JPS5896059A - Preparation of caprolactam - Google Patents

Abstract

PURPOSE:To prepare the titled compound absolutely without producing ammonium sulfate as a by-product, by using adipic acid and adiponitrile as raw materials, reducing the raw materials via cyanovaleric acid and its ester to aminocaproic acid ester, heating the product to obtain caprolactam, separating the lactam from the system, and recycling the residue to the reaction system. CONSTITUTION:Adipic acid and adiponitrile are fed through the lines 10 and 11 to the exchange reactor 1 to obtain cyanovaleric acid, which is sent as it is to the esterification reactor 2 to obtain cyano-valeric acid ester. The ester is reduced to aminocaproic acid ester in the hydrogenation reactor 7 in the presence of a catalyst. The obtained ester is heated in the cyclizatinxon reactor 8 together with a polyhydric alcohol sent from the distillation column 9 and, having a boiling point of higher than caprolactam. The resultant caprolactam is separated from the system by distilling in the distillation column 9, and the distillation residue liquid is recycled through the line 22 to the cyclization reactor 8. EFFECT:The objective compound can be produced in high yield, without producing by-products.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing caprolactam that does not produce any by-products, including ammonium sulfate.More specifically, the present invention relates to a method for producing caprolactam that produces substantially no by-products using adipic acid and adiponitrile as raw materials. .

Conventionally, the most widely used method for commercially producing caprolactam is to convert cyclohexanone into an oxime with t-hydroxylamine, and then subject the resulting cyclohexanone oxime to Beckmann rearrangement to obtain caprolactam.

However, this method has a major drawback in that ammonium sulfate is unavoidably produced as a by-product in all steps, including the production step of hydroxylamine, the oxime formation step, and the Beckmann rearrangement step. Therefore, various technological improvements are aimed at suppressing by-product ammonium sulfate in each process.For example, in the production method of hydroxylamine, ammonium nitrite is reduced with SO2,
Next, the Raschig method of producing by hydrolysis was replaced with a method of reducing No3- with hydrogen in a phosphate buffer,
Alternatively, the by-product of ammonium sulfate can be significantly suppressed by directly extracting caprolactam from a biased acid aqueous solution using an alkylphenol as an extractant, instead of neutralizing it with an aqueous sulfuric acid solution Y NH3 containing caprolactam after Beckmann rearrangement and extracting it with an extractant. It has started to be done. However, the drawback of producing a secondary product still remains, and the development of a conventional method for producing caprolactam that does not produce a shaft product has been awaited.

<V> One method is to convert cyclohexanone to ketene/
Acetyl acetate with acetic anhydride to give cyclohexenyl acetate, then nitration to liberate acetic acid to obtain nitrocyclohexanone - hydrolysis, reduce to aminocaproic acid, and heat in an aqueous solution to produce caprolactam 1 There is a method called C% Kosho 47-8542).

However, in this method, the ketene that acetylates cyclohexanone is regenerated from acetic acid and reused, but the regeneration cost is high, and there is no suitable extractant that can efficiently extract caprolactam from the water bath solution - caprolactam isolation. Distillation removal of the oil for this purpose requires a huge amount of labor costs, and it is not an economically superior method, so it has not yet been widely adopted by companies.

Alternatively, a method of reducing cyanovaleric acid or cyanovaleric acid ester to produce aminocaproic acid or aminocaproic acid ester, and then cyclizing it to produce caprolactam can be considered; however, a method for obtaining cyanovaleric acid or cyanovaleric acid ester and the method of converting the ring into caprolactam has many problems and is not practical.

That is, the industrial production method of cyanovaleric acid or cyanovaleric acid ester has been established, and in the laboratory, for example, the production method of cyanopelargonic acid (Org, 5ynth,
Cyanovaleric acid can be obtained from adipic acid by applying M, 7681, but the yield is low and it is difficult to put it into practical use industrially.

In addition, a method for producing anovaleric acid or cyanovaleric acid ester by oxo reaction of pentenenitrile (JP-A-52-1999)
36625-1) has also been disclosed, but this also has a low yield and is not yet a practical production method.Furthermore, another method for producing cyanovaleric acid uses an exchange reaction between adipic acid and cyanogen. Method (Zhur, O'bshc
29 3350 (1959) Japanese Patent Application Laid-open No. 50-47927), in an attempt to increase the conversion rate of adipic acid, the reaction time was lengthened or the amount of cyanide was increased (1"). The yield of cyanovaleric acid decreases, and adiponitrile becomes the main product instead.
Even if adipic acid and adiponitrile were subjected to a father conversion reaction (16), a light yield of cyanovaleric acid was not achieved.

