BE1021574B1 - CONTINUOUS PROCESS FOR SYNTHESIZING OLIGOESTERS FROM AN AMMONIUM SALT OF A DICARBOXYLIC ACID AND A DIOL AND DEVICE FOR CARRYING OUT SAID METHOD - Google Patents

Abstract

A method and apparatus for the continuous synthesis of oligoester comprising the steps of: introducing an aqueous solution of an ammonium salt of dicarboxylic acid; heating the aqueous solution, the heating temperature being lower than the boiling temperatures of the diol and the diacid; introduction of the diol; heating the diol to a temperature above the boiling point of the diol, of the diacid, of water and of the ammonia and to a temperature below the boiling point of the oligoester; contacting the diacid with the diol at a temperature above the boiling point of the diol, of the diacid, of water and of the ammonia and at a temperature below the boiling point of the oligoester; recovery of the oligoester.

Description

Continuous process for synthesizing oligoesters from an ammonium salt of a dicarboxylic acid and a diol and a device for carrying out

Field of the invention

The present invention relates to a process for the continuous production of oligoesters III of controlled degree of polymerization (DP) and to a device for implementing said method.

Compounds Formulas

ammonium salts of dicarboxylic acid / (I)

diol

(II)

Oligoesters /

/

(III) where x is between 2 and 6, preferably x is 4, including 0 to 4, preferably y is 2 and n is 1 to 25, preferably 1 to 10.

The oligoesters III obtained, according to the process, from an aqueous solution of ammonium salt of dicarboxylic acid I and diol II do not require a complementary purification step, in particular for the synthesis of high-density polyesters. molecular weight or for the catalytic hydrogenation of various compounds of industrial interest. In the particular case where the ammonium salt of dicarboxylic acid I is diammonium succinate and the diol II is 1,4-butanediol, the oligoesters III formed can be used directly and without resorting to an additional purification step for the synthesis of high molecular weight polybutylene succinate by transesterification or converted to 1,4-butanediol, Y-butyrolactone (GBL) or tetrahydrofuran (THF) by catalytic hydrogenation.

State of the art

Patent JP 2005/132836 and JP 2005/163032 disclose a process for producing polybutylene succinate obtained from diammonium succinate and 1,4-butanediol. These patents describe batch type processes that do not allow the complete elimination of ammonia. It is also known to those skilled in the art that heating the diammonium succinate for several hours, as described in these 2 patents, produces contaminating derivatives such as succinamide or succinimide.

Patent FR 1,175,310 describes the synthesis of polyester from diammonium terephthalate salts. However, the operating conditions do not allow continuous production, in particular by reactive distillation.

WO 2007/116005, WO 0 064 850, US 2006/0189821, JP 2007/254354, CA 2 657 666 provide methods for esterification on a reactive distillation column of diammonium of dicarboxylic acid to dialkyl carboxylate. All these patents describe the use of monohydric alcohols and do not relate to the production of oligoesters.

U.S. Patents 5,854,377; US 2011/0 039 999; US 2009/011236; US 6,100,369; US 2012/136132; US 2007/066790; US 6812321; US 2006/030727 disclose methods and / or equipment for the continuous production of polyester obtained from diacids or diesters of carboxylic acid and diols.

However, the reactions are carried out from a mixture of the reagents in the liquid phase and the processes described are not compatible with the use of aqueous solution of an ammonium salt as raw material. Indeed, the operating conditions (time and temperature of reaction) and the design of the equipment do not make it possible to limit the production of amine derivatives such as imides or amides.

There is therefore an interest for a method for combining in a single reaction step the synthesis of oligoesters of DP controlled from an aqueous solution of a dicarboxylic acid ammonium salt and which can be used directly without purification. complementary to produce a polyester of high molecular mass by transesterification or the synthesis of other compounds of industrial interest, in particular by catalytic hydrogenation.

For the purposes of the invention, the DP is defined as corresponding to the number of repeating units and not to the number of monomer units. For example, an ester formed from a diol and a diacid is composed of 2 units.

List of Figures

FIG. 1: Example of a synthesis reaction scheme according to the invention with 1,4-butanediol as diol and the ammonium salt of succinic acid as starting reagent. Figure 2: reaction device according to the invention.

BRIEF DESCRIPTION OF THE INVENTION The subject of the invention is a process for the continuous production of oligoesters III by reaction between an ammonium salt of dicarboxylic acid I in aqueous solution and a diol II. The invention also relates to equipment adapted to the continuous production process of oligoester III.

The process makes it possible to obtain oligoesters III of controlled DP and of sufficient purity to be used directly to produce a high molecular weight polyester (FIG. 1, 2a) or to synthesize various compounds of industrial interest by catalytic hydrogenation (FIG. 1, 2b).

