NL8300298A - PROCESS FOR THE PREPARATION OF DELTA-KETO-CARBONIC ACID ESTERS. - Google Patents

Description

ï · 4

Process for the preparation of delta-keto-carboxylic acid esters.

The preparation of delta-keto-carboxylic acid estera by the Michael reaction of a ketone with an aerylamide ester is known. Particularly important in the present application are improved catalysts for the reaction.

, An alkaline catalyzed

Michael reaction of a ketone with an acrylic acid ester to provide a delta-keto-carboxylic acid ester is described in Comptes Rendus, '248, 1533-1535 (1959). An alkaline catalyst as provided by sodium amide or potassium ethylate is used, which catalyst is soluble in the reaction medium and is reactive with the ketoester reaction product. Therefore, low yields are described for most ketone starting materials.

Similar addition reactions have been described using catalysts that are soluble in the reaction media. for example, British Patent 1,389,510 discloses a catalyzed Michael reaction of a ketone with a. acrylic acid ester to provide a delta-keto-carboxylic acid ester. The reaction is catalyzed with a mixture of a primary amine and one of various types of acidic compounds, all of which are soluble in the reaction medium. British Patent 1,473,184 describes a similar Michael addition reaction for preparing 5-axo-carboxylic acid esters (ie, delta-keto esters) by reacting a ketone with a acrylic acid ester in the presence of a mixture of a primary amine and one of various acids, all of which are absorbable in the reaction medium. All of these acid-catalyzed reactions have the drawback that the acidic compound of the catalyst soluble in the reaction medium is difficult to separate from the delta-ketoester reaction product. Therefore, in purifying the reaction product, such as by distillation, the combination of heat and the acid catalyst often causes the formation of undesired by-products and the result is lower yields of delta keto ester.

There is therefore a need for a process for the preparation of delta-keto-carboxylic acid ester in which high yields of pure product are obtained.

The present invention provides a process for a single pass preparation of a high yield of delta-keto-carboxylic acid ester in a liquid phase, wherein the delta-keto ester satisfies formula 1 of the formula sheet, wherein R is a benzyl group or an alkyl group having 1 to 6 carbon atoms, R 'may be selected from hydrogen, methyl, ethyl, propyl and isopropyl, and R' may be an alkyl group having 1 to 24 carbon atoms. In a first step of the process, a reaction medium formed to react a ketone with an active hydrogen in the alpha position with an acrylic acid ester of formula 2, wherein R, Rf and RM have the above meanings, said reaction medium water and an effective amount of a catalyst The catalyst is provided by a mixture of a primary amine component and a water-activated catalytic material component selected from the group consisting of an alkali half salt of phthalic acid r, an aluminum hydrosilicate mineral, a silica-alum-miniunux-oxide-sieve, a silicon dioxide-free alumina, and a sulfonated perfluorine resin. These catalytic materials are characterized in that they are completely or nearly completely insoluble in the reaction medium.

The reaction product mixture contains delta-keto-carboxylic acid ester in contact with catalytic material which is insoluble in the liquid phase of the reaction mixture. Removal of the insoluble catalytic material and subsequent distillation of the reaction product mixture provides a delta-keto-carboxylic acid ester of high 8300298 4 * 3 purity in the distillate, not contaminated with by-products, formed during the distillation by the presence of residues catalyst from the addition reaction.

The process is particularly suitable for the preparation of methyl 4-oxocaproate by the addition reaction of methyl acrylate and acetone in the presence of any member of the indicated family of catalyst material.

An advantage of the process according to the invention is that, because the catalyst is practically or completely insoluble in the reaction medium, a reaction product which is free of catalyst can be obtained. Therefore, during the distillation of the reaction product to obtain pure delta keto ester, relatively less harmful by-products are formed as compared to prior art processes in which distillation takes place in the presence of an acid catalyst.

A second advantage lies in the suitability of selected preferred species of the family of catalyst materials for use in a fixed bed reactor, insofar as the selected catalyst is insoluble in the reaction medium. Therefore, the addition reaction must be continued continuously.

In forming a reaction drum for the preparation of a delta-keto-carboxylic acid ester, active ketone and acrylic acid ester starting materials of the generally defined type are introduced into a stainless steel stirred pressure reactor. The ketone serves both as a reagent and as a reaction medium. Therefore, the ketone is usually present in an amount in molar excess to the acrylic acid ester in a range from about 7: 1 to about 15: 1.

