MXPA99003675A - t. PROCEDURE FOR THE CONTINUOUS MANUFACTURE OF (MET) ACRILATOS DE DIALQUILAMINOALQU - Google Patents

Abstract

The present invention relates to the manufacture of a dialkylaminoalkyl (meth) acrylate by transesterification of methyl or ethyl (meth) acrylate with an aminoalcohol, the transesterification catalyst d is selected from tetrabutyl, tetraethyl and tetra (2-ethylhexyl) titanates ), the reaction is carried out in a stirred reactor at 90-120 ° C, after which the crude reaction mixture is sent to a column of remnants (C1), the flow from the top of this column is sent to a column of removal of volatile parts (C2) and the bottom flow of this column is subsequently sent to a column of final rectification (C3), in this way, a high-purity dialkylaminoalkyl (meth) acrylate is obtained

Description

PROCEDURE FOR THE CONTINUOUS MANUFACTURE OF (MET) DIALKYLAMINOALKILLO ACRYLATES DESCRIPTIVE MEMORY The present invention relates to a process for the continuous manufacture of a dialkylaminoalkyl (meth) acrylate of formula (I): R 1 R2 / H2C = C - C - O R3 (I) in which: R1 is a hydrogen atom or a methyl radical; A is a straight or branched C-1-C5 alkylene radical; and R2 and R3 which may be identical to or different from each other each represent an alkyl radical of C? -C4, by reaction in a stirred reactor between a compound of formula (II): R2 / HO - A - N R3 (II) wherein A, R2 and R3 have the same meanings as before, and a compound of formula (III): CH = C - C - • o. R4 II or (ni) wherein: R1 is as defined above; and R 4 is a linear alkyl group containing 1 or 2 carbon atoms, in the presence of a tetraalkyl titanate as a transesterification catalyst and in the presence of at least one polymerization inhibitor, the azeotropic mixture of the compound (III) / R 4 OH it is continuously stirred during the reaction. French Patent No. 1, 544,542 describes the preparation of dimethylaminoethyl acrylate from H2C = CHCOOCH (CH3) 2 or from H2C = CHCOOCH2CH (CH3) 2 and from alcohols in the presence of a catalyst such as n-titanate. propyl, isopropyl or isobutyl and polybutyl titanate. This process has the disadvantage that the transesterification of titanates, either with light alcohol released during the reaction or with starting alcohol, causes the appearance of impurities in the reaction mixture and complicates the purification of the prepared acrylic ester. In an attempt to overcome this problem, the French patent No. 2,617,840 proposes a process for manufacturing compounds of the formula (I) above, in accordance with which ethyl (meth) acrylate reacts, in the presence of at least one polymerization inhibitor at 20-120 ° C and at an equal pressure ao less than the atmospheric pressure with an aminoalcohol of formula (II) higher in a molar ratio of ethyl (II) (meth) acrylate / aminoalcohol of between 1.5 and 5, in the presence of tetraethyl titanate, the azeotropic mixture of ( met) acrylate / ethyl ethanol is removed during the reaction and the compound (I) obtained is removed at the end of the reaction. Currently, the problem that arises is the production on an industrial scale, continuously and with high purity of these compounds (I). In this way, for example, it was sought to obtain dimethylaminoethyl acrylate (DMAEA) containing less than 100 ppm of ethyl acrylate (EA) and less than 300 ppm of dimethylaminoethanol (DMAE). European Patent EP-B-0, 160,427 describes a method for manufacturing DMAEA that can be schematically represented as follows: (1) Preparation of the DMAE catalyst XTi (OiPr) 4 + yMg (OiPr) 2 > . { Ti [O (CH2) 2N (CH3) 2] 4} x. { Mg [O (CH2) 2N (CH3) 2] 2) y (compound A) + PrOH where x + y = 1 (2) Synthesis of DMAEA by exchange reaction in the presence of methyl acrylate CH = CH - C - O- CH II or + compound A - »DMAEA + compound B * * compound B = compound A = partially modified with CH3OH ligands of methyl acrylate. Subsequently, the compound B is separated from the crude reaction mixture by an immediate distillation and the light phase obtained from this operation, which contains the DMAEA and the unreacted methyl acrylate in excess, is distilled to isolate the pure DMAEA. (3) Regeneration of compound A Compound B + in excess DMAE- »compound A + MeOH + DMAE Immediate distillation makes it possible to isolate compound A from the light phase containing methanol and DMAE. Compound A is recycled in step (2) and the light phase is distilled to separate the methanol from the DMAE, which is recycled in step (3).

