JP2014019644A - Method for manufacturing ethylene urea - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing ethylene urea which can induce reactions at atmospheric pressure without requiring a high-pressure reaction vessel, can lower reaction temperatures in comparison with methods of the prior art and therefore inhibit yellowish browning of reaction products, and can be industrially implemented.SOLUTION: A ring closing reaction of a monocarboalkoxy derivative of ethylenediamine expressed by general formula (2) [Chemical 1] (where Rm denotes a hydrocarbon group) synthesized by reacting ethylenediamine and a dialkyl carbonate is induced by exerting an inorganic solid base catalyst onto the monocarboalkoxy derivative.

Description

  The present invention relates to a method for producing ethylene urea, and more particularly to a method for producing ethylene urea which can lower the reaction temperature as compared with the conventional method and has a good yield.

  Ethyleneurea (2-imidazolidinone, 2-imidazolidone) has been conventionally used as an ethyleneurea-based resin in various applications such as textiles, leather, or wood processing aids. In recent years, ethylene urea has been important as an intermediate in the pharmaceutical industry. This ethylene urea can be produced industrially by various methods.

For example, in the ethylenediamine-carbon dioxide method shown in Patent Document 1 below, ethylenediamine and carbon dioxide are reacted at 300 ° C. under a high pressure of about 1 MPa (10 kgf / cm ² ). In this method, a high pressure reaction vessel is required and a high temperature reaction of 300 ° C. must be performed.

In the ethylenediamine-urea method shown in Patent Document 2 below, ethylenediamine and urea are reacted at 235 ° C. under an atmospheric pressure of about 0.1 MPa (1 kgf / cm ² ). In this method, unlike the ethylenediamine-carbon dioxide method, a reaction under atmospheric pressure is possible and a high-pressure reaction vessel is not required. Therefore, at present, the ethylenediamine-urea method capable of reacting under atmospheric pressure is most frequently used.

US2497309 US2504431

  By the way, also in the ethylenediamine-urea method of the said patent document 2, reaction under high temperature close to 250 degreeC is required. In such a high temperature, there is a problem that the yellowing of the reaction product containing ethylene urea becomes severe due to oxidation of ethylenediamine before it reacts with urea and oxidation of unreacted ethylenediamine. It was.

  When the reaction product containing ethylene urea is severely yellowish brown, it requires a large cost for the purification of ethylene urea. It cannot be used for the required application.

  Therefore, in the present invention, the reaction under atmospheric pressure is possible, a high-pressure reaction vessel is not required, the reaction temperature can be lowered as compared with the conventional method, so that yellowing of the reaction product can be suppressed, and industrially It is an object of the present invention to provide an applicable method for producing ethylene urea.

  In solving the above problems, the present inventors, as a result of diligent research, have made ethylene urea at atmospheric pressure and at a temperature lower than conventional by allowing a specific inorganic solid base catalyst to act on the reaction between ethylenediamine and dialkyl carbonate. The present invention was completed.

That is, the method for producing ethylene urea according to the present invention, according to claim 1,
Ethylenediamine and general formula (1)

（式中、Ｒ１及びＲ２は炭化水素基を示し、Ｒ１とＲ２は同一であってもよく異なっていてもよい。）に示すジアルキルカーボネートとの混合物に無機固体塩基触媒を作用させてエチレン尿素を合成することを特徴とする。

(Wherein R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different.) An inorganic solid base catalyst is allowed to act on the mixture with the dialkyl carbonate shown in It is characterized by combining.

Moreover, according to the description of claim 2, the method for producing ethylene urea according to the present invention,
Ethylenediamine and general formula (1)

（式中、Ｒ１及びＲ２は炭化水素基を示し、Ｒ１とＲ２は同一であってもよく異なっていてもよい。）に示すジアルキルカーボネートとの反応により合成される一般式（２）

(Wherein R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different.) General formula (2) synthesized by reaction with dialkyl carbonate shown in

（式中、Ｒｍは前記一般式（１）におけるＲ１又はＲ２の炭化水素基を示す。）に示すエチレンジアミンのモノカルボアルコキシ体に、無機固体塩基触媒を作用させて、当該モノカルボアルコキシ体を閉環反応させることを特徴とする。

(In the formula, Rm represents a hydrocarbon group of R1 or R2 in the general formula (1).) The monocarboalkoxy compound of ethylenediamine shown in FIG. It is made to react.

Moreover, according to the description of claim 3, the method for producing ethylene urea according to the present invention,
Ethylenediamine and general formula (1)

（式中、Ｒ１及びＲ２は炭化水素基を示し、Ｒ１とＲ２は同一であってもよく異なっていてもよい。）に示すジアルキルカーボネートとを反応させる第１工程と、
前記第１工程における反応物から一般式（２）

(Wherein R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different), and a first step of reacting with a dialkyl carbonate shown in FIG.
From the reaction product in the first step, the general formula (2)

（式中、Ｒｍは前記一般式（１）におけるＲ１又はＲ２の炭化水素基を示す。）に示すエチレンジアミンのモノカルボアルコキシ体を単離する第２工程と、
前記第２工程で単離した前記モノカルボアルコキシ体に無機固体塩基触媒を作用させて、当該モノカルボアルコキシ体の閉環反応を行う第３工程とを有することを特徴とする。

(Wherein Rm represents a hydrocarbon group of R1 or R2 in the general formula (1)), a second step of isolating a monocarboalkoxy body of ethylenediamine shown in FIG.
And a third step in which an inorganic solid base catalyst is allowed to act on the monocarboalkoxy isolated in the second step to perform a ring-closing reaction of the monocarboalkoxy.

According to the description of claim 4, the present invention is the process for producing ethylene urea according to claim 3,
The reaction product in the first step includes a monocarboalkoxy body of ethylenediamine represented by the general formula (2) and a general formula (3).