Suitable ketones have active or labile hydrogen on an alpha carbon relative to the carbonyl group of the ketone. Such ketones include acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, 8300298 ...... 4. .

methyl isopropyl ketone, cyclopentanone, cyclohexanone, 2-methylcyclohexanone and 4-methylcyclohexanone. Suitable acrylic acid esters within the general formula 2 are α, β-unsaturated carboxylic acid esters, such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methyl acrylate, methyl crotonate, ethyl crotonate, methyl maleate, ethyl maleate, methyl fumarate and ethyl fumarate.

The addition reaction proceeds in the presence of a co-catalyst combination provided by an amine and a water-activated catalytic material.

Suitable amines include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, sec-pentylamine, hexylamine, cyclopentyl amine, cyclohexylamine and hexamethylenediamine. Generally, the amount of amine present in the reaction mixture in the range of about 0.05 to about 0.5 mole per mole of acrylic acid ester starting material is initially present in the reaction mixture.

Examples of alkali metal half salts of phthalic acid suitable as catalytic materials include lithium hydrogen phthalate, sodium hydrogen phthalate and potassium hydrogen phthalate. A preferred alkali metal half salt of phthalic acid is potassium hydrogen phthalate. These semisalts are practically, but not completely, insoluble in water. Therefore, when using one of these half salts as a catalytic material, the amount of water present in the reaction mixture will be that amount needed to activate the half salt catalytic material, but insufficient to absorb a significant portion of the half salt. unload. The term "significant part" means that amount of semisalt, which, when present during the distillation of the reaction product mixture, does not promote the formation of harmful by-products. Generally, an appropriate amount of water to activate the half salt, but which is insufficient to dissolve a significant portion of the half salt, is in the range of about J to about 5 parts water per portion of the half salt throughout the reaction. % 8300298 5 mixture. Typically, an alkali metal half salt of phthalic acid as the catalytic material can be used in an amount in the range of about 0.02 to about 0.13 parts of half salt on 1 part of acrylic acid ester starting material initially present in the reaction mixture.

A second suitable catalytic material is provided by an aluminum hydrosilicate mineral. Such a material is characterized by the ideal formula 3 and is commonly known as Mbn morillonite.

Suitable Montmorillonite catalytic materials are marketed under the designation "K-Catalysts" by Süd-Chemie A.G., Munich, B.R.D. These clay-like materials are characterized in that they belong to the group of three-layer minerals, that they have a large number of exchangeable ions and that they are practically insoluble in water. Generally, the aluminum hydrosilicate material may be present in an amount in the range of from about 0.2 to about 4 parts by weight of aluminum hydrosilicate on one part acrylic acid ester starting material initially present in the reaction mixture.

A third type of catalytic material is provided by a silica-alumina-molecular sieve zeolite in which the silicon to aluminum atomic ratio is about 30: 3. Typically, useful materials are characterized by a specific surface area in the range from about 450 to about 500 m / g, and a water content in the range from about 33 to 35% by weight. The material is practically insoluble in water. Particularly suitable materials are marketed under the designation "hydrogen mordenite", Strem Chemicals, Ine., Newburyport,

Mass. USA. Generally, the silica-alumina-zeolite may be present in an amount in the range of from about 0.1 to about 4 parts by weight of silicon dioxide-alumina zeolite on 1 part of acrylic acid ester starting material initially present in the reaction mixture.

A fourth type of catalytic material 8300298 Η f 6 is provided by a silicon dioxide-free aluminum oxide, which is characterized as being substantially insoluble in water. Suitable silica-free catalytic material is marketed under the designation HA 100 S 5 by Houdry Process and Chemical Co., Div. of Air Products and Chemical Co., Inc ,, Philadelphia, Pa, USA. Generally, the silica-free alumina catalytic material may be present in an amount ranging from about 0.1 to about 4 parts by weight of alumina per part of the acrylic acid ester starting material initially present in the reaction mixture.

A fifth type of catalytic material is provided by a sulfonated perfluorinated resin prepared from copolymers of tetrafluoroethylene and monomers, such as perluoro-3,6-dioxa-4-methyl-7-octanesulfonyl fluoride. The resin is practically insoluble in water. Suitable resins are sold under the trade name NAFION 501 by DuPont Company, Wilmington, Del., USA. Generally, the sulfonated perfluorinated resin can be present in an amount in the range of from about 0.001 to about 0.04 parts resin per part acrylic acid ester starting material initially present in the reaction mixture.