This procedure, indicated in the aforementioned patent as being capable of being carried out continuously, is still relatively complicated, even if pressure or temperature information is not provided for the distillations mentioned above. Brazilian patent No. PL 87/01337 describes a transesterification of a light (methyl) acrylate (without specifying that the heavy alcohol can be DMAE) continuously, according to which the reactor used is a tubular reactor in combination with an evaporator. The steam flow obtained in the evaporator is sent to a distillation column to separate: the light acrylate azeotrope / light alcohol (methanol) at the top; and heavy acrylate and heavy alcohol with a small amount of light acrylate in the bottom. This last flow is sent to a purification column, from which a heavy alcohol-rich stream leaves, at the top, and is recycled into the reactor (removal of volatile parts). The titanate (catalyst) and the heavy acrylate is left at the bottom of this column. This flow is sent to a final column, from which the pure heavy acrylate is left at the top and the catalyst is left at the bottom. This procedure, in the case of the DMAEA synthesis, does not make it possible to obtain a product that meets the specifications mentioned above.

The Brazilian patent PI 97/01338 describes, for the same reaction (still without specifically mentioning the amino alcohols as heavy alcohols), the use of a distillation column fed in the upper part with the heavy alcohol and the catalyst (example: titanate of butyl), and in the lower part with the light acrylate. The flow left at the top is rich in light alcohol and contains light acrylate and heavy alcohol; the light acrylate is separated and recycled in the column. The flow that is left on the bottom is rich in heavy acrylate (2-ethylhexyl acrylate in the example) and contains heavy alcohol and light acrylate. The applicant company has now discovered that by carrying out a remanent operation first (removal of the catalyst and heavy products), followed by a volatile part removal operation and a final rectification, in a crude reaction mixture of the transesterification of the ( met) alkyl (III) acrylate as defined above with an amino (II) alcohol as defined above, it is possible to industrially obtain a high purity (meth) acrylate (I). Thus, an object of the present invention is, first of all, a process for the continuous production of a (meth) acrylate (I), as defined above, characterized in that the transesterification catalyst is selected from tetrabutyl titanates, tetraethyl and tetra (2-ethylhexyl) and because the reaction is carried out in the stirred reactor at a temperature of 90-120 ° C, after which the following steps are carried out: the crude reaction mixture including the desired heavy ester compound (I) with compound (II) as light products and unreacted light ester (III), and as heavy products, catalyst, polymerization inhibitor (s) and heavy reaction products, it is sent to the first distillation column (C1) under reduced pressure, and a distillation is carried out in said first column (C1), which makes it possible to obtain: in the upper part, a flow composed essentially of the heavy ester (I) and the pr light oducts, which contain a small fraction of heavy products, but free or substantially free of catalyst; and - basically, a flow of heavy products with a small fraction of heavy ester (I) and the catalyst; after which: the flow of the upper part of the first distillation column (C1) is sent to a second distillation column (C2) under reduced pressure, in which a distillation is carried out which makes it possible to obtain: the upper part, a flow of light products with a small fraction of heavy ester (I); and at bottom, the heavy ester (I) containing brands of light products, heavy reaction products and the polymerization inhibitor (s); and - the bottom flow of the second distillation column (C2) is sent to a third distillation column (C3) under reduced pressure, in which a rectification is carried out which makes it possible to obtain: in the upper part, the desired heavy ester (I); and basically, essentially the polymerization inhibitor (s). In general, the reaction is carried out in the reactor (R) in a molar ratio of alkyl (meth) acrylate (III) / amino (II) alcohol of between 1.1 and 3, preferably between 1.7 and 2.2; the catalyst is used in a proportion of 10"4 to 10" 2 mol per mol of amino alcohol (II), preferably in a ratio of 1 x 10"3 to 8 x 10" 3 mol per mol of amino alcohol (II); the reaction is carried out in the reactor (R) at a pressure of between 650 millibars and atmospheric pressure. In addition, the stabilizer (s) is selected from phenothiazine, ferbutylcatechol, hydraquinone methyl ether, hydroquinone and mixtures thereof in all proportions and is used in a proportion of 100-5000 ppm with relation to the supply of the reaction. A stabilizer such as phenothiazine can also be added to the column (C2). As examples of amino alcohols (II), dimethylaminoethanol (DMAE), dimethylaminopropanol and diethylaminoethanol may be mentioned. In accordance with specific features of the process according to the present invention, the first distillation column (C1) operates at a pressure of 3.73 x 103 - 1.04 x 104 Pa (28-78 mm Hg) at a bottom temperature of 100 -115 ° C; the second distillation column (C2) operates at a pressure of 9.33 x 103 - 1.07 x 104 Pa (70-80 mm Hg) at a bottom temperature of 110-125 ° C; the bottom flow of the column (C1) is recycled in the reactor (R) after the purification when passing through a film evaporator, as is the flow of the top of the column (C2); and the rectification column (C3) operates at a pressure of 3.73 x 103-70.7 x 103 Pa (28-53 mm Hg) at 82-94 ° C. However, the following examples illustrate the present invention without limiting its scope. The results of several operations have been checked in each of them. The percentages are given on a weight basis. Columns (Cl), C2), and (C3) were used, which were installed in accordance with the scheme of figure 1 annexed; the reactor (R) and these three columns each have a reflux vessel (RP) mounted on top of them. The columns operated under the conditions of pressure and temperatures indicated above.