（式中、Ｒｍ及びＲｎは前記一般式（１）におけるＲ１又はＲ２の炭化水素基を示し、ＲｍとＲｎは同一であってもよく異なっていてもよい。）に示すエチレンジアミンのジカルボアルコキシ体を含有し、モノカルボアルコキシ体とジカルボアルコキシ体の総モル数に対してモノカルボアルコキシ体のモル数が７０モル％以上であることを特徴とする。

(In the formula, Rm and Rn represent a hydrocarbon group of R1 or R2 in the general formula (1), and Rm and Rn may be the same or different.) The number of moles of the monocarboalkoxy compound is 70 mol% or more with respect to the total number of moles of the monocarboalkoxy compound and the dicarboalkoxy compound.

Moreover, according to the description of Claim 5, this invention is a manufacturing method of ethylene urea as described in any one of Claims 1-4,
The inorganic solid base catalyst is characterized by comprising an alkaline earth metal oxide.

Moreover, according to the description of Claim 6, this invention is a manufacturing method of ethylene urea as described in any one of Claims 1-4,
The inorganic solid base catalyst is characterized by being an oxide mainly composed of an oxide of an alkaline earth metal and a part of the alkaline earth metal substituted with an alkali metal.

Moreover, according to description of Claim 7, this invention is a manufacturing method of ethylene urea of Claim 5 or 6, Comprising:
In the ring closure reaction, the cyclization rate from the monocarboalkoxy compound represented by the general formula (2) is 60% or more.

  According to the said structure, ethylene urea is synthesize | combined by reaction of ethylenediamine and the dialkyl carbonate shown to the said General formula (1). In this reaction, by reacting the inorganic solid base catalyst, the reaction proceeds under atmospheric pressure, and the reaction proceeds at a considerably lower temperature than the ethylenediamine-urea method, which is a conventional ethyleneurea production method. Therefore, in this reaction, unreacted ethylenediamine is not extremely oxidized.

  In addition, according to the configuration of the second aspect, in the production of ethylene urea, first, by the reaction of ethylenediamine with a dialkyl carbonate represented by the general formula (1), a monocarbohydrate of the ethylenediamine represented by the general formula (2). An alkoxy compound is synthesized. The reaction at this stage can be performed under atmospheric pressure, and the reaction proceeds at a considerably lower temperature than the ethylenediamine-urea method, which is a conventional method for producing ethyleneurea. Therefore, at this stage, unreacted ethylenediamine is not extremely oxidized.

  Next, an inorganic solid base catalyst is allowed to act on the monocarboalkoxy compound synthesized by the above reaction to cyclize the monocarboalkoxy compound to synthesize ethylene urea. The reaction at this stage can be performed under atmospheric pressure, and by reacting with an inorganic solid base catalyst, the reaction is performed at a considerably lower temperature than the ethylenediamine-urea method, which is a conventional ethyleneurea production method. Progresses. Accordingly, even at this stage, the unreacted ethylenediamine and the terminal amino group of the monocarboalkoxy compound are not extremely oxidized.

  Moreover, according to the structure of the said Claim 3, the monocarbo alkoxy body synthesize | combined at the 1st process is isolated at the 2nd process. By this isolation, unreacted ethylenediamine is removed from the reaction product in the first step. Therefore, in the third step of ring-closing reaction of the monocarboalkoxy compound, the content of ethylenediamine in the reaction system is low and oxidation is rare.

  Thus, according to the above configuration, oxidation of the terminal amino group of ethylenediamine or monocarboalkoxy in each reaction stage is suppressed, and yellowing of the reaction product after the ring-closing reaction is greatly reduced compared to the conventional method. .

  Moreover, according to the structure of the said Claim 4, in addition to the monocarboalkoxy body shown to General formula (2) as a reaction body in the said 1st process as an intermediate of ethylene urea synthesis, general formula ( The dicarboalkoxy compound shown in 3) may coexist. In the molar ratio of the monocarboalkoxy compound to the dicarboalkoxy compound in the reaction product, the ratio of the monocarboalkoxy compound is preferably 70 mol% or more. This improves the yield of ethylene urea obtained through the ring closure reaction of the monocarboalkoxy compound, and further suppresses yellowing of the reaction product due to oxidation of unreacted ethylenediamine.

  Moreover, according to the structure of the said Claim 5, the inorganic solid base catalyst used for the direct reaction of ethylenediamine and the dialkyl carbonate shown in the said General formula (1), or the ring-closing reaction via a monocarboalkoxy body is an alkali. An oxide of an earth metal is preferable. As a result, the catalytic activity of the inorganic solid base catalyst is improved, and the reaction temperature in the direct reaction between ethylenediamine and dialkyl carbonate or the ring closure reaction of a monocarboalkoxy compound is the ethylenediamine-urea method, which is a conventional ethyleneurea production method. The reaction temperature can be considerably lower than the reaction temperature. Further, even when the reaction temperature is low, the yield of ethylene urea can be maintained high, and a production method applicable industrially can be provided.

  Moreover, according to the structure of the said Claim 6, the inorganic solid base catalyst used for the direct reaction of ethylenediamine and a dialkyl carbonate or the ring closure reaction of a monocarboalkoxy body is mainly composed of an oxide of an alkaline earth metal, More preferred is an oxide obtained by substituting a part of the alkaline earth metal with an alkali metal. Thus, the catalytic activity of the inorganic solid base catalyst is further improved, the yield of ethylene urea can be maintained high, and an industrially applicable production method can be provided.

  Moreover, according to the structure of the said Claim 7, it is preferable that the cyclization rate from the monocarboalkoxy body shown to General formula (2) to ethylene urea is 60% or more. This makes it possible to maintain a high yield of ethylene urea and provide an industrially applicable production method.

  Therefore, the present invention is capable of reacting under atmospheric pressure, does not require a high-pressure reaction vessel, and can lower the reaction temperature as compared with the conventional method, so that yellowing of the reaction product can be suppressed and industrially applied. A possible method for producing ethylene urea can be provided.

