Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
  • C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
  • C07C45/34—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C49/00—Ketones; Ketenes; Dimeric ketenes; Ketonic chelates
  • C07C49/587—Unsaturated compounds containing a keto groups being part of a ring
  • C07C49/603—Unsaturated compounds containing a keto groups being part of a ring of a six-membered ring
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2601/00—Systems containing only non-condensed rings
  • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
  • C07C2601/16—Systems containing only non-condensed rings with a six-membered ring the ring being unsaturated

Definitions

• This invention relates to an improved process for the preparation of 3, 5, 5-trimethylcyclohex-2-ene-l, -dione (ketoisophorone) by oxidation of 3 , 5, 5-trimethyl-cyclohex- 3-en-l-one ( ⁇ -isophorone) .
• Ketoisophorone is an important intermediate product in the synthesis of trimethylhydroquinone or trimethylhydroquinone esters, which in turn are an intermediate product in the synthesis of vitamin E.
• KIP is furthermore an intermediate product for the preparation of various carotenoids, such as, for example, astaxanthine, zeaxanthine and canthaxanthine.
• oxidation of ⁇ -isophorone to KIP is achieved by tert-butyl hydroperoxide in the presence of 10 mol% palladium acetate and an auxiliary base in yields of a maximum of 55%.
• tert-butyl hydroperoxide makes the process unattractive for an industrial reaction.
• the selectivity of this process can be increased to up to 96% by employing organic amines or alkali metal salts as additives, in addition to catalytic amounts of phospho- or silicomolybdic acid.
• the maximum conversion which can be achieved in this way is only 59%, which necessitates a working up of the product solution which is expensive and not very desirable from economic aspects .
• acetylacetonates of various transition metals can be employed as catalysts of the oxidation of ⁇ -isophorone by molecular oxygen.
• long reaction times of more than 40 h and high temperatures of 100 2 C to 130 S C are necessary, and only unsatisfactory yields of 20% to 40% are obtained.
• no economical process is known for the direct oxidation of ⁇ -isophorone to KIP, since the yield of the reaction by the processes described is low.
• the oxidation of ⁇ -IP which can be obtained from ⁇ -isophorone by known processes, can be carried out considerably more efficiently.
• the most economical variant of this oxidation also is the procedure using oxygen or an oxygen- containing gas as the oxidizing agent.
• the yields in the oxidation reaction catalyzed by transition metal acetylacetonate can be increased to up to 56% by prior isomerization, mediated by sodium acetate, of ⁇ -isophorone to ⁇ -IP, at the same time somewhat lower temperatures of 25 9 C - 75 a C and shorter reaction times of > 26 h being necessary. Nevertheless, these results are still unsatisfactory.
• EP-B 0 311 408 employs Mn tetraphenylporphyrin as the catalyst, in addition to triethylamine as a base and water as an additive. Optimum crude yields of 98% are obtained here using a solvent mixture of ethylene glycol dimethyl ether and methylene chloride. The use of a solvent mixture is not appropriate for an industrial realization both from economic and from safety aspects .
• DE 26 10 254 discloses the oxidation of ⁇ -IP to KIP using manganese (II) - or cobalt-salen or related compounds as the catalyst.
• a selectivity of the reaction catalyzed by manganese-salen of 100% is reported here in one example. Under the conditions described, this corresponds to a space/time yield of 0.09 kilograms of KIP per hour-liter (kg/h*l) .
• hydroxyisophorone Another problem which has so far not been solved satisfactorily is the formation of by-products during the oxidation, in particular hydroxyisophorone, which is formed in an amount of between 5%-20% in the preparation by conventional processes, depending on the reaction procedure. Under optimum conditions, a minimum formation of hydroxyisophorone of 5% (based on the ⁇ -IP employed) can be obtained if manganese-salen is used as the catalyst in the system NEt 3 /water/diglyme. The formation of byproducts in this order of magnitude is not desirable from economic aspects .
• ethers as the solvent for the oxidation reactions moreover involves the risk of formation of highly explosive peroxides already described.
• diglyme is a very expensive solvent, which has an adverse effect on the preparation costs of the process, so that the use of diglyme as the solvent for the reaction investigated is not very desirable from economic aspects.