EXAMPLE 1 Synthesis of DMAEA When starting with a crude reaction mixture 1, obtained by continuous reaction of DMAE with ethyl acrylate in the presence of phenothiazine as polymerization inhibitor and ethyl titanate as catalyst, giving a titre, by 100% by weight of: DMAEA 50- 55% Ethyl acrylate 20-30% DMAE 15-25% Heavy reaction products, catalyst- 1.2-2.5% and phenotizine The column of remnants (C1) is fed continuously. After purification by passing it through a film evaporator, the remaining fraction 2 of this column (C1) is sent into the reaction. A free flow of catalyst 3 is recovered in the upper part of this column (C1), with a titre, by weight of: DMAEA 50-55% Ethyl acrylate 20-30% DMAE 15-20% Heavy reaction products and 1 -5% phenothiazine This flow 3, stabilized with phenothiazine, is sent to the column of removal of volatile parts (C2). The head fraction 4 of this column (C2) has the following composition (% by weight): DMAEA 5-10% Ethyl acrylate 40-60% DMAE 25-45% Recycled into the reaction The remaining fraction 5 of this column (C2) has the following composition, by weight: DMAEA 99.8-99.9% Ethyl acrylate 0-10 ppm DMAE 50-150 ppm Phenothiazine 500-600 ppm Sends to column (C3) which makes it possible to obtain at the top (6) Pure DMAEA with a composition (by weight) of: DMAE 99.8% Ethyl acrylate < 10 ppm DMAE 120-150 ppm Phenothiazine < 1 ppm EXAMPLE 2 (Comparative) The same operations carried out with a volatile parts removal operation followed by a remaining operation leads to a DMAEA product with a title, by weight, of: DMAEA 99.5% EA 500 ppm DMAE 1000-2000 ppm

