Process for the production of ethylenically unsaturated carboxylic acids or esters

Abstract

The present invention relates to a process for the production of an ethylenically unsaturated carboxylic acid or ester, preferably ?,? ethylenically unsaturated carboxylic acids or esters, by the liquid phase reaction of formaldehyde or a suitable source thereof with a non-cyclic carboxylic acid ester in the presence of a basic metal salt.

Claims

1. A process for production of an ethylenically unsaturated carboxylic acid or ester by a liquid phase reaction of formaldehyde or a suitable source thereof with a non-cyclic carboxylic acid ester of formula R.sup.3CH.sub.2COOR.sup.4 in the presence of a basic metal salt, wherein R.sup.4 is an alkyl group and R.sup.3 is methyl wherein the basic metal salt is a group I or a group II metal salt.

2. The process according to claim 1, wherein the basic metal salt is selected from group I or group II metal oxides, hydroxides, carbonates, hydrogen carbonates, methyl carbonates, alkoxides, fluorides and phosphates.

3. The process according to claim 1, wherein the basic metal salt is selected from potassium oxide, caesium oxide, sodium oxide, rubidium oxide, barium oxide, potassium hydroxide, caesium hydroxide, sodium hydroxide, rubidium hydroxide, barium hydroxide, potassium phosphate, caesium phosphate, sodium phosphate, rubidium phosphate, barium phosphate, sodium methoxide, potassium methoxide, rubidium methoxide, sodium t-butoxide, potassium t-butoxide, rubidium t-butoxide, caesium t-butoxide, sodium fluoride, potassium fluoride, rubidium fluoride, caesium fluoride, potassium carbonate, caesium carbonate, sodium carbonate, rubidium carbonate, barium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, rubidium hydrogen carbonate, caesium hydrogen carbonate, barium hydrogen carbonate, potassium methyl carbonate, sodium methyl carbonate, caesium methyl carbonate, rubidium methyl carbonate or barium methyl carbonate.

4. The process according to claim 1, wherein the reaction is performed at a temperature below 300? C.

5. The process according to claim 1, wherein the reaction is performed at a pressure of between 5 and 2000 psi.

6. The process according to claim 1, wherein the suitable source of formaldehyde is selected from formalin, low molecular weight polyformaldehyde, gaseous formaldehyde, formaldehyde hemiacetal, trioxane or anhydrous formaldehyde.

7. The process according to claim 1, wherein the process is a batch or continuous process.

8. The process according to claim 1, wherein in a reaction medium the non-cyclic carboxylic acid ester is maintained in a molar excess compared to the formaldehyde or suitable source thereof.

9. The process according to claim 8, wherein the formaldehyde or suitable source thereof is added to the reactor at a rate from about 1 to 10 mol %/minute relative to the non-cyclic carboxylic acid ester.

10. The process according to claim 8, wherein a molar ratio of formaldehyde or suitable source thereof to the non-cyclic carboxylic acid ester is maintained at about 1:100 to 1:2 during the reaction.

11. The process according to claim 8, wherein the formaldehyde or suitable source thereof is fed to a reactor in a molar ratio of 1.1:1 to 1:1 with the non-cyclic carboxylic acid ester.

12. The process of claim 1, further comprising one or more solvents.

13. The process according to claim 12, wherein the one or more solvents is wholly or substantially aprotic.

14. The process according to claim 13, wherein the solvent is an aprotic protophilic solvent or an aprotic photophobic solvent.

15. The process according to claim 14, wherein the solvent is selected from dimethyl formamide, diethyl formamide, dimethylacetamide (DMAc), 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU), 1,3-dimethyl-2-imidazolidinone (DMEU or DMI), 3-methyl-2-oxazolidinone, propylene carbonate, diethylacetamide, 1-methyl-2-pyrrolidinone, hexamethylphosphoric triamide, pyridine, tetramethyl urea, dimethylsulfoxide, acetonitrile, propionitrile, benzonitrile, acetone, 2-butanone, 3-pentanone, acetophenone, nitromethane, nitrobenzene, tetrahydrothiophene 1,1-dioxide (sulfolane), diethyl ether, diisopropyl ether, 1,4-dioxane, dimethyl carbonate, tetrahydrofuran, 1,2-dimethoxyethane, diglyme, benzene, cyclohexane, xylene or toluene.