The problem with this technique is that the cyanide is exchange-reacted with adipic acid. This is also due to the low yield to phosphoric acid. Anti-W to obtain adiponitrile from adipic acid by exchange reaction (U.S. Pat. No. 2,677,795)
Ohem, '716 7B (196B)) mentions the yield of azobonyl l-IJ based on adipic acid, but does not describe the yield of 77-yield to calginic acid. The present inventors conducted experiments to confirm the formation of adipic acid and acetonitrile, but only about 50% of the theoretical value was obtained for acetic acid, and the formation of amyls was also observed.

The ami-Ps are sublimable (1j compound, product separation,
This makes refining extremely difficult.

Improved technology for the exchange reaction between adipic acid and cyanide (%KOKAI Publication No. 43-15201, J, o
rg, chem, 56 3050 (1971))
has also been considered, but although it contributes to improving the yield of dinitrile, it is clear that it is not suitable for producing cyanovaleric acid.

However, the problem with the method of producing caprolactam by cyclizing aminocaproic acid or -Y amitsukazolonate is that the concentration of aminocaproic acid or amitsukazolonate without the ring (k) must be low (low) to suppress the kebolimer. That is, the method of heating aminocaproic acid or aminocaproic acid ester in water or organic solution U to produce caprolactam (Tokukoku Sho 49-9473, Tokko Shoro O-6112, Tokko Shoro 8- No. 14566, JP-A-51-43780, Ind, End, Ohem, Process Des
, Dev., 179 (1978)), for example, when aminocaproic acid in aqueous solution is heated at a low concentration, caprolactam is obtained as a dilute water bath solution. To isolate it, it is necessary to remove a large amount of it with water or fire, or to extract it using an extractant such as chloroform or benzene, but the utility costs required for removing water or extractants are prohibitive. Become. Even when organic 1S is used, the utility costs required for solvent removal remain high, and
The yield is also not satisfactory.

The present inventors have overcome these drawbacks and developed a product that does not have any by-products.
As a result of intensive research to develop a production method for caprolactam using inexpensive raw materials, we found that caprolactam can be produced without producing by-products using adipic acid and adiponitrile, which are inexpensive and can be produced by hand, as raw material precursors for nylon 6.6. It was discovered that this could be obtained, leading to the invention.

That is, according to the present invention, adipic acid and adiponitrile are heated to perform an exchange reaction, and the product cyanovaleric acid 7 is isolated from the exchange reaction solution obtained (without directly adding alcohol or the like to the exchange reaction solution). In addition, esterification is performed to produce a cyanovaleric acid ester, and the cyanovaleric acid ester is reduced using a catalyst to produce a tsucasolonic acid ester.The aminocaproic acid ester is used in a polyhydric alcohol whose boiling point is lower than that of caprolactam. The caprolactam produced by heating is circulated through the thread heated with 41+lti alcohol, which has a higher boiling point than the distilled residual gamma blue liquid, than the cabrolactam, and aminocaproic acid, thereby producing by-products. Caprolactam can be obtained at a low condensation rate without any reduction in condensation.

More specifically, the present invention can produce economically advantageous caprolactam without by-products by carrying out the following six steps. In other words, the first step is to convert adipic acid and adiponitrile into caloric acid. Heat to cause an exchange reaction, and without isolating the product, cyanovaleric acid, from the reaction mixture, alcohol is directly applied to the exchange reaction solution, and esterification is performed with heating]-2 to produce a cyanovaleric acid ester. ] - It is about. The second step is a step in which the obtained cyanovaleric acid ester is reduced to an aminocaproic acid ester using or using a solvent in the presence of a catalyst.

In the sixth step, a polyhydric alcohol with a higher boiling point than the obtained aminocaproic acid ester kecaprolactam is heated as a solvent, and the resulting cabrolactamone is distilled and separated.
ii. A thread for heating the aminocaproic acid ester by heating the distillation residue solution containing unconverted substances (aminocaproic acid ester converted and caprolactam oligomers, etc., hereinafter referred to as unconverted substances) after [1 to 1)] This is a process for producing caprolactam from unconverted @ and -aminocaproic acid ester.

In the first step of the present invention, adipic acid and adiponyl)
The details of the method for producing Nisder dicyanovalerate by carrying out the exchange reaction of II and esterifying it with alcohol are as follows.
Namoσ).

In the exchange reaction of adipic acid and adiponyl,
The quantitative relationship can be chosen arbitrarily, but taking into consideration the father conversion reaction, it is preferable to use an excess of adiponitrile. 100 mol, preferably 1 to 70 mol, more preferably 1 to 50 mol is used. 10
Even if adiponitrile is used in an amount of 0 mol or more, it will only lead to an increase in the size of the anti-IC and device, and there is no particular advantage.

The temperature in the exchange reaction is usually 100°C or higher, preferably 150 to 270°C, more preferably 200 to 25°C.
It is 0°C. At temperatures above 100°C, the reaction rate is slow;
At ℃SU+, the conditions will be harsher and there will be no benefit. During reaction...1 varies depending on the quantitative relationship between adipic acid and adiponitrile used and the reaction temperature, but is usually 0.1 to 20.
The heating time is preferably 0.5 to 10 hours, more preferably 1 to 5 hours.

