JP2671152B2 - Method for purifying 1-aminopropanediol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for purifying 1-aminopropanediol. More specifically, it relates to a purification method capable of improving energy efficiency by performing distillation for dehydration in two stages. 1-Aminopropanediol is a compound useful as a raw material for an X-ray contrast agent that has been growing in demand in recent years.

[Prior Art] The following are known methods for producing 1-aminopropanediol.

(1) Method of reacting glycidol with ammonia and finally obtaining purified 1-aminopropanediol by vacuum distillation (L. Knorr et al., "Ber deutsch Chen. Ges.", Vo
L.32,750,1899, K.Baun et al., “J.Org.chem.”, Vol.27,2.
231,1962, "Published Patent Gazette", Sho 56-161357, Sho 56
-161355, 56-161356, etc.), (2) catalytic hydrogenation of the ketimine compound obtained by the reaction of glycerinaldehyde and ammonia (same as hydrogenation reaction), and finally purified by distillation 1-aminopropanediol (“Publication of Patent Application No.”) Sho 62-2307
54), (3) Glycerin-α-monochlorohydrin is reacted with ammonia, and finally purified by vacuum distillation 1-
Method for Obtaining Aminopropanediol (K. Baum et al. “J.Or
g.Chem. ", Vol.27,2231,1962), etc.

However, there is no detailed description of the purification method of 1-aminopropanediol in these prior arts. Further, in order to improve the yield in the reaction step or to manufacture with a simple facility, it is preferable to use a large excess of aqueous ammonia solution. There is no description.

That is, nothing can be known from the prior art about a method for industrially efficiently purifying 1-aminopropanediol from a water-containing crude liquid.

[Problems to be Solved by the Invention] It is necessary to use a large excess of aqueous ammonia solution in order to improve the yield in the reaction step or to simplify the production equipment by reacting at normal pressure. In that case, a large amount of water is inevitably contained in the reaction crude liquid. Efficient removal of this is industrially important from the viewpoint of energy economy, but the findings cannot be known from the above-mentioned literature.

Therefore, we tried dehydration by the most common one-stage distillation operation, but when dehydration was performed at a pressure of 10 mmHg or less, the liquid boiling point became 64 ° C or less, and the viscosity of 1-aminopropanediol remarkably increased due to an exponential function. It became difficult to dehydrate. Also, 100m
At a pressure of mHg or more, the temperature of the evaporator becomes 120 ° C. or more, which requires an energetically expensive heat source, and the amount of 1-aminopropanediol lost along with water is large. This tendency became greater as the pressure increased and the boiling point increased.

The present inventors have completed the present invention as a result of intensive studies in view of the above situation.

[Structure of the Invention] That is, the present invention relates to "a reaction crude liquid or a reaction crude liquid when producing 1-aminopropanediol from glycidol and an aqueous ammonia solution, glyceraldehyde and an aqueous ammonia solution, or glycerin-α-monochlorohydrin and an aqueous ammonia solution. , The water-containing crude liquid after distilling and recovering ammonia is treated with 10 to 90 wt% of water under atmospheric pressure deammonia water treatment, or
A method for purifying 1-aminopropanediol, which comprises dehydration under atmospheric pressure, and then dehydration under reduced pressure at 50 to 200 mmHg to a residual water content of 1 wt% or less.

Hereinafter, the method for purifying 1-aminopropanediol of the present invention will be described in detail.

The reaction crude liquid which is the target of the method for purifying 1-aminopropanediol of the present invention can be synthesized from glycidol, glyceraldehyde, or glycerin-α-monochlorohydrin and ammonia as described above. The synthesis method using glycidol as a raw material is described below.
Since the present invention relates to a purification method, the reaction conditions and starting materials are not limited as long as the reaction crude liquid contains 1-aminopropanediol, ammonia, and water.

The reaction formula of 1-aminopropanediol with glycidol and ammonia is shown in the formula.

CH2 (-O-) CHCH20H + NH3 = CH2 (NH2) CH (OH) CH20H ...... The reaction is performed at room temperature to obtain an appropriate reaction rate and yield.
Glycidol is continuously or batchwise added to an aqueous ammonia solution at 100 ° C. under normal pressure or under pressure so that ammonia does not boil.