  Ethylenediamine (EDA) used in the reaction of the present invention is a general-purpose chemical that is highly reactive and used in large quantities as an industrial chemical raw material. Therefore, ethylenediamine (EDA) is easily available and can be used at low cost, and can be easily applied to an industrial production method of ethyleneurea.

  On the other hand, the dialkyl carbonate (DAC) used in the reaction of the present invention is represented by the following general formula (1).

この一般式（１）において、Ｒ１及びＲ２は炭化水素基を示し、Ｒ１とＲ２は同一であってもよく異なっていてもよい。このＲ１及びＲ２の炭化水素基としては、例えば、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基などを挙げることができる。

In this general formula (1), R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different. Examples of the hydrocarbon group for R1 and R2 include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.

  Specific examples of the dialkyl carbonate (DAC) include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), and the like. In the present invention, among these dialkyl carbonates (DAC), it is preferable to use dimethyl carbonate (DMC). Dimethyl carbonate (DMC) is a general chemical that has high reactivity and is used in large quantities as an industrial chemical raw material. Accordingly, dimethyl carbonate (DMC) is easily available and can be used at low cost, and can be easily applied to an industrial production method of ethylene urea.

  In the reaction of the present invention, an intermediate can be used in the reaction of ethylenediamine (EDA) and dialkyl carbonate (DAC). As this intermediate, a monocarboalkoxy body (MA body) of ethylenediamine (EDA) represented by the following general formula (2) is generated.

この一般式（２）において、Ｒｍは上記一般式（１）におけるＲ１又はＲ２の炭化水素基を示す。上述のように、このＲｍの炭化水素基としては、例えば、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基などを挙げることができる。従って、ジアルキルカーボネート（ＤＡＣ）としてジメチルカーボネート（ＤＭＣ）を使用した場合には、上記一般式（２）に示す中間体としてエチレンジアミン（ＥＤＡ）のモノカルボメトキシ体（ＭＭ体）が生成する。

In the general formula (2), Rm represents a hydrocarbon group of R1 or R2 in the general formula (1). As described above, examples of the hydrocarbon group of Rm include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Accordingly, when dimethyl carbonate (DMC) is used as the dialkyl carbonate (DAC), a monocarbomethoxy form (MM form) of ethylenediamine (EDA) is formed as an intermediate represented by the general formula (2).

  In the reaction of the present invention, when the reaction between ethylenediamine (EDA) and dialkyl carbonate (DAC) further proceeds, the reaction between monocarboalkoxy (MA) and dialkyl carbonate (DAC) causes the following by-product. A dicarboalkoxy body (DA body) of ethylenediamine (EDA) represented by the general formula (3) is produced.

この一般式（３）において、Ｒｍ及びＲｎは上記一般式（１）におけるＲ１又はＲ２の炭化水素基を示し、ＲｍとＲｎは同一であってもよく異なっていてもよい。上述のように、これらＲｍとＲｎの炭化水素基としては、例えば、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基などを挙げることができる。従って、ジアルキルカーボネート（ＤＡＣ）としてジメチルカーボネート（ＤＭＣ）を使用した場合には、上記一般式（３）に示す副生物としてエチレンジアミン（ＥＤＡ）のジカルボメトキシ体（ＤＭ体）が生成する。

In the general formula (3), Rm and Rn represent R1 or R2 hydrocarbon groups in the general formula (1), and Rm and Rn may be the same or different. As described above, examples of the hydrocarbon groups of Rm and Rn include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Therefore, when dimethyl carbonate (DMC) is used as the dialkyl carbonate (DAC), a dicarbomethoxy form (DM form) of ethylenediamine (EDA) is produced as a byproduct shown in the general formula (3).

  Among the products shown here, it is a monocarboalkoxy body (MA body) as an intermediate that contributes to the synthesis of ethylene urea in the present invention. Ethyleneurea can be synthesized in the present invention by ring-closing reaction of this monocarboalkoxy (MA). On the other hand, it is difficult to synthesize ethylene urea by ring-closing reaction of a dicarboalkoxy compound (DA compound) as a by-product. Accordingly, the dicarboalkoxy compound (DA compound) cannot contribute to the synthesis of ethylene urea in the present invention.

  In the reaction of the present invention, an inorganic solid is used as a catalyst for synthesizing ethylene urea by direct reaction of ethylenediamine (EDA) and dialkyl carbonate (DAC) or ring-closing reaction of monocarboalkoxy (MA). A base catalyst is used. These inorganic solid base catalysts are heterogeneous catalysts, and a base point and an acid point as active sites are fixed on the oxide and can act simultaneously. Accordingly, in the present invention, it is considered that the proton abstraction from the amino group by the base point and the activation of the carbonyl oxygen by the acid point occur simultaneously, and the direct reaction or the ring closure reaction is promoted.

  The inorganic solid base catalyst used in the reaction of the present invention is preferably composed of an oxide of an alkaline earth metal. When these alkaline earth metal oxides act as a strong base catalyst, the ring closure reaction of the monocarboalkoxy (MA) can be efficiently performed at a low temperature.

  Examples of these oxides include beryllium oxide (BeO), magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). Among these oxides, it is preferable to use magnesium oxide (MgO), calcium oxide (CaO), or strontium oxide (SrO) in the present invention.

  These alkaline earth metal oxides can usually be obtained by firing an alkaline earth metal hydroxide or carbonate. The firing temperature and firing time at that time are not particularly limited, and may be appropriately selected in consideration of the decomposition temperature of each substance. For example, in order to obtain an oxide from a hydroxide or carbonate of magnesium (Mg), calcium (Ca), or strontium (Sr), it may be usually fired at a temperature of about 500 ° C to 1200 ° C. The obtained alkaline earth metal oxide is appropriately pulverized and used as an inorganic solid base catalyst.