When esterifying the exchange reaction solution with alcohol to obtain a cyanovaleric acid ester, it is essential to directly add alcohol to the exchange reaction solution for esterification without isolating the cyanovaleric acid produced in the exchange reaction. The reason for this will be explained using a diagram.

Figure 1 shows the yield of cyanovaleric acid produced by heating 1 mol of adipic acid and 10 mol of adiponic acid at 230°C for the reaction time shown in the drawing, and the exchange reaction solution, which was heated at 200°C with methanol added. 2
This figure shows the yield of methyl cyanovalerate obtained by time esterification.

As is clear from FIG. 1, the yield of cyanovaleric acid produced when adipic acid and adiponitrile are heated and subjected to an exchange reaction reaches a maximum of about 160% and decreases over time, but the method of the present invention Accordingly, by adding methanol to the exchange reaction solution and esterifying it, methyl cyanoyoshisenate can be obtained with a yield of about 190%.

It is impossible to proceed with the exchange IW reaction and the esterification simultaneously because the esterification of adipic acid proceeds preferentially.

The alcohol used for esterification of the exchange reaction solution of adipic acid and adiponitrile may be any -grade alcohol, such as methanol, ethanol, n-zolopanol + 1-propanol, n-butanol, 5ea-butanol, t- Although butanol and the like are preferred, methanol and ethanol are particularly preferred from the viewpoint of distillation separation of the produced cyanovaleric acid ester and adiponitrile.

The amount of alcohol used for esterification of the exchange reaction solution is small (at least twice the mole of adipic acid used in the exchange reaction is sufficient, but it is usually 2 to 400 moles per mole of adipic acid, and the preferable fL<2 ~200 mol, more preferably 2-1
00 moles are used. If it is more than 4(]U molar, the reaction apparatus will become larger and it is not practical.The reaction temperature is usually 70~
650°C, preferably 100 to 00°C, more preferably 150 to 200°C. At temperatures below 708C, the reaction rate is slow, and at temperatures above 300°C, the reaction pressure increases and there is no advantage. Reaction time is usually 0.5-2
0 hours, preferably 1 to 10 hours.

It is also possible to use adipic acid monoester in place of the adipic acid used in the exchange reaction of the present invention.

Furthermore, it goes without saying that the distillation residue after distilling off the produced cyanovaleric acid ester reaction solution can be further subjected to an exchange reaction as adiponitrile; Amounts of azobic acid and adibonyl) IJ are added to the distillation residue and subjected to an exchange reaction and esterified to obtain cyanovaleric acid ester with a yield of about 200% using the newly added adipic acid as standard VC. is possible.

In addition, the adipic acid diester produced as a by-product during ester (lj) can be taken out of the reaction solution and removed from the system (it can also be recycled to the exchange reaction system and used internally, and can be recycled and reused). This is particularly advantageous for the process of the present invention, which provides a process for producing caprolactam that does not produce by-products.

In the second step of the present invention, the details of the method for producing aminocaproic acid ester by converting the cyanovaleric acid ester obtained in the previous step using a catalyst are as follows.

Generally, nickel, palladium, platinum, rhodium, cobalt, etc. are used for the reduction of nitrile to a primary amine, but Raney catalysts, such as phosphorous nickel and phosphorous cobalt, are preferably used, and Raney cobalt is more preferably used.

Raney Cobalt Y Catalyst 17- It is also possible to use ammonia as a cocatalyst in reducing the cyanovalerate ester as a catalyst.

The amount of monocobalt in the reduction reaction is chosen arbitrarily relative to the cyanovalerate ester. Reaction preparation is usually 20 to 1
00°C, u-JL<&i40-80'C is used.

If the reaction temperature is lower than 20℃, the reaction rate will be slow, and if the reaction temperature is lower than 100℃
Will the above result in significant side reactions and lower yields? invite The reaction pressure is preferably 5 to 100 ki9/cm2 in terms of hydrogen pressure, preferably 10 to 50 9/CrrL. 5 kg/am
``The reaction rate is slow when it is lower than (,10C)C9/am.'' Above that, there is no advantage to increasing the hydrogen pressure on the yield and reaction rate (only the strength of the pressure vessel is required. The solvent is replaced. It is possible to use alcohol, ether, dioxane, etc. that are used to esterify the reaction solution, and even a solvent can be used.The reaction form can be either a batch process or a continuous process. In this method, most of the amitsukazolonic acid ester obtained after the hydrogenation reaction is circulated through the reaction thread again, and the cyanovaleric acid ester is reduced in a large amount of aminocaproic acid ester.

In the sixth step of the present invention, details of the method for producing caprolactam by heating the aminocaproic acid ester obtained in the previous step in a polyhydric alcohol having a higher boiling point than caprolactam are as follows.