It is preferable to use an aqueous ammonia solution having an ammonia concentration of 30 wt% or less so that the equipment does not have expensive high pressure gas specifications. Further, in order to increase the yield in the reaction step, it is better to use a large excess, specifically about 15 times the molar ratio of ammonia.

As a result, the reaction crude product obtained contains 9 wt times or more water of 1-aminopropanediol.

For example, containing 15 mol times more ammonia than glycidol 2
The reaction crude liquid obtained by semi-batch addition of glycidol to an 8 wt% aqueous ammonia solution contained 66.5 wt% of water.
In this case, the reaction temperature is preferably 40 ° C. or higher, and the ammonia vaporizes violently at a boiling point, while the reaction temperature becomes slower at 30 ° C. or lower, so that it is desirable to maintain 35 ° C.

Ammonia and water can be removed from this reaction crude liquid by a continuous or batch distillation operation at an arbitrary pressure, but if only ammonia is recovered by pressure distillation, the water content of the water-containing crude liquid will be concentrated to 88 wt%. Become.

As described above, the dehydration of the water-containing crude liquid is generally performed in one dehydration distillation step in order to simplify the process. However, the higher the pressure, the higher the boiling point, because the yield deteriorates in inverse proportion to the pressure, and when the boiling point becomes 100 ° C. or less, the viscosity sharply increases and the distillation operation becomes difficult,
A single-stage distillation results in a large loss of active ingredient.

Therefore, when the water content in the crude liquid is 10 wt% or more and the boiling point is 130 ° C. or less, distillation is carried out at normal pressure to concentrate 1-aminopropanediol. (This is because if the water content of 10 wt% or more is left, the loss of 1-aminopropanediol in the next dehydration under reduced pressure cannot be ignored, and if it is concentrated to less than that, the boiling point becomes 130 ° C or more.) As a result, most of the water is removed under conditions where the relative volatility of water and 1-aminopropanediol (the vapor pressure ratio of water and 1-aminopropanediol) is large, and the loss of 1-aminopropanediol is reduced. .

Next, the pressure reduction is performed when the evaporation rate becomes small due to the boiling point increase accompanying the concentration, and the remaining water is removed. Here, by reducing the pressure to 200 mmHg or less, the decrease in specific volatility due to temperature rise is suppressed, and by setting it to 50 mmHg or more,
Prevents increase in viscosity and decrease in evaporation rate due to decrease in boiling point of can solution.

Specifically, the water-containing crude liquid is charged into the first-stage distillation column to obtain a concentrated liquid containing water at the top of the column and 10 wt% of water at the bottom. This is charged into the second-stage distillation column to obtain water from the top of the column and crude 1-aminopropanediol from the bottom of which dehydration has been completed.

Hereinafter, the effects of the present invention will be specifically described by showing Examples and Comparative Examples.

[Example 1] A glass reactor equipped with a mechanical stirrer and a condenser and equipped with a 2 liter jacket was charged with a 28 wt% ammonia solution 91
2 g (ammonia 15 mol) was charged. Move the stirrer,
Water in a constant temperature water tank capable of both heating and cooling is circulated by an electric pump in the jacket, and the internal temperature of the reactor is 35 ± 2 ° C.
Held.

Glycidol (purity of 99.0 wt% or more is desirable for the purpose of reducing the concentration of by-products) 75 g (1 mo
The whole amount of l) was added dropwise in 3 hours. At this time, the inside of the reactor was sufficiently stirred to maintain a turbulent state. After the completion of the dropping, the temperature was kept at 35 ± 2 ° C. for a further 2 hours, and the reaction was continued to completely react the residual glycidol.

The composition of the reaction crude liquid was determined by gas chromatography analysis to be 24.4 wt% ammonia, 1-aminopropanediol.
It was 6.9 wt%, water 66.5 wt% and other 2.2 wt%.

