Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
1999-08-26
2001-01-16
Killos, Paul J. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S130000
Reexamination Certificate
active
06175036
ABSTRACT:
The invention relates to a process for the preparation of an alkyl pentenoate respectively an aryl pentenoate by contacting an alkoxy-butene respectively an aryloxy-butene with carbon monoxide in the presence of a catalyst system comprising palladium, a phosphorus ligand and an acid promotor.
Such a process is described for the preparation of an alkyl pentenoate ester in WO-A-9629300. This patent application describes the carbonylation reaction of a mixture of 3-methoxy-1-butene and 1-methoxy-2-butene in a molar ratio of 1.1 with carbon monoxide in the presence of a catalyst system comprising a palladium compound, a phosphine ligand and an acid promotor. The yield reported to methyl pentenoate was 63% after 5 hours, using a catalyst system consisting of PdCl
2
, diphenylphosphinopyridine and para-toluene sulphonic acid.
A disadvantage of this process is that the rate of the carbonylation reaction is relatively low. Furthermore the yield to the pentenoate compound needs to be improved in order to make this process more attractive for commercial use on a large scale.
The object of this invention is to provide a process for the preparation of a pentenoate compound starting from alkoxy butene or aryloxy butene, in which the rate of the reaction and the selectivity to the pentenoate compound are improved.
This object is achieved in that the molar ratio of 3-alkoxy-1-butene to 1-alkoxy-2-butene, respectively the molar ratio of 3-aryloxy-1-butene to 1-aryloxy-2-butene, is higher than 4.
It was found that the rate of the reaction of the process according to the invention is significantly higher than the rate of the reaction disclosed in WO-A-9629300. Furthermore the selectivity to the 3-pentenoate compound is significantly improved. Another advantage is that the process can be performed at a lower temperature, because of the higher rate of reaction. High temperatures result in degradation of the phosphine ligand. Consequently the rate of consumption of the phosphine ligand per kg of pentenoic acid derivative is lower when using the process according to the invention at lower temperatures.
A further advantage is that these improved results can be achieved in a process in which no or only a slight amount of halogen compounds are present. Furthermore the process according to the invention does not have to make use of the strong acids as disclosed in WO-A-9629300. Good results can be achieved using weak acids. The fact that the process can be performed in the absence of halogens and/or strong acids can be regarded as a major advantage.
Another advantage is that the selectivity to the 2-pentenoic acid derivative isomer is lower than when the state of the art process is used. This is, for example, advantageous when the mixture of isomers is used as starting compound in the hydroformylation reaction to 5-formylvalerate starting from mixture of isomers of pentenoate esters. The 2-pentenoate ester result in undesirable side reactions in the hydroformylation and lowering the amount of 2-pentenoate ester results in a lower by-product formation in the hydroformylation. This is for example illustrated in WO-A-9506027.
The alkoxy and aryloxy group may be a C
1
-C
20
alkoxy and a C
6
-C
20
aryloxy group respectively. These groups may be substituted. The alkoxybutenes and aryloxybutenes can be presented by the following formula's:
in which R is preferably an aliphatic, cyclo-aliphatic or aromatic group. Examples of possible RO-groups having an aromatic group R
1
are phenyl, cresyl, xylenyl or naphthyl. Most preferred is phenyl. Preferably alkyl pentenoates are prepared by the process according to the invention, wherein R is an alkyl group having 1-20 carbon atoms. Examples of possible alkyl groups are methyl, ethyl, isopropyl, n-propyl, n-butyl, octyl, 2-ethylhexyl, 2-propylheptyl, iso-nonyl, decyl or benzyl. Most preferably methyl or ethyl are used because the resulting methyl or ethyl pentenoate can be easily handled, because of their low boiling point. Furthermore these compounds can be advantageously used as precursors in other processes, e.g. to prepare E-caprolactam or adipic acid as described in for example WO-A-9519331 or EP-A-662467.