  The inorganic solid base catalyst used in the reaction of the present invention is preferably composed of an oxide composed mainly of an alkaline earth metal oxide and a part of the alkaline earth metal substituted with an alkali metal. This is considered that the divalent alkaline earth metal in the oxide is replaced with a monovalent alkali metal, whereby the polarization of oxygen atoms is increased and it acts as a super strong base catalyst. An oxide obtained by substituting a part of these alkaline earth metals with an alkali metal acts as a super strong base catalyst, whereby a direct reaction between ethylenediamine (EDA) and dialkyl carbonate (DAC), or a monocarboalkoxy compound ( The ring closure reaction of the MA form can be carried out more efficiently at a low temperature.

  These oxides are mainly composed of, for example, beryllium oxide (BeO), magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), and the like of these alkaline earth metals. Examples thereof include oxides partially substituted with an alkali metal. Among these oxides, in the present invention, oxides mainly composed of magnesium oxide (MgO), calcium oxide (CaO), and strontium oxide (SrO), and a part of these alkaline earth metals are replaced with alkali metals. Is preferably used.

  Examples of the alkali metal that substitutes a part of the alkaline earth metal include lithium (Li), sodium (Na), and potassium (K), and it is particularly preferable to substitute with sodium (Na). The blending ratio of the alkaline earth metal and the alkali metal substituting a part thereof is not particularly limited, but it is usually preferably 1 mol% to 90 mol% with respect to the alkaline earth metal. More preferably, it is 5 mol%-50 mol%.

  An oxide obtained by substituting a part of these alkaline earth metals with an alkali metal is usually an alkali metal hydroxide or a part of the alkaline earth metal hydroxide or carbonate when calcined. It can be obtained by mixing carbonate or the like. The firing temperature and firing time at that time are not particularly limited, and may be appropriately selected in consideration of the decomposition temperature of each substance. Usually, firing may be performed at a temperature of about 500 ° C. to 1200 ° C. The obtained oxide obtained by replacing a part of the alkaline earth metal with an alkali metal is appropriately pulverized and used as an inorganic solid base catalyst.

  Next, one embodiment of the method for producing ethylene urea according to the present invention will be described, but the method for producing ethylene urea according to the present invention is not limited to this embodiment.

  In the present embodiment, the ethylene urea production method includes a first step of synthesizing a monocarboalkoxy body (MA body) by reacting ethylenediamine (EDA) and dialkyl carbonate (DAC), and a reaction product of the first step. A second step of isolating the monocarboalkoxy compound (MA-form) from the second step, and a third process in which the monocarboalkoxy compound (MA-form) isolated in the second step is allowed to act on the inorganic solid base catalyst to perform a ring-closing reaction And have. Hereinafter, this embodiment is described along each process.

First step:
In the first step, ethylenediamine (EDA) and dialkyl carbonate (DAC) are reacted to synthesize a monocarboalkoxy body (MA body). This reaction does not require the addition of a catalyst. This is thought to be due to the autocatalytic function of ethylenediamine (EDA).

  In the first step, as described above, in addition to the monocarboalkoxy body (MA body) as an intermediate that contributes to the synthesis of ethyleneurea, the dicarboalkoxy body (by-product that does not contribute to the synthesis of ethyleneurea ( DA body) is generated. Therefore, in this embodiment, the synthesis ratio of the monocarboalkoxy body (MA body) and the dicarboalkoxy body (DA body) becomes a problem.

  In the present embodiment, the number of moles of the monocarboalkoxy body (MA body) is 70 with respect to the total number of moles of the monocarboalkoxy body (MA body) and dicarboalkoxy body (DA body) produced in the first step. It is preferably at least mol%. When the synthesis ratio of the monocarboalkoxy compound (MA compound) is 70 mol% or more, the yield of ethylene urea is improved and the industrial applicability is increased.

  According to the study of the present inventors, in the reaction of the first step, first, a monocarboalkoxy compound (MA isomer) is produced, and the monocarboalkoxy compound (MA isomer) is produced to a certain degree at a certain stage. The alkoxy form (MA form) reacts with the unreacted dialkyl carbonate (DAC) in the reaction bath to produce a dicarboalkoxy form (DA form). Therefore, in the first step, the monocarboalkoxy compound (MA compound) should be promptly generated to avoid a long-time reaction.

  The amount of dialkyl carbonate (DAC) blended with ethylenediamine (EDA) is stoichiometrically equimolar, and the blending ratio is close to this to suppress the formation of dicarboalkoxy (DA). Is preferred. In this embodiment, it is preferable to mix 0.7 mol to 1.3 mol of dialkyl carbonate (DAC) with respect to 1 mol of ethylenediamine (EDA), and further 0.8 mol to 1.2 mol. It is more preferable to mix. When the blending amount of dialkyl carbonate (DAC) exceeds this range, the amount of dicarboalkoxy compound (DA compound) produced increases.

  Moreover, although you may react after mix | blending the whole quantity ethylenediamine (EDA) and dialkyl carbonate (DAC) at the beginning of reaction, dialkyl carbonate (DAC) is dripped over time in ethylenediamine (EDA). It is preferable to react or, conversely, react while adding ethylenediamine (EDA) dropwise to the dialkyl carbonate (DAC) over time.

  The reaction temperature in the first step is not particularly limited, but is preferably in the range of 40 ° C to 130 ° C, and more preferably in the range of 60 ° C to 120 ° C. Even at a low temperature such as room temperature, a monocarboalkoxy compound (MA compound) is produced, but the reaction time becomes long and it is difficult to apply industrially. On the other hand, at a high temperature exceeding 130 ° C., oxidation of ethylenediamine (EDA) proceeds, and when the reaction time is prolonged, a large amount of dicarboalkoxy (DA) is produced. This temperature range is greatly different from the reaction at a high temperature close to 250 ° C. in the conventional ethylenediamine-urea method, and the oxidation of ethylenediamine (EDA) is greatly suppressed.

