JPH0428256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently converting ethyleneamine carbonates into ethyleneamines.
More specifically, 200% of ethyleneamines obtained by thermally decomposing an aqueous solution of ethyleneamines
For the carbonate radical of an ethyleneamine aqueous solution containing undecomposed ethyleneamine carbonate in an amount of
150 g/or more of an aqueous solution of an alkali metal hydroxide is added in an equivalent amount or more to form two phases: an ethylene amine aqueous solution phase and an alkali metal carbonate aqueous solution phase,
The present invention relates to a method for obtaining ethyleneamines from carbonates of ethyleneamines, which comprises phase-separating the two phases to obtain an aqueous solution of ethyleneamines.

In the present invention, ethyleneamines include chain-like ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, tris-(2-aminoethyl)-amine, piperazine, and N-aminoethylpiperazine. , means a single amine or a mixture of amines including cyclic ethylene amines.

These ethyleneamines are used in a wide range of fields as main raw materials, auxiliary raw materials, or additives. For example, it is used for agricultural chemicals, paper strength enhancers, epoxy curing agents, lubricating oil additives, polyamides, etc.

Further, these ethyleneamines are mainly produced by the following two methods, but the ethyleneamines referred to in the present invention are not limited to those produced by these methods.

(a) EDC method: Ethylene dichloride (EDC) and ammonia are reacted under high temperature and pressure to produce hydrochloride of ethyleneamines, and the hydrochloride is metathesized with caustic soda to separate by-product sodium chloride.

(b) MEA method: Monoethanolamine (EMA) and ammonia are reacted under high temperature and pressure in the presence of a hydrogen catalyst to obtain ethyleneamines.

Ethylene amine carbonates are produced during the process of producing ethylene amines, or when ethylene amines are used in a reaction, when unreacted ethylene amines are treated with carbon dioxide and recovered as carbonates of ethylene amines. etc. to generate it.

For example, Japanese Patent Application No. 57-130482, Japanese Patent Application No. 59-20253
As in the publication, ethylene amines are selectively extracted from an aqueous solution containing ethylene amines using an organic solvent, and ethylene amine acid is converted into carbonate from the organic phase using carbon dioxide gas or carbonated water. Generated when collecting as .

The ethyleneamine carbonate of the present invention is basically a reaction product of ethyleneamine and carbon dioxide, and is sometimes called a carbamate of ethyleneamine.

These ethyleneamine carbonates are rarely made into products as they are, and in many cases they are commercialized and sold as ethyleneamines. Therefore, the carbonate of ethyleneamines must be converted into ethyleneamines by removing the carbonate radical.

One possible method for this is to add a strong alkaline agent such as sodium hydroxide or calcium hydroxide to cause double decomposition and separate the by-products of sodium carbonate and calcium carbonate. however,
This method is not economical because it consumes a large amount of strong alkaline agent.

Therefore, the present inventors have conducted various studies on methods that completely convert ethyleneamine carbonates into ethyleneamines, which is economical and easy to operate. As a result, we learned that ethyleneamine carbonate decomposes into ethyleneamines when heated. However, it was found that heating alone could not completely decompose it, so further studies were conducted. As a result, it was found that ethyleneamines can be completely converted into ethyleneamines by adding alkali metal hydroxide after thermally decomposing ethyleneamines carbonate, and that the concentration of ethyleneamines aqueous solution after thermally decomposing and the concentration of alkali metal hydroxide aqueous solution They discovered that by limiting the concentration, two phases, an ethyleneamine aqueous solution phase and an alkali metal carbonate aqueous solution phase, could be formed, and the present invention was completed.

That is, in the present invention, 150 g of carbonate radicals of an ethylene amine aqueous solution containing 200 g or more of undecomposed ethylene amine carbonate are classified as ethylene amines obtained by thermally decomposing an ethylene amine carbonate aqueous solution. Add an equivalent or more of the above aqueous solution of alkali metal hydroxide to form two phases: an aqueous ethyleneamine solution phase and an aqueous alkali metal carbonate solution phase, and phase-separate the two phases to obtain an aqueous solution of ethyleneamines. A method for obtaining ethylene amines from ethylene amine carbonates, characterized by the following.

The present invention will be explained in more detail below.

