JPS58116437A - Preparation of 7-octenoic acid - Google Patents

Abstract

PURPOSE:To prepare the titled substance useful as a raw material of 8-aminocaprylic acid, etc., economically, with a simple process, by using an easily available 2,7-octadien-1-ol as a starting material, isomerizing the material in the presence of a catalyst, and oxidizing the product in a liquid phase in the presence of an oxidation catalyst. CONSTITUTION:The titled compound is prepared from 2,7-octadien-1-ol, by (1) isomerizing the starting material at 100-250 deg.C, especially 130-220 deg.C in the presence of a catalyst selected from a copper-based catalyst and a chromium- based catalyst, e.g. reduced copper, Raney copper, copper-chromium oxide, etc. preferably in the atmosphere of an inert gas, and (2) contacting the resultant 7-octen-1-al with an oxygen-containing gas in the presence of an oxidation catalyst and an organic solvent. The oxidation catalyst is preferably the copper or iron salt of an aliphatic monocarboxylic acid. The reaction temperature is about 40-120 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing 7-octenoic acid, and more specifically, the present invention relates to a novel method for producing 7-octenoic acid. The present invention relates to a method for producing 7-octenoic acid, which comprises oxidizing R with oxygen in the liquid phase in the presence of an oxidation catalyst.

7-octenoic acid is a raw material for 8-aminocaprylic acid.
It is also a useful compound as a modifier for vinyl polymers and as a starting material for various organic syntheses, but at present, almost no industrial method for producing it is known. Previously, the present inventors discovered that 2,7-octarenin-1-ol could be produced industrially advantageously by reacting Ptadiei and water in the presence of a palladium complex catalyst. (Refer to Publication No.-138129). In light of this background, the present inventors have conducted intensive studies on methods for synthesizing various useful derivatives using 2,7-octarenin-1-ol as a starting material. As a result, 2,7-octarenin-1-ol is isomerized in the presence of a catalyst selected from the group consisting of a copper-based catalyst and a chromium-based catalyst to produce 7-oct/-
The present inventors have discovered that 7-octenoic acid is produced in high yield when 1-al is oxidized with oxygen in the liquid phase in the presence of an oxidation catalyst, and the present invention has been completed. This method has advantages that are suitable for industrial implementation, such as easy availability of starting materials and simple steps.

The copper-based catalyst and chromium-based catalyst used as a catalyst in the isomerization reaction of 2,7-octadien-1-ol according to the method of the present invention include reduced steel, Raney steel, copper zinc oxide, steel chromium oxide, zinc Examples include chromium oxide. The above-mentioned metal oxide catalysts are commercially produced and can be easily obtained.
It can also be produced according to the method described on pages 65-367 (February 25, 1967, published by Chijinshokan Co., Ltd.). The above literature describes, as an example of producing copper chromium oxide, a method in which chromium trioxide is added to powdered or paste oxidized steel, an appropriate amount of water is added thereto, the mixture is mixed and crushed for several hours, and then dried. ing. These catalysts may be partially modified with other metal components selected from tungsten, molybdenum, rhenium, zirconium, manganese, titanium, iron, barium, and the like. Further, a catalyst supported on a carrier such as alumina, silica, diatomaceous earth, etc. can also be used.

These catalysts may be used alone or in combination of two or more. Catalyst activity may be improved if the catalyst is previously treated with hydrogen prior to use. When the reaction is carried out in a liquid phase, the catalyst is used in an amount of 0.1 to 20 weight percent based on the reaction mixture in terms of metal.

2.7 with the catalyst partially poisoned by coexisting appropriate amounts of sulfur compounds, antimony compounds, bismuth compounds, phosphorus compounds, nitrogen compounds, etc. in the reaction system.
- When performing the isomerization reaction of octadie/-1-ol, 7
-The selectivity of octene-1-al may be improved. The sulfur compounds include sulfur, sodium sulfate, etc., the antimony compounds include antimony oxide, the bismuth compounds include bismuth oxide, and the phosphorus compounds include phosphoric acid, triphenylphosphine, etc.
Examples of nitrogen compounds include pyridine and aniline. As an isomerization and hydrogenation catalyst, commonly used baradium catalysts, nickel catalysts, cobalt catalysts, rhodium catalysts, platinum catalysts, etc. are used.
When the isomerization reaction of octarenin-1-ol is subjected to SJ, the production of 7-octen-1-al is small;
-Octen-1-ol isomerized to
It cannot be used in the reaction for producing -octen-1-al.

The isomerization reaction of 2,7-octarenin-1-ol according to the method of the present invention is preferably carried out under an inert gas atmosphere under reaction conditions such as nitrogen gas, carbon dioxide scum, helium gas, argon gas, etc. It is preferable to replace part or all of the inert gas with hydrogen gas. However, when carrying out the reaction in the coexistence of hydrogen gas, the partial pressure of hydrogen gas is reduced to 1
It is better to keep the pressure below 0 atm. When the partial pressure of hydrogen gas exceeds 10 atm, the rate of hydrogenation reaction increases and 7-octene-
This is not preferred because the selectivity of 1-R decreases. The reaction temperature is selected from the range of 100 to 250°C, particularly 130 to 220°C. The reaction can be carried out in a stirred reactor, a bubble column reactor or a packed column reactor in a liquid phase or a gas phase in a continuous mode or a patch mode. When the reaction is carried out in the liquid phase, the starting material 2,7-octarenin-1-ol or the product 7-octen-1-
R can also function as a solvent.

This reaction can also be carried out using other organic solvents that are inert under the reaction conditions. Usable organic solvents include saturated aliphatic hydrocarbons such as hexane, octane, decane, and liquid paraffin, saturated fatty acids such as cyclohexane and methylcyclohexane, aromatic compounds such as benzene, toluene, xylene, and biphenyl. group hydrocarbons, carbonyl ether, dibutyl ether,
Examples include ethers such as dioctyl ether, diphenyl ether, tetrahtomifuran, diethylene glycol diethyl ether, and polyethylene glycol dimethyl ether, and alcohols such as ethanol, butanol, octatool, ethylene glycol, glycerin, and polyethylene glycol.

Since 7-octen-1-al produced by the method of the present invention has a lower boiling point than 2.7-octazin-l-ol, which is the reaction raw material, the reaction is carried out while distilling 7-octen-1-al out of the reaction system. (reactive distillation method) is one of the particularly desirable embodiments of the method of the present invention, and thereby the formation of by-products is further suppressed. In addition, it is also possible to carry out the reaction in the gas or liquid phase while continuously flowing 2,7-octarenin-1-ol in a reactor filled with a shaped isomerization catalyst for a short contact time.
This is effective in increasing the selectivity of oct/-1-r. 7-octen-1-al produced in the reaction can be separated and obtained from the reaction mixture or distillate by a conventional distillation operation.

7-octen-1-al is prepared by contacting it with an oxygen-containing gas in the presence of an oxidation catalyst and an organic solvent.
-converted to octenoic acid. Oxygen-containing gas [7] Oxygen gas, air, a mixed gas of nitrogen and oxygen in any proportion, or a mixed gas of these and carbon dioxide gas is used. Since the reaction pressure varies depending on the amount of oxygen contained in the oxygen-containing gas, it cannot be unambiguously determined, but it is generally selected from within the range of 1 to 15 absolute atmospheres. Oxidation catalysts include cobalt salt, manganese salt, and nickel salt.

Metal salts known per se as aldehyde oxidation catalysts, such as copper salts and iron salts, can be used. Aliphatic monocarboxylic acid salts are preferable as metal salts in terms of dissipation into the reaction mixture, corrosivity to the reaction equipment, and ease of availability;
In consideration of solubility in the reaction mixture, etc., fatty acid group monocarboxylate salts of steel or iron are particularly preferred as the fermentation catalyst.

These oxidation catalysts may be used alone or in combination of two or more. The oxidation catalyst is generally used in a proportion of 0.01 to 50 mmol per ton of reaction mixture. Examples of organic solvents that can be used in the oxidation reaction according to the present invention include aliphatic monocarbo/acids and their esters, but aliphatic monocarboxylic acids are preferred in consideration of catalyst solubility and stability.

Specific examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, hexanoic acid, hepta/acid, octanoic acid, nonanoic acid, etc., and specific examples of aliphatic monocarboxylic acid esters include the aliphatic monocarboxylic acids mentioned above. Examples include methyl ester, ethyl ester, n-propyl ester, inobutyl ester, n-butyl ester, inobutyl ester, n-pentyl ester, and the like. The reaction temperature is generally in the range of about 40 to about 120°C, but when using a copper salt and/or iron salt as the oxidation catalyst, the reaction temperature is preferably 60 to 80°C.
It is. In addition, when using a cobalt salt, manganese salt or nickel salt as an oxidation catalyst, the reaction temperature is preferably Fi
The temperature is 40-60°C.

The oxygen oxidation reaction of 7-oct-i-al according to the method of the present invention is carried out by continuously or intermittently feeding an oxygen-containing gas and 7-octen-1-al into a reaction solvent in which an oxidation catalyst is dissolved. be done. In this case, the concentration of 7-ocd/-1-al in the reaction mixture is 0650
Adjusting the feed rate of 7-octen-1-al to keep it below mol/l suppresses the accumulation of reaction heat, and
Side reactions such as the combination of -octen-1-al and 7-oct/es and decarboxylation are prevented, and the selectivity of the reaction is further improved. Also, the concentration of 7-octenoic acid in the reaction mixture is always about 3 mol/! It is also effective to maintain the following value in order to prevent the polymerization of the product 7-octenoic acid and improve the selectivity of the reaction. As the reaction apparatus, a stirred reaction tank or a bubble column type reaction tank is preferably used. After the oxidation catalyst is removed from the reaction mixture by a known method, 7-octenoic acid can be separated and obtained in good yield by distillation.

The method of the present invention will be specifically explained below with reference to Examples.

Example 1 1) Production of 7-octen-1-al In a 100*L Mitsuro flask equipped with a stirring device, liquid and gas feedlot, and connected to a distillation device, 2.7-
Octarenin-1-ol (purity: 99.9% or more) 3
0d and powdered steel chromium oxide catalyst2. Or (manufactured by 8Kokugaku Co., Ltd., N-203) was charged, and the flask was immersed in an oil bath maintained at 205°C. While vigorously stirring and flowing nitrogen gas at a rate of 3017 hr, 2,7-octarenin-1-ol was continuously supplied at a rate of 170 wl/br using a metered feed pump.

The isomerization (distillation) reaction of 2.7-octarenin-1-ol was carried out in this manner for a total of 8 hours.

170 d of distillate was obtained per hour, and the liquid volume in the flask was maintained at about 30 dK throughout one reaction. A total of 1350 t# of distillate was obtained after 8 hours of reaction. Analysis by gas chromatography revealed that unreacted 2 was present in the distillate.
．． 16.9 mol-1n of 7-octarenin-1-ol
- Octylaldehyde di 2.7-4 Ru, n-octatool and octen-1-ols were found to contain a total of 8.9 mol, and 7-octene-1-al or 70.7 mol. .

The distillate 1°01# obtained in this way was heated to 4 theoretical plates.
When purified using a 0-stage glass distillation column, the temperature was 58℃/
Approximately 700 f of 7-octen-1-al (purity 98%, containing approximately 2-n-octylaldehyde) was obtained as a fraction of 10■He.

2) Production of 7-octenoic acid In a four-bottle flask with an internal volume of 100 d equipped with a temperature needle, a stirrer, a reflux condenser, a raw material feedlot, and an oxygen gas inlet, propio/acid 3Qt#, vinegar ferrous iron 32"f (3.0 mmol per 1j of reaction mixture) was added, and the contents were heated while stirring to completely dissolve the ferrous acetate.

A microfeeder connected to the raw material feeder was charged with 50 liters of a 4 mol/l 7-octen-1-al propionic acid solution which had been purged with nitrogen gas. When the temperature inside the reactor became constant at 65°C, the contents were stirred at a rotational speed of 80 Orpm, and while introducing oxygen gas at a flow rate of 10 I/hr, the raw material was heated for 10-7 hours. An oxidation reaction was carried out by continuously adding a solution of 7-octen-1-al in propionic acid over a period of 3 hours at a feed rate of . After the addition of 7-octen-1-al was completed, stirring was continued for 2 hours at the same temperature. During the reaction period, the internal temperature was kept constant at 65°C. The conversion rate of 7-octene-1-alno at the end of the oxidation reaction (5 hours after the start of the reaction) was t188'1 g, and the selectivity to 7-octenoic acid (conversion of 7-octen-1-al groups flk) H8
It took 5 minutes. Analysis of the reaction product by gas chromatography revealed small amounts of by-products such as heptene and formic acid. Further, off-gas analysis conducted every hour from the start of the reaction revealed that the carbon dioxide generation rate (based on converted 7-octen-1-al) was 3.5 mol. After washing the reaction mixture obtained above with 60 Wl of 1N aqueous hydrochloric acid solution, the organic layer was distilled under reduced pressure to obtain 102 7-octenoic acids as fractions 98-b.

Reactions similar to 1) above were carried out for 1 hour using various catalysts instead of steel chromium oxide.

Table 1 shows the selectivity of 7-octen-1-al contained in the distillate.

Table 1 Examples 2 to 7 Using the 7-octen-1-al obtained in Example 1, 1), the catalyst was prepared in the same manner as in Example 1, 2).
Type and amount, % of S type in solvent 7-octene-1- for feed
Table 2 shows the concentration of R, oxygen-containing gas, reaction temperature, and reaction time.
It was oxidized with moderate changes as shown in the figure. The results are summarized in Table 2.

Claims (1)

[Claims] 2. 7-octarenin-1-ol is isomerized in the presence of a catalyst selected from the group consisting of chromium-based catalysts, and the resulting 7-octen-1-al is converted into a liquid phase in the presence of an oxidation catalyst. 7 characterized by oxygen oxidation in
-Production method of octenoic acid.