For an addition reaction using one / the second to fifth type catalytic materials, an amount of water must be present in the reaction mixture sufficient to promote the activity of the catalytic material. Since none of these indicated catalytic materials are observably soluble in any amount of water, the amount of water to be used can be primarily determined by the amount of acrylic acid ester starting materials. Thus, excessive amounts of water play no role in the formation of harmful by-products in the reaction product mixture. In general will. the amount of water used for each of the described second to fifth type catalytic materials in the range of about 0.02 to about 8300298 r.

% 0.12 parts by weight of catalytic material per part are acrylic acid ester starting material.

In providing the catalyst for a reaction mixture, the amine component and the cat alysate material component can be added separately or in the form of a mixture of the two components.

Prior to distillation at temperatures high enough to recover a fraction of pure delta-keto-carboxylic acid ester, the insoluble or substantially insoluble catalytic material must be removed from contact with the liquid phase containing delta-keto-carboxylic acid ester. In reactions using an alkali metal half salt of phthalic acid as the catalytic material component, a preliminary distillation must be conducted at about 305 ° C to remove all water from the reaction product mixture. Once the reaction product mixture is free from water, the alkali metal semisalt of phthalic acid becomes substantially insoluble in the reaction product mixture and can be removed by filtration. For the second to fifth type catalytic materials, there is no need for a preliminary distillation step because these materials can be easily filtered from the reaction product mixture, given their insolubility in the mixture, regardless of the amount of water present. A filtrate obtained from one of these reaction mixtures can then be subjected to fractional distillation under reduced pressure to recover a fraction containing high purity delta-keto-carboxylic acid ester.

The following examples illustrate specific embodiments of the invention. However, the invention is not to be construed as being limited to these embodiments. There are, of course, numerous variations and modifications. All parts and percentages in the examples, by the way throughout the application, are by weight unless otherwise indicated.

8300298 t - 8.

Example I

1660 g of acetone, 5 215 g of methyl acrylate, 22 g of isopropylamine, 2 g of hydroquinone, 10 g of potassium hydrogen phthalate and 18 g of water were introduced into a stainless steel, mechanically stirred pressure reactor, provided with means for detecting and controlling the temperature. The remaining space in the reactor was purged with nitrogen to remove substantially all of the ambient oxygen in the reactor. The reaction mixture was then heated under stirring to a temperature of 183 to 185 ° C and held under these conditions for about 6 hours. A pressure of 2.07 MPa was observed after the reaction temperature was reached. After the reaction vessel was cooled to room temperature, the entire reaction mixture was transferred to a distillation apparatus.

Unreacted acetone, methyl acrylate, isopropylamine and water were then separated as distillate at a distillation temperature maintained at a maximum of about 105 ° C. The material remaining in the distillation device was transferred to a filtration device.

Since the potassium hydrogen phthalate was substantially insoluble in the liquid reaction product, there was a nearly complete separation of the potassium hydrogen phthalate from the liquid filtrate containing crude methyl 4-oxocaproate (MOC) product.

The crude MOC was passed through a bed of sodium bisulfate to remove residual basic material, such as isopropylamine, from the MOC product. The MQC product was then placed in a distillation apparatus and recovered as a distillate at a distillation temperature of 320 to 324 ° C under a pressure of 5.33 kPa absolute. Purified MOC in an amount of 328 g was recovered, which corresponds to a yield of 91 mol%, based on methyl acrylate starting material. A distillation residue of 14 g was obtained. Gas chromatographic analysis of the MOC product showed an MOC purity of more than 99.5%. A trace contamination was identified as a foron.

8300298 t 9

Example II

An addition reaction was performed with the equipment, the starting materials and in accordance with the procedures generally described in Example 5 I. To demonstrate the conversion rate of starting reagents to methyl 4-oxo-caproate, samples of the reaction medium were taken during a reaction period of 5 hours. Table A shows the methyl acrylate conversion and the yield of methyl 4-oxocaproate for each of the samples.

10 Table A

Reaction of acetone and methyl acrylate to form methyl 4-oxocaproate over 5 hours.