That is, the significance of using a polyhydric alcohol with a higher boiling point than caprolactam is that after heating in a polyhydric alcohol with a higher boiling point than caprolactam, which is an aminocaproic acid ester, to form caprolactam, the product caprolactam is distilled off. Conversion to caprolactam is achieved by allowing the distillation residue to exist in a diluted state with Yushin 1 alcohol, which has a higher boiling point than caprolactam, and returning the distillation residue liquid to the system in which aminocaproic acid ester is heated. This makes it possible to obtain caprolactam quantitatively from aminocaproic acid ester. Incidentally, even if the distillation residue liquid is heated alone, the substance not converted to caprolactam can be converted to caprolactam! not.

In this way, the polyhydric alcohol with a higher boiling point than caprolactam as used in the present invention refers to the polyhydric alcohol that is obtained by distilling off caprolactam as described above and contains the residue that has not been converted to caprolactam. It has a sufficient boiling point difference and has good performance, such as triethylene glycol, tetraethylene glycol, polypropylene glycol, butyl alcohol, glycerin, diglycerin-bentaerythritol, 1.2.3--7' tantriol, 2. 6.4-Pentanetriol etc. are extracted.

It has a higher boiling point than caprolactam other than polyhydric alcohols (
When a compound (hydrocarbons, -hydric alcohol, etc.) is used as a solvent, an insoluble polymer is formed, and when a compound with a boiling point lower than caprolactam is used, after the solvent is distilled off, caprolactam is distilled off. The substance that has not been converted to caprolactam undergoes polymerization and other changes, making it impossible to convert it to caprolactam.

The reaction temperature for heating aminocaproic acid esderke is usually 8
The temperature is 0 to 600°C, preferably 100 to 280°C, more preferably 180 to 250°C.

At temperatures higher than 300'C, the conditions become harsher and there is little advantage in terms of yield. Reaction time is usually 0.1 to 10 hours,
Preferably the sail time is 5 to 5.0 hours.

The concentration of Nisder aminocaproate used in the reaction is usually 0.
．． 5-3 Q wt - preferably 3-'l Q wt
%, more preferably 5 to 15 wt, and 30
If the concentration is higher than wt%, a large amount of insoluble polymer will be produced, which is not preferable.

When aminocaproic acid ester is heated in the above solvent to convert it into caprolactam, alcohol is produced along with it, but the reaction may proceed while removing this alcohol, or alternatively, the alcohol can be converted using a closed reaction apparatus. The reaction may proceed while remaining in the system.

As described above, the method of the present invention provides a high-yield caprolactam production method that uses adipic acid and adiponitrile as starting materials and does not produce any by-products, which is completely different from conventional caprolactam production techniques. The practical value of 7 is extremely important to recite.

Next, as an example of the method for producing caprolactam from adipic acid and adiponic acid (IJ) according to the present invention, the method for producing caprolactam from adipic acid and adiponitrile (IJ) is carried out based on a preferred embodiment using the flow sheet shown in the drawings. The process will be divided into six steps: second step - methyl aminocaproate production step, and sixth step - caprolactam production step.

Figure 2 shows the case where the exchange reaction solution of adipic acid and adiponitrile is esterified with methanol, methyl cyanovalerate is reduced in a continuous manner without a solvent, and methylchemethanol amitsukazoronate is heated while being converted to caprolactam. This is a flow sheet shown as an example of a method for producing caprolactam from Azibia RLT/11 hyadivonitrile.

In the first step of producing methyl cyanovalerate, 1
is an exchange reactor, and adipic acid and adiponitrile are each sent to the exchange reactor 1 through the conduit 10 and 11 valves, and vaporized M
Dimethyl adipate and adiponitrile taken out from the column 5 and the distillation column 6 are also recycled. The exchange reaction between adipic acid and adiponitrile is carried out in the exchange reactor 1, and no separation or other operations are performed. be done. The reaction solution containing methyl cyanovalerate produced in the pressurized esterification reactor 2 is distilled in a demethanol tower 3, a dehydration tower 4, and an adipate removal tower 5 to remove methanol, water, and dimethyl adipate, respectively. Sent to Tower 6. The distilled methanol is sent to the esterification reactor through conduit 1.
3, water is extracted from the system through 14 conduits, and dimethyl adipate is circulated through conduit 15 to exchange reactor 1.
is circulated. Methyl cyanovalerate is distilled in the distillation column 6, the distilled methyl cyanovalerate is sent to the water surface reactor 7, and the distillation residue liquid containing adiponitrile as a main component is extracted from the lower part of the distillation column 6. After that, it is circulated to the exchange reactor 1.

