Abstract:
An improved method of producing 3,5,5-trimethylcyclohex-2-ene-1,4-dione (KIP) by the oxidation of 3,5,5-trimethylcyclohex-3-ene-1-one (β-IP) in the presence of managansalene-like catalysts and certain catalytic additives. ##STR1## KIP is an important intermediary product in the synthesis of trimethylhydroquinone, an initial substance in the synthesis of vitamin E. Furthermore, KIP is an initial compound for the synthesis of various carotinoids.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on application no. DE 19619570.5 filed in Germany on May 15, 1996, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an improved method of producing 3,5,5-trimethylcyclohex-2-ene-1,4-dione (KIP) by the oxidation of 3,5,5-trimethylcyclohex-3-ene-1-one(β-IP) in the presence of mangansalene-like catalysts and certain catalytic additives. ##STR2## 
     2. Background Information 
     KIP is an important intermediary product in the synthesis of trimethylhydroquinone, an initial substance in the synthesis of vitamin E. Furthermore, KIP is an initial compound for the synthesis of various carotinoids. ##STR3## State of the art 
     It is known that β-IP can be oxidized to KIP by molecular oxygen in the presence of a transition-metal-containing catalyst (DE-OS 24 57 157, DE-OS 38 42 547). The use of mangansalene is described in DE-OS 26 19 254. 
     The space-time yield (product in kg per hour and reaction volume in liters) as well as the amount of catalyst necessary for this are of decisive importance to the economy of a catalytic process. Of the above-mentioned methods for the synthesis of ketoisophorone, the reaction of β-IP with O 2  in the presence of mangansalene complexes of the composition shown above has the best selectivities and space-time yields. 
     DE-OS 26 10 254 reports in example 11 about a selectivity of homogeneous catalytic oxidation of 100%. A space-time yield (RZA) of 0.09 kg/(hr·1) can be calculated from the data contained in it. Even these not very convincing values were no longer mentioned in a scientific publication by the same authors (M. Constantini, A. Dromard, M. Jouffret, B. Brossard, J. Varagnat, J. Mol. Catal 1980, 7, 89-97) a few years after the public disclosure of the application. A maximal KIP selectivity of only 85% is disclosed therein, which is achieved with mangansalene as oxidation catalyst. The influence of the educt concentration on the selectivity had not been investigated previously. The problems which can occur upon an increased educt concentration (here &gt;90%) (selectivity 55%, RZA: 0.08 kg/hr·1 (20°-23° C., O 2  =1 bar)) can be read only from example 17 of DE-OS 26 10 254. 
     A disadvantage in these methods is the large amount of solvent which must be used in order to assure a high selectivity. 
     JP-OS 64-90150 teaches a similar method in which, however, the Mn is used in oxidation stage III in the mangansalene. 
     JP-OS 1-175955 possibly aims in the same direction since, according to the method it describes, the manganese complex is oxidized with tert. alkylhydroperoxides before its usage as catalyst. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a method with good selectivity at a rather high concentration of β-IP. This simplifies carrying out the reaction and purifying the product KIP, thereby providing a method with increased economy. 
     The invention provides a method of producing 3,5,5-trimethylcyclohex-2-ene-1,4-dione (KIP) by the oxidation of 3,5,5-trimethylcyclohex-3-ene-1-one (β-IP) with molecular oxygen in the presence of mangansalene or its derivatives as catalyst, an organic base and water. The method is characterized in that a further, catalytically active compound X is added. X is selected from the group of the following compounds: 
     1. An organic acid with a pKa value between 2 and 7 or a corresponding aldehyde; 
     2. An aliphatic alcohol with C 1  -C 4  atoms or phenol; 
     3. Compounds which can form an enol structure; 
     4. Lithium sulfate. 
     Compound X is added in a molar ratio between about 1:1 to about 100:1 to the catalyst, and the amount of β-IP is at least 15% relative to the total amount of the mixture. 
     At these relatively low concentrations of β-IP the reaction mixture additionally contains inert organic solvents. 
     β-IP is contained in the reaction mixture in an amount &gt;15% by weight, preferably up to 40% by weight. 
     The reaction is generally carried out at 0° to 50° C. in the presence of the manganese-containing catalyst used in accordance with the invention (0.001 to 2% by weight relative to β-IP, preferably 0.05 to 1.0% by weight). 
     Water is present in an amount of 0.05 to 30% by weight relative to the total amount of the reaction mixture and the reaction is generally allowed to take place in an inert solvent in the presence of an organic, basically acting compound, especially one from the group of alkylamines, trialkylamines with C 1  to C 4  alkyl groups, including, with particular preference, triethylamine, tert. amines or 1,4-diazabicyclo 2,2,2!octane. 
     It is especially advantageous to add weak, organic acids and/or bidentately complexing compounds to the reaction mixture. Acetic acid, butyric acid, salicylic acid, oxalic acid, malonic acid, citric acid and other aliphatic or aromatic mono-, di- or tricarboxylic acids are especially preferable. Amino acids such as, for example, glycine, leucine, methionine or asparaginic acid are also suitable. 
     Aliphatic alcohols such as methanol, ethanol, butanol, isobutanol and tert-butanol or phenol also function as catalytic, selectivity-increasing additives. Compounds which can form an enol structure such as, for example, ethyl acetoacetate, phenyl acetone and especially acetyl acetone (FIG. 1) are especially advantageous. The molar ratio of catalyst:X is between 1:1 and 1:100. Even the addition of different buffer systems (buffer action between pH 6 and 9) to the water added shows a selectivity-increasing action. In addition to increasing of selectivity, a dramatic increase in the turnover number (mole product per mole catalyst) is achieved. The following inert solvents have proven to be especially advantageous: aliphatic ketones, such as acetone or methylisobutylketone, aliphatic ethers, such as ethylether diethylene glycol dimethylether and ethylene glycol dimethylether. 
     The production of KIP in accordance with the invention has considerable advantages over methods of the prior art: 
     The selectivity of the oxidation of β-isophorone at β-isophorone concentrations greater than 15% by weight is influenced by the addition of the catalytically active compound added in accordance with the invention. Yields of up to 85% are achieved at an educt concentration of 35% by weight. If β-IP is used as solvent the yield can be increased to over 72%, an increase of 17 percentage points compared to the traditional technique. This is a significant advantage in the workup of the accumulating reaction solutions. 
     The catalytic amounts required can be reduced even at very high concentrations of β-IP to amounts below 0.1% relative to β-IP. Without the addition of X, super-proportionally increasing catalytic amounts are necessary with increasing amounts of β-IP to achieve a complete reaction. 
     The space-time yield rises up to 0.5 kg/(hr·1), representing a considerable economic advantage of the reaction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1. Influence of acetylacetone (acacH) on selectivity. Conditions:  β-IP!/ mangansalene!=280;  acacH!/ cat!=30;  NEt 3  !=0.30 mol/l;  water!=0.90 mol/l; solvent: Diglyme; temperature: 20° C.; oxidizing agent oxygen (1 bar). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     EXAMPLES 
     The invention is described further in the following using exemplary embodiments. 
     
