CA2193408A1 - Esterification of (meth)acrylic acid with an alkanol - Google Patents
Esterification of (meth)acrylic acid with an alkanolInfo
- Publication number
- CA2193408A1 CA2193408A1 CA002193408A CA2193408A CA2193408A1 CA 2193408 A1 CA2193408 A1 CA 2193408A1 CA 002193408 A CA002193408 A CA 002193408A CA 2193408 A CA2193408 A CA 2193408A CA 2193408 A1 CA2193408 A1 CA 2193408A1
- Authority
- CA
- Canada
- Prior art keywords
- meth
- acid
- acrylic acid
- bottom product
- oligomeric
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 238000005886 esterification reaction Methods 0.000 title claims abstract description 33
- 230000032050 esterification Effects 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 claims abstract description 35
- -1 acrylic ester Chemical class 0.000 claims abstract description 21
- 239000003054 catalyst Substances 0.000 claims abstract description 14
- 239000003377 acid catalyst Substances 0.000 claims abstract description 9
- 238000004821 distillation Methods 0.000 claims abstract description 9
- 239000007858 starting material Substances 0.000 claims abstract description 9
- 239000000047 product Substances 0.000 claims description 47
- 238000010494 dissociation reaction Methods 0.000 claims description 46
- 230000005593 dissociations Effects 0.000 claims description 46
- 239000002253 acid Substances 0.000 claims description 27
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 150000007513 acids Chemical class 0.000 claims description 8
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 6
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 4
- 206010013457 Dissociation Diseases 0.000 claims description 4
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 4
- 229910001882 dioxygen Inorganic materials 0.000 claims description 4
- 208000018459 dissociative disease Diseases 0.000 claims description 4
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 3
- 239000011707 mineral Substances 0.000 claims description 3
- 150000007524 organic acids Chemical class 0.000 claims description 3
- 235000005985 organic acids Nutrition 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 229940098779 methanesulfonic acid Drugs 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 20
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 15
- 150000002148 esters Chemical class 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 7
- 238000005755 formation reaction Methods 0.000 description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 5
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 4
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical compound CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000006845 Michael addition reaction Methods 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 3
- 229960003903 oxygen Drugs 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000010626 work up procedure Methods 0.000 description 3
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 description 2
- YIWUKEYIRIRTPP-UHFFFAOYSA-N 2-ethylhexan-1-ol Chemical compound CCCCC(CC)CO YIWUKEYIRIRTPP-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 150000002170 ethers Chemical class 0.000 description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 2
- GOXQRTZXKQZDDN-UHFFFAOYSA-N 2-Ethylhexyl acrylate Chemical compound CCCCC(CC)COC(=O)C=C GOXQRTZXKQZDDN-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 241000153282 Theope Species 0.000 description 1
- ZZAGLMPBQOKGGT-UHFFFAOYSA-N [4-[4-(4-prop-2-enoyloxybutoxy)benzoyl]oxyphenyl] 4-(4-prop-2-enoyloxybutoxy)benzoate Chemical compound C1=CC(OCCCCOC(=O)C=C)=CC=C1C(=O)OC(C=C1)=CC=C1OC(=O)C1=CC=C(OCCCCOC(=O)C=C)C=C1 ZZAGLMPBQOKGGT-UHFFFAOYSA-N 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 1
- 150000001253 acrylic acids Chemical class 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 125000003545 alkoxy group Chemical group 0.000 description 1
- 125000005907 alkyl ester group Chemical group 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- PYRZPBDTPRQYKG-UHFFFAOYSA-N cyclopentene-1-carboxylic acid Chemical compound OC(=O)C1=CCCC1 PYRZPBDTPRQYKG-UHFFFAOYSA-N 0.000 description 1
- 238000007700 distillative separation Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- BQUDLWUEXZTHGM-UHFFFAOYSA-N ethyl propaneperoxoate Chemical compound CCOOC(=O)CC BQUDLWUEXZTHGM-UHFFFAOYSA-N 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011552 falling film Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- BDJSOPWXYLFTNW-UHFFFAOYSA-N methyl 3-methoxypropanoate Chemical compound COCCC(=O)OC BDJSOPWXYLFTNW-UHFFFAOYSA-N 0.000 description 1
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- NWVVVBRKAWDGAB-UHFFFAOYSA-N p-methoxyphenol Chemical compound COC1=CC=C(O)C=C1 NWVVVBRKAWDGAB-UHFFFAOYSA-N 0.000 description 1
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007127 saponification reaction Methods 0.000 description 1
- 238000010517 secondary reaction Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 150000003460 sulfonic acids Chemical class 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/60—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/62—Use of additives, e.g. for stabilisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
- C07C69/52—Esters of acyclic unsaturated carboxylic acids having the esterified carboxyl group bound to an acyclic carbon atom
- C07C69/533—Monocarboxylic acid esters having only one carbon-to-carbon double bond
- C07C69/54—Acrylic acid esters; Methacrylic acid esters
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
In a process for esterifying (meth)acrylic acid with an alkanol in the presence of an esterification catalyst in which unreacted starting com-pounds and the (meth)acrylic ester formed are separated off by distillation and a bottom product containing oxy esters is obtained, the bottom product is separated off and either the bottom product is directly admixed with oligomeric (meth)acrylic acid and the oxy esters present in the bottom product are dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid, or the oxy esters are first separated by distillation from the bottom product, the distillate is admixed with oligomeric (meth)acrylic acid and is dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid.
Description
2193~08 I
- Estt~:r~ n of (meth)acrylic acid with an alkanol The invention relates to a process for the esterification of (meth)acrylic acid with an alkanol in the pl~sence of an esterification ca-5 talyst, in which unreacted starting compounds and the (meth)acrylic esterformed are separated off by ~i~till~ion and a bottom product co,~ ising oxy esters is obtained. The term (meth)acrylic acid here denotes, as is cus-tomary, acrylic or ,llellla~ lic acid.
