Catalyst and process for the production of aldehydes by...

Details Catalyst and process for the production of aldehydes by... Catalyst and process for the production of aldehydes by...

1999-07-01

2001-02-20

Padmanabhan, Sreeni (Department: 1621)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Organic compound containing

C502S213000, C556S021000, C556S136000, C568S451000, C568S454000

Reexamination Certificate

active

06191063

ABSTRACT:

The invention relates to a novel catalyst and to a process for the hydroformylation of olefinically unsaturated compounds, whose hydroformylation products are insoluble or virtually insoluble in water, in the presence of this catalyst.
It is known that by reacting olefins with carbon monoxide and hydrogen (hydroformylation), it is possible to prepare aldehydes and alcohols which contain one more carbon atom than the starting olefin. The reaction is catalyzed by hydridometal carbonyls, preferably those of the metals of group VIII of the Periodic Table. Besides cobalt, the classic catalyst metal, catalysts based on rhodium have been increasingly used for some years. In contrast to cobalt, rhodium allows the reaction to be carried out at low pressure, and moreover when terminal olefins are used, straight-chain n-aldehydes are formed preferentially and isoaldehydes are formed only to a subordinate degree. Finally, the hydrogenation of olefinic compounds to give saturated hydrocarbons in the presence of rhodium catalysts is also significantly lower than when cobalt catalysts are used.
In industry, the hydroformylation of olefinically unsaturated compounds using the catalytic effect of rhodium-phosphine complex compounds is essentially carried out in two variants. The first involves the process being carried out in homogeneous phase, i.e. starting olefin, catalyst system (rhodium carbonyl and organic phosphine) and reaction products are present in solution together. The reaction products are separated off from the mixture by distillation. The other variant is characterized by the presence of an aqueous catalyst phase, separate from the reaction product, which comprises rhodium carbonyl complexes and a sulfonated or carboxylated organic phosphine. This variant permits isolation of the hydroformylation products without use of thermal process steps, simplifies catalyst recovery and produces a particularly high proportion of unbranched aldehydes when terminal olefins are used.
Both of these processes are frequently described in the literature, for example in W. A. Herrmann, C. W. Kohlpaintner, Angew. Chem. 1993,105, p. 1588 and also in DE-C-26 27 354 and EP-B-0 103 810.
In the processes which have been implemented in industry, the rhodium catalyst is used in the form of hydridorhodium carbonyls which contain additional ligands, in particular tertiary organic phosphines or phosphites. In most cases, the ligands are present in excess relative to the metal atom, so that the catalyst system consists of complex compounds and a free ligand. Use of the rhodium catalysts described makes it possible to carry out the hydroformylation reaction at pressures below 300 bar.
The different way in which the reaction is carried out affects inter alia the extent of conversion of starting materials and the formation of by-products. In general, the process in the two-phase reaction medium gives better conversions at higher selectivity than the homogeneous (single-phase) process. An advantage of the reaction in the system with separate catalyst phase is the trouble-free removal of the catalyst. It can be removed by simple separation of aqueous and organic phases, i.e. without distillation and thus without thermal process steps. On the other hand, in single-phase homogeneous catalyzed processes, the reaction product has to be distilled off from the catalyst, or the catalyst has to be separated off from the crude product by another method. Due to the thermal sensitivity of the reaction products, distillation is frequently associated with losses in yield. Other process variants, such as, for example, precipitation or membrane separation of the catalyst are industrially complex and thus disadvantageous.
The two-phase hydroformylation process has proven successful for the hydroformylation of propene and 1-butene (from butene mixtures, e.g. raffinate 2) on an industrial production scale. It is known as the Ruhrchemie/Rhône-Poulenc process. The catalyst system used is a hydridorhodium carbonyl complex which is modified and stabilized by the water-soluble ligands TPPTS (triphenylphosphine trisulfonate sodium salt).
The TPPTS ligand, which is water-soluble by virtue of the sulfonato groups, has the function of solubilizing the rhodium complex in the water phase and of preventing loss of the rhodium complex into the organic phase. The chemical reaction, i.e. the complex-catalyzed addition of a hydrogen and a carbon monoxide molecule to the double bond takes place, according to current understanding, either in the aqueous catalyst phase or in the phase interface. The product formed can pass into the organic phase by adjusting the phase equilibrium.
For the hydroformylation of higher olefins, i.e. olefins having more than 6 carbon atoms, the Ruhrchemie/Rhône-Poulenc process is unsuitable since only very low space-time yields are obtained. The decrease in the rate of the reaction during the two-phase hydroformylation of olefins, which is observed with increasing carbon number, is generally attributed to the poorer solubility of the higher olefins in the water phase. Since the two-phase hydroformylation process has both the advantage of relatively mild reaction conditions, as well as permitting simple separation of the product phase from the catalyst phase, there is an industrial interest in also hydroformylating higher olefins by this process.
The hydroformylation products of higher olefins are mostly used as intermediates for the preparation of higher alcohols and, to a lesser extent, for the preparation of medium- to long-chain carboxylic acids by oxidation, or for the synthesis of amines by reductive amination of aldehydes. Moreover, straight-chain aldehydes having seven or more carbon atoms are used in the fragrance industry as such or in the form of their acetals for perfumes or for perfuming soaps. Linear and branched alcohols having from 8 to 12 carbon atoms are used industrially on a large scale as plasticizer alcohols, which are in most cases used in the form of their bisphthalates or bismaleates as plasticizers for plasticized PVC. Other fields of application for higher, largely linear alcohols are components for detergents, coating base materials and enameling base materials (Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Vol. 7, publisher Chemie Weinheim 1974, p. 118-141). Catalysts for the hydroformylation are also known from J. prakt. Chem. 338 (1996), 124-128.
The object was to develop a process which permits higher molecular weight olefinically unsaturated compounds to be hydroformylated with the highest possible activity and selectivity to give the corresponding aldehydes. Moreover, it should be possible to readily separate reaction product and catalyst system from one another, and noble metal losses should be largely avoided.
This object is achieved by a catalyst comprising rhodium and a compound of the formula (I)
in which
m is a number from 1 to 1000, preferably from 2 to 300, particularly preferably from 2 to 100;
x is a number from 0 to 4, preferably 0 or 1;
W is a group of the formulae —CH
2
—CH
2
—, —CH(CH
3
)CH
2
— or —CH
2
CH(CH
3
)—;
R is hydrogen, a straight-chain or branched C
1
-C
5
-alkyl radical; or a group of the formulae
where
a, b, c, d and e independently of one another are a number from 0 to 1000, at least one of the numbers a, b, c, d and e being greater than 0;
R
5
, R
6
, R
7
, R
8
and R
9
are identical or different and are hydrogen, C
1
-C
5
-alkyl or a group of the formula
R
1
and R
2
are identical or different and are a straight-chain, branched or cyclic C
1
-C
30
-alkyl radical or C
6
-C
10
-aryl radical, which is unsubstituted or substituted by from one to five C
1
-C
3
-alkyl radicals, or R
1
and R
2
together with the trivalent P atom form a dibenzophospholyl of the formula
or a 3,4-dimethyiphospholyl of the formula
and
L is C
1
-C
5
-alkyl, C
1
-C5-alkoxy, NO
2
, NR
3
R
4
, where R
3
and R
4
independently of one another are hydrogen or C
1
-C
4
-alkyl, or L is Cl or OH.
The alkylene glycol groups on the phenyl ring can be in the ortho, meta o

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