                       TABLE 1______________________________________Influence of various additives on selectivity and reaction rate           Selectivity                     Reaction rate           re        accd. to  after!                               RZA up to 80           β-   kinetics 1.sup.st order                               % conversionNo.  Additive   isophorone                     in min.sup.-1 × 10.sup.-2                                kg/(hr · l)!______________________________________1    without    84%       2.5       0.162    acetaldehyde           85%       3.5       0.223    acetylacetone           92%       4.4       0.284    benzoic acid           87%       4.3       0.275    acetic acid           85%       5.3       0.346    ethylene glycol           89%       2.4       0.157    glucose    78%       1.8       0.128    lithium sulfate           83%       5         0.329    nicotinic acid           73%       0.6       0.0410   salicylaldehyde           85%       4.5       0.29______________________________________ 
    
     Reaction conditions: 
     Solvent: Diglyme; base: NEt 3  ;  β-IP!=1.40 mol/l;  NEt 3  !=0.31 mol/l;  mangansalene!=1.20 mmol/l);  H 2  O!=0.83 mol/l;  additive!=20 mmol/l; T=35° C.; p(O 2 )=1.0 bar 
     
                       TABLE 2______________________________________Comparison of the selectivity at rising β-IP concentrationwith and without addition of acetylacetone                                  selectivity            β-IP! in                     cat! in                            X! in re β-No.  Additive   (mol/l)  (mmol/l)                           (mmol/l)                                  isophorone______________________________________11   acetylacetone           0.54     3.79   113    91%12   without    0.55     3.87    0     90%13   acetylacetone           1.09     3.80   112    91%14   without    1.10     4.38    0     76%15   acetylacetone           1.63     5.83   168    83%16   without    1.65     5.83    0     67%17   acetylacetone           2.13     7.90   226    73%18   without    2.22     8.10    0     48%19   acetylacetone           2.70     9.59   279    69%20   without    2.78     9.84    0     53%21   acetylacetone           4.03     14.47  417    65%22   without    4.03     14.46   0     53%23   acetylacetone           5.86     20.93  606    60%24   without    6.28     20.86   0     50%______________________________________ 
    