The preparation of alkyl esters of (meth)acrylic acid is usually o carried out by esterification of (meth)acrylic acid with alkanols at elevated lempe,alul~ in the liquid phase in the p~sellce or absence of solvent and in the ~l~sel1ce of acid as catalyst (DE-A 23 39 519). A disadvantage of this method of plepal~tion is the secondary reactions occulling under the abo~ elltioned esterification conditions, viz. as yet u~ ,acled starting alcohol adds onto the double bond of alkyl (meth)acrylate already formed (Michael addition) to give a colllpoul1d of the general formula I below and as yet umeac~ed (meth)acrylic acid adds onto the double bond of the ester formed to give a colllpound of the general formula II. Multiple addition is also possible. In addition, mixed types can occur. These adducts (alkoxy 20 esters and acyloxy esters) are abb~iattd as oxy esters.
RO--(CH2-CH--C02),~--R (I) R' R' CH2=C--CO2--(CH2--CH--C02)y--R (II) 2193~D~
- Estt~:r~ n of (meth)acrylic acid with an alkanol The invention relates to a process for the esterification of (meth)acrylic acid with an alkanol in the pl~sence of an esterification ca-5 talyst, in which unreacted starting compounds and the (meth)acrylic esterformed are separated off by ~i~till~ion and a bottom product co,~ ising oxy esters is obtained. The term (meth)acrylic acid here denotes, as is cus-tomary, acrylic or ,llellla~ lic acid.
The preparation of alkyl esters of (meth)acrylic acid is usually o carried out by esterification of (meth)acrylic acid with alkanols at elevated lempe,alul~ in the liquid phase in the p~sellce or absence of solvent and in the ~l~sel1ce of acid as catalyst (DE-A 23 39 519). A disadvantage of this method of plepal~tion is the secondary reactions occulling under the abo~ elltioned esterification conditions, viz. as yet u~ ,acled starting alcohol adds onto the double bond of alkyl (meth)acrylate already formed (Michael addition) to give a colllpoul1d of the general formula I below and as yet umeac~ed (meth)acrylic acid adds onto the double bond of the ester formed to give a colllpound of the general formula II. Multiple addition is also possible. In addition, mixed types can occur. These adducts (alkoxy 20 esters and acyloxy esters) are abb~iattd as oxy esters.
RO--(CH2-CH--C02),~--R (I) R' R' CH2=C--CO2--(CH2--CH--C02)y--R (II) 2193~D~
where x,y = 1-S
R = alkyl R' = H or CH3 When R' = H, the esterification is of acrylic acid, when s R' = CH3, the esterification is of metllaclylic acid.
The problem of oxy ester formation is particularly acute in the p.eyaralion of esters of acrylic acid, with the main oxy esters formed being alko~yyroyionic esters and acylor~yylopionic esters where x,y = 1. In the ~,~palalion of esters of ,.,~ clylic acid, oxy ester formation occurs to a o lesser extent. The formation of oxy esters is described in DE-A 23 39 529.
This indicates that the formation of oxy esters occurs esse~ lly indepen-dently of the specific esterification conditions. Of very particular importance is oxy ester formation in the ylepalation of acrylates of Cl-C8-alkanols, in particular C4-C8-alkanols, very particularly in the preyalation of n-butyl S acrylate and 2-ethylhexyl acrylate.
It is a characleli~lic of the oxy esters that their boiling point is above the boiling point of starting acid, starting alcohol, target ester formed and any organic solvent also used.
The work-up of any such esterification reaction mixture is normally 20 carried out by sepalating ul~l~aeled starting comyuul~ds and the target esterfrom the reaction lllL~tUlC by ~i.ctill~tion, with the acid catalyst used for the esterification being able to be removed berul~hand, if app,oyliate~ by extrac-tion with water and/or aqueous alkali (cf. for example, Ullmann's Encyclo-pedia of Industrial Chemistry, Vol. A1, 5th Ed., VCH, p. 167 ff.). The 25 bottom product rem~inin~ in such a (li~till~tive work-up contains the oxy esters which result in a considelable loss in yield.
For this reason, various further methods have been Px~minP~I in order to solve the problems resulting from formation of the oxy esters.
Thus, JP-A-82t62229 describes the ~lk~linP saponification of the high-boiling 30 esterification residues. In this way, part of the alcohol used and acrylic acid and ,B-hydro~yl,lopionic acid or- their salts are recovered. A simple and eco-nomical return of the products to the esterification reaction is therefore not possible. JP-B-72/15936 describes the preparation of acrylic esters by reac-ting ,l~-alko~y~ropionic esters with acrylic acid in the presellce of strong 5 acids (lr~nSeSlel iGcation) However, this forms as by-product equimolar amounts of ~-alkuAy~ropionic acid which cannot be relull.ed to the esterifi-cation reaction and thererole .el,resellt waste material. JP-A-93/25086 des-cribes the dissociation of the Michael addition product butyl ,~-butoxypro-pionate (see formula I, x = 1, R = butyl) at elevated te~ le and in o the plesel~ce of sulfuric acid and an excess of water. However, the yield is only about 30% Finally, JP-A-94/65149 describes the dissociation of the Michael addition products I and II (see above, x = y = 1) in the p,esellce of ~ ,i...,. alkoxides. In this reaction, the CO~ ion is likewise low (< 60%) and large amounts of titanate are llecessal~. This process is there-15 fore ~necollo...ical and e~vilor~ entally unfriendly because of the largeamounts of titanate to be disposed of.
GB 923 595 describes the recovery of monomers from the residue of the esterification of acrylic acid with alkanols in the absence of molecu-lar oxygen. It reCol~....el~, inter alia, the removal of all volatile monomers 20 prior to the dissociation, dissocialion in the l,resellce of sulfuric acid and removal of the dissociation products by means of a stream of inert gas.
According to the examples, the dissociation is always carried out at at least 300C. Coke is formed as residue (17~0%) and this has to be dug out of the reactor. This process is therefore neither economical nor can it be 25 carried out on an industrial scale. A further disadvantage is the need to exclude oxygen.
CN-A 1,063,678 describes the dissociation of the alko~y~,opionic ester present in the esterification residue in the l~,esence of sulfuric acid ina c~scade, with temperature and catalyst concelllr~tion (0.8-1.5%) being dif-30 ferent in each reactor. Coupled with the dissociation is a ~ till~ion to separate alkanol and acrylate. The process is very cumbersomeand does not achieve high conversions.
