Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-05-06
2004-12-07
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S875000, C568S885000, C568S909500
Reexamination Certificate
active
06828468
ABSTRACT:
The present invention relates to a process for preparing higher &agr;,&bgr;-unsaturated alcohols by monoethynylation of a ketone by the NH
3
/KOH method, if desired hydrogenation of the acetylene alcohol in the presence of hydrogen over a Pd-containing thin layer catalyst, purifying distillation of the hydrogenation product, preferably in a dividing wall column with recirculation of the unreacted ketone to the ethynylation step, and, if desired, preparation of higher alcohols having in each case 5 more carbon atoms in the chain by reacting the alcohols prepared by monoethynylation and, if desired, partial hydrogenation with alkyl acetoacetatesor diketene in a Carroll reaction to form ketones and using these as starting materials for the steps ethynylation, optional hydrogenation and fractional distillation.
The continuously operated ethynylation of ketones with acetylene in liquid ammonia using catalytic amounts of base (usually KOH or potassium methoxide in a polar, protic solvent; 10-40° C.; 20 bar), e.g. as described in DE 1232573, is prior art.
In general, the NH
3
/KOH process selectively gives the monoacetylene alcohol. The recirculation of the solvent NH
3
and of unreacted acetylene are likewise prior art. They are indispensable for the economics of the step.
The work-up of the reaction mixtures obtained by neutralization with water/CO
2
and subsequent phase separation/drying is likewise conventional prior art.
The continuously operated hydrogenation of alkynes and alkynenes over impregnated thin layer catalysts based on Pd/Ag and the production of these catalysts is described in EP 827 944. As regards hydrogenation using other catalysts or processes, reference may be made to the prior art disclosed in EP 827 944.
A number of process variants are customary for the continuous fractional distillation of multicomponent mixtures. In the simplest case, the feed mixture is separated into 2 fractions, namely a low-boiling fraction taken off at the top and a high-boiling bottom fraction. In the fractionation of feed mixtures to give more than 2 fractions, a plurality of distillation columns have to be used in this process variant. To limit the number of apparatus items required, columns in which liquid or gaseous streams are taken off at side offtakes are used where possible in the fractionation of multicomponent mixtures. However, the ability to employ distillation columns having side offtakes is greatly restricted by the fact that the products taken off at the side offtakes are never completely pure. In the case of streams taken off at side offtakes in the enrichment section, which are usually in liquid form, the side product still contains proportions of low-boiling components which are supposed to be separated off via the top. An analogous situation applies to streams taken off at side offtakes in the stripping section, which are usually gaseous, in which case the side product still contains high-boiling components. The use of conventional side offtake columns is therefore restricted to cases in which contaminated side products are acceptable.
A possible remedy is provided by dividing wall columns. This type of column is described, for example, in U.S. Pat. No. 2,471,134; U.S. Pat. No. 4,230,533; EP 0 122 367; EP 0 126 288 and EP 0 133 510.
In contrast to side offtake columns, dividing wall columns allow side products to be taken off in pure form. In the middle region above and below the feed point and the side offtake, there is a dividing wall which seals the feed section off from the offtake section and prevents crossmixing of liquid and vapor streams in this part of the column. This reduces the total number of distillation columns required in the fractionation of multicomponent mixtures. Since this type of column is a simplification in terms of apparatus of thermally coupled distillation columns, it also has a particularly low energy consumption. A description of thermally coupled distillation columns, which may have a variety of configurations, may likewise be found in the abovementioned literature references. Compared to an assembly of conventional distillation columns, dividing wall columns and thermally coupled columns offer advantages in respect of energy consumption and capital costs and are therefore increasingly being used in industry.
Various regulation strategies have been described for regulating dividing wall columns and thermally coupled columns. Descriptions may be found in U.S. Pat. No. 4,230,533; DE 35 22 234 and EP-780 147.
The preferred variants for carrying out the Carroll reaction are described in EP 1000 922, EP 1008 582 and EP 0983 988.
The essential features of the preparation of unsaturated ketones by reaction of &agr;,&bgr;-unsaturated alcohols with alkyl acetoacetates in the presence of organic aluminum compounds with elimination of the parent alcohol of the acetoacetate are already known. The uncatalyzed reaction between an unsaturated alcohol and an alkyl acetoacetate was described for the first time by M. F. Carroll [J. Chem. Soc. (London) 1940, pp. 704-706]. The range of uses and the mechanism of this reaction were reported in 1941 by the same author [J. Chem. Soc. (London) 1941, pp. 507-511].
A description of a process for preparing 6,10,14-trimethylpentadec-5-en-2-one by transesterification of ethyl acetoacetate with 3,7,11-trimethyldodec-1-en-3-ol in the presence of aluminum trialkoxides may be found in the French patent 1 219 166 (1959). In this process, the reactants and the catalyst are both placed in the reaction vessel and the reaction is carried out batchwise with the alcohol which is liberated being separated by distillation. This gives the desired ketone in a yield of 77% after a reaction time of about 10 hours. Both the relatively long reaction times and the low yields are unsatisfactory for an industrial synthesis.
A number of further patent documents in which different variants of this Carroll reaction are described are known. Thus, U.S. Pat. No. 2,795,617 (1957) or DE-B 1 053 498 (1959) or Swiss patent 342947(1959) states that “although it is generally neither necessary nor desirable, a solvent can be used to temper the exothermic reaction”. According to these patent documents, the aluminum trialkoxide is added to the acetoacetate of the &agr;,&bgr;-unsaturated alcohol and the mixture is refluxed while stirring vigorously, with yields of up to 80% being achieved. The corresponding acetoacetate has to be prepared in a preceding step.
In U.S. Pat. No. 2,839,579 (1958) or DE-C 1078112 (1960), it is reported that the reaction can be carried out in a solvent. The corresponding acetoacetate is prepared in a separate step by condensation of diketene with an appropriate unsaturated alcohol. DE-C 1 068 696 also states that the concomitant use of a solvent might be advantageous.
In all cases, the solvents mentioned are high-boiling solvents whose boiling points are far above the reaction temperature. The yields indicated in these patents are unsatisfactory for industrial use. Even the concomitant use of a high-boiling solvent generally results in no appreciable increases in yield and therefore leads to a reduction in the space-time yields. A considerable disadvantage is that a further process step is necessary for preparing the acetoacetate of the &agr;,&bgr;-unsaturated alcohol, since this is associated with further costs.
A process for preparing 2-methyl-2-hepten-6-one is described in DE-B 2652863 (1978). Here, alkyl acetoacetate, methylbutenol and catalyst are placed in a reaction vessel fitted with a superposed fractionation column and a mixture of alkyl acetoacetate and methylbutenol are subsequently metered in. During the reaction, the alkyl acetoacetate content of the reaction mixture should be no more than 15% by weight in order to avoid secondary reactions. However, a disadvantage of this process is that simple introduction of alkyl acetoacetate into excess methylbutenol is not possible since the boiling point of methylbutenol is far below the reaction temperature. The use of a high-boiling solvent, on th
Ansmann Andreas
Bockstiegel Bernhard
Dobler Walter
Etzrodt Heinz
Henkelmann Jochem
BASF - Aktiengesellschaft
Keil & Weinkauf
Shippen Michael L.
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