Tam M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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