16. A process according to claim 1, wherein the ethylenically unsaturated carboxylic acid or ester is an ?,? ethylenically unsaturated carboxylic acid or ester.

Description

EXAMPLES

(1) All examples show the preparation of methyl methacrylate and methacrylic acid from methyl propionate.

Example 1

(2) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 1.96 g caesium carbonate (6 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was then heated with stirring to 135? C. over 35 minutes. 2.65 g Methyl propionate (30 mmol) and 3 g methyl alcoform (55 mmol formaldehyde) were then injected under nitrogen pressure into the mixture in the autoclave. Injection caused a temperature decrease to 117? C. followed by a temperature spike to 155? C. After the temperature spike, the mixture was heated to 160? C. over 10 minutes. The mixture was maintained at the 160? C. for 4 hours after which stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(3) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios were 68.0% methyl propionate:15.7% caesium propionate:13.5% methyl methacrylate:2.8% caesium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 15.8% conversion of methyl propionate to products and a selectivity with respect to methyl propionate to methyl methacrylate and methacrylic acid of 99.83%.

Example 2

(4) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 2.5 g caesium methylcarbonate (12 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was heated with stirring to 135? C. over 35 minutes. 2.65 g methyl propionate (30 mmol) and 3 g methyl alcoform (55 mmol formaldehyde) were then injected under nitrogen pressure into the mixture in the autoclave. Injection caused a temperature decrease to 118? C. followed by a temperature spike to 152? C. After the temperature spike, the mixture was heated to 160? C. over 10 minutes. The mixture was maintained at the 160? C. for 4 hours after which stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(5) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios were 69.8% methyl propionate:9.4% caesium propionate:18.0% methyl methacrylate:2.8% caesium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 13.8% conversion of methyl propionate to products and a selectivity to methyl methacrylate and methacrylic acid of 99.25%.

Example 3

(6) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 2.5 g caesium methylcarbonate (12 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was then heated with stirring to 135? C. over 35 minutes. 2.65 g methyl propionate (30 mmol) and 0.165 g methyl alcoform (3 mmol formaldehyde) were then injected under nitrogen pressure into the mixture in the autoclave. Injection caused a temperature decrease to 125? C. The mixture was then heated to 160? C. over 10 minutes and was maintained at this temperature for 2 hours after which stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(7) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios were 78.0% methyl propionate:16.0% caesium propionate:3.8% methyl methacrylate:2.2% caesium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 4.4% conversion of methyl propionate to products and a selectivity to methyl methacrylate and methacrylic acid of 99.64%.

Example 4

(8) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 1.368 g potassium methylcarbonate (12 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was heated with stirring to 135? C. over 35 minutes. 2.65 g methyl propionate (30 mmol) and 0.33 g methyl alcoform (6.0 mmol formaldehyde) were then injected under nitrogen pressure into the mixture in the autoclave. Injection caused a temperature decrease to 118? C. followed by a temperature spike to 138? C. After the temperature spike, the mixture was heated to 160? C. over 10 minutes. The mixture was maintained at the 160? C. for 30 minutes after which stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(9) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios were 84.3% methyl propionate:10.3% potassium propionate:5.2% methyl methacrylate:0.2% potassium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 5.5% conversion of methyl propionate to products and a selectivity to methyl methacrylate and methacrylic acid of 99.32%.