Finally, CN-A 1,058,390 describes the dissociation of alkoxypropionic esters in the presence of sulfuric acid, etc., into alkanols and acrylic esters. This is carried out stepwise. The dissociation is first carried out under reflux and the reaction products are subsequently distilled off. The dissociation of the acrylic acid-containing ester residues from the preparation of ethyl/methyl acrylate (ethyl 10 ethoxypropionate, methyl methoxypropionate) is carried out in the presence of ethanol or methanol. Here too, the process is complicated and does not achieve high conversions.
It is an object of the present invention to carry out the redissociation of the oxy esters present in this bottom product and to reuse the starting acid, starting alcohol and target ester obtained thereby for the purposes of the esterification without the disadvantages of the processes of the prior art.
We have found that this object is achieved by a 20 process for esterifying (meth)acrylic acid with an alkanol in the presence of an esterification catalyst in which unreacted starting compounds and the (meth)acrylic ester formed are separated off by distillation and a bottom product containing oxy ester is obtained, wherein the bottom product is separated off and either (a) the bottom product is admixed directly with oligomeric (meth)acrylic acid and the oxy esters present in the bottom product are dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid or (b) the oxy esters are first separated by distillation from the bottom product, the distillate is admixed with oligomeric (meth)acrylic acid and is dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid. The alkanol is preferably n-butanol or 2-ethylhexanol. In general, from 10 to 50% by weight, preferably from 10 to 40% by weight, based on the amount of bottom product in (a) or distillate in (b), 219340g 4a of oligomeric (meth)acrylic acid is added. Oligomeric acrylic acid is normally employed in a form known per se, stabilized by means of polymerization inhibitors. Advantageously, the oligomeric (meth)acrylic acid used for this purpose is the b ~
distillative purification of raw acrylic acid; this botlom product comprises mainly compounds of forn1ula III below (see, for example, DE 22 35 326):
CH2= CH-C02-(CH2 CH2 C02) -H (III) x = 1 - 5 The (meth)actylic acid oligomers can be added to the mixture to be dissociated prior to the dissociation. They can also be fed separately into the dissociation reactor.
o These oligomers are not free-radical oligomers, but Michael adducts of the acid with itself, as are obtained as by-products in, for example, the distillation of (meth)acrylic acid. These oligomers are usually burnt as nu~uc ~clable by-pl~lucls from (meth)acrylic acid p~uduction. Under the redissociation conditions, these oligolnelic (meth)acrylic acids are also 15 redissocialed, continuously generating free (meth)acrylic acid in statu nascen-di.
Col"pa~d with a prior addition of (meth)acrylic acid, this has the advantage that the (meth)actylic acid added does not immediately distill off together with the dissociation products, but the dissociation proceeds continu-20 ously in the plesence of (meth)acrylic acid, which results in led~ced forma-tion of by-products (diallcyl ethers, olefins). According to an advantageous embodiment of the invention, the process of dissociation is carried out in the p~sence of molecular oxygen.
According to a further advantageous embodiment of the invention, 25 the product to be dissociated has added to it, in addilion to the acid esteri-fication catalyst which is different from oligomeric (meth)acrylic acid and may already be present, further acids selected from the group collsi~ g of mineral acids such as sulfuric acid or phosphoric acid, and organic acids different from oligonlelic (meth)acrylic acid, for example alkyl- or arylsul-30 fonic acids such as methanesulfonic acid or p-toluenesulfonic acid. The totalamount of acid different ftom oligomeric (meth)acrylic acid which is then present can be from 1 to 20% by weight, preferably from 5 to 15 % by weight, based on the amount of the bottom product in (a) or distillate in (b). It is particularly useful if a ~llipping gas preferably cont~ining molecu-lar oxygen is passed through the bottom product in (a) or the ~ictill~te in (b) as an entrainer for the dissociation products. Air or mixtures of air with inert gas (e.g. nitrogen) are advantageously used as sl~ipping gas.
The advantages of the process of the present invention are, in particular, that the dissociation proceeds more quickly and that a smaller amount of by-products such as ethers or olefins is formed. Thus, among o other things, smaller losses of starting materials, particularly of alcohols, occur than in known processes. In addition, high dissociation yields can be achieved. The direct return of the dissociation mixture does not adversely affect the purity of the (meth)acrylic ester and leads to a low ether content.
For this reason, no complicated separation of the ether from the easily poly~ i~ble (meth)acrylic ester is ll~cess~-~. All in all, this also means reduced environmental pollution, since smaller amounts of residue are obtained.
In the distillative separation of the oxy esters from the bottom product, the (li.ctill~tion conditions depend on the type of alcohol col.,pon~n used in the esterification. In general, a l~l~.pc~al~lre of from 100 to 300C
and a ple~i~UlC of from 1 to 50 mbar are employed. Any con~el-lional dictill~ion appa,~lus is suitable for the distillation process. Since only a sirnple sep~tion task is to be pclr~ .cd, a simple splash guard is gener-ally sufflcient, i.e. a column is not normally required.
For the dissociation of the oxy esters sepal~led o~ by tlic~illation or present in the bottom product, a simple heatable stirred reactor with jacket heating or heating coil, or else a forced-circulation evaporator, for example a falling-film evaporator or flash evaporator, coupled with a resi-dence time vessel, can be used. To achieve better sepalation of the dis-sociation products, it may be advantageous to use a rectification attachment -superposed on the dissociation apparatus, for example a packed or tray column. This rectification attachment is generally operated using stabilization by pol~ c~i~ation inhibitors (e.g. phenothi~7.ine, hydroquinone monomethyl ether, etc.).
The conditions for ca"ying out the process of the present invention for dissociating oxy esters formed in the bottom product in the esterification or sepaldled from the bottom product are as follows:
Catalyst: at least one acid selected from the group consi-sting of mineral acids, for example sulfuric acid o and phosphoric acid, and organic acids dilIcl~nl from oligomeric (meth)acrylic acid, for example alkyl- or arylsulfonic acids such as fonic or p-toluenesulfonic acid Amount of catalyst: 1-20% by weight, preferably 5-15% by weight, based on the amount of bottom product in (a) or of the oxy ester (li.ctill~te sepalaled from the bottom product in (b) Amount of oligo,neric (meth)acrylic acid: 5-50% by weight, preferably 10-40% by weight, based on the amount of bottom product in (a) or of the oxy ester ~i.still~te separated from the bottom product in (b) Te"lpendl~,e: 150-250C, preferably 180-230C
Pressure: preferably at atmospheric p,c~u,e or under 2S ~cduced ~IcS~ulc (so that the dissociation pro-ducts immediately vaporize) ( < 1 atm) Sl.ipphlg gas, if used: amount: 1-100 I/h Reaction time: 1-10 hours 30 Ccsll~ ioll: 2 90%
2193~08 . ~
The reaction is carried out, for example, by the bottom product to be dissociated being taken continuously from the dictillative work-up of the esterification mixture and fed together with the dissociation catalyst to the dissociation reactor. However, the reaction can also be carried out 5 batchwise. It is also possible to use a semicontinuous reaction procedure in which the product to be dissociated is continuously fed to the dissociation reactor (which contains the dissociation catalyst), and the bottom product is removed batchwise from the dissociation reactor only after the dissociation is complete. The dissociation products are scpalated off continuously by lO di~till~tion.