Next, in the 21st step of producing methyl aminocaproate, methyl cyanovalerate sent from the distillation column 6 through 24 pipes 16 is mixed with Raney cobalt supplied from the conduit 17 and hydrogen supplied from the dedicated pipe 21. and hydrogenation reactor 7
By contacting with 1-, it is reduced to methyl aminocaproate, cyclized, and introduced into reactor 8.

In the fifth stage of caprolactam production, methyl aminocaproate sent from hydrogenation reactor I is heated in ring reactor 8 together with a polyhydric alcohol having a higher boiling point than caprolactam led from distillation column 9 to produce caprolactam. is manufactured.

The polyhydric alcohol with a higher boiling point than caprolactam, which contains caprolactam, is sent to the distillation column 9, where caprolactam is extracted from the upper part. 22 is recycled to the reactor 8, where it is heated together with newly supplied methyl aminocaproate and converted into caprolactam.

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

Example 1 First, as a raw material liquid, liquids A and B, which are added next, are each used as IA1.
gshita.

A-liquid adipic acid 43. d,? (0,600 mol), dimethyl adipate 52.2.9 (0,500 mol),
Adiponitrile 624. [1 g (3,000 mol) is the content of 1! The mixture was placed in a stainless steel autoclave, and stirred at 260°C for 2.5 hours after the desired substitution.
Production of 6 g was confirmed. ,) Methanol 160 after cooling
．． 09 (5,000 mol) and heated to 2'OO℃.
Stirring was performed for 2 hours. Esther (lj anti-iE finishing H1
By chromatography, methyl cyanovalerate 7
6.1 g (0,540 mol), dimethyl adipate 5
The production of 1.8.9 (0,298 mol) was confirmed. Methanol, water, dimethyl adipate, and methyl cyanovalerate were distilled off from the reaction solution by a conventional method, and the distillation residue 301.
I got 2.9 tons. (This distillation residue is referred to as Solution A.) Solution B Methyl aminocaproate 82.4, ? (0,56d
mole) and tetraethylene glycol 741', 6 &
Put it in a stainless steel autoclave with Y content x 2g,
The mixture was replaced with nitrogen and stirred at 260°C for 1 hour. After the reaction is complete,
The reaction solution was distilled under reduced pressure to remove methanol and caprolactam 56.5F (0,5110 mol), and the distillation residue 7 was distilled off.
49.5g was obtained. (This distillation residual liquid is called Solution B.) 301.2 g of Solution A, 39.4 g of adipic acid (0.27 g)
[ ] mol), dimethyl adipate 51.8 g (fl,
298 mol) and adiponitrile 29.2.9' (0
, 270 mol) was placed in a 1fHiill stainless steel autoclave and stirred at 260°C for 2.5 hours.

After cooling, add 160.09 methanol and heat at 200°C for 2
Stirring was performed for hours. Methyl cyanovalerate 77.5.9 (0,550 cells) was obtained by distilling the reaction solution under reduced pressure.
I got it. (Yield 21 based on charged adipic acid) 3.
It corresponds to 74. ) Next, the contents kk! > 00 ml stainless steel
Tocrepe contains methyl cyanovalerate 70.5 & (0,
A methanol slurry (Ufuichi cobalt 20.0 &, methanol 20.U, After replacement, hydrogen pressure is 60
9/cIn2, reaction temperature 60°C, hydrogen pressure 30 kg
The reaction was carried out while supplying hydrogen to keep the temperature at /cm2 until hydrogen absorption stopped. After the reaction was completed, the reaction solution was analyzed by gas chromatography and the result was methyl aminocaproate: 69.6. 7 (0,480 mol) and 1.9 g (0,017 mol) of caprolactam were confirmed. (Total yield of methyl aminocaproate and caprolactam: 99.4). While washing the catalyst with methanol, this reaction solution was placed in a stainless steel autoclave having an internal capacity of 21 cm, and 749.3 #'a' of liquid B was further added thereto, and methanol was distilled off at room temperature under reduced pressure.

Then, after purging with nitrogen, the mixture was stirred at 230° C. for 1 hour. Analysis of the reaction solution by chromatography confirmed the production of 56.4 g (0,499 mol) of caprolactam. The yield was 99.84 based on Yoshi JE's methyl standards, indicating that even substances that were not recognized as reduction products could be converted to caprolactam. ) Comparative Example 1 Same as Example 1, methyl cyanovalerate 70.5,
! l/(0,500 mol) deficient reduction (~reaction solution (methyl aminocaproate 69.8, ?, caprolactam 1
．． 9 g of ethylene glycol) and 652.5 g of ethylene glycol were placed in a stainless steel autoclave with a capacity of 21 kg, methanol was distilled off at room temperature under reduced pressure, and the pressure was brought to normal pressure with nitrogen.
The mixture was stirred at 260°C for 1 hour. As a result of analyzing the reaction solution Y, it was confirmed that 49.1.9 (0,455 mol) of caprolactam was produced.