Example 5

(10) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 2.5 g caesium methylcarbonate (12 mmol), 2.65 g methyl propionate (30 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was heated with stirring to 160? C. over 50 minutes. 1.65 g methyl alcoform (30 mmol formaldehyde) was then drip fed at 0.05 mL min.sup.?1 for 33 minutes. The mixture was sealed and heated at 160? C. for a further 27 minutes after which stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(11) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios were 55.2% methyl propionate:24.2% caesium propionate:9.6% methyl methacrylate:14.0% caesium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 23.9% conversion of methyl propionate to products and a selectivity to methyl methacrylate and methacrylic acid of 99.46%.

Example 6

(12) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 2.5 g caesium methylcarbonate (12 mmol), 2.65 g methyl propionate (30 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was heated with stirring to 160? C. over 50 minutes. 1.65 g methyl alcoform (30 mmol formaldehyde) was then drip fed at 0.05 mL min.sup.?1 for 33 minutes. The mixture was sealed and heated at 160? C. for a further 27 minutes after which stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(13) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios of propionates and methacrylates were 56.3% methyl propionate:22.5% caesium propionate:10.7% methyl methacrylate:10.5% caesium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 24.3% conversion of methyl propionate to products and a selectivity to methyl methacrylate and methacrylic acid of 99.13%.

Example 7

(14) In a nitrogen-filled glovebox, a 25 mL Parr Series 4590 Pressure reactor autoclave was charged with 2.5 g caesium methylcarbonate (12 mmol), 2.65 g methyl propionate (30 mmol) and 6 mL N,N-dimethylacetamide. The autoclave was pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was heated with stirring to 160? C. over 50 minutes. 1.65 g methyl alcoform (30 mmol formaldehyde) was then drip fed at 0.05 mL min.sup.?1 for 66 minutes. The mixture was sealed and the stirring was stopped and the mixture cooled to below 25? C. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(15) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios of propionates and methacrylates were 49.0% methyl propionate:27.0% caesium propionate:12.0% methyl methacrylate:12.0% caesium methacrylate. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC and showed 25.5% conversion of methyl propionate to products and a selectivity to methyl methacrylate and methacrylic acid of 99.24%.

(16) TABLE-US-00001 TABLE 1 Conversion and selectivity results for examples 1-7 Example no. 1 2 3 4 5 6 7 Conversion/% 15.8 13.8 4.4 5.5 23.9 24.3 25.5 Selectivity/% 99.83 99.25 99.64 99.32 99.46 99.13 99.24

(17) Table 1 summarises the conversion and selectivity results for examples 1-7 and shows that selectivity is independent of yield for the reaction of the invention.

Examples 8-21

General Procedure

(18) A 25 mL Parr Series 4590 Pressure reactor autoclave was charged with base metal salt (12 mmol), solvent (6 mL) and methyl propionate (2.65 g, 30 mmol), then pressurized with nitrogen to 15 bar, purged slowly to 1.5 bar and then sealed. The mixture was heated with stirring to the reaction temperature over 50 minutes. Methyl alcoform (55 weight % formaldehyde, 45 weight % methanol) was added through dropwise addition at 0.05 mL min.sup.?1 until the desired quantity had been added using a Gilson pump. The mixture was stirred for a time to complete the total reaction time at the reaction temperature after which stirring was stopped and the mixture cooled to room temperature. The residual pressure was purged slowly and the exit mixture diluted with methanol until all of the salts had dissolved.

(19) A sample of the solution was analysed by .sup.1H NMR which showed the relative ratios of propionates and methacrylates as methyl propionate, propionate anion, methyl methacrylate and methacrylate anion. The mixture was taken to dryness under high vacuum with collection of the volatile material in a liquid nitrogen trap. The reaction volatiles were analysed by GC using an Agilent 6890N GC equipped with a Restek Rtx-1701 60 meter 0.32 mm ID, 1 micron df column.

Examples 8-21

Results

(20) The data from the analyses carried out as described in the general procedure section above are shown in Table 2.