The present invention requires that the ethyleneamine carbonate aqueous solution be thermally decomposed. An aqueous solution of ethyleneamines can be obtained even by adding an alkali metal hydroxide without thermal decomposition. however,
The amount is large and implementation is difficult. The ethylene amine carbonate aqueous solution is required in an amount of 200 g or more as ethylene amines (hereinafter referred to as ethylene amines). If the concentration is low, thermal decomposition is easy, but the commercial value is low because of the high moisture content, and even if dehydration is performed, energy consumption is high and it is not economical. Conversely, if the concentration is high, thermal decomposition becomes difficult, so
600g/or less is desirable. In addition, the carbonate concentration of the carbonate aqueous solution is converted into carbon dioxide (hereinafter referred to as CO ₂
0.5 times the mole or more of ethyleneamines (referred to as ethylene amines) is recommended. If it is smaller than 0.5 times the mole, there is little point in thermally decomposing it.

When thermally decomposed, carbon dioxide gas is volatilized and free ethyleneamines (simply referred to as ethyleneamines in the present invention) are produced. Thermal decomposition is usually carried out at normal pressure because it simplifies operation and equipment. However, it may also be carried out under pressure; in this case, the operation and equipment will be more complicated, but the decomposition of the carbonate will be easier. The pressure is preferably 1 to 10 Kg/cm ² in absolute terms, and preferably under boiling. Also, at this time, water vapor,
It is more effective to introduce nitrogen gas or the like.

As the ethyleneamines, the above-mentioned substances may be used alone or in mixtures.

By thermal decomposition, _CO2 content decreases and an aqueous solution of ethyleneamines is obtained. However, completely _CO2
It is difficult to remove this amount, and usually 0.01 to 0.3 times the mole of ethyleneamine remains. In order to remove this residual CO2, the present invention adds _an alkali metal hydroxide.

That is, in the present invention, the ethyleneamine class obtained by thermal decomposition is 150g/or more per carbonate radical (CO ₂ minutes) of an ethyleneamine aqueous solution containing 200g/or more of terminally decomposed ethyleneamine carbonate. It is essential that an equivalent amount or more of an aqueous solution of an alkali metal hydroxide is added to form two phases, an ethylene amine aqueous solution phase and an alkali metal carbonate aqueous solution phase, and that these two phases are phase-separated.

Here, the ethyleneamine class is the sum of free ethyleneamines and ethyleneamines constituting the ethyleneamine carbonate. If the ethyleneamine content is lower than 200g/2, two liquid phases will not be formed and it will be difficult to obtain ethyleneamines. In this case, there is a means to increase the concentration of the aqueous alkali metal hydroxide solution. However, it is difficult to implement because it requires an extremely high concentration and a large amount. The ethylene amine classification is preferably 200 to 600 g/. As the alkali metal, potassium and sodium are desirable, and sodium is particularly preferred because it is economical. The concentration is 150g/or more. At low concentrations, two liquid phases are not formed. At high concentrations, two-liquid phase formation is possible. However, it is expensive;
Since it becomes difficult to handle, 1000g/or less is desirable.

Further, the amount of alkali metal hydroxide used must be at least equivalent to the carbonate radical of the aqueous ethyleneamine solution. If it is too low, ethyleneamine carbonates remain. If more than the equivalent amount is used, it will exist as an alkali metal hydroxide, but it will not interfere with the formation of a two-phase liquid. However, if the amount is too large, the alkali metal carbonate produced will precipitate, making phase separation difficult and uneconomical. It is desirably 10 times the equivalent or less.

Moreover, the temperature is suitably 20 to 100°C.

In the two-phase formation, the ethylene amine aqueous solution phase becomes the upper phase and the alkali metal carbonate aqueous solution becomes the lower phase. The concentration of alkali metal carbonate in the ethyleneamine aqueous solution phase varies depending on the temperature and the concentration of ethyleneamine, but it can be extremely low, usually 30 g/or less,
It can also be less than 10g/. Furthermore, the concentration of ethylene amines in the aqueous alkali metal carbonate solution phase can also be lowered, usually at 50 g/or less.

Further, the alkali metal carbonate may precipitate in the alkali metal carbonate aqueous solution phase, which is the lower phase. In this case, it is sufficient to extract it as slurry.

As described above, according to the present invention, ethylene amines can be obtained easily and economically from ethylene amine carbonates.