Reaction time Methyl acrylate% yield per% final 15 (h) conversion (%) passage of me yield of methyl-4-oxomethyl-4-oxo-caproate (%) caproate (%) 2 79 70 89 3 88 79 89 20 4 94 86 91 5 97 90 93

Example III

An addition reaction was carried out with the equipment, the starting reagents and according to the procedures generally described in Example 1. In order to obtain the activating effect of water on the water-activated catalytic material as provided by 4.0 g of potassium hydrogen phthalate per mole of methyl acrylate to demonstrate starting reagent, two parallel reactions were performed which differed only 30 from each other due to the presence or absence of water. In reaction (a), 7.2 g of water per mole of methyl acrylate was used. No water was added in reaction (b).

The results are shown in Table B.

Example IV

An addition reaction was performed with the equipment, the starting reagents and according to the procedures as generally described in Example 1. To the 8300298 i JQ "

activating effect of water on the water-activated catalytic material as provided by 40 g of montmorillo staple (K-306, Süd Chemie AG) per mole of methyl acrylate starting reagent, two parallel reactions were performed, differing only by the presence or absence of water. In reaction (a), 7.2 g of water per mole of methyl acrylate was used. No water was added in reaction (b). The results are shown in Table B. Example V

An addition reaction was carried out with the equipment, the starting reagents and according to the procedures as generally described in Example 1. To evaluate the activating effect of water on the water-activated catalytic material as provided by 60 g of silica 15 free aluminum oxide (HA-1005 To demonstrate demonstrating two parallel reactions differing from each other only by the amount of water present, in reaction (a), 7.2 g of water per mole of methyl acrylate was used. (b) 2.0 g of water was used per mole of methyl acrylate The results are shown in Table Ξ.

Example VI

An addition reaction was carried out with the equipment, the starting reagents and according to the procedures as generally described in Example 1, except that as catalytic material 40 g of silica-alumina molecular sieve zeolite ("Hydrogen Mor- denite, Strem Chem., Ine.) was used per mole of methyl acrylate starting reagent. The results are shown in Table B.

Example VII

An addition reaction was carried out with the equipment, the starting reagents and according to the procedures generally described in Example I, except that 0.4 g of sulfonated perfluorinated resin (NAFION® 501, DuPont Co.) was used per mole of methyl acrylate starting 8300298 4

IJ

reagent. The results are shown in Table B.

Table B

Preparation of methyl 4-oxocaproate (MOC) from acetone and methyl acrylate (MA.) With selected catalytic or non-water activated catalytic materials.

Ex. Reaction Catalytic Activation MOC-on time material water yield _ (h) (g / mol HA) (mol.Z) 111 (a) 5 potassium hydrogen 7.2 90 10 (b.) 5 phthalate none 67 IV ( a) 5 montmorillonite 7.2 89 (b) 5 none 55 V (a) 4 aluminum oxide 7.2 89 (b) 5.5 2.0 74 15 VI 6 silicon dioxide 7.2 74 aluminum oxide VII 6 sulfonated 7 .2 74 perfluorinated resin 20

Example VIII

To demonstrate that the method of the invention is useful for short reactions, such as taking place in continuous processes, an addition reaction was performed with the equipment, the starting reagents and according to the procedures generally described in Example I, with the following exceptions: 880 g of acetone was used and the reaction mixture was heated from room temperature to 235 ° C over a period of 1.5 hours. Once the temperature of the reaction mixture reached 235 ° C, the reaction mixture was cooled to a temperature of 180 ° C in 5 minutes and then reached room temperature after an additional 4 hours. After distilling the reaction mixture, a yield of 90% methyl 4-oxocaproate was obtained.

Although specific examples of the present invention have been presented above, it is not intended to limit the invention solely thereto, the invention includes all variations and modifications which fall within the following claims, read in the light of the description.