When the oligoesters III produced have a high mean DP, that is to say of the order of 10 to 50, then these oligoesters can advantageously be used for the synthesis of high molecular weight polyesters.

Whereas when the average DP of the oligoesters III produced is low, ie between 2 and 10, preferably between 2 and 5, these oligoesters III may advantageously be hydrogenated for the synthesis of compounds of industrial interest.

The ammonium salt of dicarboxylic acid I and diol II are preferably diammonium succinate and 1,4-butanediol, respectively. In this case, the oligoesters III produced can be used without further purification for the production of high molecular weight polybutylene succinate by transesterification or the synthesis of 1,4-butanediol, Y-butyrolactone or tetrahydrofuran by catalytic hydrogenation.

In addition, the process according to the invention allows the recovery of the ammonia produced during the oligomerization reaction (FIG. 1, 1) in the form of an aqueous solution. Ammonia that can be recycled in the process for producing the ammonium salt of dicarboxylic acid I.

The process according to the invention can be applied to any type of aqueous solutions containing an ammonium salt of dicarboxylic acid I, and in particular to the solutions resulting from a fermentation process.

The device used comprises a reaction column maintained at reduced pressure with a 2-point continuous feed spatially separated from an ammonium salt of an aqueous dicarboxylic acid I and a diol II (FIG. 2).

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a process for the continuous and one-step production of oligoesters III by reaction between an ammonium salt of dicarboxylic acid I and a diol II. The invention also relates to equipment adapted to the process.

The process of continuously synthesizing oligoesters III comprises the steps of: a. Continuous introduction into a reaction device of an aqueous solution comprising an ammonium salt of dicarboxylic acid I, this solution may optionally comprise a diol II. b. Heating the aqueous solution in order to dissociate the ammonium salt of dicarboxylic acid I to diacid and ammonia, the heating temperature being lower than the boiling temperatures of the diol II and of the diacid obtained during the dissociation of the salt of ammonium dicarboxylic acid (I). vs. Continuous introduction into the reaction device of the diol (II) in gaseous form, or liquid which will then be vaporized. d. Heating the diol (II) to a temperature above the boiling point of diol (II), diacid and water and at a temperature below the boiling point of the oligoester (III). e. Contacting the diacid obtained from the dissociation of the ammonium salt of dicarboxylic acid I with diol II at a temperature above the boiling point of diol II, diacid and water and at a temperature of less than the boiling point of oligoester III. f. Recovery of oligoester III in liquid form. boy Wut. Advantageously, the gaseous ammonia can be recovered in the form of an aqueous solution.

The pressure used in the reaction device is preferably between 1 mbar (100 Pa) and 500 mbar (50 000 Pa).

The boiling point of the compounds being defined as a function of the pressure conditions used. While the boiling point corresponds to the boiling temperature under normal pressure conditions, ie under one atmosphere.

Thus, the diacid obtained during the dissociation of the ammonium salt of dicarboxylic acid (I) preferably has a boiling point of between 150 and 350 ° C. and the diol (II) preferably has a boiling point comprised between between 150 and is below 350 ° C.

Depending on the operating conditions defined by the operator, such as temperature, pressure, feed rate reagent, or the presence of catalyst, the operator can control the DP of the oligoesters III produced by the process. In particular, the method makes it possible to produce oligoesters III of average DP of between 10 and 50, more preferably between 10 and 20. The oligoesters III produced have a residual nitrogen content in any form whatsoever (ammonium, imide compounds, amides ...), less than 1% by weight, preferably less than 0.1% and more preferably less than 0.01%. Thus, the purity of the oligoesters III, that is to say the low residual nitrogen content, allows them to be integrated directly in the production of a high molecular weight polyester (FIG. 1, 2a) without it is necessary to resort to a subsequent purification step.

In the case where the formation of the high molecular weight polyester leads to the production of diol II as a coproduct, it can be advantageously recycled for the production of oligoesters III (Figure 1, 1).

According to a preferred method of the process, the ammonium salt of dicarboxylic acid I and diol II are respectively diammonium succinate and 1,4-butanediol. In this case, the oligoesters III obtained can be used directly for the production of high molecular weight polybutylene succinate by the techniques known to those skilled in the art. The 1,4-butanediol in excess can be recycled for the production of oligoesters III (Figure 1, 1).