980 g of crude reaction liquid was charged into a pressurized distillation column and the absolute pressure was 8 to
While applying an appropriate reflux amount under a pressure of 9 kg / cm2, 237 g of ammonia having a purity of 99.9 wt% or more was recovered from the top of the column. 741 g of the water-containing crude liquid obtained from the bottom of the column contained 9.1 wt% of 1-aminopropanediol, 88.0 wt% of water, and 2.9 wt% of others.

After the completion of ammonia recovery, 741 g of a water-containing crude liquid was charged into a round bottom flask equipped with a condenser, and heated under a normal pressure with a mantle heater to distill water. The dehydration was terminated by stopping heating when the liquid temperature reached 120 ° C. Distilled water is 613g 1-
It contained 0.1 wt% of aminopropanediol.

Next, the inside of the evaporator was depressurized to 100 mmHg by an aspirator and reheated to distill the remaining water. The resulting bottom liquid was 90.1 g and contained 73.0 wt of 1-aminopropanediol.
%, 1.0% water.

From the comparison of the amount of 1-aminopropanediol before and after dehydration, the yield in the dehydration process was 96.6% under atmospheric pressure and 98.2% under reduced pressure.
%, And the total dehydration process was 94.9%.

Example 2 980 g of the reaction crude product obtained in the same manner as in Example 1 was placed in a 2 liter round bottom flask equipped with a condenser connected to a dilute hydrochloric acid water sealer for ammonia absorption, and heated with a mantle heater.

The distillation operation was performed under atmospheric pressure until the temperature of the liquid in the flask was 120 ° C. When the liquid temperature reaches 120 ° C, heating is stopped, and the atmosphere side of the condenser is reconnected from the water sealer to the aspirator 15
The pressure was reduced to 0 mmHg and reheating was performed.

The dehydration was completed when the liquid temperature reached 139 ° C. 89 g of liquid remained in the can and 64 g of 1-aminopropanediol was obtained.

The yield of 1-aminopropanediol in the dehydration step is
93.7%.

[Example 3] The same operation as in Example 2 was repeated except that the pressure in the reduced pressure dehydration step was 200 mmH.
It changed to g-10mmHg. The yield of 1-aminopropanediol at that time is shown in Table 1.

[Comparative Example 1] 980 g of the reaction crude liquid obtained in the same manner as in Example 1 was placed in a 2 liter glass round bottom flask equipped with a condenser. The pressure was reduced to 100 mmHg with a water aspirator, and ammonia and water were distilled off. Liquid temperature of the flask is 124 ℃
The heating was terminated at the point when the temperature became, and 55.6 g of residual liquid was obtained. 1-
The amount of aminopropanediol was 31.5 g as determined by gas chromatography analysis.

The yield of 1-aminopropanediol by this method is
It was 46.1%.

Comparative Example 2 980 g of the reaction crude liquid obtained in the same manner as in Example 1 was placed in a 2 liter glass round bottom flask having a condenser whose atmospheric side was connected to an ammonia absorption tower. After heating with a mantle heater, ammonia and water were distilled off by simple distillation. When the liquid temperature in the flask was 190 ° C., heating was completed, and 3.2 g of 1-aminopropanediol was obtained in 18 g of the residual liquid.

The yield of 1-aminopropanediol by this method is
Only 4.7%.

[Comparative Examples 3, 4 and 5] Similar to Comparative Examples 1 and 2, the yields of 1-aminopropanediol in the one-stage flash distillation experiment under various pressures, the liquid boiling point, and the 1-aminopropanediol were determined. The viscosity is shown in Table 2 together with the viscosity.

Claims (1)

(57) [Claims] 1. From glycidol and ammonia aqueous solution, glyceraldehyde and ammonia aqueous solution, or glycerin-α-monochlorohydrin and ammonia aqueous solution 1-
In the production of aminopropanediol, the reaction crude liquid or the water-containing crude liquid obtained by distilling and recovering ammonia is subjected to (a) 10 to 90 wt% of water under atmospheric pressure dehydration step, and (b) residual water content at 50 to 200 mmHg. The method for purifying 1-aminopropanediol is characterized in that dehydration is carried out under reduced pressure to 1 wt% or less.