The applicability of the dissociation process described is not l~lliclcd to a specific type of esterification process from which the oxy esters, i.e. the addition compounds I and II, are obtained as by-products.
In general, the esters are p~ cd by customary methods (see Ullmann's ~5 Encyclopedia of InJu~llial Ch.,lni~lly, Vol. A1, 5th Ed., VCH, p. 167 fl.).
A typical example of the conditions under which the esterification prece~lin~ the dissociation of the oxy esters can take place can be briefly ~lcsenlcd as follows:
Alcohol: (meth)acrylic acid 1:0.7-1.2 (molar) 20 Catalyst: sulfuric acid or sulfonic acids Amount of catalyst: 0.1-10% by weight (preferably 0.5-5%
by weight) based on starting material Stabili_ation: 200-2,000 ppm of phellotlli~7in~ (based on the weight of the starting materials) Reaction t~ ,: 80-160C, preferably 90-130C
Reaction time: 1-10 hours, plcrclably 1-6 hours If desired, an entrainer (e.g. cyclohexane or toluene) may be used to remove the water of esterification. The esterification can be carried out 2193~08 g at atmospheric ples~u.~, under superatmospheric pressure or subatmospheric pressure, either continually or batchwise.
In the acid-catalyzed esterification of acrylic acid with alkanols, the bottom product obtained after separating off the acid esterification 5 catalyst, the unreacted starting materials and the acrylic ester generally has the following composition:
1-20% by weight of acrylic ester 50-80% by weight of alkv~yL,Ivpionates (see formula I) 5-30% by weight of acylo~y~lupionates (see formula II) l0 re~ n~er: mainly stabili~ers (phenoll~iA~i~u) and polymers Further details and advantages of the process of the present invention may be taken from the examples described below.
Firstly, a result achieved using a process not acco~ g to the present invention will be described by means of a con~al~ e example.
COMPARATIVE EXAMPLE
A glass circulation reactor (volume: 1 1) heated by means of a heating plug was chalged with 500 g of an oxy ester ~ till~te obtained from an esterification residue from n-butyl acrylate production which has been freed of the acid esterification catalyst, together with 40 g of p-tolue-20 nesulfonic acid. The oxy ester ~ till~t~ co-~p-ised 11.0% by weight of butyl acrylate, 64.8% by weight of butoxy ester I ( R = C4Hg) 20.5% by weight of acyloxy ester II ( R = C4Hg).
The dissociation ~e~ e.alu.e was 195C and the opel~ g ples~llre 25 was 1 atm.
During the dissociation, the esterification residue to be dissociated was co,.ti...lv~lsly fed to the dissociation reactor, regulated by the level in the reactor.
The dissociation products were taken off in vapor form and 30 condensed at the top of the column (50 cm x 2.8 cm, empty) superposed on the dissociation reactor. Over a period of 119.5 hours, 7,401 g of mixture were fed to the dissociation reactor and 7,080 g of dissociation products were condensed.
According to analysis by gas chromatography, the condencate s complised:
72.0% by weight of butyl acrylate 13 .9% by weight of butanol 4.8% by weight of acrylic acid 1.4% by weight of dibutyl ether o 6.6% by weight of butenes 0.2% by weight of butyl bulo~yl~ol)iollate Conversion: 96% by weight based on oxy esters.
The dissociation bollollls were still readily handleable (pumpable) at 25C and contained no solids.
A glass circulation reactor (volume: 1 1) heated by means of a heating plug was chal~ed with 500 g of the oxy ester dictillqte from the Col~ slative Exarnple, with addition of 40 g of p-toluenesulfonic acid and 10 g of a ~li.ctillqtion residue obtained in the production of a pure acrylic 20 acid ~ic~illqte and having the following co",~osilion:
5.5% by weight of acrylic acid 54.0% by weight of diacrylic acid 14.5% by weight of dodecylbe.~el-e~.llfonic acid remqin~er: mainly polymers of acrylic acid and phenothiq7ine.
The dissocialion l~ lul~; was 195C and the ope~ g pl`es~ul'e was 1 atm.
The oxy ester dictillq-te and the cGllespollding amount of acrylic acid dic~illqtion residue (20% by weight) were continuously fed to the reactor, regulated by the level in the reactor. 10% by weight of the feed 30 flow was continuously removed from the reactor.
11 2193~û8 Over a period of 302 hours, 23,985 g of the mixture of oxy ester ~ictill~te and acrylic acid distillation residue was fed to the dissociation reactor and 21,580 g of product mixture were conl1el1.ced. According to analysis by gas c~umatography, the condensate cûlll~ ed:
569.5% by weight of butyl acrylate 6.1% by weight of butanol 19.5% by weight of acrylic acid 0.6% by weight of dibutyl ether 3.1% by weight of butenes l0 Conversion: 96% by weight based on oxy esters.
It can be seen from the above example of the process of the present invention that this process is able to achieve higher conversions and results in smaller losses of starting material than in known processes.
R = alkyl R' = H or CH3 When R' = H, the esterification is of acrylic acid, when s R' = CH3, the esterification is of metllaclylic acid.
The problem of oxy ester formation is particularly acute in the p.eyaralion of esters of acrylic acid, with the main oxy esters formed being alko~yyroyionic esters and acylor~yylopionic esters where x,y = 1. In the ~,~palalion of esters of ,.,~ clylic acid, oxy ester formation occurs to a o lesser extent. The formation of oxy esters is described in DE-A 23 39 529.