  Further, the reaction time of the first step is not particularly limited, but it is usually preferably in the range of 1 hour to 48 hours, and more preferably in the range of 3 hours to 24 hours. preferable. In order to complete the reaction between ethylenediamine (EDA) and an equimolar amount of dialkyl carbonate (DAC) and increase the yield of monocarboalkoxy (MA), it is necessary to lengthen the reaction time. Produces a dicarboalkoxy form (DA form). Conversely, in order to suppress the production of dicarboalkoxy (DA), the reaction time must be shortened, but in this case, the yield of monocarboalkoxy (MA) is reduced. Therefore, the reaction time in the above range is preferable at the above reaction temperature.

Second step:
In the second step, a monocarboalkoxy body (MA body) is isolated from the reaction product of the first step. The reaction product of the first step includes the produced monocarboalkoxy (MA) and dicarboalkoxy (DA), alkanol as a by-product of the reaction, and a small amount of unreacted ethylenediamine (EDA). And dialkyl carbonate (DAC).

  Here, at room temperature, the monocarboalkoxy body (MA body) is liquid, and the dicarboalkoxy body (DA body) is solid. Further, ethylenediamine (EDA) has a boiling point of 117 ° C., and dialkyl carbonate (DAC) has a boiling point of 90 ° C. In addition, the boiling point of the by-product alkanol is lower than these. Therefore, the monocarboalkoxy compound (MA compound) can be isolated by distillation under reduced pressure of the reaction product in the first step. This isolation operation will be described later.

  Thus, by increasing the purity of the monocarboalkoxy compound (MA compound) in the second step, the efficiency of the ring-closing reaction in the subsequent third step is improved, and the ethylenediamine (EDA) remaining in a trace amount and before the ring-closing are improved. The oxidation of the terminal amino group of the monocarboalkoxy body (MA body) is suppressed.

Third step:
In this 3rd process, an inorganic solid base catalyst is made to act on the monocarboalkoxy body (MA body) isolated at the 2nd process, and ethylene urea is synthesize | combined by ring-closing reaction. As the inorganic solid base catalyst used in this reaction, it is preferable to use the above-mentioned alkaline earth metal oxide or an oxide obtained by substituting a part of the alkaline earth metal with an alkali metal.

  The amount of the inorganic solid base catalyst used may be appropriately selected depending on the type of catalyst, base activity, particle size, surface area, and the like, but is usually 3% by weight to 20% based on the isolated monocarboalkoxy compound (MA compound). % By weight is preferable, and 5% by weight to 15% by weight is more preferable.

  In this third step, the monocarboalkoxy compound (MA-form) isolated in the second step is used, but its purity is preferably 90% or more, and more preferably 95% or more. . The higher the purity of the monocarboalkoxy (MA), the higher the efficiency of the ring closure reaction, and the less oxidation of ethylenediamine (EDA) and the terminal amino group of the monocarboalkoxy (MA) are suppressed. Because it is.

  In the present embodiment, the cyclization rate of the ring closure reaction in the third step is preferably 60% or more, and more preferably 80% or more. When the cyclization rate of the ring-closing reaction is 60% or more, the yield of ethylene urea is improved and industrial applicability is increased.

  The reaction temperature in the third step may be appropriately selected depending on the type and amount of the inorganic solid base catalyst, but is usually preferably 110 ° C to 140 ° C, and more preferably 120 ° C to 130 ° C. Is more preferable. At temperatures lower than 110 ° C., the efficiency of the ring closure reaction becomes poor. On the other hand, at a high temperature exceeding 140 ° C., the terminal amino group of the monocarboalkoxy body (MA body) is oxidized, and the reaction product becomes severely yellowed.

  Further, the reaction time of the third step is not particularly limited, but it is usually preferably within a range of 1 hour to 24 hours, and more preferably within a range of 3 hours to 12 hours. preferable. In order to complete the ring closure reaction of the monocarboalkoxy (MA) and increase the yield of ethylene urea, it is necessary to lengthen the reaction time. In this case, however, the unclosed monocarboalkoxy (MA) ) Oxidation of the terminal amino group occurs and the reaction product becomes yellowish brown. On the other hand, in order to suppress the oxidation of the terminal amino group of the monocarboalkoxy body (MA body), it is necessary to shorten the reaction time. In this case, the yield of ethylene urea is lowered. Therefore, the reaction time in the above range is preferable at the above reaction temperature.

  Hereinafter, the manufacturing method of ethylene urea according to the present embodiment will be described with reference to Examples and Comparative Examples. In each of the following examples, dimethyl carbonate (DMC) was used as the dialkyl carbonate (DAC), and a monocarbomethoxy form (MM form) as an intermediate was obtained by reaction with ethylenediamine (EDA). Synthesized. This reaction is shown in the following formula (4).

次に、単離したモノカルボメトキシ体（ＭＭ体）に無機固体塩基触媒を作用して閉環反応を行ってエチレン尿素を得た。この反応を下記式（５）に示す。

Next, the isolated monocarbomethoxy body (MM body) was reacted with an inorganic solid base catalyst to perform a ring-closing reaction to obtain ethylene urea. This reaction is shown in the following formula (5).

First step:
In Example 1, 100 mmol (6.0 g) of ethylenediamine (EDA) was added dropwise over 1.5 hours under the condition of 120 ° C. with respect to 100 mmol (9.03 g) of dimethyl carbonate (DMC). The mixture was stirred at 0 ° C. for 24 hours to obtain a reaction product containing a monocarbomethoxy body (MM body) and a dicarbomethoxy body (DM body).

The reaction was a light yellow suspension. Moreover, the production ratio of the monocarbomethoxy body (MM body) and the dicarbomethoxy body (DM body) in this reaction product was MM body: DM body = 76: 24. This production ratio was quantified by measurement of ¹ H-NMR.

Second step:
A monocarbomethoxy form (MM form) was isolated from the reaction product. The isolation operation was performed by distillation under reduced pressure with the pressure in the system set to 1333 Pa (10 mmHg). In this vacuum distillation, distillation of a monocarbomethoxy body (MM body) was observed from around 90 ° C., and the steady distillation temperature was 95 ° C. When ¹ H-NMR of the distillate was measured, the purity of the monocarbomethoxy form (MM form) was about 98%. Trace amounts of ethylenediamine (EDA) and methanol were detected as impurities.