     Reaction conditions: 
     Solvent: Diglyme; base: NEt 3  ;  NEt 3  !=0.31 mol/l;  mangansalene!=1.20 mmol/l;  H 2  O!=0.88 mol/l; T=35° C. p(O 2 )=1.0 bar; conversion of β-isophorone is 100% in all examples 
     
                       TABLE 3______________________________________Examples for the solvent-free oxidation of β-isophoronein the presence of acetylacetone (AcacH)                                     selectivity β-IP!       base!                        AcacH!       re β-in       cat! in in    in      H.sub.2 O! in                                     iso-No.  (mol/l) (mmol/l) (mol/l)                       (mmol/l)                              (mmol/l)                                     phorone______________________________________25   6.20    11.49    0.29  97     1.08   74%26   6.37    5.84     0.29  20     0.00   72%27   6.25    5.73     0.28  19     1.07   70%28   6.07    11.25    0.47  38     1.06   69%29   6.36    11.78    0.29  40     0.00   66%______________________________________ 
    
     Reaction conditions: 
     Base: NEt 3  ; T=20° C.; p(O 2 )=1.0 bar; conversion β-isophorone in all examples 100% 
     
                                           TABLE 4__________________________________________________________________________Examples for increasing the selectivity with low β-IPconcentration in various solvents (base: NEt.sub.3)    β-IP!             base!       T  p(O.sub.2)                               Selectivity   in  c cat! in            in   X! in   in in re β-No.   Solvent   (mol/l)       (mmol/l)            (mol/l)                (mmol/l)                      H.sub.2 O!                         (°C.)                            (bar)                               isophorone__________________________________________________________________________30 DEGDME   1.85       3.3  0.26                0.00 0.75                         20 1.0                               85%31 DEGDME   1.84       3.4  0.26                93   0.74                         20 1.0                               87%32 MIBK 0.60       2.2  0.34                0.00 0.83                         23 1.0                               85%33 MIBK 0.60       2.1  0.33                58.83                     0.93                         23 1.0                               87%34 DME  0.60       2.2  0.33                0.00 0.94                         23 0.2                               87%35 DME  0.60       2.1  0.33                58.83                     0.93                         23 0.2                               91%__________________________________________________________________________ 
    
     
                       TABLE 5______________________________________Influence of increasing carboxylic acid concentration onthe reaction selectivity Acetate conc.            Formate conc.                        Acid in diglyme in diglyme  equivalent                               Selectivity reNo.   used (mg/kg)            used (mg/kg)                        (mmol/l                               β-isophorone______________________________________36      0        0           0.0    91%37     660       51.5        4.5    91%38     730       200         6.1    87%39    1504       0           9.3    85%40    1530       316         12.0   84%41    2252       383         16.9   83%42    4640       562         33.1   80%______________________________________ 
    
     Reaction conditions: 
     Solvent: Diglyme; base: NEt 3  ;  NEt 3  !=0.30 mol/l;  β-IP!=1.35 mol/l;  mangansalene!=1.25 mmol/l;  H 2  O!=0.83 mol/l; T=20° C.; p(O 2 )=1.0 bar. 
     
                       TABLE 6______________________________________Influence of various additives on selectivity and reaction rate           Selectivity                      Reaction rate                                RZA           re         accd. to kinetics                                up to 80%           β-    1.sup.st order in                                conversionNo.  Additive   isophorone min.sup.-1 × 10.sup.-2                                 kg/(hr · 1)!______________________________________1    without    84%        2.5       0.162    acetaldehyde           85%        3.5       0.223    acetylacetone           92%        4.4       0.284    benzoic acid           87%        4.3       0.275    acetic acid           85%        5.3       0.346    ethylene glycol           89%        2.4       0.157    glucose    78%        1.8       0.128    lithium sulfate           83%        5         0.329    nicotinic acid           73%        0.6       0.0410   salicylaldehyde           85%        4.5       0.29______________________________________ 
    