This indicates that the formation of oxy esters occurs esse~ lly indepen-dently of the specific esterification conditions. Of very particular importance is oxy ester formation in the ylepalation of acrylates of Cl-C8-alkanols, in particular C4-C8-alkanols, very particularly in the preyalation of n-butyl S acrylate and 2-ethylhexyl acrylate.
It is a characleli~lic of the oxy esters that their boiling point is above the boiling point of starting acid, starting alcohol, target ester formed and any organic solvent also used.
The work-up of any such esterification reaction mixture is normally 20 carried out by sepalating ul~l~aeled starting comyuul~ds and the target esterfrom the reaction lllL~tUlC by ~i.ctill~tion, with the acid catalyst used for the esterification being able to be removed berul~hand, if app,oyliate~ by extrac-tion with water and/or aqueous alkali (cf. for example, Ullmann's Encyclo-pedia of Industrial Chemistry, Vol. A1, 5th Ed., VCH, p. 167 ff.). The 25 bottom product rem~inin~ in such a (li~till~tive work-up contains the oxy esters which result in a considelable loss in yield.
For this reason, various further methods have been Px~minP~I in order to solve the problems resulting from formation of the oxy esters.
Thus, JP-A-82t62229 describes the ~lk~linP saponification of the high-boiling 30 esterification residues. In this way, part of the alcohol used and acrylic acid and ,B-hydro~yl,lopionic acid or- their salts are recovered. A simple and eco-nomical return of the products to the esterification reaction is therefore not possible. JP-B-72/15936 describes the preparation of acrylic esters by reac-ting ,l~-alko~y~ropionic esters with acrylic acid in the presellce of strong 5 acids (lr~nSeSlel iGcation) However, this forms as by-product equimolar amounts of ~-alkuAy~ropionic acid which cannot be relull.ed to the esterifi-cation reaction and thererole .el,resellt waste material. JP-A-93/25086 des-cribes the dissociation of the Michael addition product butyl ,~-butoxypro-pionate (see formula I, x = 1, R = butyl) at elevated te~ le and in o the plesel~ce of sulfuric acid and an excess of water. However, the yield is only about 30% Finally, JP-A-94/65149 describes the dissociation of the Michael addition products I and II (see above, x = y = 1) in the p,esellce of ~ ,i...,. alkoxides. In this reaction, the CO~ ion is likewise low (< 60%) and large amounts of titanate are llecessal~. This process is there-15 fore ~necollo...ical and e~vilor~ entally unfriendly because of the largeamounts of titanate to be disposed of.
GB 923 595 describes the recovery of monomers from the residue of the esterification of acrylic acid with alkanols in the absence of molecu-lar oxygen. It reCol~....el~, inter alia, the removal of all volatile monomers 20 prior to the dissociation, dissocialion in the l,resellce of sulfuric acid and removal of the dissociation products by means of a stream of inert gas.
According to the examples, the dissociation is always carried out at at least 300C. Coke is formed as residue (17~0%) and this has to be dug out of the reactor. This process is therefore neither economical nor can it be 25 carried out on an industrial scale. A further disadvantage is the need to exclude oxygen.
CN-A 1,063,678 describes the dissociation of the alko~y~,opionic ester present in the esterification residue in the l~,esence of sulfuric acid ina c~scade, with temperature and catalyst concelllr~tion (0.8-1.5%) being dif-30 ferent in each reactor. Coupled with the dissociation is a ~ till~ion to separate alkanol and acrylate. The process is very cumbersomeand does not achieve high conversions.
Finally, CN-A 1,058,390 describes the dissociation of alkoxypropionic esters in the presence of sulfuric acid, etc., into alkanols and acrylic esters. This is carried out stepwise. The dissociation is first carried out under reflux and the reaction products are subsequently distilled off. The dissociation of the acrylic acid-containing ester residues from the preparation of ethyl/methyl acrylate (ethyl 10 ethoxypropionate, methyl methoxypropionate) is carried out in the presence of ethanol or methanol. Here too, the process is complicated and does not achieve high conversions.
It is an object of the present invention to carry out the redissociation of the oxy esters present in this bottom product and to reuse the starting acid, starting alcohol and target ester obtained thereby for the purposes of the esterification without the disadvantages of the processes of the prior art.
We have found that this object is achieved by a 20 process for esterifying (meth)acrylic acid with an alkanol in the presence of an esterification catalyst in which unreacted starting compounds and the (meth)acrylic ester formed are separated off by distillation and a bottom product containing oxy ester is obtained, wherein the bottom product is separated off and either (a) the bottom product is admixed directly with oligomeric (meth)acrylic acid and the oxy esters present in the bottom product are dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid or (b) the oxy esters are first separated by distillation from the bottom product, the distillate is admixed with oligomeric (meth)acrylic acid and is dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid. The alkanol is preferably n-butanol or 2-ethylhexanol. In general, from 10 to 50% by weight, preferably from 10 to 40% by weight, based on the amount of bottom product in (a) or distillate in (b), 219340g 4a of oligomeric (meth)acrylic acid is added. Oligomeric acrylic acid is normally employed in a form known per se, stabilized by means of polymerization inhibitors. Advantageously, the oligomeric (meth)acrylic acid used for this purpose is the b ~
distillative purification of raw acrylic acid; this botlom product comprises mainly compounds of forn1ula III below (see, for example, DE 22 35 326):
CH2= CH-C02-(CH2 CH2 C02) -H (III) x = 1 - 5 The (meth)actylic acid oligomers can be added to the mixture to be dissociated prior to the dissociation. They can also be fed separately into the dissociation reactor.
o These oligomers are not free-radical oligomers, but Michael adducts of the acid with itself, as are obtained as by-products in, for example, the distillation of (meth)acrylic acid. These oligomers are usually burnt as nu~uc ~clable by-pl~lucls from (meth)acrylic acid p~uduction. Under the redissociation conditions, these oligolnelic (meth)acrylic acids are also 15 redissocialed, continuously generating free (meth)acrylic acid in statu nascen-di.
Col"pa~d with a prior addition of (meth)acrylic acid, this has the advantage that the (meth)actylic acid added does not immediately distill off together with the dissociation products, but the dissociation proceeds continu-20 ously in the plesence of (meth)acrylic acid, which results in led~ced forma-tion of by-products (diallcyl ethers, olefins). According to an advantageous embodiment of the invention, the process of dissociation is carried out in the p~sence of molecular oxygen.