(21) Abbreviations used in the table are as follows:

(22) CsMC=caesium methylcarbonate

(23) KMC=Potassium methylcarbonate

(24) CsP=caesium propionate

(25) CsMA=caesium methacrylate

(26) DMAc=dimethylacetamide

(27) NMP=1-methyl-2-pyrrolidinone

(28) MIB=methyl isobutyrate

(29) DMAcr=dimethylacrylamide

(30) MeP=methyl propionate

(31) MMA=methyl methacrylate

(32) HCHO=formaldehyde

(33) Excluding methyl 3-methoxyisobutyrate, which can be converted to MMA and methanol by mild treatment as shown in example 24, the selectivities are maintained at high selectivities over a range of conversions of methyl propionate to methyl propionate.

(34) TABLE-US-00002 TABLE 2 Results from examples 8-21 Example No. 8 9 10 11 12 13 14 Base Salt CsMC CsMC CsMC CsMC CsMC CsMC CsMC Solvent DMAc DMAc DMAc DMAc DMAc DMAc DMAc Feed Ratio HCHO:MeP 0.5 1 1 1 1 1 1 Moles Cs/Mole MeP 0.4 0.4 0.4 0.4 0.4 0.4 0.4 T 160 160 160 160 160 160 180 Feed Rate HCHO added/MeP 6.45 6.45 6.45 6.45 6.45 6.45 6.45 equivalents/%/min Total hold time incl feed time 1 1 0.5 2 3 4 1 (hrs) Conversion of Propionate to 15.0 26.4 18.4 31.4 29.7 39.7 33.5 Methacrylate/% Selectivity to methacrylates vs Not measured 99.9 99.8 99.9 99.3 99.7 MeP excluding methyl 3-methoxy- isobutyrate/% Example No. 15 16 17 18 19 20 21 Base Salt KMC CsMC CsMC CsMC CsMC CsMC CsMC Solvent DMAc NMP DMAc DMAc DMAc DMAc DMAc Feed Ratio HCHO:MeP 1 1 1 1 1 1 1 Moles Cs/Mole MeP 0.4 0.4 0.4 0.4 0.4 0.4 0.4 T? C. 160 160 100 100 130 130 180 Feed Rate HCHO added/MeP 6.45 6.45 6.45 6.45 6.45 6.45 6.45 equivalents/%/min Total hold time incl feed time 1 1 2 3 2 3 3 (hrs) Conversion of Propionate to 12.7 26.6 1.5 2.1 12.8 14.5 39.5 Methacrylate/% Selectivity to methacrylates vs 99.8 99.9 99.2 98.5 99.8 99.7 99.8 MeP excluding methyl 3-methoxy- isobutyrate/%

Example 22

(35) Into a 1 L Hastelloy autoclave was added Methyl propionate (160 ml), dry methyl alcoform (0.1 wt water) (140 ml, 55 wt % formaldehyde) and Caesium fluoride (145.5 g). The autoclave was then closed and then heated to 160? C. for two hours. The autoclave was allowed to cool to room temperature and the contents exited. The exit solution was heated under vacuum and the reaction volatiles condensed with liquid Nitrogen. The volatiles were allowed to thaw and were analysed by GC. The GC analysis showed 17.7% conversion of the MeP and a reaction selectivity of 99.7%.

Example 23

(36) Into a 1 L Hastelloy autoclave was added Methyl propionate (160 ml), dry methyl alcoform (0.1 wt water) (140 ml, 55 wet % formaldehyde), methanol (100 ml) and Caesium fluoride (156.6 g). The autoclave was then closed and then heated to 160? C. for two hours. The autoclave was allowed to cool to room temperature and the contents exited. The exit solution was heated under vacuum and the reaction volatiles condensed with liquid Nitrogen. The volatiles were allowed to thaw and were analysed by GC. The GC analysis showed 8.0% conversion of the MeP and a reaction selectivity of 96.6%.