8300298

Claims (26)

1. Process for the preparation of a delta-keto-carboxylic acid ester, characterized in that a compound of formula I, wherein R is a benzyl group or an alkyl group with 1 to 6 carbon atoms, R 'is hydrogen, methyl, ethyl, propyl or is isopropyl and R, T is alkyl of 1 to 24 carbon atoms, prepared by forming a reaction mixture to react a ketone with an active hydrogen atom in the α position 10 with an acrylic acid ester of formula 2, wherein R, RT and R, T have the aforementioned meaning which reaction medium contains a catalyst provided by a mixture of a primary amine component and a water-activated catalytic material component which is substantially insoluble in the reaction medium, wherein the water-activated catalytic material component is selected from the group consisting of an alkali metal half salt of phthalic acid, an aluminum hydrosilicate mineral, a silica-alumina molecular sieve zeolite, a silicon dioxide-free aluminum m ^ 20 oxide and a sulfonated perfluorinated resin; whereby a reaction product mixture containing delta-keto-carboxylic acid ester can be formed in contact with the selected substantially insoluble catalytic component, which component can be substantially removed from the reaction product mixture prior to distillation to obtain a delta-keto high purity carboxylic acid ester. 2. Process according to claim 1, characterized in that the water-activated catalytic material component is an alkali metal semisalt of phthalic acid, the process further comprising a second step of forming a distillate residue substantially free of water by distilling the reaction product of the first step, wherein said distillate residue consists of a liquid portion in contact with a solid material containing the alkali metal semisalt of phthalic acid, the liquid portion containing delta-keto-carboxylic acid ester; wherein the 8300298 liquid portion can be separated from the solid material, then treating the liquid portion to recover delta-keto-carboxylic acid ester which is relatively free of by-products, and then treating the solid material to recover the alkali metal half salt of phthalic acid to be recovered for reuse as a catalytic material. . Process according to claim 2, characterized in that the alkali metal half salt of lingic acid is sodium hydrogen phthalate. Process according to claim 2, characterized in that the alkali metal semisalt of phthalic acid is potassium hydrogen phthalate. 5. Process according to claim 2, characterized in that the acrylic acid ester is methyl acrylate, the ketone is acetone, the delta-keto-carboxylic acid ester is methyl 4-oxocaproate and the alkali metal half salt of phthalic acid is potassium hydrogen phthalate, sodium hydrogen phthalate or a mixture of the two . Process according to claim 1, 20, characterized in that the water-activated catalytic material component which is insoluble in the reaction medium is selected from the group consisting of an aluminum hydrosilicate mineral, a silica-alumina molecular sieve zeolite, a silica-free aluminum oxide and a sulfonated perfluorinated resin, the process further comprising a second step of filtering the selected insoluble catalytic material component from the reaction product mixture so that the reaction product mixture can be distilled in the practical absence of the catalyst material component to obtain high purity delta-keto-carboxylic acid ester. Process according to claim 6, characterized in that the water-activated catalytic material component is an aluminum hydrosilicate. Process according to claim 6, characterized in that the water-activated catalytic 8300298 material component is a silica-alumina molecular sieve zeolite. 9. Process according to claim 6, characterized in that the water-activated catalytic material component is a silicon dioxide-free aluminum oxide. Process according to claim 6, characterized in that the water-activated catalytic material component is a sulfonated perforced resin. 11. Process for the preparation of methyl 4-oxoeaproate, characterized in that (a) methyl acrylate is reacted with acetone in a reaction medium containing water and a catalyst to prepare a reaction product mixture containing methyl 4-oxocaproate wherein the catalyst is a mixture of a primary, amine and potassium hydrogen phthalate, the water being present in an amount at least sufficient to act as an activator for the catalyst but in an insufficient amount to provide a significant portion of the potassium hydrogen phthalate to unload; (B) the reaction product mixture of step (al still distillates to form a distillate residue containing methyl 4-oxocaproate and potassium hydrogen phthalate, which distillate residue is substantially free of water; and (c this distillate residue treats to remove potassium hydrogen phthalate from the residue and thereby providing a residue of the distillate residue containing methyl 4-axocaproate, the remainder of the distillate residue being treated by distillation to provide purified methyl 4-oxocaproate which is substantially free of by-products. 12. A method according to claim 11, characterized in that the potassium hydrogen phthalate is initially present in the reaction medium in an amount of about 0.07 to about 0.013 parts of potassium hydrogen phthalate per part of methyl acrylate. 