According to a further advantageous embodiment of the invention, 25 the product to be dissociated has added to it, in addilion to the acid esteri-fication catalyst which is different from oligomeric (meth)acrylic acid and may already be present, further acids selected from the group collsi~ g of mineral acids such as sulfuric acid or phosphoric acid, and organic acids different from oligonlelic (meth)acrylic acid, for example alkyl- or arylsul-30 fonic acids such as methanesulfonic acid or p-toluenesulfonic acid. The totalamount of acid different ftom oligomeric (meth)acrylic acid which is then present can be from 1 to 20% by weight, preferably from 5 to 15 % by weight, based on the amount of the bottom product in (a) or distillate in (b). It is particularly useful if a ~llipping gas preferably cont~ining molecu-lar oxygen is passed through the bottom product in (a) or the ~ictill~te in (b) as an entrainer for the dissociation products. Air or mixtures of air with inert gas (e.g. nitrogen) are advantageously used as sl~ipping gas.
The advantages of the process of the present invention are, in particular, that the dissociation proceeds more quickly and that a smaller amount of by-products such as ethers or olefins is formed. Thus, among o other things, smaller losses of starting materials, particularly of alcohols, occur than in known processes. In addition, high dissociation yields can be achieved. The direct return of the dissociation mixture does not adversely affect the purity of the (meth)acrylic ester and leads to a low ether content.
For this reason, no complicated separation of the ether from the easily poly~ i~ble (meth)acrylic ester is ll~cess~-~. All in all, this also means reduced environmental pollution, since smaller amounts of residue are obtained.
In the distillative separation of the oxy esters from the bottom product, the (li.ctill~tion conditions depend on the type of alcohol col.,pon~n used in the esterification. In general, a l~l~.pc~al~lre of from 100 to 300C
and a ple~i~UlC of from 1 to 50 mbar are employed. Any con~el-lional dictill~ion appa,~lus is suitable for the distillation process. Since only a sirnple sep~tion task is to be pclr~ .cd, a simple splash guard is gener-ally sufflcient, i.e. a column is not normally required.
For the dissociation of the oxy esters sepal~led o~ by tlic~illation or present in the bottom product, a simple heatable stirred reactor with jacket heating or heating coil, or else a forced-circulation evaporator, for example a falling-film evaporator or flash evaporator, coupled with a resi-dence time vessel, can be used. To achieve better sepalation of the dis-sociation products, it may be advantageous to use a rectification attachment -superposed on the dissociation apparatus, for example a packed or tray column. This rectification attachment is generally operated using stabilization by pol~ c~i~ation inhibitors (e.g. phenothi~7.ine, hydroquinone monomethyl ether, etc.).
The conditions for ca"ying out the process of the present invention for dissociating oxy esters formed in the bottom product in the esterification or sepaldled from the bottom product are as follows:
Catalyst: at least one acid selected from the group consi-sting of mineral acids, for example sulfuric acid o and phosphoric acid, and organic acids dilIcl~nl from oligomeric (meth)acrylic acid, for example alkyl- or arylsulfonic acids such as fonic or p-toluenesulfonic acid Amount of catalyst: 1-20% by weight, preferably 5-15% by weight, based on the amount of bottom product in (a) or of the oxy ester (li.ctill~te sepalaled from the bottom product in (b) Amount of oligo,neric (meth)acrylic acid: 5-50% by weight, preferably 10-40% by weight, based on the amount of bottom product in (a) or of the oxy ester ~i.still~te separated from the bottom product in (b) Te"lpendl~,e: 150-250C, preferably 180-230C
Pressure: preferably at atmospheric p,c~u,e or under 2S ~cduced ~IcS~ulc (so that the dissociation pro-ducts immediately vaporize) ( < 1 atm) Sl.ipphlg gas, if used: amount: 1-100 I/h Reaction time: 1-10 hours 30 Ccsll~ ioll: 2 90%
2193~08 . ~
The reaction is carried out, for example, by the bottom product to be dissociated being taken continuously from the dictillative work-up of the esterification mixture and fed together with the dissociation catalyst to the dissociation reactor. However, the reaction can also be carried out 5 batchwise. It is also possible to use a semicontinuous reaction procedure in which the product to be dissociated is continuously fed to the dissociation reactor (which contains the dissociation catalyst), and the bottom product is removed batchwise from the dissociation reactor only after the dissociation is complete. The dissociation products are scpalated off continuously by lO di~till~tion.
The applicability of the dissociation process described is not l~lliclcd to a specific type of esterification process from which the oxy esters, i.e. the addition compounds I and II, are obtained as by-products.
In general, the esters are p~ cd by customary methods (see Ullmann's ~5 Encyclopedia of InJu~llial Ch.,lni~lly, Vol. A1, 5th Ed., VCH, p. 167 fl.).
A typical example of the conditions under which the esterification prece~lin~ the dissociation of the oxy esters can take place can be briefly ~lcsenlcd as follows:
Alcohol: (meth)acrylic acid 1:0.7-1.2 (molar) 20 Catalyst: sulfuric acid or sulfonic acids Amount of catalyst: 0.1-10% by weight (preferably 0.5-5%
by weight) based on starting material Stabili_ation: 200-2,000 ppm of phellotlli~7in~ (based on the weight of the starting materials) Reaction t~ ,: 80-160C, preferably 90-130C
Reaction time: 1-10 hours, plcrclably 1-6 hours If desired, an entrainer (e.g. cyclohexane or toluene) may be used to remove the water of esterification. The esterification can be carried out 2193~08 g at atmospheric ples~u.~, under superatmospheric pressure or subatmospheric pressure, either continually or batchwise.
In the acid-catalyzed esterification of acrylic acid with alkanols, the bottom product obtained after separating off the acid esterification 5 catalyst, the unreacted starting materials and the acrylic ester generally has the following composition:
1-20% by weight of acrylic ester 50-80% by weight of alkv~yL,Ivpionates (see formula I) 5-30% by weight of acylo~y~lupionates (see formula II) l0 re~ n~er: mainly stabili~ers (phenoll~iA~i~u) and polymers Further details and advantages of the process of the present invention may be taken from the examples described below.
Firstly, a result achieved using a process not acco~ g to the present invention will be described by means of a con~al~ e example.