The process also makes it possible to produce oligoesters III of average DP of between 2 and 10, more preferably between 2 and 5. The oligoesters III produced have a residual nitrogen content, in whatever form (ammonium, imide compounds, amides. ..), less than 1%, preferentially less than 0.1% and more preferably less than 0.01%. Thus, the purity of the oligoesters III, that is to say the low residual nitrogen content, is sufficient for them to be integrated directly and without purification step, in an industrial process of catalytic hydrogenation for the production of compounds industrial interest (Figure 1, 2b). In the case where the product resulting from the hydrogenation of the oligoesters is diol II, a fraction thereof can be recycled for the production of oligoesters III (Figure 1, 1).

In a particular case of the process, the ammonium salt of dicarboxylic acid I and diol II are respectively diammonium succinate and 1,4-butanediol. In this case, the catalytic hydrogenation of the oligoesters III leads to the production of 1,4-butanediol and / or THF and / or GBL. A 1,4-butanediol product fraction that can be recycled for the production of oligoesters III (Figure 1, 1). In general, the process allows the recovery of ammonia produced (Figure 1, (3) and Figure 2) in the form of an aqueous solution and its recycling in the process of producing the ammonium salt of dicarboxylic acid I.

Also, the process is applicable to any type of aqueous solutions containing an ammonium salt of dicarboxylic acid I, in particular aqueous solutions obtained during fermentation processes.

Therefore, the process can be integrated into a process for purifying a diacid produced by fermentation. In this case, the process makes it possible to conjugate a step of purification of the ammonium salt of dicarboxylic acid I with the first phase of the production of high molecular weight polyesters or the synthesis of compounds of industrial interest by catalytic hydrogenation. Preferably, the process is applicable to the purification of diammonium succinate produced by a fermentative process.

Mode of realization

Preferably, the continuous production of oligoesters III is carried out in a distillation column reactive with feed at two spatially separated points. The aqueous solution of ammonium salt of dicarboxylic acid I is introduced continuously into the upper part b of column c and the diol II is introduced continuously through the lower part of column c (Figure 2).

According to an advantageous embodiment, the aqueous solution may contain a quantity of diol II of between 0 and 100% by weight of the amount of ammonium salt of dicarboxylic acid I.

Depending on the operating conditions such as the pressure and the temperature profile of the column c, the feed rate of the reagents, the temperature of the solution of the ammonium salt of dicarboxylic acid I and / or diol II, the use or not of a catalyst, the device makes it possible to produce oligoesters III whose mean DP is between 2 and 50 and more preferably between 2 and 20.

Column c is maintained at a pressure below atmospheric pressure, preferably between 1 mbar and 500 mbar, more preferably between 50 and 400 mbar and even more preferably between 100 and 300 mbar.

Also, the temperature profile in the column c is such that: the temperature of the lower part a is between 100 and 300 ° C., more preferably between 150 and 200 ° C. the temperature of the upper part b of the column c must be lower than the temperature of the lower part a and is between 100 ° and less than 300 ° C., more preferably between 100 and 200 ° C.

FIG. 2 represents an operational device that can be used for carrying out the synthesis of oligoesters according to the invention. The device consists of a reactive column c and a heating device (reboiler) d.

The heating temperature, the pressure in the column c, the feed rate of the ammonium salt solution of dicarboxylic acid I and the temperature of the aqueous solution of ammonium salt of dicarboxylic acid I and the diol II make it possible to obtain a temperature profile in column c such that: the temperature of the upper part b of column c allows the dissociation of the ammonium salt of dicarboxylic acid I in diacid and ammonia while limiting the formation of amine derivatives such as imides or amides. The diol II and the diacid are in the vapor phase in the lower part of the column c and in the liquid phase in the upper part b of the column c. - Water and ammonia are in the gas phase at any point in column c and are recovered at the top of column c. Advantageously, an inert gas may be injected into the lower part of column c to facilitate removal of water and ammonia at the top of column c. - The oligoester III product is in liquid phase at any point of the column c and is easily recovered at the bottom of column c. The use of packed columns, trays or any other type of column known to those skilled in the art can be envisaged for carrying out this reaction.

The reaction can be carried out with or without a catalyst. In the case of the use of a catalyst, any type of homogeneous (e.g., p-toluenesulfonic acid) or heterogeneous esterification catalyst (e.g., strong acid resins of the Amberlyst type) may be used.

Examples

Equipment The equipment consists of a 250 ml flask surmounted by a device (bell) to separate the rising vapors and the descending liquid phase. The latter can be recovered in a first bulb. The bell has a double envelope to maintain its temperature via a circulation of oil at a controlled temperature. The bell is surmounted by a column c 60 cm high and inside diameter of 3 cm and filled throughout its length with glass Raschig rings (diameter 6 mm and length 6 mm). The vapors leaving the column head c are condensed and recovered in a second bulb.