Further, if it is desired to further lower the concentration of the alkali metal carbonate dissolved in the aqueous ethyleneamine solution phase mentioned above, the following method is preferable.

That is, the ethyleneamine aqueous solution phase is dehydrated. Then, alkali metal carbonates precipitate, so
This may be introduced into the step of settling and forming a two-phase concentrated slurry. In this way, the concentration of alkali metal carbonate in the ethyleneamine aqueous solution phase is reduced to 1.
g/ or less.

In this case, the aqueous solution of alkali metal hydroxide may be added to the static fixing section. Then, it may be introduced into the step of forming two phases as a slurry together with the precipitated alkali metal carbonate.

In addition, in this dehydration, when the ethylene amines are a mixture of ethylenediamine, which is a low boiling point, and high molecular weight ethylene amines, such as diethylenetriamine and triethylenetetramine, which are high boiling points, ethylenediamine is distilled and removed at the same time as the dehydration. It's okay.

The advantages of the method of the invention are listed below.

(1) Ethyleneamine carbonate salts can be completely converted into ethyleneamines.

(2) The process is simple as it involves heating and two-phase formation.

(3) It is economical because only a small amount of drugs are used.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Ethylenediamine: 168g/, piperazine:
6.3g/, diethylenetriamine: 77g/,
N-aminoethylpiperazine: 11g/, triethylenetetramine: 46g/, tetraethylenepentamine: 21g/, pentaethylenehexamine: 15g/, CO ₂ minutes: 500ml of an aqueous solution of ethylene amine carbonate was added to the reflux condenser. Ethylenediamine: 169
g/, piperazine: 6.3 g/, diethylenetriamine: 78 g/, N-aminoethylpiperazine: 11 g/, triethylenetetramine: 47 g/
, Tetraethylenepentamine: 21g/, Pentaethylenehexane: 15g/, CO ₂ minutes: 26g/
An aqueous solution of ethyleneamines was obtained.

Next, 27 ml of a 210 g/aqueous sodium hydroxide solution was added to 100 ml of the aqueous solution, stirred at 40°C, and allowed to settle. Ethylenediamine: 146 g/, piperazine: 5.4 g/, diethylenetriamine: 67 g/
, N-aminoethylpiperazine: 9.5g/,
The upper phase is 114ml of an aqueous solution of ethyleneamines containing triethylenetetramine: 41g/, tetraethylenepentamine: 18g/, pentaethylenehexamine: 13g/, and sodium carbonate: 17g/, and the lower phase containing the precipitate is sodium carbonate: 440g/. Ethylene amines: 15 g/aqueous sodium carbonate solution was obtained. Next, the two liquid phases were separated to obtain an upper phase.

When the aqueous solution of ethylene amines in the upper phase was distilled at atmospheric pressure to distill out water and ethylene diamine, ethylene amines containing crystals of sodium carbonate were obtained as the residue, and the sodium carbonate in the supernatant liquid was
It was 0.5g/.

Example 2 Ethylenediamine was extracted from an aqueous solution of ethylenediamine and sodium chloride with a mixed solvent of cyclohexanone and n-butanol (volume ratio 1:2), and carbon dioxide gas and a small amount of water were passed through the extract to obtain ethylenediamine: 250 g/, CO ₂ minutes: 183g/
The aqueous solution was thermally decomposed in the same manner as in Example 1 to obtain an aqueous solution containing ethylenediamine: 255 g/2 min, CO ₂ min: 120 g/min.

Next, 100 ml of an aqueous solution of 330 g of sodium hydroxide was added to 100 ml of the aqueous solution, stirred at 40°C, and allowed to settle. 85 ml of an aqueous solution of ethylene amines containing 270 g of ethylene diamine and 25 g of sodium carbonate.
obtained in the upper phase.

Claims (1)

[Claims] 1. As the ethyleneamine class obtained by thermally decomposing an ethyleneamine carbonate aqueous solution, 150g/carbonate radical of an ethyleneamine aqueous solution containing 200g/or more of undecomposed ethyleneamine carbonate is added.
An equivalent amount or more of the above aqueous alkali metal hydroxide solution is added to form two phases, an ethyleneamine aqueous solution phase and an alkali metal carbonate aqueous solution phase, and the two phases are separated to obtain an ethyleneamine aqueous solution. A method for obtaining ethylene amines from ethylene amine carbonates.