Process for producing aldehyde

Details Process for producing aldehyde Process for producing aldehyde

2001-09-18

2003-06-24

Padmanabhan, Sreeni (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S454000, C568S881000

Reexamination Certificate

active

06583324

ABSTRACT:

The present invention relates to a process for producing an aldehyde by reacting hydrogen and carbon monoxide with an olefinic compound in the presence of a rhodium complex catalyst containing an organic phosphite as a ligand. Particularly, the present invention relates to a process for preventing a catalyst activity from lowering in recycle use of the rhodium complex catalyst.
Rhodium is widely known as a catalyst for hydroformylation reaction, and it is also known to those skilled in the art that activity and selectivity of hydroformylation reaction can be improved by modifying the catalyst with a ligand such as a trivalent phosphorus compound. Therefore, the trivalent phosphorus compound to be used as a ligand has been variously studied. Particularly, a hydroformylation catalyst containing an organic phosphite exhibiting high reactivity and selectivity as a ligand has been variously studied in recent years.
For example, JP-A-57-123134 discloses a method for using a triarylphosphite having a substituent at a specified position of a phenyl ring as a ligand. JP-A-59-51228 and JP-A-59-51230 disclose a method for using a cyclic phosphite having a phosphorus atom at a bridgehead as a ligand. JP-A-61-501268 discloses a method for using a diorganophosphite having a cyclic structure as a ligand. JP-A-62-116587 discloses a bidentate phosphite compound wherein one of the two phosphite groups has a cyclic structure, and JP-A-62-116535 discloses a bidentate phosphite compound wherein both of the two phosphite groups have cyclic structures. JP-A-4-290551 discloses a method for using a bisphosphite having a cyclic structure as a ligand. Also, JP-A-5-339207 of the present applicant discloses a method for using a bisphosphite or polyphosphite having a substituent at a specified position as a ligand.
However, when industrially using an organic phosphite as a ligand, it is desired to improve its stability.
That is, since rhodium is very expensive, it is desired to recover a rhodium complex catalyst from a reaction product solution for recycle use in the hydroformylation reaction of an olefinic compound using a rhodium complex catalyst containing an organic phosphite. However, when an aldehyde is distilled out by distilling a reaction product solution and a reaction medium containing a rhodium complex catalyst recovered from the bottom of a distillation column is recycled into a reaction zone as a catalyst solution, in accordance with usual method, the catalytic activity is gradually lowered. It is one of the causes that an organic phosphite constituting the rhodium complex catalyst is decomposed and the decomposed product poisons the catalyst or causes further decomposition of the organic phosphite.
The present inventors have studied the lowering of catalyst activity caused by recycling the rhodium complex catalyst in the hydroformylation reaction, and have discovered that an organic phosphite is decomposed to form an organic phosphonate, which poisons the catalyst and becomes a precursor of a compound accelerating further decomposition of the organic phosphite. It has been discovered that the poisoning of the catalyst by this organic phosphonate is easily caused in a separation step and a recycling step, wherein an aldehyde is taken by distilling a reaction product solution of hydroformylation and a catalyst solution containing a rhodium complex catalyst is recovered and recycled into a reaction zone. That is, in such a hydroformylation reaction zone where large amounts of carbon monoxide and hydrogen are present, the organic phosphonate must compete with them to be coordinated with rhodium, and therefore a degree of poisoning the rhodium complex catalyst is relatively little. However, in the separation and recycling steps, carbon monoxide and hydrogen are not present, and therefore the organic phosphonate is easily coordinated with rhodium to lower the catalyst activity.
The present inventors have studied a method for preventing the rhodium complex catalyst from poisoning by the organic phosphonate in the separation and recycling steps, and have discovered that the poisoning of the catalyst can be reduced by separating an aldehyde so as to have the aldehyde remained in the catalyst solution in the separation step. It is considered that the aldehyde in the catalyst solution reacts with the organic phosphonate to convert the organic phosphonate into a compound less poisoning the catalyst.
The present invention has been accomplished on the basis of the above-mentioned discoveries, and according to the present invention, the degradation of the catalyst activity can be prevented by a process for producing an aldehyde, which comprises a reaction step of producing an aldehyde by reacting an olefinic compound with carbon monoxide and hydrogen in the presence of a rhodium complex catalyst comprising at least rhodium and an organic phosphite in a reaction zone, a separation step of obtaining a catalyst solution containing the rhodium complex catalyst by separating the aldehyde from a reaction solution taken from the reaction zone, and a recycling step of recycling the catalyst solution into the reaction zone, wherein the aldehyde is separated from the reaction solution in such a manner as to make an aldehyde concentration at least 0.5 wt %, preferably from 0.5 to 99 wt %, in the catalyst solution.
The present invention is described further in more details hereinafter. The hydroformylation reaction of the present invention can be carried out in accordance with a usual hydroformylation reaction method using a rhodium complex catalyst having an organic phosphite as a ligand.
The rhodium complex catalyst used in the reaction can be prepared in accordance with a well known method of preparing a rhodium-organic phosphite complex catalyst. The rhodium complex catalyst may be previously prepared to be used in the reaction, or may be prepared from a rhodium compound and an organic phosphite in the reaction system. Examples of the rhodium compound used for preparing the catalyst include an inorganic or organic salt of rhodium such as rhodium chloride, rhodium nitrate, rhodium acetate, rhodium formate, sodium chlororhodate, potassium chlororhodate or the like, rhodium metal carried on a carrier such as alumina, silica, activated carbon or the like, a rhodium chelate compound such as rhodium dicarbonyl acetylacetonate, rhodium (1,5-cyclooctadiene)acetylacetonate or the like, and a rhodium carbonyl complex compound such as tetrarhodium dodecacarbonyl, hexarhodium hexadecacarbonyl, &mgr;, &mgr;′-dichlororhodium tetracarbonyl, [Rh(OAc)(COD)]
2
(COD represents 1,5-cyclooctadiene), [Rh(&mgr;-S-t-Bu)(CO)
2
]
2
, or the like.
Examples of the organic phosphite as a ligand include an organic phosphite such as a triarylphosphite, a trialkylphosphite, an alkylarylphosphite or the like. Also, a polyphosphite having a plurality of phosphite structures in the same molecule, such as a bisphosphite, a trisphosphite or the like, can be used.
Among these organic phosphites, a monophosphite can be classified into a compound having a cyclic structure containing a phosphorus atom and a compound not having such a structure. The former monophosphite is expressed by the following formula (1),
P(OR
1
)(OR
2
)(OR
3
)  (1)
wherein R
1
to R
3
are respectively independently a C
1
-C
30
hydrocarbon group such as an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or the like (or a C
5
-C
30
heteroaromatic hydrocarbon group), and they may have a substituent which will not inhibit hydroformylation reaction. Examples of these substituents include a halogen atom, a C
1
-C
20
alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, an alkylamino group, an acyl group, an acyloxy group, an alkoxycarbonyl group, and the like.
Among these organic phosphites expressed by the formula (1), at least one of R
1
to R
3
is preferably a substituted aryl group expressed by the following formula (2),
wherein R
4
is an aryl group which may have a substituent that will not inhibit hydroformyl

Affiliated with

Also associated with

Rating

Process for producing aldehyde does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing aldehyde, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing aldehyde will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3107253