Characterization

The liquid phase oligoesters III recovered in the first ampoule are characterized by mass spectrometry. The sample is dissolved in acetonitrile (hplc grade) to obtain a solution of 1 μΐ / ml. The fresh solution is added at a rate of 0.5 μl / ml with a solution of sodium iodide in acetonitrile at a concentration of 1 mg / ml. The mass spectrometry analyzes were carried out by direct infusion (5 μl / min) on a Waters QToF2 type mass spectrometer (flight time type analyzer). The analysis conditions are as follows: - Ionization mode: Electrospray - positive

- Voltage of the capillary: 3.1 kV

- Voltage of the cone: 25 V - desolvation gas: nitrogen

- Source temperature: 80 ° C

- Desolvation temperature: 120 ° C - Mass range (m / z): 50 to 1000

The amount of residual nitrogen in the oligomers is determined on a VARIO MAX CUBE elementary analyzer of the ELEMENTAR brand (dry combustion method or Dumas method).

Examples 1 and 2 make it possible to carry out the synthesis of oligoesters of low DP.

Example 1

The device is maintained at a pressure of 100 mbar. 150 ml of 1,4-butanediol are introduced into the flask and brought to the boil.

An aqueous solution of diammonium succinate 100 g / l maintained at ambient temperature is introduced continuously into the upper part b of column c at a flow rate of 15 ml / min.

The temperature of the bell is controlled by an oil bath circulation at 170 ° C.

The reaction is carried out in the absence of catalyst.

The following table indicates the proportions in% by weight of the oligoesters III obtained according to the invention for which 56% of the oligoesters have a DP of 3.

The residual nitrogen concentration in the oligoesters III is equal to 0.15%.

Example 2

The device is maintained at a pressure of 100 mbar. 150 ml of 1,4-butanediol are introduced into the flask and brought to the boil.

The aqueous solution of diammonium succinate (100 g / l) maintained at ambient temperature is introduced continuously into the upper part b of column c at a flow rate of 5 ml / min. The temperature of the bell is controlled by an oil bath circulation at 170 ° C. The reaction is carried out in the absence of catalyst.

The following table indicates the proportions in% by weight of the oligoesters III obtained according to the invention for which 61% of the oligoesters have a DP of 3.

The residual nitrogen concentration in the oligoesters III is equal to: 0.08%

Claims (8)

claims A process for the continuous synthesis of oligoester (III) from an ammonium salt of dicarboxylic acid (I) and a diol (II) comprising the steps of: a. continuous introduction into a reaction device of an aqueous solution comprising a dicarboxylic acid ammonium salt (I); b. heating the aqueous solution in order to dissociate the ammonium salt of dicarboxylic acid (I) to diacid and ammonia, the heating temperature being lower than the boiling temperatures of the diol (II) and the diacid; vs. continuous introduction into the reaction device of the diol (II) in gaseous form; d. heating of the diol (II) to a temperature above the boiling point of the diol (II), the diacid obtained during the dissociation of the ammonium salt of dicarboxylic acid (I), the water and the ammonia and at a temperature below the boiling point of the oligoester (III); e. contacting the diacid with the diol (II) at a temperature above the boiling point of the diol (II), the diacid, the water and the ammonia and at a temperature below the boiling point oligoester (III); f. recovery of the oligoester (III) in liquid form. 2. Method according to claim 1 characterized in that the ammonia gas is recovered in the form of an aqueous solution. 3. Method according to one of the preceding claims characterized in that the diacid obtained during the dissociation of the ammonium salt of dicarboxylic acid (I) has a boiling point between 150 and 350 ° C. 4. Method according to one of the preceding claims characterized in that the diol (II) has a boiling point between 150 and less than 350 ° C. 5. Method according to one of the preceding claims characterized in that the ammonium salt of dicarboxylic acid (I) is diammonium succinate and the diol (II) is 1,4-butanediol. 6. Method according to one of the preceding claims characterized in that the aqueous solution of ammonium salt of dicarboxylic acid (I) contains diol (II). 7. Method according to one of the preceding claims characterized in that the pressure is between 1 mbar and 500 mbar. 8. Apparatus suitable for the process as described in claims 1 to 7 comprising a column (c) of reactive distillation characterized in that the supply of the aqueous solution of the ammonium salt of dicarboxylic acid (I) is carried out in the column (c) and that the diol (II) feed is carried out in the lower part (a) of the reactive distillation column (c), the temperature of the lower part (a) of column (c) is greater than the boiling point of the dicarboxylate (I) and the diol (II) but lower than the boiling point of the oligoester (III), the temperature of the upper part (b) of column (c) is lower than the boiling point of dicarboxylate (I) and diol (II) but is sufficient to decompose the ammonium salt of dicarboxylic acid (I) to ammonia and diacid, the oligoester (III) is recovered at the bottom of the column.