Then reaction 1'& distillation, methanol, ethylene glycol and caprolactam 48.2M? (0,427 mol)'? : Distilled away. The presence of caprolactam was not observed in the distillation residue. A reaction solution obtained by reducing this distillation residue, methyl cyanovalerate 60.2 & (0,427 mol), and ethylene glycol 652.5.9 Y content 2
The mixture was placed in a stainless steel autoclave in step 1, and the same operations as described in section 1 were performed. As a result of analysis of the reaction solution, caprolactam 42
．． 5,! / (0,576 mol) was confirmed to be produced. (Equivalent to a caprolactam yield of 88.1% based on newly added methyl cyanovalerate.) Example 2 Tetraethylene glycol containing caprolactam obtained in Example 1 instead of Solution B used in Example 1 Methanol and caprolactam from bath liquid 56.1,! i' (0
, 496 mol) was distilled off (no presence of caprolactam was detected as a result of gas chromatography analysis).
9 El (11,496 mol) Y was placed in a stainless steel autoclave with an internal capacity of 21 cm together with the reduced reaction solution as in Example 1, and the reaction was carried out in the same manner as in Example 1. Results of analysis of the reaction solution. , cuff 0 lorlactam 56.
6,)i' (0,478 mol) was observed. This corresponds to a caprolactam yield of 100.4% based on methyl cyanovalerate freshly subjected to the reaction. (Repeat experiment 1) In the same manner, a reaction solution obtained by reducing methyl cyanovalerate in an amount equivalent to the caprolactam that had been distilled off was sequentially added to the above distillation residue, and the reaction and distillation were repeated. (Repetitive practice 111i2-6) The results are shown in Table 1.

(Hereafter, extra colors) 111 mouth 85B-! JbO 9(9) Example 6 29.2 g (0,200 mol) of adipic acid and 324.0.9 (3,000 mol) of adiponitrile were placed in a stainless steel autoclave with an internal capacity of 1J, and the mixture was purged with nitrogen.
Stirring was performed at 40°C for 6 hours. (As a result of analysis by fast liquid chromatography, the production of 11.5 g of cyanovaleric acid was confirmed.) After cooling, ethanol 138.09 (3
,000 mol) and stirred at 190°C for 6 hours. After the ester reaction, gas chromatography revealed ethyl cyanovalerate 60.1 & (0,6
88 mol), diethyl adipate 1.0 & (0,0
05 mol) was confirmed. Ethanol, water, diethyl adipate, and ethyl cyanovalerate were distilled off from the reaction solution by a conventional method.

Next, 29.1 g (0.1 g) of adipic acid was added to the distillation residue liquid.
99 mol) and adiponitrile 21.09 (0,194 mol) were added thereto, and the mixture was placed in a stainless steel autoclave having an internal capacity of 11, and after purging with nitrogen, the mixture was stirred for 7 hours at 240°C for 6 hours.

After cooling ethanol i6B, og (3, Ll 00 mol)
was cooled and stirred at 190°C for 6 hours. Analysis results: Ethyl cyanovalerate 60.5.9 (0,589
mol), diethyl adipate 1.2.9 (0,006
The production of mol) was confirmed.

1 of the ethyl cyanovalerate obtained in the above two reactions
08.5 g (0,700 mol) and an ethanol slurry of Raney cobalt (Raney cobalt 21.7,!i
/, ethanol 60.09) and ethanol 374.
09 Y was placed in an autoclave with an internal capacity of 11, and after replacing with nitrogen, the hydrogen pressure was increased to 60 kg/cm2 while replenishing hydrogen to maintain the hydrogen pressure of 60 kg/cm2Y at a reaction temperature of 45°C.
The reaction was carried out until hydrogen absorption ceased. After the reaction was completed, chromatographic analysis of the reaction solution confirmed the production of 109.4 g (0,688 mol) of ethyl aminocaproate and 1.1 g (0,010 mol) of caprolactam. (Total yield of ethyl aminocaproate and caprolactam 99.7%), the catalyst was separated from this reaction solution, washed with ethanol, and added to the reaction solution at 700.0 II
was made into an ethanol solution. This ethanol bath solution 100.
0 El (L as ethyl cyanovalerate provided to M source)
l, 100 mol) and diglycerin 90. OF Y inside
Three pieces of 300 mb were placed in a flask, the internal temperature was raised to 80°C, the ethanol bath was removed, and the mixture was stirred at 20°C for 4 hours while removing the ethanol that had distilled out. After the reaction was completed, the reaction solution was subjected to state pressure distillation to obtain 9.39 (0,082 mol) of caprolactam.

