Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1998-01-05
2001-07-31
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S517000, C540S529000, C540S538000
Reexamination Certificate
active
06268530
ABSTRACT:
The invention relates to a process to separate linear 5-formylvaleric acid from a mixture of 5- and 3- and/or 4-branched formylvaleric acids. The invention also relates to a process to prepare 5-formylvaleric acid starting from pentenoic acid by hydroformylation.
Furthermore the invention relates to an improved process to prepare ∈-caprolactam starting from a mixture of branched and linear formylvaleric acids or starting from pentenoic acid.
It is known from DE-C-952442 that 5-formylvaleric acid can be prepared by hydroformylation of pentenoic acids, for example 3-pentenoic acid. When 5-formylvaleric acid is prepared by hydroformylation branched by-products (3- and/or 4-formylvaleric acid) are also formed. Two methods for separating the linear 5-formylvaleric acid from 3- and 4-formylvaleric acid are described in DE-C-952442: (1) The mixture of branched and linear acids can first be subjected to a reductive amination. The resulting amide product mixture can be separated in linear and branched amide products. (2) The separation of 5- formylvaleric acid from the mixture can be performed by esterification of the linear and branched formylvaleric acids and a subsequent separation of the 5-formylvaleric ester. By hydrolysis of the isolated 5-formylvaleric ester 5-formylvaleric acid can be obtained.
A disadvantage of the first method is that a nitrogen containing waste stream of branched amide products is obtained which is difficult to dispose of. Furthermore, 5-formylvaleric acid is not obtained as an isolated product.
A disadvantage of the second method is that several chemical reactions have to be performed to obtain 5-formylvaleric acid starting from pentenoic acid. Loss of valuable product in these reactions and the need for extra process equipment, and thus an extra investment makes this process unattractive when performed on a large and commercial scale.
The aim of the present invention is to provide a process to separate 5-formylvaleric acid from its isomers, 3- and/or 4-formylvaleric acid, with a high yield to 5-formylvaleric acid in a more simple process than the process described in DE-C-952442.
This aim is accomplished in that the separation is performed by fractional extraction with two immiscible solvents of which one solvent is an aqueous solvent (resulting in an aqueous phase) and the other solvent is an organic solvent (resulting in an organic phase) which has the following characteristics:
−2.8
<A<−
0.2 and 0.14
<B<
2.39 (2)
or
1.7
<A<
4.0 and −4.0
<B<−
1.64 (3)
in which, A and B are:
A =
0.23 * (T
B
− 138.54)/62.36 +
(5)
0.24 * (&rgr; − 935.64)/184.82 +
0.0554 * (n
d
−1.4370)/0.0635 +
0.3916 * (&egr;
r
− 15.02)/18.66 +
0.1208 * (&dgr;
d
− 16.68)/1.738 +
0.4135 * (&dgr;
p
− 6.11)/5.16 +
0.3462 * (&dgr;
h
− 8.05)/6.97 +
0.4177 * (&dgr; − 20.69)/5.087 +
0.3370 * (&mgr; − 1.73)/1.20 +
0.3723 * (E
T(30)
− 41.14)/7.61
B =
− 0.3009 * (T
B
− 138.54)/62.36 −
(6)
0.3882 * (&rgr; − 935.64)/134.82 −
0.5914 * (n
d
− 1.470)/0.0635 +
0.1225 * (&egr;
r
− 15.02)/18.66 −
0.5506 * (&dgr;
d
− 16.68)/1.738 +
0.0970 * (&dgr;
p
− 6.11)/5.16 +
0.2291 * (&dgr;
h
− 8.05)/6.97 +
0.0583 * (&dgr; − 20.69)/5.087 +
0.0381 * (&mgr; − 1.73)/1.20 +
0.1550 * (E
T(30)
− 41.14)/7.61
in which T
B
represents the normal boiling point (° C.), &rgr; the density measured at 20° C. (kg/m
3
), n
d
the refractive index (−), ∈
r
the dielectric constant measured at 20° C. (−), &dgr;
d
the Hansen solubility parameter of dispersion (MPa
½
), &dgr;
p
the Hansen solubility parameter of polarity (MPa
½
), &dgr;
h
the Hansen solubility parameter of hydrogen bonding (MPa
½
), &dgr; the Scatchard-Hildebrand solubility parameter (MPa
½
), &mgr; the dipole moment (Debey) and E
T(30)
the Lewis donor/acceptor property (kcal/mol) (all properties of the organic solvent) or the organic solvent is an ether or an ester with 2 to 10 carbon atoms represented by the following formula
R
1
—O—R
2
(7)
in which R
1
, R
2
, R
3
and R
4
are independently an alkyl or aryl group with 1 to 7 carbon atoms and in which R
1
and R
2
is optionally a divalent group.
In this invention it is understood that two solvents are immiscible when two separate phases form when the solvents are mixed.
The values for the above described solvent properties for most of the generally applied solvents can be found in the following references: Properties of liquids and gases, fourth edition, Reid, Prausknitz & Poling, Mc-Graw Hill, 1987; Properties of polymers (Their correlation with chemical structure), D. W. van Krevelen, Elsevier Scientific Publishing Company, Amsterdam 1990; Solvents and Solvent Effects in Organic Chemistry, Ch. Reichardt, VCH Verlagsgesellschaft mbH, Weinheim (Germany, FRG, 1990) and DIPPR—Tables, Physical and thermodynamic properties of pure components, Daubert & Danner, Taylor & Francis, 1994.
It has been found that with the process according to the invention it is possible to separate the linear 5-formylvaleric acid from this mixture with an extraction process. This was unexpected. In particular because the linear and the branched formylvaleric acids have very comparable physical properties. The fact that an extraction process can be used for solving this problem is very advantageous because extraction processes are easily applied in large scale processes.
A further advantage is that it is possible to obtain relatively pure 5-formylvaleric acid in a high yield calculated on the starting amount of 5-formylvaleric acid in the (crude) mixture of formylvaleric acids.
Another advantage is that possible pentenoic acid or valeric acid, can also be separated from the linear 5-formylvaleric acid in the process according to the invention. These compounds are the starting compound and a possible by-product respectively of the hydroformylation process to prepare 5-formylvaleric acid. Thus an additional separation of 5-formylvaleric acid and pentenoic acid and/or valeric acid is not needed if these products are present.
It has been known to prepare 5-formylvaleric acid by hydrolysis of the corresponding methyl 5-formylvaleric as described in U.S Pat. No. 4,730,040. A disadvantage of this process is that methanol is obtained as a by-product and that the yield of the hydrolysis to 5-formylvaleric acid, as shown in the examples of U.S. Pat. No. 4,730,040, is too low for a commercially interesting process. The methyl 5-formylvaleric is preferably prepared by hydroformylation of a methyl pentenoate ester which is preferably prepared by carbonylation of butadiene with methanol. By preparing the pentenoic acid by carbonylation of butadiene with water, followed by the preparation of the formylvaleric acid by hydroformylation of the pentenoic acid the use of methanol or any other alkanol is avoided. Moreover with the present invention it is possible to prepare and isolate 5-formylvaleric acid in less process steps starting from butadiene.
The aqueous solvent used in the process according to the invention may be optionally a mixture of water and another solvent which is miscible with water and has a low solubility in the organic solvent of the other phase such that two separate phases are formed. Preferably water is used as the aqueous solvent.
The organic solvent used in the process according to the invention is characterized with A and B which have values within the A-B space as described by the formula's above or is an ether or ester with formula (7) or (8) respectively.
The organic solvent used in the process according to the invention may be any organic solvent which has a higher or lower affinity for 5-formylvaleric acid (5FVA) than its affinity for both the 3- and the 4-formylvaleric acids (3FVA+4FVA). In describing the present invention, it may be useful to u
Gelling Onko
Guit Rudolf P. M.
Niemann Simon Hans H.
Simons Antonius J. F.
Toth Imre
DSM N.V.
Keys Rosalynd
Pillsbury & Winthrop LLP
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