• the object of the present invention is thus to discover, on the basis of the prior art, a suitable, stable reaction system, in particular solvent, which avoids the disadvantages described for the processes already known, which are in come cases considerable, while retaining or increasing the good selectivities and reaction yields, specifically in the catalyst system manganese-salen / auxiliary base / optionally water / co-additive.
• This invention provides an improved process for the preparation of 3, 5, 5-trimethylcyclohex-2-ene-l, 4-dione (ketoisophorone, KIP) by oxidation of 3, 5, 5-trimethyl- cyclohex-3-en-l-one ( ⁇ -isophorone, ⁇ -IP) in the presence of an oxidizing agent and a catalyst system comprising a transition metal complex catalyst, an auxiliary base, possibly water, and a catalytically active co-additive chosen from the group consisting of:
• Figure 1 depicts diagram showing the KIP yield as a function of the ⁇ -IP concentration.
• Figure 2 depicts diagram showing the KIP yield as a function of the oxygen supplied.
• co-additives are acetic acid, butyric acid, salicylic acid, oxalic acid, malonic acid, citric acid and further aliphatic or aromatic mono-, di- or tricarboxylic acids.
• a ino acids such as e.g. glycine, leucine, methionine or aspartic acid, are also suitable.
• aliphatic alcohols such as methanol, ethanol, butanol, isobutanol and tert-butanol, or phenol serve as the co-additive.
• Co-additives which can form an enol structure such as e. g. acetoacetic esters, phenylacetone and, in particular, acetylacetone, are particularly advantageous.
• Acetylacetone is particularly preferably employed as the co-additive, since it additionally allows higher reaction selectivities to be achieved than with other suitable co-additives .
• a molar ratio of the co-additive to the catalyst of 1:1 to 100:1, preferably 4:1 to 40:1, based on the catalyst, can be employed.
• Suitable carboxylic acid amides in the process according to the invention are dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide or mixtures thereof. Dimethylformamide is particularly preferred as the carboxylic acid amide.
• the amount in which the suitable carboxylic acid amides can be used is not critical for carrying out the process according to the invention, but it is preferable to use carboxylic acid amides in amounts of 50 wt.% to 95 wt.%, preferably 65 wt.% to 85 wt.%, based on the total amount of the reaction mixture.
• the oxygen supply in the carboxylic acid amides even had to increased up to at least about 0.8 liter of oxygen per hour and gram of ⁇ -IP. Not taking account of or not knowing these circumstances thus unavoidably leads to poor results in the reaction procedure in carboxylic acid amides, from which a supposedly lower suitability of carboxylic acid amides as the solvent for the reaction under consideration compared with the ethers and ketones described as having priority has been incorrectly assumed.
• the catalyst system also has a significantly better stability in carboxylic acid amides than in ethers, which allows premixing of the reaction matrix in continuous operation of the process, without a drop in the selectivity of the reaction taking place over a period of time.
• carboxylic acid amides Another great advantage of carboxylic acid amides is that the effect of the catalytically active co-additive described on the educt concentration which can be realized without a serious loss in selectivity is significantly more pronounced than, for example, in diglyme, which results in economic advantages in respect of the space/time yield of the reaction.
• a selectivity of more than 85% is still observed, a value which can be achieved in diglyme only at educt concentrations up to a maximum of 20 wt.%.
• the amount of auxiliary based employed can be reduced down to 10 mol%, based on the ⁇ -IP employed, without serious losses in the selectivity of the reaction which can be achieved occurring.
• carboxylic acid amides as the solvent, in particular inexpensive dimethylformamide, offers an enormous economic advantage over the use of the very expensive ethylene glycol ethers, such as diglyme and ethylene glycol dimethyl ether, which have hitherto been described as the preferred solvents for achieving high selectivities .
• ⁇ -IP is continuously or discontinuously brought into contact with the reaction matrix, which comprises the catalyst and the auxiliary base, as well as a catalytically active co-additive and optionally water and which is dissolved or suspended in a carboxylic acid amide as the solvent, and reacted with oxygen or an oxygen-containing gas mixture under normal pressure or increased pressure.
• Catalysts which are used are the transition metal- containing complex catalysts mentioned in the prior art, such as manganese-salen, manganese-tetraphenylporphyrin and manganese-phthalocyanine, manganese-salen being preferred.