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. - A process for the continuous manufacture of a dialkylaminoalkyl (meth) acrylate of formula (I): R1 R2 I / H2C = C - C - • O - A - N R3 (I) wherein R1 is a hydrogen atom or a methyl radical; A is a linear or branched C1-C5 alkylene radical; and R2 and R3 which may be identical to or different from each other each represent a C1-C4 alkyl radical, by reaction in a stirred reactor between a compound of formula (II): R2 / HO - A - R3 (II) wherein A, R2 and R3 have the same meanings as the above, and a compound of formula (III): R1 CH? = C-C-O-R4 II O (III) wherein R1 is as defined above; and R 4 is a linear alkyl group containing 1 or 2 carbon atoms, in the presence of a tetraalkyl titanate as a transesterification catalyst and in the presence of at least one polymerization inhibitor, the azeotropic mixture of the compound (III) / R 4 OH is stirring continuously during the reaction, characterized in that the transesterification catalyst is chosen from tetrabutyl, tetraethyl and tetra (2-ethylhexyl) titanates and because the reaction is carried out in the stirred reactor at a temperature of 90-120 ° C, then from which the following steps are carried out: the crude reaction mixture including the desired heavy ester compound (I) with the compound (II) as light products and the unreacted light ester (III), and as heavy products , the catalyst, the polymerization inhibitor (s) and heavy reaction products, is sent to the first distillation column (C1) under reduced pressure, and a distillation is carried out in said first column (C1), which makes it possible to obtain: in the upper part, a flow composed essentially of the heavy ester (I) and the light products, which contain a small fraction of heavy products, but free or substantially free of catalyst; and in the background, a flow of heavy products with a small fraction of heavy ester (I) and catalyst; after which: the flow of the upper part of the first distillation column (C1) is sent to a second distillation column (C2) under reduced pressure, in which a distillation is carried out which makes it possible to obtain: upper part, a flow of light products with a small fraction of heavy ester (I); and in the background, the heavy ester (I) containing brands of light products, heavy reaction products and the polymerization inhibitor (s); and the bottom flow of the second distillation column (C2) is sent to a third distillation column (C3) under reduced pressure, in which a rectification is carried out which makes it possible to obtain: in the upper part, the desired one heavy ester (I); and basically, essentially the polymerization inhibitor (s).

2. The process according to claim 1, further characterized in that the reaction is carried out in the reactor (R) in a molar ratio of alkyl (meth) acrylate (III) / amino alcohol (II) of between 1.1 and 3, preferably between 1.7 and 2.2.

3. The process according to any of claims 1 and 2, further characterized in that the catalyst is used in a proportion of 10"4 to 10" 2 mol per mole of amino alcohol (II), preferably in a proportion of 1. x 10"3 to 8 x 10" 3 mol per mol of amino alcohol (II).

4. The process according to any of claims 1 to 3, further characterized in that the reaction is carried out in the reactor (R) at a pressure of between 650 millibars and atmospheric pressure.

5. The process according to any of claims 1 to 4, further characterized in that the polymerization inhibitor (s) is chosen from phenothiazine, tert-butylcatechol, hydroquinone methyl ether, hydroquinone and mixtures thereof. the same in all proportions, the polymerization inhibitor (s) is used in a proportion of 100-5000 ppm relative to the reaction supply.

6. The method according to any of claims 1 to 5, further characterized in that dimethylaminoethanol, dimethylaminopropanol or diethylaminoethanol is used as amino alcohol (II).

7. The process according to any of claims 1 to 6, further characterized in that the first distillation column (C1) operates at a pressure of 3.73 x 103 - 1.04 x 104 Pa and at a bottom temperature of 110-115 ° C.

8. The process according to any of claims 1 to 7, further characterized in that the second distillation column (C2) operates at a pressure of 9.33 x 103 - 1.7 x 104 Pa at a bottom temperature of 110-125. ° C.

9. The process according to any of claims 1 to 8, further characterized in that the bottom flow of the column (C1) is recycled to the reactor (R) after purification by passing it through a film evaporator, as is the flow from the top of the column (C2).

10. The process according to any of claims 1 to 9, further characterized in that the rectification column (C3) operates at a pressure of 3.73 x 10"3 - 70.7 x 103 Pa at 82-94 ° C.