8300298 A method according to claim 12, characterized in that the water is initially present in the reaction medium in an amount of from about 1 to about 5 parts of water per part of potassium hydrogen phthalate. 14. Process for the preparation of methyl 4-oxocaproate, characterized in that (a) methyl acrylate is reacted with acetone in a reaction medium containing water and a catalyst to prepare a reaction product mixture containing methyl 4-oxocaproate, the catalyst consisting of a mixture of a primary amine and an aluminum hydrosilicate mineral, the water being present in an amount at least sufficient to act as an activator for the catalyst; (B) filtering the reaction product mixture of step (a) to remove the aluminum hydrosilicate mineral insoluble in the reaction product mixture, to provide a filtrate free of this aluminum hydrosilicate mineral; and (c) distilling the filtrate from step (b) to obtain high purity methyl 4-oxocaproate. 15. A method according to claim 14, characterized in that the aluminum hydrosilicate mineral is variably present in the reaction medium in an amount of from about 0.1 to about 4 parts of aluminum hydrosilicate mineral per part of methyl acrylate starting material. 16. A method according to claim 14, characterized in that step (a) is accomplished by continuously passing methyl acrylate and acetone through a fixed bed comprising said aluminum hydrosilicate material. 17. Process for the preparation of methyl 4-oxocaproate, characterized in that (a) methyl acrylate is reacted with acetone in a reaction medium containing water and a catalyst to prepare a reaction product mixture containing methyl 8300298 16; 4-oxocaproate, the catalyst consisting of a mixture of a primary amine and a silica-alumina molecular sieve zeolite, the water being present in an amount at least sufficient to act as the catalyst activator ; (b) filtering the reaction product mixture of step (a) to remove the silica-alumina molecular sieve zeolite which is insoluble in the reaction product mixture, to provide a filtrate free of the silica-alumina molecular sieve zeolite. ; and (cl distillates the filtrate from step (b) to obtain high purity methyl 4-oxocaproate » The process according to claim 17, characterized in that the silica-alumina molecular sieve zeolite is initially present in the reaction medium in an amount of from about 0.1 to about 4 parts of silica-alumina molecular sieve zeolite per 20 parts of methyl acrylate. starting material. 19. A method according to claim 18, characterized in that step (a) is accomplished by continuously passing methyl acrylate and acetone through a fixed bed comprising said silica-alumina molecular sieve zeolite. 20. Process for the preparation of methyl 4-oxocaproate, characterized in that (a) methyl acrylate is reacted with acetone in a reaction medium containing water and a catalyst to prepare a reaction product mixture containing methyl 4-oxocaproate, wherein the catalyst consists of a mixture of a primary amine and a silica-free alumina, the water being present in an amount at least sufficient to act as an activator for the catalyst; (b) filter the reaction product mixture of 8300298 * step (a) to remove the alumina insoluble in the reaction product mixture to provide a filtrate free of said alumina; and 5 (c) the distillate of step (b ) distill to obtain high purity methyl 4-oxocaproate. 21. A process according to claim 20, characterized in that the aluminum oxide is initially present in the reaction medium in an amount of about 0.1 to about 4 parts of aluminum oxide per part of methyl acrylate starting material. 22. A method according to claim 20, characterized in that step (a) is accomplished by continuously passing methyl acrylate and acetone through a fixed bed comprising said aluminum oxide. 23. Process for the preparation of methyl 4-oxocaproate, characterized in that (a) methyl acrylate is reacted with acetone in a reaction medium which resumes water and a catalyst to prepare a reaction product mixture containing methyl 4-oxocaproate, the catalyst consisting of a mixture of a primary amine and a sulfonated perfluorinated resin, the water being present in an amount at least sufficient to act as an activator for the catalyst; (b) filtering the reaction product mixture of step (a) to remove the sulfonated perfluorinated resin insoluble in the reaction product mixture, to provide a filtrate free of the sulfonated perfluorinated resin; and (c) distilling the filtrate from step (b) to obtain high purity methyl 4-oxocaproate. 24. Process according to claim 23, characterized in that the sulfonated perfluorinated resin is 8300298? initially in. the reaction medium is present in an amount of from about 0.003 to about 0.04 parts of sulfonated perfused resin per part of methyl acrylate starting material. 25. A process according to claim 24, characterized in that step (a) is accomplished by continuously passing methyl acrylate and acetone through a fixed bed comprising said sulfonated perfluorinated resin. 26. Methods and articles essentially as described in the description and / or the examples. 8300298 * ν '* O r' R1 Η O II III II R -CCCC — C - OR .1 l · r 'o ch * = c— c - o - r "2 I, R AliOj. 4 Si Ot. HjO + HaO 3 Koppers Company, Inc., Pittsburgh., Pa. United States America 8300298