Third step:
In Example 1, calcium oxide (CaO) was used as the inorganic solid base catalyst. Adjustment of calcium oxide (CaO) as an inorganic solid base catalyst was performed as follows. After sufficiently crushing 10 g of calcium carbonate (CaCO ₃ ) with a mortar, it was calcined at 550 ° C. for 4 hours in an air atmosphere to prepare calcium oxide (CaO). This calcium oxide (CaO) was sufficiently ground with a mortar and then used as an inorganic solid base catalyst.

The ring closure reaction of the monocarbomethoxy form (MM form) was performed as follows. 10 wt% (0.24 g) of an inorganic solid base catalyst was added to 20 mmol (2.36 g) of the isolated monocarbomethoxy body (MM body) and heated at 130 ° C. for 12 hours to obtain a reaction product. The reaction was a light brownish suspension. Further, ¹ H-NMR of this reaction product was measured, and the cyclization rate to ethylene urea was determined from the mixing ratio of the produced ethylene urea and the unreacted monocarbomethoxy body (MM body). The cyclization rate in Example 1 was 62.6%.

  On the other hand, Comparative Example 1 was obtained by heating the monocarbomethoxy body (MM body) isolated in the second step to 130 ° C. for 12 hours without adding an inorganic solid base catalyst. The reaction product obtained in Comparative Example 1 was a dark brown liquid. The cyclization rate in Comparative Example 1 was 30.2%, which was a low value.

First step:
In Example 2, the same operation as in Example 1 was performed except that the temperature at the time of dropping ethylenediamine (EDA) with respect to dimethyl carbonate (DMC) and the subsequent reaction temperature were set to 80 ° C. A reaction product containing a carbomethoxy form (MM form) and a dicarbomethoxy form (DM form) was obtained. The reaction was a light yellow suspension. Moreover, the production ratio of the monocarbomethoxy form (MM form) and the dicarbomethoxy form (DM form) in this reaction product was MM form: DM form = 74: 26.

Second step:
The same operation as in Example 1 was performed, and a monocarbomethoxy form (MM form) was isolated from the reaction product. The purity of the monocarbomethoxy body (MM body) was about 98% as in Example 1.

Third step:
In Example 2, magnesium oxide (MgO) was used as the inorganic solid base catalyst. Adjustment of magnesium oxide (MgO) as an inorganic solid base catalyst was performed as follows. Magnesium carbonate (MgCO ₃ ) 10 g was sufficiently pulverized with a mortar and then fired at 900 ° C. for 4 hours in an air atmosphere to prepare magnesium oxide (MgO). This magnesium oxide (MgO) was sufficiently pulverized with a mortar and then used as an inorganic solid base catalyst.

  The ring closure reaction of the monocarbomethoxy body (MM body) was carried out in the same manner as in Example 1 except that magnesium oxide (MgO) was used as the inorganic solid base catalyst. The resulting reaction product was a light brownish suspension. Further, the cyclization rate in Example 2 was 62.9%.

First step:
In the present Example 3, dimethyl carbonate (DMC) was dripped with respect to ethylenediamine (EDA) contrary to the said Example 1. FIG. Specifically, 100 mmol (9.03 g) of dimethyl carbonate (DMC) was added dropwise to ethylenediamine (EDA) 100 mmol (6.0 g) at 120 ° C. over 1.5 hours, and then at 120 ° C. The mixture was stirred for 24 hours to obtain a reaction product containing a monocarbomethoxy form (MM form) and a dicarbomethoxy form (DM form).

  The reaction was a light yellow suspension. Moreover, the production ratio of the monocarbomethoxy body (MM body) and the dicarbomethoxy body (DM body) in this reaction product was MM body: DM body = 76: 24.

Second step:
The same operation as in Example 1 was performed, and a monocarbomethoxy form (MM form) was isolated from the reaction product. The purity of the monocarbomethoxy body (MM body) was about 98% as in Example 1.

Third step:
In Example 3, strontium oxide (SrO) was used as the inorganic solid base catalyst. Adjustment of strontium oxide (SrO) as an inorganic solid base catalyst was performed as follows. 10 g of strontium carbonate (SrCO ₃ ) was sufficiently pulverized with a mortar and then fired at 900 ° C. for 4 hours in an air atmosphere to prepare strontium oxide (SrO). This strontium oxide (SrO) was sufficiently pulverized with a mortar and then used as an inorganic solid base catalyst.

  The ring closure reaction of the monocarbomethoxy body (MM body) was carried out in the same manner as in Example 1 except that strontium oxide (SrO) was used as the inorganic solid base catalyst. The resulting reaction product was a light brownish suspension. Further, the cyclization rate in Example 3 was 60.4%.

First step:
In Example 4, the same reaction temperature and operation as in Example 3 were performed to obtain a reaction product containing a monocarbomethoxy form (MM form) and a dicarbomethoxy form (DM form). The reaction was a light yellow suspension. Moreover, the production ratio of the monocarbomethoxy body (MM body) and the dicarbomethoxy body (DM body) in this reaction product was MM body: DM body = 76: 24.

Second step:
The same operation as in Example 1 was performed, and a monocarbomethoxy form (MM form) was isolated from the reaction product. The purity of the monocarbomethoxy body (MM body) was about 98% as in Example 1.

Third step:
In Example 4, an oxide obtained by substituting a part of strontium oxide (SrO) with sodium (Na) as an inorganic solid base catalyst (hereinafter referred to as “Na-substituted strontium oxide-1 (Na—SrO-1)”). )It was used. Adjustment of Na substituted strontium oxide-1 (Na-SrO-1) as an inorganic solid base catalyst was performed as follows.