• the catalyst is conventionally added in amounts of 0.001 to 3 wt.%, based on the ⁇ -IP, preferably in amounts of 0.05 to 1 wt.%.
• the organic and inorganic bases known according to the prior art can be used as the auxiliary base, such as e.g.
• alkylamines di- and trialkylamines , aromatic and aliphatic heterocyclic bases, sodium or potassium hydroxide solution or alcoholates, or a quaternary ammonium hydroxide, preferably trialkylamines, in particular triethylamine.
• bases can be employed in conventional amounts, such as e.g. 5 to 60 mol%, based on the ⁇ -IP, amounts of 10 to 35 mol% being particularly preferred.
• Carboxylic acid amides such as e.g. dimethylformamide (DMF) , diethylformamide (DEFA) and the corresponding acetamides, such as dimethylacetamide or diethylacetamide, are employed as the solvent in the process according to the invention.
• the reaction is carried out in dimethylformamide.
• the content of carboxylic acid amide in the reaction mixture is conventionally 50 wt.% to 95 wt.%, and amounts of 65 wt.% to 85 wt.% are preferably employed.
• the water content in the total reaction mixture can vary between 0 and 30 wt.%. Without the addition of water, very high selectivities are achieved, but with uneconomical reaction times .
• Water is therefore preferably employed as a reaction accelerator, in particular between 0.05 wt.% and 30 wt.%, preferably between 0.5 and 20 wt.%, particularly preferably between 0.5 wt.% and 5 wt.%, based on the total weight of the reaction mixture.
• Oxidizing agents which can be employed in this invention are oxygen or oxygen-containing gas mixtures, such as e.g. air or oxygen diluted by addition of an inert gas, such as, for example, nitrogen.
• the reaction can be carried out under normal pressure or increased pressure.
• the reaction can be carried out under between 1 and 12 bar, depending on the volume content of oxygen in the oxidizing agent employed.
• the reaction temperature can be between -30 2 C and 80 2 C, preferably between 10 2 C and 45 2 C.
• the process according to the invention is simple to carry out and gives the reaction product in a good yield and high purity.
• the reaction product can be isolated from the product mixture by the usual processes, in particular by vacuum distillation.
• the yields were determined on an HP 5890 or an HP 6890 gas chromatograph using a J&W DB-5 capillary column of 30 m length, 0.32 mm internal diameter and 1 ⁇ m film thickness. Diethylacetamide was used as the internal standard. KIP, which was purified by distillation, was used as the reference substance.
• the HPLC measurements were carried out on a system comprising a Biotronik BT 3035 UV detector, a Jasco 880 PU pump and a Spectra Physics Chrom Jet integrator.
• the column used was an RP 18, 5 ⁇ , 250 x 4 mm internal diameter.
• the KIP reference substance described above was used as the external standard.
• Examples 23 to 26 illustrate the enormous influence the oxygen supply has on the ketoisophorone selectivity in the solvent DMF which can be achieved. Comparative Examples J to M demonstrate that such an effect is to be observed to only a small extent in the solvent diglyme, which is particularly preferred according to the prior art. Not knowing this sensitivity of the selectivity of the reaction in DMF to a deficient supply of oxygen thus unavoidably leads to poor results (Examples 23 to 24), from which a supposedly lower suitability of carboxylic acid amides as the solvent for the reaction under consideration compared with the ethers and ketones described as having priority in the prior art results .

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• 2002
  • 2002-01-23 CN CNB028274202A patent/CN1267396C/zh not_active Expired - Fee Related
  • 2002-01-23 JP JP2003562068A patent/JP2005526017A/ja active Pending
  • 2002-01-23 KR KR10-2004-7011365A patent/KR20040086284A/ko not_active Application Discontinuation
  • 2002-01-23 MX MXPA04006987A patent/MXPA04006987A/es not_active Application Discontinuation
  • 2002-01-23 EP EP02701264A patent/EP1467961A1/en not_active Withdrawn
  • 2002-01-23 WO PCT/EP2002/000621 patent/WO2003062184A1/en not_active Application Discontinuation
  • 2002-01-23 BR BR0215533-8A patent/BR0215533A/pt not_active Application Discontinuation
  • 2002-01-23 CA CA002473941A patent/CA2473941A1/en not_active Abandoned

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