(Yield 8 according to the standard of ethyl cyanovalerate subjected to reduction)
2.04, Hereinafter, in this example (・ indicates the caprolactam yield based on 7 ethyl anovalerate). Furthermore, an ethanol solution of ethyl aminocaproate (-F) was added to the distillation residue. 82.0.9 Caprolactam (subject to reduction (l as ethyl 5-7-anovalerate), 082 mol) was added, and the reaction and distillation were carried out under the same conditions.
), 081-T-ru) was obtained, which is a yield of 98.8% based on the newly added ethyl aminocaproate to ethyl cyanovalerate. (Repeated Experiment 1) In the same manner as above, the above ethanol solution containing the same mole of ethyl cyanovalerate as the caprolactam that had been distilled off was sequentially added to the previous distillation residue, and the reactive distillation was repeated. (Repeat experiments 2 to 5) Seven results are shown in Table 2.

Examples 4 to 6 The solvent in Example 6 was changed from diglycerin to tetraethylene glycol (Example 4) and penmeerythritol (Example 5).
), 1.2.3-butanetriol (Example 6), but otherwise the reaction was carried out in the same manner as in Example 3. The results are shown in Table 2. (The yield is the yield of caprolactam based on ethyl cyanovalerate as in the case of ?+13.) Table 2 Example 7 Adipic acid 73.0,! 7 (1L 500 mol), adiponitrile 462.09 (4,000 mol), and dimethyl adipate 26.1.9 (0,150 mol) were placed in a stainless steel autoclave with an internal capacity of 21, and after purging with nitrogen, the mixture was heated at 220°C for 5 hours. After stirring and cooling, 32 [J, OS (10, OC] O mol) of methanol was added, followed by stirring at 220° C. for 1 hour. By distilling this reaction liquid, 114.2 g of methyl cyanovalerate was obtained.
((1,810 mol), dimethyl adipate 26.8
F ('0.154 mol) was obtained.

Next, adipic acid 59.1, i9 (0
, 405 mol), adiponitrile 43.7.9 (0,4
05 mol) and dimethyl adipate 26.8 fl (0,
154 mol) was added to the autoclave, and the reaction was carried out in the same manner. Distillation σ) Result, methyl cyanovalerate 120.0,! 9 (0,851 mol) and 25.69 (0,147 mol) of dimethyl adipate were obtained. (Repeated experiment - ■) Following - Same as below - σ) By repeating the experiment (same amount of adipic acid as in 0) and the same amount of adipic acid as shown in Table 6, The same amount of adiponitrile was added, and the reaction and distillation were repeated. (Repeated experiments ■～■)
The results are shown in Table 6.
y *r)i Tope 1st 4, 4
℃C鵠（N （´、l N
(N Yuki -, . . , Gu Nen □ 'Oy In α Todoroki 11
1℃ α ℃ri Jon
' Obtained/゛Anovaleric acid canal out of which 141.0 &(
1,00Q mol) and a methanol slurry of Raney cobalt (Raney cobalt 14.1, ?, methanol 40
．． 0 g)' was placed in a stainless steel t-crepe with a content of 50 o ml, and all methanol was distilled off under reduced pressure at room temperature, brought to normal pressure with nitrogen, and replaced with nitrogen twice for 7 times to remove hydrogen [7 , 20kg/crl'-reaction temperature 8
While replenishing hydrogen to maintain a hydrogen pressure of 20 kg/CrrL2 at 0"O, the reaction was carried out until hydrogen absorption stopped. A catalyst was poured from the reaction solution, washed with methanol,
In addition to the reaction solution, the mixed solution 200.0,! As a result of gas chromatography analysis of il, it was confirmed that methyl aminocaproate 125.0.9 (0,862 mol) and caprolactam 15.3.9 (0,135 mol) were produced. o, y and 480.0 g of triethylene glycol were placed in a flask with a content of 11, and the methanol was distilled off at an internal temperature of 70°C.
The mixture was then stirred at 250°C for 1 hour while removing methanol that had distilled out. Reaction completion value: The reaction solution was distilled under reduced pressure to give 5 o of caprolactam, 9. vro, 4ri o 7ru)
The yield was 90.9%, which was traced back to cyanoacetic acid.
It has a width of 0. Next, the 4v4 residual liquid was filtered and reacted at night 9.
+, ), U & 1, and the same way as below, perform the reaction, and the result of vacuum distillation is 1 rolactam 5 + 3.99
(+'J, 450 mol) was obtained. This is the yield i based on methyl tetraate applied to the newly prepared reduction reaction solution.
o Corresponds to o, o section.

Example day Methyl cyanovalerate 141, C1 was prepared in the same manner as in Example 7.
, I got 9Y. In contrast, this menal cyanokitylate was reduced with the reliability shown in Table 4. (Real M rot 1-5) Seven results as 4th
Shown in the table.

(Leaving space below) Next, the reaction solution obtained in 11161 and 7 tophetelene glycol 50 (1, Oi Y content [1j!) were placed in a stainless steel-backed autoclave, and at room temperature and under reduced pressure, the bath medium was completely removed. Distill, ♀ element 1d conversion # 5 o'clock IW'f at 210°C
ft. stirred. After reaction e: 'r, caprolactam 18.1, ? (0,160 mol) was obtained.