Sodium hydrogen carbonate (NaHCO ₃ ) was added to 10 g of strontium carbonate (SrCO ₃ ) so that the molar ratio of sodium (Na) to strontium (Sr) was 50 mol%, and the mixture was thoroughly mixed in a mortar, and then air atmosphere The mixture was calcined at 900 ° C. for 4 hours to prepare Na-substituted strontium oxide-1 (Na—SrO-1). This Na-substituted strontium oxide-1 (Na-SrO-1) was sufficiently ground with a mortar and then used as an inorganic solid base catalyst.

  The ring closure reaction of the monocarbomethoxy body (MM body) was carried out in the same manner as in Example 1 except that Na-substituted strontium oxide-1 (Na-SrO-1) was used as the inorganic solid base catalyst. The resulting reaction product was a light brownish suspension. Further, the cyclization rate in Example 4 was 66.4%.

First step:
In Example 5, the same operation as in Example 3 was performed except that the temperature at the time of dropping dimethyl carbonate (DMC) with respect to ethylenediamine (EDA) and the subsequent reaction temperature were set to 80 ° C. A reaction product containing a carbomethoxy form (MM form) and a dicarbomethoxy form (DM form) was obtained. The reaction was a white suspension. Moreover, the production ratio of the monocarbomethoxy body (MM body) and the dicarbomethoxy body (DM body) in this reaction product was MM body: DM body = 73: 27.

Second step:
The same operation as in Example 1 was performed, and a monocarbomethoxy form (MM form) was isolated from the reaction product. The purity of the monocarbomethoxy body (MM body) was about 98% as in Example 1.

Third step:
In this Example 5, an oxide obtained by substituting a part of strontium oxide (SrO) obtained by an adjustment method different from Example 4 as an inorganic solid base catalyst with sodium (Na) (hereinafter referred to as “Na substituted oxidation”). Strontium-2 (Na-SrO-2) ") was used. Preparation of Na-substituted strontium oxide-2 (Na-SrO-2) as an inorganic solid base catalyst was performed as follows.

Sodium hydrogen carbonate (NaHCO ₃ ) was added to 10 g of strontium hydroxide octahydrate (Sr (OH) ₂ .8H ₂ O) so that the molar ratio of sodium (Na) to strontium (Sr) was 10 mol%. After adding and thoroughly mixing with a mortar, it was fired at 900 ° C. for 4 hours in an air atmosphere to prepare Na-substituted strontium oxide-2 (Na—SrO-2). This Na-substituted strontium oxide-2 (Na-SrO-2) was sufficiently pulverized with a mortar and then used as an inorganic solid base catalyst.

  The ring closure reaction of the monocarbomethoxy body (MM body) was carried out in the same manner as in Example 1, except that Na-substituted strontium oxide-2 (Na-SrO-2) was used as the inorganic solid base catalyst. The resulting reaction product was a white solid. The cyclization rate in Example 5 was about 100%.

First step:
In Example 6, the same reaction temperature and operation as in Example 5 were performed, and a reaction product containing a monocarbomethoxy form (MM form) and a dicarbomethoxy form (DM form) was obtained. The reaction was a white suspension. Moreover, the production ratio of the monocarbomethoxy body (MM body) and the dicarbomethoxy body (DM body) in this reaction product was MM body: DM body = 73: 27.

Second step:
The same operation as in Example 1 was performed, and a monocarbomethoxy form (MM form) was isolated from the reaction product. The purity of the monocarbomethoxy body (MM body) was about 98% as in Example 1.

Third step:
In Example 6, an oxide obtained by substituting part of magnesium oxide (MgO) with sodium (Na) (hereinafter referred to as “Na-substituted magnesium oxide (Na—MgO)”) was used as the inorganic solid base catalyst. . The Na-substituted magnesium oxide (Na—MgO) as an inorganic solid base catalyst was adjusted as follows.

Sodium bicarbonate (NaHCO ₃ ) was added to 10 g of magnesium hydroxide (Mg (OH) ₂ ) so that the molar ratio of sodium (Na) to magnesium (Mg) was 10 mol%, and the mixture was thoroughly mixed in a mortar. Thereafter, it was fired at 900 ° C. for 4 hours in an air atmosphere to prepare Na-substituted magnesium oxide (Na—MgO). This Na-substituted magnesium oxide (Na—MgO) was sufficiently pulverized with a mortar and then used as an inorganic solid base catalyst.

  In the ring closure reaction of the monocarbomethoxy body (MM body), Na-substituted magnesium oxide (Na—MgO) was used as the inorganic solid base catalyst. Moreover, although reaction temperature was the same 130 degreeC with respect to the said Example 1-Example 5 as reaction conditions, heating time was shortened with 3 hours. The obtained reaction product was in the form of a white slurry. Further, the cyclization rate in Example 6 was 90%.

  In the above Examples 1 to 6, in producing ethylene urea, first, in the first step, a monocarbomethoxy form (MM) of ethylenediamine (EDA) is obtained by reaction of ethylenediamine (EDA) and dimethyl carbonate (DMC). Body). The reaction at this stage can be performed at atmospheric pressure, and the reaction is performed at 80 ° C. or 120 ° C., which is considerably lower than the ethylenediamine-urea method, which is a conventional method for producing ethylene urea. I was able to. Therefore, at this stage, unreacted ethylenediamine is not extremely oxidized.

  Next, in the second step, the monocarbomethoxy body (MM body) synthesized in the first step was isolated. By this isolation operation, the purity of the monocarbomethoxy body (MM body) was improved, and unreacted ethylenediamine (EDA) in the first step was removed. Therefore, during the subsequent ring-closing reaction in the third step, the content of ethylenediamine in the reaction system was small, and oxidation was rare.

  Further, in the third step, ethylene urea was synthesized by ring-closing reaction of the isolated monocarbomethoxy body (MM body) with an inorganic solid base catalyst. The reaction at this stage can be carried out under atmospheric pressure, and by using an inorganic solid base catalyst, the temperature is considerably lower than the ethylenediamine-urea method, which is a conventional ethyleneurea production method. The reaction could be carried out at 130 ° C. Therefore, even at this stage, the remaining unreacted ethylenediamine and the terminal amino group of the monocarbomethoxy body (MM body) were not extremely oxidized.