COMPARATIVE EXAMPLE
A glass circulation reactor (volume: 1 1) heated by means of a heating plug was chalged with 500 g of an oxy ester ~ till~te obtained from an esterification residue from n-butyl acrylate production which has been freed of the acid esterification catalyst, together with 40 g of p-tolue-20 nesulfonic acid. The oxy ester ~ till~t~ co-~p-ised 11.0% by weight of butyl acrylate, 64.8% by weight of butoxy ester I ( R = C4Hg) 20.5% by weight of acyloxy ester II ( R = C4Hg).
The dissociation ~e~ e.alu.e was 195C and the opel~ g ples~llre 25 was 1 atm.
During the dissociation, the esterification residue to be dissociated was co,.ti...lv~lsly fed to the dissociation reactor, regulated by the level in the reactor.
The dissociation products were taken off in vapor form and 30 condensed at the top of the column (50 cm x 2.8 cm, empty) superposed on the dissociation reactor. Over a period of 119.5 hours, 7,401 g of mixture were fed to the dissociation reactor and 7,080 g of dissociation products were condensed.
According to analysis by gas chromatography, the condencate s complised:
72.0% by weight of butyl acrylate 13 .9% by weight of butanol 4.8% by weight of acrylic acid 1.4% by weight of dibutyl ether o 6.6% by weight of butenes 0.2% by weight of butyl bulo~yl~ol)iollate Conversion: 96% by weight based on oxy esters.
The dissociation bollollls were still readily handleable (pumpable) at 25C and contained no solids.
A glass circulation reactor (volume: 1 1) heated by means of a heating plug was chal~ed with 500 g of the oxy ester dictillqte from the Col~ slative Exarnple, with addition of 40 g of p-toluenesulfonic acid and 10 g of a ~li.ctillqtion residue obtained in the production of a pure acrylic 20 acid ~ic~illqte and having the following co",~osilion:
5.5% by weight of acrylic acid 54.0% by weight of diacrylic acid 14.5% by weight of dodecylbe.~el-e~.llfonic acid remqin~er: mainly polymers of acrylic acid and phenothiq7ine.
The dissocialion l~ lul~; was 195C and the ope~ g pl`es~ul'e was 1 atm.
The oxy ester dictillq-te and the cGllespollding amount of acrylic acid dic~illqtion residue (20% by weight) were continuously fed to the reactor, regulated by the level in the reactor. 10% by weight of the feed 30 flow was continuously removed from the reactor.
11 2193~û8 Over a period of 302 hours, 23,985 g of the mixture of oxy ester ~ictill~te and acrylic acid distillation residue was fed to the dissociation reactor and 21,580 g of product mixture were conl1el1.ced. According to analysis by gas c~umatography, the condensate cûlll~ ed:
569.5% by weight of butyl acrylate 6.1% by weight of butanol 19.5% by weight of acrylic acid 0.6% by weight of dibutyl ether 3.1% by weight of butenes l0 Conversion: 96% by weight based on oxy esters.
It can be seen from the above example of the process of the present invention that this process is able to achieve higher conversions and results in smaller losses of starting material than in known processes.
Claims (10)
1. A process for esterifying (meth)acrylic acid with an alkanol in the presence of an esterification catalyst in which unreacted starting compounds and the (meth)acrylic ester formed are separated off by distillation and a bottom product containing oxy esters is obtained, wherein the bottom pro-duct is separated off and either (a) the bottom product is admixed directly with oligomeric (meth)acrylic acid and the oxy esters present in the bottom product are dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid or (b) the oxy esters are first separated by distillation from the bottom pro-duct, the distillate is admixed with oligomeric (meth)acrylic acid and is dissociated at an elevated temperature in the presence of acid catalysts different from oligomeric (meth)acrylic acid.
2. A process as claimed in claim 1, wherein the amount of oligome-ric (meth)acrylic acid added is from 5 to 50% by weight, preferably from 10 to 40% by weight, based on the amount of bottom product in (a) or distillate in (b).
3. A process as claimed in claim 1, wherein the process of dissocia-tion is carried out in the presence of molecular oxygen.
4. A process as claimed in claim 1, wherein the process of dissocia-tion is carried out at from 150 to 250°C, preferably from 180 to 230°C.
5. A process as claimed in claim 1, wherein the acid catalyst added is an acid selected from the group consisting of mineral acids such as sulfuric acid or phosphoric acid, and organic acids different from oligomeric (meth)acrylic acid, for example alkyl- or arylsulfonic acids such as methane-sulfonic acid or p-toluenesulfonic acid.
6. A process as claimed in claim 5, wherein the added amount of added acid catalyst is from 1 to 20% by weight, preferably from 5 to 15%
by weight, based on the amount of bottom product in (a) or distillate in (b).
by weight, based on the amount of bottom product in (a) or distillate in (b).
7. A process as claimed in claim 1, wherein the dissociation is carried out under reduced pressure (< 1 atm).
8. A process as claimed in claim 1, wherein a stripping gas is passed through the bottom product in (a) or distillate in (b) in order to remove the dissociation products.
