JPH03141272A - Production of lactones - Google Patents

Abstract

PURPOSE:To obtain lactones in high purity by hydrogenating dicarboxylic acids, distilling out the reaction solvent from the hydrogenation reaction product together with lactones at a specific ratio and distilling the distillate using properly combined purification processes. CONSTITUTION:A dicarboxylic acid, dicarboxylic acid anhydride or dicarboxylic acid ester is hydrogenated in liquid phase in the presence of a ruthenium catalyst to obtain a lactone-containing hydrocarbon product. The lactone is separated from the reaction product by the following processes A to C. (A) The lactone, water and 3-50wt.% of the solvent are distilled out by a 1st distillation column, the distillate is transferred to a 2nd distillation column and the unreacted raw material and the residual bottom liquid are recycled to the hydrogenation process. (B) Low-boiling component composed mainly of water is separated from the top of the 2nd distillation column and the column bottom composed mainly of lactones and solvent is transferred to a 3rd distillation column. (C) Lactones are distilled out from the top of the 3rd distillation column and the bottom product composed mainly of the solvent is extracted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing lactones. Specifically, the purpose is to improve a method for producing highly pure lactones from a reaction product containing lactones obtained by hydrogenating dicarboxylic acids, dicarboxylic acid anhydrides, or dicarboxylic acid esters in a liquid phase. .

(Prior Art) Methods for producing lactones by hydrogenating dicarboxylic acids, dicarboxylic acid anhydrides, dicarboxylic acid esters, or mixtures thereof have been studied for a long time, and many proposals have been made so far. Nickel-based catalyst (Japanese Patent Publication No. 43-6947), cobalt-based catalyst (Japanese Patent Publication No. 51-95057), steel-chromium catalyst (Japanese Patent Publication No. 38-20119), copper-zinc catalyst (Japanese Patent Publication No. 1982-20119) 4
A method is known in which the hydrogenation reaction is carried out in a fixed bed or in a suspension phase using, for example, JP 2-14463.

On the other hand, methods of carrying out the above hydrogenation reaction using a homogeneous ruthenium-based catalyst are also known, for example, in US Pat.
No. 827 describes a method for producing lactones by hydrogenation using a [RuXn(PRi2Rs)xLy] type ruthenium-based catalyst under a pressure of 40 to 400 ρs1,
Further, US Pat. No. 4,485,246 describes that a similar catalytic hydrogenation reaction is carried out in the presence of an organic amine.

(Problem to be Solved by the Invention) However, in conventional methods using solid catalysts such as the above-mentioned nickel-based catalysts, cobalt-based catalysts, copper-chromium-based catalysts, copper-zinc-based catalysts, etc., the reaction conditions are several tens of atmospheres. There was a problem in that the adoption of the above harsh conditions was unavoidable. On the other hand, the method using the homogeneous ruthenium-based catalyst has the characteristic that the hydrogenation reaction proceeds under relatively mild conditions, but the catalyst activity is at a rather low level and the catalyst life is short. Furthermore, since halogen is used, there is a problem in that the reaction equipment is corroded.

Therefore, the present applicant previously proposed a method of hydrogenation in a liquid phase using a ruthenium catalyst containing ruthenium, an organic phosphine, and a conjugated base of an acid with a pKa value of less than 2 (JP-A-25771-1). Publication No.).

This method uses a highly active ruthenium catalyst, so
Lactones can be efficiently produced under mild conditions, but when distilling and separating lactones from the hydrogenation reaction product, the catalyst activity may decrease, the solvent may become colored, or the raw materials may There are problems such as by-products from the decomposition of the solvent contaminating the lactones, resulting in a decrease in purity, and solving these problems has been a major challenge when industrially producing lactones.

The present invention aims to solve the above-mentioned problems in the method of industrially producing lactones using ruthenium catalyst, and to produce highly purified lactones industrially with advantage.

(Means for Solving the Problems) As a result of studies to achieve the above object, the present inventors found that the above problems that occur when separating and purifying lactones from hydrogenation reaction products by distillation are mainly caused by distillation. This is caused by the tower bottom temperature being too high, but if you simply lower the pressure at the top to lower the tower bottom temperature, the boiling point at the top becomes too low, so a refrigerator is required to cool the tower top condenser. It was found that the cost burden for industrial implementation was excessive and was extremely disadvantageous.

As a result of further studies based on the above knowledge, it was found that when lactones are distilled and separated from the hydrogenation reaction product, a specific proportion of the solvent is distilled out together with the lactones, and the subsequent purification process is appropriately combined. The present invention has been achieved by discovering that lactones can be produced industrially advantageously without causing problems such as a decrease in catalyst activity, coloring of the solvent, and a decrease in the purity of lactones. That is, the gist of the present invention is that a reaction product containing lactones obtained by hydrogenating dicarboxylic acid, dicarboxylic anhydride, or dicarboxylic acid ester in the liquid phase using a solvent in the presence of a ruthenium catalyst, (A ) The lactones, water and 3 to 50% by weight of the solvent are distilled out from the top of the column by supplying the distillate to the first distillation column, and the distillate is supplied to the second distillation column, and the distillate is supplied to the first distillation column. (B) The bottoms containing unreacted raw materials, residual solvent, and catalyst are drawn out from the bottom of the distillation column, and at least a portion of it is recycled to the hydrogenation process; While distilling and separating the light boiling point substances as the components, a bottoms mainly composed of lactones and solvent is derived from the bottom of the second distillation column and supplied to the third distillation column, (C) A method for producing lactones, which comprises distilling and collecting lactones from the top of a third distillation column, and deriving a bottoms mainly composed of a solvent from the bottom of the third distillation column. Exists.

To explain the present invention in detail, the raw materials for the lactones in the present invention include saturated or unsaturated dicarboxylic acids having 3 to 7 carbon atoms, anhydrides thereof, esters of such dicarboxylic acids, or Mixtures of these may be mentioned,
The ester is preferably a lower alkyl ester, specifically, for example, maleic acid, fumaric acid, succinic acid,
Maleic anhydride, succinic anhydride, dimethyl maleate,
Diethyl fumarate, di-n-butyl succinate, etc. are used.

Further, examples of the ruthenium catalyst include a ruthenium-based catalyst containing (a) ruthenium, (b) an organic phosphine, and (c) a military base of an acid with a pKa of less than 2. A catalyst containing a functional ligand is preferably used.

In order to obtain a reaction product containing lactones, which is a target of the treatment of the present invention, the above-mentioned raw material, catalyst component, and solvent are introduced into a reaction vessel, and hydrogen is further introduced into the reaction vessel. Hydrogen may be diluted with a gas inert to the reaction such as nitrogen or carbon dioxide.The reaction temperature is usually 50 to 250°C.
, preferably 100 to 200°C.The hydrogen partial pressure in the reaction system is not particularly limited, but in industrial practice it is usually 0.1=
100 kg/cm2, particularly preferably! 0-50
kg/c Akebono 2. The reaction can be carried out either batchwise or continuously, and the required reaction time in the case of the batchwise method is usually 1 to 20 hours.

The present invention provides the above-mentioned (A), (, Jll) from a reaction product containing lactones obtained by the above-mentioned hydrogenation reaction.
The main point of this process is to separate lactones by the steps (C) and 1), and thereby high purity lactones can be obtained in good yield without deterioration of catalytic activity or coloring of the solvent.

To explain the method of the present invention more specifically, in the present invention, a reaction product containing lactones, a solvent, a catalyst, an unreacted raw material, water, etc. is first supplied to (A) a first distillation column. Lactones, water, and an amount of solvent corresponding to 3 to 50% by weight of the distillate are distilled from the top of the column, and this distillate is supplied to the second distillation column, and at the same time from the bottom of the first distillation column. unreacted raw materials,
The bottoms containing the remaining solvent and catalyst are taken out and recycled to the hydrogenation process.

In order to distill 3 to 50% by weight of the solvent from the distillate from the top of the first distillation column, it is sufficient to carry out distillation by appropriately setting the number of plates in the distillation column, the reflux ratio, etc. As a result, the bottom temperature of the first distillation column is maintained at 170° C. or lower.

The operating conditions such as the number of plates in the distillation column and the reflux ratio are determined by setting the number of plates in the distillation column and reflux ratio in various ways beforehand, and performing distillation, analyzing the amount of solvent in each distillate, and calculating the amount of solvent distilled out. The weight % of the total solvent is determined, and the value is set appropriately based on that value.

When separating lactones from the solvent and catalyst by distilling a reaction product containing lactones, solvent, catalyst, unreacted raw materials, water, etc., generally a multi-stage distillation column of 30 or more stages is used, Although a large reflux ratio is required,
In a multi-stage distillation column, the pressure at the bottom of the column increases due to the large pressure difference within the column, resulting in a significantly high temperature, which causes a decrease in catalyst activity and decomposition of the solvent. Moreover, increasing the reflux ratio causes a large energy loss and is not economical.

In the present invention, as described above, a first distillation column having a relatively small number of stages is used, and the reflux ratio is made relatively small, so that 3 to 5% of the distillate is collected from the top of the column together with lactones and water.
Distillation conditions are selected so that 0% by weight of the solvent is distilled out, thereby preventing a significant rise in the bottom temperature of the distillation column and avoiding a decrease in catalyst activity and decomposition of the solvent and raw materials. At the same time, the distilled solvent is recovered and recycled in subsequent steps.

On the other hand, bottoms containing unreacted raw materials, remaining solvent, and catalyst are taken out from the bottom of the first distillation column and recycled to the hydrogenation process for reuse. Note that it is not necessary to circulate the entire amount of the bottoms liquid to the hydrogenation process, and a portion of the bottom liquid can be extracted from the system as necessary. The distillate consisting of lactones, water, and solvent supplied from the top of the first distillation column to the second distillation column in step (A) is then distilled in the second distillation column (B), and the filtered water is discharged from the top of the column. The light boiling point substances mainly composed of are separated by distillation and discharged from the system. on the other hand,
From the bottom of the second distillation column, a bottoms containing lactones and solvent as main components is drawn out and supplied to the third M distillation column. The bottom temperature in the second distillation column should be kept at about 170°C or less, as in the first distillation column, in order to prevent a decrease in catalyst activity and coloration of the solvent, and to obtain high-purity lactones. Desirably, the bottoms mainly composed of lactones and solvent supplied from the bottom of the second distillation column to the third distillation column in step (B) are then distilled in the third distillation column (C), The desired lactones are distilled out from the top of the tower and analyzed. On the other hand, the bottoms derived from the bottom of the third distillation column and containing the solvent as a main component may be recycled as is to the hydrogenation reaction, or
It can also be recycled to the distillation column. Alternatively, a catalyst component can be added to the bottoms and reused as a catalyst liquid. As in the first and second distillation columns, the bottom temperature in the third distillation column is maintained at about 170°C or less to prevent a decrease in catalyst activity and coloration of the solvent, and to prevent high-purity lactone. It is desirable to obtain the same kind of results.

In addition, in the present invention, Imizu (a) ruthenium, (b) organic phosphine, and (c) ruthenium containing a military base of an acid with a pKa of less than 2, and further optionally containing a neutral ligand. Specific examples of the catalyst are as follows.

(a) Ruthenium: As ruthenium, both metal ruthenium and ruthenium compounds can be used. As the ruthenium compound, ruthenium oxides, halides, hydroxides, inorganic acid salts, organic acid salts, or complex compounds are used, and specifically, for example, ruthenium dioxide, ruthenium tetroxide,
Ruthenium trihydroxide, ruthenium chloride, ruthenium bromide, ruthenium iodide, ruthenium nitrate, ruthenium acetate, tris(acetylacetone)ruthenium, sodium hexachlororuthenate, dipotassium tetracarbonylruthenate, pentacarbonylruthenium, cyclopentadienyl dihydroporpe Niruthenium, dibromotricarbonylruthenium, chlorotris(triphenylphosphine)hydridoruthenium, bis(trilobylphosphine)tricarbonylruthenium, dodecacarbonyltriruthenium, tetrahydridodecacarbonyltetraruthenium, octadecacarbonylhexarthenate, dicesium Examples include decacarbonylhydridotriruthenate tetraphenylphosphonium. The amount of these metal ruthenium and ruthenium compounds used is o, o as ruthenium in 1 liter of reaction solution.
oot~10G mmol, preferably 0.001-10
Millimoles.

(b) Organic phosphine: The organic phosphine is thought to contribute to controlling the electronic state of ruthenium (a), which is the main catalyst, and to stabilizing the active state of ruthenium.

Specific examples of organic phosphine include tri-octylphosphine, tri-n-butylphosphine, dimethyl-
Trialkylphosphines such as n-octylphosphine, tricycloalkylphosphines such as tricyclohexylphosphine, triarylphosphines such as triphenylphosphine, alkylarylphosphine such as dimethylphenylphosphine, 1.2- Examples include polyfunctional phosphines such as bis(diphenylphosphino)ethane. The amount of organic phosphine used is usually about 0.1-1000 mol, preferably 1-too mol, per 1 mol of ruthenium. Further, the organic phosphine can be supplied to the reaction system either alone or in the form of a complex with a ruthenium catalyst.

(c) Conjugate base of acid with pKa value smaller than 2: a to ρ
The conjugate base of an acid with a pKa value of less than 2 may act as an additional promoter for the ruthenium catalyst and produce the conjugate base of an acid with a pKa value of less than 2 during catalyst preparation or in the reaction system, As its supply form, a Brønsted acid having a pKa value of less than 2 or various salts thereof is used. Specifically, for example, sulfuric acid, sulfite, nitric acid, nitrous acid, perchloric acid, phosphoric acid, fluoroboric acid, hexafluorophosphoric acid, tungstic acid, phosphomolybdic acid, phosphotungstic acid, silicon tungstic acid, polysilicic acid, fluorosulfone Inorganic acids such as trichloroacetic acid, dichloroacetic acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, laurylsulfonic acid, benzenesulfonic acid, p-)luenesulfonic acid, etc., or organic acids such as these acids. Examples include ammonium salts and phosphonium salts.

Further, the same effect can be obtained even if the conjugate base of these acids is added in the form of an acid derivative thought to be produced in the reaction system, such as an acid halide, an acid anhydride, an ester, or an acid amide. The amount of these acids or their salts used is ruthenium 1
0.01 to 1000 mol, preferably 0.01 to 1000 mol.
The amount is in the range of 1 to 100 mol, more preferably 0.5 to 20 mol.

In addition to the above components (i), (b), and (c), (ii) neutral ligands that may be optionally contained include hydrogen, ethylene, propylene, butene, cyclopentene,
Olefins such as cyclohexene, butadiene, cyclopentadiene, cyclooctadiene, turbonasien,
-carbon oxide, diethyl ether, anisole, dioxane, tetrahydrofuran, acetone, acetophenone,
Benzophenone, cyclohexanone, propionic acid, caproic acid, butyric acid, benzoic acid, ethyl acetate, allyl acetate,
Oxygenated compounds such as benzyl benzoate and benzyl stearate, nitrogen oxide, acetonitrile, propionitrile,
Nitrogen-containing compounds such as benzonitrile, cyclohexylisonitrile, butylamine, aniline, toluidine, triethylamine, virol, pyridine, N-methylformamide, acetamide, 1,1,3.3-tetramethylurea, N-methylpyrrolidone, caprolactam, nitromethane, etc. , carbon disulfide, n-butyl mercaptan, thiophenol, dimethyl sulfide, dimethyl disulfide, thiophene, dimethyl sulfoxide, diphenyl sulfoxide, and other sulfur-containing compounds, tributylphosphine oxide, ethyl diphenylphosphine oxide, triphenylphosphine oxide, diethyl Organic phosphines such as phenylphosphinate, diphenylmethylphosphinate, diphenylethylphosphinate, 0.0-dimethylmethylphosphonothiolate, triethylphosphite, triphenylphosphite, triethylphosphate, triphenylphosphate, hexamethylphosphoric triamide, etc. Other examples include phosphorus-containing compounds.

As the solvent of the present invention, the raw material itself can be used, but in addition to the raw material, for example, the following solvents can be used.

diethyl ether, anisole, tetrahydrofuran,
Ethers such as ethylene glycol diethyl ether, triethylene glycol dimethyl ether, and dioxane; Ketones such as acetone, methyl ethyl ketone, and acetophenone; Alcohols such as methanol, ethanol, n-butanol, benzyl alcohol, ethylene glycol, and diethylene glycol; Phenols Carboxylic acids such as formic acid, acetic acid, propionic acid, and toluic acid; Esters such as methyl acetate, lobutyl acetate, and benzyl benzoate; Aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and tetralin; n-hexane, n-octane, Aliphatic hydrocarbons such as cyclohexane;
Halogenated hydrocarbons such as dichloromethane, trichloroethane, and chlorobenzene; Nitrated hydrocarbons such as nitromethane and nitrobenzene; Carboxylic acid amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; Hexamethylphosphoric acid Other amides such as triamide, N,N,N',N'-tetraethylsulfamide; ureas such as N,N'-dimethylimidazolitone, N,N,N,N-tetramethylurea; dimethylsulfone , Sulfones such as tetramethylene sulfone; Sulfoxides such as dimethyl sulfoxide and diphenyl sulfoxide; Lactones such as γ-butyrolactone and ε-caprolactone; Triprime (triethylene glycol dimethyl ether), Tetraglyme (tetraethylene glycol dimethyl ether), 18 - Polyethers such as Crown-6, nitriles such as acetonitrile and benzonitrile; carbonate esters such as dimethyl carbonate and ethylene carbonate (Examples) The present invention will be described in more detail below with reference to Examples and Comparative Examples. However, the present invention is not limited to these embodiments unless it exceeds the gist thereof.

Example 1 Catalyst liquid preparation 11 = 0.039% by weight of ruthenium acetylacetonate)
, 0.37% by weight trioctylphosphine and 0.1
A catalyst solution was prepared by dissolving 6% by weight of pi-mylene sulfone in triethylene glycol dimethyl ether (triprime, solvent) and heat-treating at 200° C. for 2 hours.

Hydrogenation reaction: A hydrogenation reaction was carried out using the flow-type reaction equipment shown in FIG. In Figure 1, l is a reactor, 2 is a catalyst liquid container, 3 is a compressor, 4 is a raw material container, 5 is a cooler, 6 is a gas-liquid separator, 7 is a first distillation column, and 8 is a second distillation column. Column 9 is the third distillation column.

The catalyst liquid prepared by the above method was poured into the catalyst liquid container 2.
Reactor with a flow rate of 3/hr! (+01 pressure cooker), hydrogen gas was supplied from compressor 3 to reactor L at a flow of 8 Ns3/hrO, and the pressure of reactor L was set to 40 kg/cm2.
G, temperature was held at 205°C. On the other hand, water succinic acid 8
A raw material liquid consisting of 0% by weight and 20% by weight of γ-butyrolactone was continuously supplied from the raw material container 4 to the reactor 1 at a flow rate of 200 g/hr to carry out a hydrogenation reaction.

The reaction product liquid was cooled to 130°C in a cooler 5, and then separated into gas and liquid under normal pressure in a gas-liquid separator 6, resulting in a gas component of 100 Nl.
/hr was purged, and the remainder was circulated to compressor 3.

The reaction product liquid was supplied to the first distillation column 7 under the conditions described below, and γ-butyrolactone, water, and trime (solvent) were distilled out from the top of the column. On the other hand, bottoms containing unreacted raw materials, remaining solvent and catalyst were drawn out from the bottom of the column and circulated to reactor 1. Note that the bottom temperature of the tower was 13.
The temperature rose from 7°C to 149°C, and the tower top temperature was 80°C.

The distillate from the top of the first distillation column 7 was supplied to the second distillation column 8 under the conditions described below, and a light boiling point substance mainly composed of filtrate water was distilled from the top of the column. On the other hand, bottoms containing γ-butyrolactone and a solvent as main components were extracted from the bottom of the second distillation column and supplied to the third distillation column under the conditions described below.

Purified γ-butyrolactone was distilled and collected from the top of the third distillation column. From the bottom of the third distillation column, a bottom solution containing a solvent as a main component and a small amount of high-boiling components was drawn out.

The conditions of the first, second and third distillation columns were as follows.

Table of Operating Conditions for Distillation Columns 1 Maintaining the top temperature of each distillation column under the above conditions was easy in industrial practice, and no refrigeration equipment was required.

After 800 hours of continuous operation using the above method, 77
When the distillate from the top of the first distillation column and the third distillation column obtained during 6 to 800 hours was analyzed by gas chromatography, the composition of each was as shown in Table 1.

(Note) γ-BL: γ-butyrolactone DE GME
Nidiethylene glycol monomethyl ether As shown in the composition of the distillate from the third distillation column in Table 1, the concentration of diethylene glycol monomethyl ether (a decomposition product of the raw material) in the distillate is extremely small, and there is almost no coloration. No decrease in catalyst activity was observed.

Example 2 In Example 1, the amount of heated steam in the first distillation column was increased,
Example 1 except that the distillation rate from the top of the column was increased by about 1.5 times.
Continuous operation was carried out for 170 hours in exactly the same manner as above, and 15
When the distillate from the top of the first distillation column and the third distillation column obtained from 0 to 170 hours was analyzed by gas chromatography, the composition of each was as shown in Table 2.

Table 2 No difference from Example 1 was observed.

Example 3 Continuous operation for 168 hours was carried out in the same manner as in Example 1, except that γ-butyrolactone was used instead of tripime in the preparation of the catalyst liquid in Example 1.
When the distillate from the top of the first distillation column and the third distillation column obtained for ~168 hours was analyzed by gas chromatography, the composition of each was as shown in Table 3.

Table 3 The bottom temperature of the first distillation column was determined after 170 hours of operation.
Note that the temperature rose from 138°C to 144°C after the top of the first, second, and third distillation columns, but otherwise the temperature was 89°C, 46°C, and 70°C, respectively, and the bottom temperature of each column was 89°C, 46°C, and 70°C, respectively. 115°C (24°C after 16868 hours), 127
℃ and 111 ℃.

