WO2003093218A1

WO2003093218A1 - Method for continuously producing dimethylaminoethyl acrylate

Info

Publication number: WO2003093218A1
Application number: PCT/FR2003/001173
Authority: WO
Inventors: Jean-Philippe Gendarme; Gilles Herbst; Alain Riondel
Original assignee: Atofina
Priority date: 2002-04-30
Filing date: 2003-04-14
Publication date: 2003-11-13
Also published as: FR2839070A1; AU2003264876A1

Abstract

The invention concerns a method for making dimethylaminoethyl acrylate by transesterification from dimethylaminoethanol and ethyl acrylate in the presence of a transesterification catalyst and at least one polymerisation inhibitor, the azeotropic acrylate ethyl-ethanol mixture being continuously tapped during the reaction. The invention is characterized in that it consists in carrying out the reaction by using tubular piston reactor technology. In particular, it consists in using several tubular piston reactors mounted in series (R1, R2, R3), the reaction mixture being injected at the base of the first reactor (R1) and exiting in the upper part thereof to be re-injected at the base of the second reactor (R2) and so on, said azeotropic mixture exiting from each reactor (R1, R2, R3) being re-injected in a distillation column (C) equipped with a condenser.

Description

PROCESS FOR THE CONTINUOUS MANUFACTURE OF DIMETHYLAMINOETHYL ACRYLATE

The present invention relates to a continuous manufacturing process for dimethylaminoethyl acrylate:

CH ₃ H ₂ C = CH-CO-CH ₂ -CH ₂ -N (ADAME)

Y ^N CH ₃

by reaction between dimethylaminoethanol:

CH ₃ HO-CH ₂ - CH ₂ -N (DMAE)

CH ₃

and ethyl acrylate

CH ₂ = CH— C-OC ₂ H ₅ (AE) II O in the presence of at least one transesterification catalyst, the azeotropic mixture AE-ethanol being drawn off continuously during the reaction. The catalysts used are usually tetraalkyl titanates such as tetraethyl titanate, the latter being particularly solution DMAE as described- in the requested ^'to' French Patent No. 2 811 986. Furthermore, the fact that this transesterification reaction involves an acrylic monomer, it must be stabilized. It is therefore generally carried out in the presence of oxygen from the air and in the presence of at least one polymerization inhibitor, such as 2-orthoditertio-butylparacresol (BHT), phenothiazine (PTZ) and hydroquinone methyl ether (EMHQ).

At present, the manufacture of ADAME by the transesterification described above is carried out in a perfectly stirred continuous reactor (see FR-A-2 777 561).

This process, although effective, can however be further improved as regards the residence time and the conversion of DMAE.

Seeking to improve the known process, the Applicant Company has discovered that the synthesis of ADAME using the technology in a tubular piston reactor instead of the perfectly agitated reactor allows: - a reduction in residence time of approximately half ; and better conversion of DMAE (90% in the best of cases against 60% in the case of the perfectly stirred reactor). The subject of the present invention is therefore a process for the continuous manufacture of dimethyla inoethyl acrylate by transesterification from dimethylaminoethanol and ethyl acrylate, in the presence of at least one transesterification catalyst and in the presence of at least one polymerization inhibitor, the azeotropic ethyl acrylate-ethanol mixture being drawn off continuously during the reaction, characterized in that the reaction is carried out by implementing the technology in a tubular piston reactor. In accordance with a particular embodiment of the method according to the invention, several piston tubular reactors mounted in series (Ri, R2, R3) are used, the reaction mixture being injected at the base of the first piston tubular reactor (RI) and leaving at the top of said first piston tubular reactor (Ri) to be reinjected at the base of the second piston tubular reactor (R2) and so on, the azeotropic mixture of ethyl acrylate-ethanol exiting at the top of each piston tubular reactor (RI , R2, R3) being injected into a distillation column (C) equipped with a condenser, said injection being carried out in particular at mid-height of said column (C).

Preferably, the distillation column (C) is mounted above a stirred reactor (R), which is mounted on the path of the reagent mixture sent to the first tubular piston reactor (RI), the injection of the catalyst being performed downstream of the stirred reactor (R).