     Reaction conditions: 
     Solvent: Diglyme; base: NEt 3  ;  β-IP!=1.40 mol/l;  NEt 3  !=0.31 mol/l;  mangansalene!=1.20 mmol/l);  H 2  O!=0.83 mol/l;  additive!=20 mmol/l; T=35° C.; p (O 2 )=1.0 bar 
     
                       TABLE 7______________________________________Comparison of the selectivity at rising β-IP concentrationwith and without addition of acetylacetone                                  selectivity            β-IP! in                     cat! in                            X! in re β-No.  Additive   (mol/l)  (mmol/l)                           (mmol/l)                                  isophorone______________________________________11   acetylacetone           0.54     3.79   113    91%12   without    0.55     3.87    0     90%13   acetylacetone           1.09     3.80   112    91%14   without    1.10     4.38    0     76%15   acetylacetone           1.63     5.83   168    83%16   without    1.65     5.83    0     67%17   acetylacetone           2.13     7.90   226    73%18   without    2.22     8.10    0     48%19   acetylacetone           2.70     9.59   279    69%20   without    2.78     9.84    0     53%21   acetylacetone           4.03     14.47  417    65%22   without    4.03     14.46   0     53%23   acetylacetone           5.86     20.93  606    60%24   without    6.28     20.86   0     50%______________________________________ 
    
     Reaction conditions: 
     Solvent: Diglyme; base: NEt 3  ;  NEt 3  !=0.31 mol/l;  mangansalene!=1.20 mmol/l;  H 2  O!=0.88 mol/l; T=35° C.; p(O 2 )=1.0 bar; conversion of β-isophorone is 100% in all examples 
     
                       TABLE 8______________________________________Examples for the solvent-free oxidation of β-isophorone inthe presence of acetylacetone (AcacH)                                     selectivity β-IP!       base!                        AcacH!       re β-in       cat! in in    in      H.sub.2 O! in                                     iso-No.  (mol/l) (mmol/l) (mol/l)                       (mmol/l)                              (mmol/l)                                     phorone______________________________________25   6.20    11.49    0.29  97     1.08   74%26   6.37    5.84     0.29  20     0.00   72%27   6.25    5.73     0.28  19     1.07   70%28   6.07    11.25    0.47  38     1.06   69%29   6.36    11.78    0.29  40     0.00   66%______________________________________ 
    
     Reaction conditions: 
     Base: NEt 3  ; T=20° C.; p(O 2 )=1.0 bar; conversion β-isophorone in all examples 100% 
     
                                           TABLE 9__________________________________________________________________________Examples for increasing the selectivity with low β-IPconcentration in various solvents (base: NEt.sub.3)    β-IP!             base!       T  p(O.sub.2)                               Selectivity   in  c cat! in            in   X! in   in in re β-No.   Solvent   (mol/l)       (mmol/l)            (mol/l)                (mmol/l)                      H.sub.2 O!                         (°C.)                            (bar)                               isophorone__________________________________________________________________________30 DEGDME   1.85       3.3  0.26                0.00 0.75                         20 1.0                               85%31 DEGDME   1.84       3.4  0.26                93   0.74                         20 1.0                               87%32 MIBK 0.60       2.2  0.34                0.00 0.83                         23 1.0                               85%33 MIBK 0.60       2.1  0.33                58.83                     0.93                         23 1.0                               87%34 DME  0.60       2.2  0.33                0.00 0.94                         23 0.2                               87%35 DME  0.60       2.1  0.33                58.83                     0.93                         23 0.2                               91%__________________________________________________________________________ 
    
     
                       TABLE 10______________________________________Influence of increasing carboxylic acid concentration onthe reaction selectivity Acetate conc.            Formate conc.                        Acid in diglyme in diglyme  equivalent                               Selectivity reNo.   used (mg/kg)            used (mg/kg)                        (mmol/l                               β-isophorone______________________________________36      0        0           0.0    91%37     660       51.5        4.5    91%38     730       200         6.1    87%39    1504       0           9.3    85%40    1530       316         12.0   84%41    2252       383         16.9   83%42    4640       562         33.1   80%______________________________________ 
    
     Reaction conditions: 
     Solvent: Diglyme; base: NEt 3  ;  NEt 3  !=0.30 mol/l;  β-IP!=1.35 mol/l;  mangasalene!=1.25 mmol/l;  H 2  O!=0.83 mol/l; T=20° C.; p(O 2 )=1.0 bar. 
     References and patents cited herein are hereby incorporated by reference.