  Thus, in each said Example, the oxidation of ethylenediamine in each process was suppressed, and the yellowish browning of the reaction material after a ring closure reaction was reduced significantly compared with the conventional method. Actually, the reactants of Examples 1 to 4 were thin brownish suspensions, and the reactants of Examples 5 and 6 were white solids or slurries. These reactants could be purified to ethyleneurea having high whiteness by a simple operation. On the other hand, since the reaction product of Comparative Example 1 is a dark brown liquid and has a low cyclization rate, a considerable amount of labor is required for the purification of ethylene urea, and the purified urea is still yellowed. Was seen.

  In each of the above examples, the ratio of the monocarbomethoxy body (MM body) in the molar ratio of the monocarbomethoxy body (MM body) to the dicarbomethoxy body (DM body) in the reaction product of the first step is , Both were 70 mol% or more. As a result, the yield of ethylene urea obtained through the ring closure reaction of the monocarbomethoxy body (MM body) was improved, and yellowing of the reaction product due to the oxidation of ethylenediamine was further suppressed.

  Thus, in each Example, the cyclization rate from a monocarbomethoxy body (MM body) to ethylene urea is 60% or more, and particularly in Example 5 and Example 6, 90% or more. The cyclization rate of was able to be realized. Thereby, in this embodiment, the yield of ethylene urea can be maintained high, and the manufacturing method applicable industrially can be provided.

  From the above, in this embodiment, the reaction under atmospheric pressure is possible, a high-pressure reaction vessel is not required, the reaction temperature can be lowered as compared with the conventional method, and thus yellowing of the reaction product is suppressed, and In addition, an industrially applicable method for producing ethylene urea can be provided.

In carrying out the present invention, the following various modifications are possible without being limited to the above embodiments.
(1) In each of the above embodiments, the first step of synthesizing a monocarbomethoxy body (MM body), the second step of isolating the monocarbomethoxy body (MM body), and the isolated monocarbomethoxy Ethyleneurea was synthesized by a third step in which an inorganic solid base catalyst was allowed to act on the body (MM body) to carry out a ring closure reaction. However, the method for producing ethylene urea according to the present invention is not limited to this, and the isolation operation in the second step is not an essential requirement. That is, the ring closure reaction may be performed by directly reacting the reaction product of the first step with the inorganic solid base catalyst without performing the isolation of the second step.
(2) In each of the above examples, ethylene urea was synthesized via a monocarbomethoxy body (MM body). However, the method for producing ethylene urea according to the present invention is not limited to this, and an inorganic solid base catalyst is allowed to act on a mixture of ethylenediamine (EDA) and dialkyl carbonate (DAC), directly without using an intermediate. You may make it synthesize | combine ethylene urea.
(3) In each of the above examples, the reaction temperature in the first step was 80 ° C. or 120 ° C., and the reaction time was 24 hours. However, the reaction temperature and reaction time in the first step are not limited to this, and the reaction may be performed at a lower temperature or a higher temperature. Further, the reaction time may be shorter than this. However, when reacting at a temperature exceeding 120 ° C., the reaction must be completed in a short time in consideration of the oxidation of ethylenediamine.
(4) In each of the above examples, the reaction temperature in the third step was 130 ° C., and the reaction time was 12 hours or 3 hours. However, the reaction temperature and reaction time in the third step are not limited to these, and may be appropriately selected in consideration of the catalytic activity of the inorganic solid base catalyst to be used. However, when the reaction is performed at a temperature exceeding 130 ° C., the reaction must be completed in a short time in consideration of the oxidation of the terminal amino group of the monocarbomethoxy body (MM body).

Claims (7)

Ethylenediamine and general formula (1)

(Wherein R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different.) An inorganic solid base catalyst is allowed to act on the mixture with the dialkyl carbonate shown in A method for producing ethylene urea, comprising synthesizing. Ethylenediamine and general formula (1)

(Wherein R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different.) General formula (2) synthesized by reaction with dialkyl carbonate shown in

(In the formula, Rm represents a hydrocarbon group of R1 or R2 in the general formula (1).) The monocarboalkoxy compound of ethylenediamine shown in FIG. A process for producing ethylene urea, characterized by reacting. Ethylenediamine and general formula (1)

(Wherein R1 and R2 represent a hydrocarbon group, and R1 and R2 may be the same or different), and a first step of reacting with a dialkyl carbonate shown in FIG.
From the reaction product in the first step, the general formula (2)

(Wherein Rm represents a hydrocarbon group of R1 or R2 in the general formula (1)), a second step of isolating a monocarboalkoxy body of ethylenediamine shown in FIG.
And a third step in which an inorganic solid base catalyst is allowed to act on the monocarboalkoxy isolated in the second step to perform a ring-closing reaction of the monocarboalkoxy. The reaction product in the first step includes a monocarboalkoxy body of ethylenediamine represented by the general formula (2) and a general formula (3).

(In the formula, Rm and Rn represent a hydrocarbon group of R1 or R2 in the general formula (1), and Rm and Rn may be the same or different.) 4. The method for producing ethylene urea according to claim 3, wherein the number of moles of the monocarboalkoxy compound is 70 mol% or more with respect to the total number of moles of the monocarboalkoxy compound and the dicarboalkoxy compound. .   The said inorganic solid base catalyst consists of an oxide of alkaline-earth metal, The manufacturing method of ethylene urea as described in any one of Claims 1-4 characterized by the above-mentioned.   The inorganic solid base catalyst is an oxide mainly composed of an oxide of an alkaline earth metal, and a part of the alkaline earth metal is replaced with an alkali metal. The manufacturing method of ethylene urea as described in any one.   In the said cyclization reaction, the cyclization rate from the said monocarboalkoxy body shown to the said General formula (2) is 60% or more, The manufacturing method of ethylene urea of Claim 5 or 6 characterized by the above-mentioned.