The reaction of the invention is preferably carried out under air bubbling and preferably with an ethyl acrylate / dimethylaminoethanol molar ratio of between 1.1 and 3.5, preferably between 1.7 and 2.2.

An esterification catalyst is advantageously chosen from tetraalkyl titanates, in particular tetraethyl titanium. In particular, the catalyst is used in an amount of 5 x 10 ^{~ 4} to 5 x 10 ^{~ 2} mole per mole of dimethylaminoethanol, preferably in an amount of 5 x 10 ^{~ 3} to 2 x 10 ^{~ 2} mole per mole of dimethylaminoethanol.

Preferably, the tetraalkyl titanate is introduced in solution, in all proportions, in dimethylaminoethanol.

Furthermore, the polymerization inhibitors (or stabilizers) are chosen from phenothiazine

(PTZ), tertiobutylcatechol, 2-orthoditertiobutyl paracresol (BHT), 'methyl ether' - hydroquinone.

(EMHQ), hydroquinone and their mixtures in all proportions, the polymerization inhibitor (s) being used at the rate of 100-5000 ppm relative to the reaction charge. The reaction is advantageously carried out at a boiler temperature (B) of between 90 and 135 ° C and under a pressure of between 800 mbar and atmospheric pressure.

In addition, the reaction of the invention is carried out with a residence time of 2 to 6 hours. The following Examples illustrate the present invention without, however, limiting its scope.

In these examples, the following abbreviations have been used:

AE: ethyl acrylate

DMAE: dimethylaminoethanol [HO-CH ₂ -CH ₂ -N (CH ₃ ) ₂ ]

ADAME: dimethylaminoethyl acrylate

PTZ: phenothiazine (stabilizer)

CPG: gas chromatography.

The samples were analyzed in GPC to determine the content of DMAE, ADAME and ethanol and calculate the yield in ADAME, the conversion of DMAE and the selectivity in ADAME. Since dimethylaminoethanol is the limiting reagent (faulty reagent), all calculations have been made from this reagent.

nADAME trained

- ADAME yield

ΠDM E introduced

Π _D M _A E ntroduced n _DM AE remaining

- Conversion _D MAE ⁼ n _DMAE introduced

nADAME trained

Selectivity _A DAME n _DMA E introduced - n _DM AE remaining

n representing the number of moles.

The single Figure in the accompanying drawing is a diagram of the installation used in these Examples.

The installation shown comprises: a capacity (c) in which the reaction mixture AE / DMAE to be introduced is stored and which is placed on a balance (B); two positive displacement pumps e and g, following each of which is mounted a back pressure valve; a distillation column (C) of 10 theoretical plates, equipped with a reflux or condenser head; three jacketed piston tubular reactors

(RI), (R2) and (R3), with a capacity of 150 ml each 5 and each comprising a filling of Raschig rings; a jacketed reactor (R) with a capacity of 150 ml, equipped with a mechanical stirrer; bubbling dry air; two heated oil baths; 10 - a refrigeration system; a vacuum pump; a syringe driver for the introduction of the catalyst; five temperature sensors (foot and head of the column

(C), piston piston reactors (RI), (R2) and 15 (R3)); a temperature recorder; a mass flow controller-regulator (noted

P); and a recipe (rc).

20

EXAMPLE 1

In this example, the flow rates given, as well as the temperatures, correspond to a residence time 25 of 3 hours at atmospheric pressure.

A solution composed of AE and DMAE is prepared with an AE / DMAE molar ratio of 1.6, stabilized with 2000 ppm of PTZ, by successively introducing into a capacity (c) of 5 1: 30 - 1500 g of DMAE ( 99.8% purity);

- 8.3 g of PTZ; and

- 2628 g of EA (99.5% purity).

A catalytic solution containing 25% of catalyst and 75% of EA (mass ratio) is prepared in a medium the

35 as dry as possible by introducing 30 g of catalyst and 90 g of EA into a bottle. The catalyst here is Ti (OEt), at the rate of 1.7 × 10 ^-2 mole / mole of DMAE introduced. The solution of AE and DMAE is placed under the pump s, this solution being ready to be introduced into the stirred reactor (R).

The vacuum pump and the refrigeration system are put into operation.

The compressed air tap is opened slightly and a slight bubbling of dry air is introduced into the reactor (R) at the bottom of the column (C).

The oil heaters of the reactors (R1, R2, R3) and of the stirred reactor (R) are put into service (T reactor oil R1, R2, R3: 138 ° C; T reactor oil R: 152 ° C).

The pumps are then put into service, the flow rate of the reaction mixture pump being adjusted by the programmer (P) (152 g / h) and the flow rate of the return pump £ being adjusted manually using a burette so that the level in the reactor (R) remains constant at around 80% filling rate. The agitation is put into service as well as the catalyst introduction pump.

(flow rate: 7.46 ml / h). As soon as the column head (C) is at the boiling point of the azeotrope AE / ethanol, the column (C) is in operation (T column head: 79 ° C at atmospheric pressure).

We then put into service the withdrawal of the azeotrope with ^• a reflux rate ^' of 2. ^'" . - ^{'•• •}

After two residence times (ie 6 hours) necessary to bring the installation into operation, samples are taken at the outlet of each reactor RI, R2, R3 and analyzed by gas chromatography to ^' determine the yield and the selectivity to ADAME as well as the conversion of DMAE.

The results are reported in Table 1. EXAMPLES 2 to 4

Example 1 is reproduced, except that the parameters appearing in Table 1 are modified. The results obtained are also reported in Table 1.

Table 1

Claims

1 - Process for the continuous manufacture of dimethylaminoethyl acrylate by transesterification from dimethylaminoethanol and ethyl acrylate, in the presence of a transesterification catalyst and in the presence of at least one polymerization inhibitor, the mixture azeotropic ethyl acrylate-ethanol being drawn off continuously during the reaction, characterized in that the reaction is carried out by implementing the technology in a tubular piston reactor.

2 - Process according to claim 1, characterized in that several piston tubular reactors connected in series are used (RI, R2, R3), the reaction mixture being injected at the base of the first piston tubular reactor (RI) and leaving at the top of said first piston tubular reactor (RI) to be reinjected at the base of the second piston tubular reactor (R2) and so on, the azeotropic mixture of ethyl acrylate-ethanol leaving at the head of each piston tubular reactor ( RI, R2, R3) being injected into a distillation column (C) equipped with a condenser, said injection being carried out in particular at mid-height of said column (C).

3 - Process according to claim 2, characterized in that the distillation column (C) is mounted above a stirred reactor (R), which is mounted on the path of the mixture of reagents sent to the first piston tubular reactor (Ri), the injection of the catalyst being carried out downstream of the stirred reactor (R). 4 - Method according to one of claims 1 to 3, characterized in that the reaction is carried out with a molar ratio of ethyl acrylate / dimethylaminoethanol of between 1.1 and 3.5, preferably between 1.7 and 2.2.

5 - Method according to one of claims 1 to 4, characterized in that one uses a catalyst chosen from tetraalkyl titanates, in particular tetraethyl titanium, the tetraalkyl titante can be introduced in solution in dimethylaminoethanol.

6 - Method according to one of claims 1 to 5, characterized in that the catalyst is used in an amount of 5 x 10 ^-4 to 5 x 10 ^"2 mole per mole of dimethylaminoethanol, preferably in an amount of 5 x 10 ^"3 to 2 x 10 ^{" 2} mole per mole of dimethylaminoethanol.

7 - Method according to one of claims 1 to 6, characterized in that one or the polymerization inhibitors are chosen from phenothiazine, tertiobutylcatechol, 2-orthoditertiobutylparacresol, methyl ether of hydroquinone, l 'hydroquinone and. their mixtures in all proportions, the polymerization inhibitor or inhibitors being used at a rate of 100-5000 ppm relative to the reaction charge.

8 - Method according to one of claims 3 to 7, characterized in that the reaction is carried out at a temperature of the boiler (B) between 90 and 135 ° C.

9 - Method according to one of claims 1 to 8, characterized in that the reaction is carried out under a pressure between 800 mbar and atmospheric pressure.

10 - Method according to one of claims 1 to 9, characterized in that the reaction is carried out with a residence time of ^' 2 to 6 hours. ... ^' - •; ^•