9. A process as claimed in claim 8, wherein the stripping gas used is an oxygen-containing gas.
10. A process as claimed in any of claims 1 to 9, wherein the dis-sociation products obtained are returned directly to the esterification.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19547485A DE19547485A1 (en) | 1995-12-19 | 1995-12-19 | Methacrylic] acid esterification with alkanol for alkyl methacrylate] |
| DE19547485.6 | 1995-12-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2193408A1 true CA2193408A1 (en) | 1997-06-20 |
Family
ID=7780594
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002193408A Abandoned CA2193408A1 (en) | 1995-12-19 | 1996-12-18 | Esterification of (meth)acrylic acid with an alkanol |
Country Status (13)
| Country | Link |
|---|---|
| EP (1) | EP0780359B1 (en) |
| JP (1) | JP3830595B2 (en) |
| KR (1) | KR100460248B1 (en) |
| CN (1) | CN1095827C (en) |
| BR (1) | BR9703408A (en) |
| CA (1) | CA2193408A1 (en) |
| CZ (1) | CZ369096A3 (en) |
| DE (2) | DE19547485A1 (en) |
| DK (1) | DK0780359T3 (en) |
| ES (1) | ES2145371T3 (en) |
| MX (1) | MX9606243A (en) |
| MY (1) | MY118758A (en) |
| SG (1) | SG79928A1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19536184A1 (en) * | 1995-09-28 | 1997-04-03 | Basf Ag | Process for the esterification of (meth) acrylic acid with an alkanol |
| DE19536191A1 (en) * | 1995-09-28 | 1997-04-03 | Basf Ag | Process for the esterification of (meth) acrylic acid with an alkanol |
| DE19536183A1 (en) * | 1995-09-28 | 1997-04-03 | Basf Ag | Process for the preparation of alkyl esters of (meth) acrylic acid |
| SG81213A1 (en) * | 1995-12-15 | 2001-06-19 | Rohm & Haas | Process for producing butyle acrylate |
| DE19701737A1 (en) * | 1997-01-20 | 1998-07-23 | Basf Ag | Process for the esterification of (meth) acrylic acid with an alkanol |
| US5877345A (en) | 1997-02-07 | 1999-03-02 | Rohm And Haas Company | Process for producing butyl acrylate |
| MY120051A (en) * | 1997-07-30 | 2005-08-30 | Mitsubishi Rayon Co | Process for purification of (meth)acrylic acid |
| DE19814387A1 (en) * | 1998-03-31 | 1999-10-07 | Basf Ag | Process for the production of acrylic acid and acrylic acid esters |
| DE19851983A1 (en) | 1998-11-11 | 2000-05-18 | Basf Ag | Process for the continuous production of alkyl esters of (meth) acrylic acid |
| DE19851984A1 (en) * | 1998-11-11 | 2000-05-18 | Basf Ag | Process for the esterification of (meth) acrylic acid with an alkanol |
| DE19922722A1 (en) | 1999-05-18 | 2000-11-23 | Basf Ag | Process for the preparation of (meth) acrylic acid esters |
| DE10007213A1 (en) * | 2000-02-17 | 2001-08-23 | Basf Ag | Process for the preparation of esters of alpha, beta-unsaturated carboxylic acids |
| DE10127941A1 (en) | 2001-06-08 | 2002-05-29 | Basf Ag | Production of (meth)acrylate esters by transesterification comprises recycling by-product alcohol to the production of the starting (meth)acrylate |
| WO2005007609A1 (en) | 2003-07-11 | 2005-01-27 | Basf Aktiengesellschaft | Thermal separation method for separating at least one (meth)acrylmonomer-enriched material flow |
| EP4015498B1 (en) | 2020-12-18 | 2024-04-24 | Basf Se | Method for the continuous production of acrylic acid n-butylester |
| CN117299040B (en) * | 2023-11-30 | 2024-03-12 | 万华化学集团股份有限公司 | Device system and method for simultaneously preparing butyl acetate and butyl acrylate |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB923595A (en) | 1960-12-03 | 1963-04-18 | Distillers Co Yeast Ltd | Improvements in and relating to the production of acrylic esters |
| US3868410A (en) | 1972-08-03 | 1975-02-25 | Celanese Corp | Conversion of oligomeric acrylates to acrylate monomers |
| DE2339529A1 (en) | 1973-08-03 | 1975-02-13 | Ardie Werk Gmbh | Accelerator linkage for heavy vehicle with fuel injection pump - has hydraulic servo to alter linkage length when changing gear |
| JPS5762229A (en) | 1980-10-02 | 1982-04-15 | Mitsubishi Petrochem Co Ltd | Recovery of useful component from heavy substance obtained as by-product in preparation of acrylic ester |
| CN1058390A (en) | 1990-07-13 | 1992-02-05 | 梁效成 | The treatment process of waste liquid containing alkoxyl propionic ester |
| JPH0768168B2 (en) | 1991-07-12 | 1995-07-26 | 東亞合成株式会社 | Decomposition method of Michael adduct of acrylic acid ester |
| CN1026104C (en) | 1992-03-17 | 1994-10-05 | 侯玉里 | Waste oil reproducing process for acrylate ester |
| JP2943523B2 (en) | 1992-08-12 | 1999-08-30 | 東亞合成株式会社 | Method for producing useful compound from Michael adduct of acrylic acid ester |
-
1995
- 1995-12-19 DE DE19547485A patent/DE19547485A1/en not_active Withdrawn
-
1996
- 1996-12-09 MY MYPI96005168A patent/MY118758A/en unknown
- 1996-12-09 MX MX9606243A patent/MX9606243A/en unknown
- 1996-12-13 DK DK96120074T patent/DK0780359T3/en active
- 1996-12-13 DE DE59605038T patent/DE59605038D1/en not_active Expired - Lifetime
- 1996-12-13 EP EP96120074A patent/EP0780359B1/en not_active Expired - Lifetime
- 1996-12-13 ES ES96120074T patent/ES2145371T3/en not_active Expired - Lifetime
- 1996-12-16 JP JP33583696A patent/JP3830595B2/en not_active Expired - Lifetime
- 1996-12-16 CZ CZ963690A patent/CZ369096A3/en unknown
- 1996-12-17 SG SG9611746A patent/SG79928A1/en unknown
- 1996-12-18 CA CA002193408A patent/CA2193408A1/en not_active Abandoned
- 1996-12-18 KR KR1019960067283A patent/KR100460248B1/en not_active IP Right Cessation
- 1996-12-18 CN CN96121570A patent/CN1095827C/en not_active Expired - Lifetime
-
1997
- 1997-05-27 BR BR9703408A patent/BR9703408A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DE19547485A1 (en) | 1996-05-09 |
| JP3830595B2 (en) | 2006-10-04 |
| BR9703408A (en) | 1999-01-05 |
| KR100460248B1 (en) | 2005-01-15 |
| EP0780359A1 (en) | 1997-06-25 |
| SG79928A1 (en) | 2001-04-17 |
| JPH09183752A (en) | 1997-07-15 |
| DK0780359T3 (en) | 2000-08-07 |
| EP0780359B1 (en) | 2000-04-26 |
| CN1095827C (en) | 2002-12-11 |
| MY118758A (en) | 2005-01-31 |
| CN1158841A (en) | 1997-09-10 |
| KR970042477A (en) | 1997-07-24 |
| DE59605038D1 (en) | 2000-05-31 |
| CZ369096A3 (en) | 1997-07-16 |
| MX9606243A (en) | 1998-04-30 |
| ES2145371T3 (en) | 2000-07-01 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |