Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1999-06-02
2001-09-25
Geist, Gary (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
Reexamination Certificate
active
06294693
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a production process for an ether carboxylate salt involving the use of a catalyst containing a rare earth element.
B. Background Art
A conventional production process for an ether carboxylate salt comprises the etherification step of reacting a hydroxyl-group-containing organic compound and a carboxyl-group-containing organic compound, wherein the carboxyl-group-containing organic compound is at least one compound selected from the group consisting of carboxyl-group-containing unsaturated organic compounds and carboxyl-group-containing epoxy compounds.
Sodium carboxymethoxysuccinate, which is one of the ether carboxylate salts, is useful as a phosphorus-free detergent builder and obtainable by a process comprising the step of reacting maleic anhydride and glycolic acid in an aqueous medium in the presence of calcium hydroxide (Chemical Abstract, 75, 89458 (1971)).
It is reported that the lanthanum (III) ion is also usable as the catalyst in place of the calcium ion in the same homogeneous reaction as above (Jeroen van Westrenen et al., J. Chem. Soc. Dalton Trans., 2723-2728 (1988)).
Processes involving the use of rare earth element ions such as lanthanum ion as the catalyst are more excellent in respect to higher activity of the catalyst, and further, higher selectivity and yield of the aimed product when compared with processes involving the use of the calcium ion.
However, the above conventional processes involving the use of rare earth element ions have problems as follows.
In those processes, a large amount of catalyst is used to smoothly run the reaction. However, the rare earth element is expensive, so it is desired to save the amount of the rare earth element, as used, or to recover and reuse the catalyst as already used for the reaction, for the purpose of saving the production cost.
The etherification reaction in a solution generally has problems in that: as the reaction advances, the concentration of raw compounds gradually lowers, so the reaction becomes difficult to advance, and the aimed ether compound therefore cannot be obtained with a high yield. The cause of such problems is that the ether compound, as once obtained, easily reverts to the raw compounds due to the reverse reaction, or that a side reaction competing with the reverse reaction occurs to give a by-product.
SUMMARY OF THE INVENTION
A. Objects of the Invention
An object of the present invention is to save the amount of expensive catalyst as used.
Another object of the present invention is to facilitate the recovery of the expensive catalyst.
Yet another object of the present invention is to suppress the reverse reaction or side reaction, thus obtaining an ether compound with a high yield.
B. Disclosure of the Invention
To achieve the above first object, the present invention is characterized in that: in the etherification step, the pH of the aqueous medium is in the range of 9~13, but not including 9, and the amount of the catalyst, as used, is in the range of 0.0001~0.4 mol per 1 mol of the carboxyl-group-containing organic compound.
To achieve the above second object, in the present invention, the rare earth element is separated and recovered in the form of a water-insoluble salt after the reaction.
To achieve the above third object, in the present invention, the resultant ether carboxylic acid or its salt is deposited in the course of the reaction.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
The above Jeroen van Westrenen et al.'s process is a process comprising the step of reacting sodium glycolate and sodium maleate at the pH of 5~9 in water in the presence of lanthanum trichloride, thus obtaining carboxymethoxysuccinate salts (sodium salt and lanthanum salt).
In the course of the study of processes to solve the above problems, the present inventors traced the above Jeroen van Westrenen et al.'s experiment and found that the carboxymethoxysuccinate salt, which is a reaction product, is not in the form of a sodium salt, but mainly in the form of a lanthanum salt at the pH of 5~9, and that the free lanthanum ion has catalytic activity, whereas the above lanthanum salt does not. Thus, the inventors concluded that the reason why a large amount of catalyst is necessary at the pH of 5~9 is because the active free lanthanum ion is gradually consumed by a reaction product. Then, the inventors studied a process to prevent the consumption of the active free lanthanum ion, and as a result, completed the present invention by finding that if the pH is high, the carboxymethoxysuccinate salt, which is a reaction product, has the form of not a lanthanum salt, but a sodium salt, so the active free lanthanum ion is not consumed during the reaction, and thus the amount thereof, as used, can be saved.
Next, the recovery of the lanthanum ion is usually carried out by allowing an ion-exchange resin to adsorb the lanthanum ion, and its recovery efficiency is low, and the ion-exchange resin is also expensive. Furthermore, the reuse of the lanthanum ion, as adsorbed to the ion-exchange resin, necessitates the step of desorbing the lanthanum ion from the ion-exchange resin by using a large quantity of mineral acid (e.g. sulfuric acid, hydrochloric acid), so there are problems in that such a process inevitably involves a high cost. Thus, the present inventors intended to solve such problems by separating and recovering the rare earth element in the form of a water-insoluble salt after the reaction.
The present inventors diligently studied and made experiments to intend to suppress the reverse reaction or side reaction. As a result, the inventors completed the present invention by finding that: if the ether compound, which is a product, is deposited in the course of the reaction, the ether compound is removed from the liquid-phase reaction system, so the concentration of the raw compounds becomes higher than that in a state before the deposition (state where the ether compound is present in the reaction system), and therefore, the etherification reaction is promoted, and the side reaction is inhibited from occurring.
Hereinafter, the present invention is described in detail.
The production process for an ether carboxylate salt, according to the present invention, comprises the etherification step of reacting raw compounds, which step is carried out in an aqueous medium in the presence of a catalyst containing a rare earth element. The raw compounds include a hydroxyl-group-containing organic compound and a carboxyl-group-containing organic compound, wherein the carboxyl-group-containing organic compound is at least one compound selected from the group consisting of carboxyl-group-containing unsaturated organic compounds and carboxyl-group-containing epoxy compounds.
Examples of the hydroxyl-group-containing organic compound include hydroxycarboxylic acid compounds, polyhydric alcohol compounds, higher alcohol compounds with 6 to 22 carbon atoms, and saccharides. These hydroxyl-group-containing organic compounds are more specifically illustrated as follows:
Hydroxycarboxylic Acid Compounds
(a) Compounds of the following general formula (1):
wherein: R
1
and R
2
, independently of each other, denote a hydrogen atom or an alkyl with 1 to 3 carbon atoms; X denotes a hydrogen atom, an alkaline metal atom, an alkaline earth metal atom, an ammonium group, an alkylammonium group, or an alkanolammonium group; and m denotes an integer of 1 to 10. Typical examples are glycolic acid, &bgr;-hydroxypropionic acid, and lactic acid.
(b) Compounds of the following general formula (2):
wherein: R
3
denotes a hydrogen atom or an alkyl with 1 to 3 carbon atoms; n denotes an integer of 1 to 10; and X is the same as that in general formula (1) above. Typical examples are glyceric acid and gluconic acid.
(c) Compounds of the following general formula (3):
OH—CH
2
—(CH
2
—O—CH
2
)
p
—COOX (3)
wherein: p denotes an
Asakawa Miaki
Kitajima Mitsuhiro
Sumida Yasutaka
Geist Gary
Nippon Shokubai Co. , Ltd.
Oh Taylor V
Roylance Abrams Berdo & Goodman L.L.P.
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