It was found to be essential to perform the process of the present invention at the claimed ratio of butene-1-derivative relative to butene-2-derivative. In this manner higher reaction rates are achieved. Preferably the amount of butene-1-derivative relative to the total amount of butene derivatives in the starting composition is higher than 80% and more preferably higher than 95%. Lower consumption of catalyst system per kg product is observed when performing the process according to the invention within these ranges.
The reaction is performed using a catalyst system comprising palladium, a phosphorus ligand and an acid promotor.
The phosphorus ligand can be the ligands as described in WO-A-9629300, which patent application is hereby incorporated by reference. Preferably the ligand is a monodentate or multidentate phosphine ligand. The monodentate phosphine ligand can be described by the following general formula:
wherein R
1
, R
2
and R
3
each individually represent an optionally substituted organic group. This organic group can be a C
1
-C
20
alkyl group, a C
6
-C
18
aryl group or a cyclic group with 4-12 carbon atoms in which the ring of the cyclic group also contains one or more heteroatoms, for example nitrogen. Alkyl groups include, among others, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl or cyclooctyl. Exemplary cyclic groups containing heteroatoms include, among others, 6-methyl-2-pyridyl and 4,6-dimethyl-2-pyridyl.
Aryl groups include, for example, naphthyl, phenyl, benzyl, cumenyl, mesityl, tolyl and xylyl. The organic group can be substituted, for example, with halogen atoms, for example Cl, Br or F, or with C
1
-C
6
alkyl, C
6
-C
18
aryl, C
1
-C
6
alkoxy, carboxy, carbalkoxy, acyl, trihalogenmethyl, cyano, dialkylamino, sulphonylalkyl or alkanoyloxy groups. Substituents can be groups with electron withdrawing or electron donating properties.
Monodentate phosphine ligands include, for instance, tri-p-tolylphosphine, tri-p-methoxyphenyl-phosphine, diphenylpentylphosphine or dimethylphenyl-phosphine. Preferably triphenylphosphine is used because this compound is readily available.
Preferaly multidentate phosphine ligands are used, represented by the following general formula (4):
wherein n is 2-6, W is a multivalent (valency equals n) organic bridging group with 2 to 40 carbon atoms and R
4
and R
5
each individually represent an optionally substituted organic group. By preference, n is 2 in formula (4). Organic groups for R
4
and R
5
can be the same as described above for R
1
, R
2
and R
3
. Furthermore R
1
and R
2
can form one divalent organic group, for example a diaryl group or a C
2
-C
20
alkenyl group. An exemplary alkenyl group is butenyl. Examples of diaryl groups include diphenyl and dinaphthyl groups. The substituents for the organic groups in formula (4) can be the same as described above for the monodentate phosphine ligands.
Preferably the multidentate phosphine ligand is a bidentate phosphine ligand (n=2) according to formula (5).
in which R
6
and R
7
can be the same as described above for R
4
and R
5
. Preferably one or more of groups R
4
, R
5
, R
6
and/or R
7
are aliphatic groups. Examples of possible aliphatic and aryl groups are described above for R
1
, R
2
, R
3
, R
4
and R
5
.
Divalent organic bridging groups include C
2
-C
10
alkylidene groups, for example ethylene, trimethylene, tetramethylene, pentamethylene or trans-1, 2-cyclobutene; and C
6
-C
20
divalent arylgroups such as, for example, dinapthyl or diphenyl. Preferably the number of carbon atoms in the shortest chain connecting the phosphorus atoms is three or four. In this chain one non-terminal hetero atom may be present, for example oxygen or sulphur. A class of divalent bridging group W having 4 carbon atoms in the shortest chain connecting the two phosphorus atoms is illustrated by formula (6)
in which X is
Burke Patrick M
Oevering Henk
Sielcken Otto E
DSM N.V.
Killos Paul J.
Pillsbury Madison & Sutro Intellectual Property Group
LandOfFree
Process to prepare a pentenoic acid derivative 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 to prepare a pentenoic acid derivative, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process to prepare a pentenoic acid derivative will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2524755