Example 24

Conversion of Methyl 3-Methoxyisobutyrate to MMA

(37) Into a 100 ml Schlenk flask under Nitrogen was added Sodium methoxide (NaOMe; 0.61 g, 11 mmol), this was dissolved in methanol (16.16 g, 517 mmol). Into a separate 250 ml Schlenk flask under Nitrogen was added the methyl 3-methoxyisobutyrate (66.78 g, 505 mmol) and this was heated to 95? C. Once the temperature had stabilised, the NaOMe and methanol solution was added to the methyl 3-methoxyisobutuyrate using a cannula under Nitrogen. A sample of the resultant solution was taken every two minutes for ten minutes, and then 15 minutes for an hour. The samples were passed through silica gel to remove any NaOMe. The samples were then analysed by the use of a GC. After one hour the percentage conversion of methyl 3-methoxyisobutyrate to MMA was 37.27%.

Comparative Example 25

(38) A silica gel catalyst with composition 0.93 wt Zr, 6.35 wt Cs, prepared according to example 3B of WO 03026795, was tested for catalytic performance under conditions described below.

(39) The catalytic performance of the catalyst samples was determined in an atmospheric pressure microreactor charged with 3 g of catalyst beads (2-4 mm diameter). The dry catalysts heated to 350? C. under nitrogen and then fed with a mixture of 68.3 wt % methyl propionate, 19.5 wt % methanol, 6.8 wt % water and 5.4 wt % formaldehyde overnight at a residence time of about 16 seconds. The reaction was then switched to a feed mixture of 74.0 wt % methyl propionate, 19.9 wt % methanol, 0.5 wt % water and 5.6 wt % formaldehyde at such a rate that contact time was varied in steps from 2.9 seconds to 16.5 seconds. After the feed flow had stabilized at each flow rate, the gases from the reactor were condensed by cooling to room temperature and collected in glass vials via canulae fed through plastic lids of the vials to prevent ingress of air and condensation of water.

(40) The samples were transferred to sealed vials immediately after completion of collection of each sample and were analysed by Gas Chromatography, using a Shimadzu GC, equipped with a DB1701 column & a Flame Ionization Detector, in order to determine composition. For each analysis, the resultant chromatograph was processed using Shimadzu's GC solution software to obtain peak areas for individual components. FID response factors for the individual components are applied to convert peak areas, first into wt, and then into mol, of detectable material in the sample.

(41) The principle product was methyl methacrylate, which in addition to methacrylic acid, represents the desired product for calculation of reaction selectivity. Selectivity with respect to desired products was calculated from the sum of molar amount of the methyl methacrylate and methacrylic acid components produced as percentage of the molar amount of propionate converted to products. A part of the methyl propionate was converted to propionic acid. This by-product was excluded from the calculations on the basis that it can be readily converted back to the starting methyl propionate by esterification. All of the other products identified were irreversibly converted from the starting materials and are therefore not able to be recycled.

(42) The identification of the major by-products was made by GCMS and the selectivities to these by-products based on methyl propionate converted to products other than propionic acid are shown in the table 3 below:

(43) TABLE-US-00003 TABLE 3 Results from comparative example 25 Contact time/seconds 2.90 4.72 7.59 16.46 Main Product Yields/% MeP Conversion to prods 14.90 18.46 21.28 24.30 including Propionic Acid Methylmethacrylate (MMA) 11.30 14.14 16.03 17.10 Methacrylic Acid (MAA) 0.43 0.51 0.59 0.66 MMA + MAA 11.72 14.65 16.62 17.76 Propionic Acid 2.47 2.71 2.99 3.22 MeP Reaction Selectivity-PA/% MMA 90.89 89.78 87.71 81.13 MAA 3.45 3.20 3.21 3.13 MMA + MAA 94.34 92.98 90.92 84.26 Total Lights 1.19 1.02 0.88 0.75 Mediums 0.25 0.31 0.43 0.88 Heavy By-products 4.22 5.69 7.77 14.11

(44) Thus, the selectivity of conversion of methyl propionate of methyl methacrylate plus methacrylic acid falls from 94% to 84% as the yield is increased from 11.7% to 17.8% based on methyl propionate fed. None of the major by-products can be converted back to methyl methacrylate by simple chemical processing.

(45) Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

(46) All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

(47) Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(48) The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.