Thereafter, a hydrogenated solution (mixed with 54 minutes of water cooling) was added to the residual solution, and after the solvent was distilled off in the same manner, the reaction and distillation were repeated. Seven results, 99.6 section,
Caprolactam was obtained in yields of 101.4%, 97.2%, 98.1%, and 100.8%.

[Brief explanation of the drawing]

Figure 1 shows the time-dependent changes in the yield of cyanovaleric acid and the yield of methyl cyanovalerate in the exchange reaction of adipic acid and adiponitrile (also a graph). This is a flow sheet showing an example of a method for producing caprolactam. Patent applicant: Asahi Kosei 1-Yi Co., Ltd.

Claims (1)

[Scope of Claims] Adipic acid and adiponitrile are heated to perform an exchange reaction, and the product, cyanovaleric acid, is not isolated from the exchange reaction solution obtained, but alcohol is added to the reaction solution. Esterify to produce a cyanovalerate, reduce the cyanovalerate using a catalyst to produce an aminocaproate, and heat the aminocaproate in a polyhydric alcohol with a boiling point higher than caprolactam to produce caprolactam. 2. A method for producing caprolactam from adipic acid and adiponitrile, characterized in that the produced caprolactam is distilled off and the distillation residue is recycled to a system that heats a polyhydric alcohol with a higher boiling point than caprolactam and an aminocaproic acid ester. Claim 1, wherein the exchange reaction is carried out with 1 to 70 mol of adiponitrile per mol of adipic acid - Process 6 according to claim 1, wherein the exchange reaction is carried out with 1 to 50 mol of adiponitrile per mol of adipic acid. Method 4 according to claim 2, wherein the exchange reaction is carried out at 150 to 270°C Process 5 according to claim 1, wherein the exchange reaction is carried out at 2130 to 250 °C Process 6 according to claim 4, the reaction time of the exchange reaction is 1 to 5 hours. σ) Method 8 The exchange reaction is carried out at a temperature of ~270°C and a reaction time of 1 to 5 hours. The exchange reaction uses 1 to 5'O mol of adiponitrile to 1 mol of adipic acid, and Method 9 according to claim 7, which is carried out at a temperature of ~250° C. and a reaction time of 1 to 5 hours. Claim 1, wherein the alcohol to be esterified with the exchange reaction solution is methanol or ethanol. Method 10. Method 11 according to claim 1, wherein the alcohol for esterifying the exchange reaction solution is Kamethanol, and the alcohol for esterifying the exchange reaction g is 2 to 200 mol per 1 mole of adipic acid subjected to the exchange reaction. method 12 according to claim 1, wherein the amount is 2 to 100 mol per 1 mol of adipic acid subjected to the alcohol conversion reaction for esterifying the exchange reaction solution, according to claim 11. Method 13 Ester concentration of exchange reaction solution is 150-230℃
Method 14 according to claim 1 carried out in
The alcohol that esterifies the exchange reaction solution (
method 15 according to claim 1, in which the exchange reaction solution is esterified in an amount of 2 to 100 mol per mol of adipic acid, and the reaction temperature is 150 to 260°C; A method 16 according to claim 1, in which the distillation residue liquid after distilling off the cyanovaleric acid ester Z obtained by distillation under reduced pressure is recycled to the exchange reaction thread, and the adipic acid diester as a by-product after esterification of the exchange reaction liquid. A process according to claim 1, wherein the adipic diester is recycled to the exchange reaction system.Claim 1z, wherein the catalyst is Raney cobalt.
Method 18 described in Section 18 Using Raney cobalt as a catalyst at a reaction temperature of 40 to 8
19. Process according to claim 17, in which cyanovaleric acid ester is reduced to aminocaproic acid ester at 0°C1 hydrogen pressure of 10 to 50 kg/CnL2 Aminocaproic acid ester is a polyhydric alcohol having a boiling point higher than that of caprolactam. 20. The method of claim 1, wherein the aminocaproic acid ester is heated to a concentration of 5 to 15 wt4 in a polyhydric alcohol having a higher boiling point than caprolactam. Method 21 Aminocaproic acid ester is prepared in a polyhydric alcohol with a higher boiling point than caprolactam at 180-250°C, 3-
2Q wt method according to claim 19, in which Nisder aminocaproate is heated once in a polyhydric alcohol with a boiling point higher than that of caprolactam at 180-250°C, 5-1
5wt4 is heated once, method 23 according to claim 2O, method 24 according to claim 1, which is a polyhydric alcohol catetraethylene glycol with a higher boiling point than caprolactam, Claim 1: The exchange reaction solution of alcohol kaadibic acid and adiponitrile produced by heating Nisder aminocaproate in a polyhydric alcohol at a boiling point with caprolactam is circulated to a system for esterification with alcohol. How to describe