Comparative Example 1 The reflux ratio (1,0) of the first distillation column in Example 1 was changed to 4
．． Continuous operation was carried out for 72 hours in exactly the same manner as in Example 1, except that the temperature was 0. After 72 hours, the distillate from the top of the first distillation column and the third distillation column was subjected to gas chromatography. As a result of analysis, the respective compositions were as shown in Table 4.

Table 4 The bottom temperature of the first distillation column was 1 after 72 hours of operation.
The temperature rose from 37°C to 142°C. Further, the bottom liquid of the third distillation column was not extracted for 72 hours.

As shown in the composition of the distillate from the third distillation column in Table 4, the concentration of diethylene glycol monomethyl ether (solvent decomposition product) in the distillate was high, and significant coloration was observed.

Comparative Example 2 Continuous operation for 72 hours was carried out in the same manner as in Example 1 except that the number of theoretical plates in the first distillation column in Example 1 was changed to 60. When the distillate from the top of the three distillation columns was analyzed by gas chromatography, the composition of each was as shown in Table 5.

Table 5 The bottom temperature of the first distillation column was 1 after 72 hours of operation.
The temperature rose from 72°C to 178°C. Moreover, the catalyst activity after 72 hours of operation decreased to 115.

As shown in the composition of the distillate from the third distillation column in Table 5, the concentration of diethylene glycol monomethyl ether in the distillate was high, and considerable coloration was observed.

Comparative Example 3 In the method of Example 1, the reaction product liquid from which gas components were separated in the gas-liquid separator 6 was passed through the second distillation column 7 without passing through the first distillation column 7.
It is supplied to the distillation column 8 (dotted line route in Figure 1), and the light boiling point substance mainly composed of water is distilled from the top of the column, and the bottoms mainly composed of γ-butyrolactone and the solvent are distilled from the bottom of the column. It was taken out and supplied to the third distillation column. γ-Butyrolactone was distilled and collected from the top of the third distillation column, and the bottoms containing solvent as a main component was extracted from the bottom of the column and circulated to reactor 1.

The distillate from the top of the third distillation column was analyzed by gas chromatography after 72 hours of continuous operation using the above method, and the composition was as follows. Decomposition occurred and the resulting water was mixed into γ-butyrolactone, resulting in a significant decrease in purity.

γ-B L 9B, 52 wt% D E G
M E 0.04% water by weight
1.02% by weight After 163 hours of operation, the bottom temperature of the second distillation column rose from 138°C to 145°C.

(Effects of the Invention) According to the method of the present invention, lactones are distilled from the hydrogenation reaction product obtained by hydrogenating dicarboxylic acid, dicarboxylic acid anhydride, or dicarboxylic acid ester in a liquid phase using a ruthenium catalyst. By distilling a specific proportion of the solvent together with the lactones during separation and appropriately combining the purification process, problems such as a decrease in catalyst activity, coloring of the solvent, and a decrease in the purity of the lactones can be avoided. , it is possible to produce lactones with industrial advantage, and its practical value is great.

[Brief explanation of the drawing]

FIG. 1 shows a process diagram of a flow-through reaction facility used to carry out the present invention. In the figure, l is a reactor, 2 is a catalyst liquid container, 3 is a compressor, 4 is a raw material container, 5 is a cooler, 6 is a gas-liquid separator, 7 is a first distillation column, 8 is a second distillation column, 9 is the third distillation column.

Claims (1)

[Claims] (1) A reaction product containing lactones obtained by hydrogenating dicarboxylic acid, dicarboxylic acid anhydride, or dicarboxylic acid ester in the liquid phase using a solvent in the presence of a ruthenium catalyst, (A) First distillation The lactones, water, and 3 to 50% by weight of the solvent are distilled from the top of the column to the distillate, and the distillate is supplied to the second distillation column, and the distillate is fed to the column of the first distillation column. (B) A bottom liquor containing unreacted raw materials, residual solvent and catalyst is drawn out from the bottom and at least a part of it is recycled to the hydrogenation process. Boiling point substances are distilled and separated, and a bottoms containing lactones and solvent as main components is derived from the bottom of the second distillation column and supplied to the third distillation column, (C) the third distillation column. A method for producing lactones, which comprises distilling and collecting lactones from the top of a third distillation column, and deriving a bottoms containing a solvent as a main component from the bottom of a third distillation column.