JPH0761972B2 - Method for producing carboxylic acid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a carboxylic acid by oxidative cleavage of olefins.

[Prior Art] A carboxylic acid obtained by oxidatively cleaving an unsaturated bond of an olefin obtained in large quantities at low cost from petroleum and animal and vegetable oils and fats is widely used as a raw material for esters, imides, amides and the like.

Various methods for producing carboxylic acid by oxidative cleavage of olefins have been proposed so far. For example, a method of oxidizing with a metal compound such as potassium permanganate, potassium dichromate, or ruthenium tetraoxide, or a method of adding a catalytic amount of these and using an oxidizing agent such as sodium hypochlorite or sodium periodate. (Bull.Chem.
Soc. Jpn., 59 , 2637 (1986)) and the like are known.

[Problems to be Solved by the Invention] However, these methods are toxic to metals such as chromium and ruthenium, and corrosive to sodium hypochlorite and sodium periodate. In addition, it was expensive and could not be put to practical use. Furthermore, these oxidizing agents are unstable under acidic conditions and the reaction must be carried out under basic conditions. Therefore, a neutralization step is required, which complicates the manufacturing process and is industrially disadvantageous. From these, a method for safely and inexpensively producing a carboxylic acid by oxidatively cleaving an olefin under acidic conditions has been desired.

Hydrogen peroxide is a suitable oxidant in the production of carboxylic acids because it is inexpensive, non-corrosive and stable under acid. However, since this is water-soluble, when acting on an oil-soluble substance, a special and expensive catalyst is used, such as tungstic acid or molybdic acid, to which alkyl-substituted ammonium or phosphonium is introduced to impart oil solubility. Only the method (JP-A-60-34929) is known, and the method of applying a water-soluble catalyst is not yet known.

Further, when cations such as sodium, potassium, ammonium, phosphonium and the like coexist in the reaction system as in the above-mentioned method, the purity and yield of the carboxylic acid produced are lowered, and a separate purification step is required. There's a problem. That is,
The presence of any cation other than a proton causes a production disadvantage in order to produce the carboxylic acid simply and inexpensively.

However, according to the research conducted by the present inventors, unexpectedly even tungstic acid which is not oil-soluble is used as a catalyst without any treatment as described above, and hydrogen peroxide acts on olefins as an oxidizing agent. It was revealed that by doing so, the double bond was oxidatively cleaved very effectively and the corresponding mono- and / or dicarboxylic acid was obtained. or,
It has been found that the double bond of olefins is also oxidatively cleaved when molybdic acid is used as a catalyst as in the case of tungstic acid.

Furthermore, the present inventors have found that even when a heteropoly acid such as tungstic acid or molybdic acid is used as a catalyst, the double bond of the olefins is efficiently oxidatively cleaved by hydrogen peroxide, and the corresponding mono- and / or dicarboxylic acid is increased. It has been found that the production can be performed with high yield and high purity.

The present invention has been completed based on the above new findings.

That is, an object of the present invention is to provide a novel and useful catalyst for a method for producing a carboxylic acid by oxidatively cleaving olefins with hydrogen peroxide.

[Means for Solving Problems] In the present invention, when oxidatively cleaving olefins to produce a carboxylic acid, one or two kinds selected from the group consisting of tungstic acid, molybdic acid and heteropolyacids thereof are used. The gist of the invention is to perform oxidative cleavage with hydrogen peroxide in the presence of the above catalyst.

Examples of the olefins in the present invention include butene, pentene, hexane, octene, cyclopentene, cyclohexene, cyclooctene, and other aliphatic groups having 4 to 8 carbon atoms, alicyclic hydrocarbons, dicyclopentenol, sulfolene, phorone, isophorone, Oleic acid, palmitoleic acid, linoleic acid, linoleic acid, ricinoleic acid and esters thereof such as olefins having a functional group such as a carbonyl group, a hydroxyl group, a carboxyl group, an ester group and a sulfone group are exemplified. The functional group may be a group that is oxidized in the same manner as olefins as long as it does not inhibit the reaction according to the present invention, and may contribute to the progress of the reaction depending on the conditions.

Examples of the catalyst according to the present invention include tungstic acid, molybdic acid, and heteropolyacids thereof. The heteropolyacid referred to herein is a condensed acid composed of two or more kinds of oxygen acids, the polyacid atom is tungsten and molybdenum, and the heteroatom may be any of the followings. Heteroatoms in the heteropolyacid of tungstic acid include P, As, Si, Ti,
Examples include Co, Fe, B, V, Be, I, Ni, Ga and the like. Specific examples of the heteropoly acid of tungstic acid include the following structural formulas: H ₃ [PW ₁₂ O ₄₀ ], H ₃ [AsW ₁₂ O ₄₀ ], H ₄ [SiW ₁₂ O ₄₀ ], H ₄ [TiW ₁₂ O ₄₀ ], H ₅ [CoW ₁₂ O ₄₀ ], H ₅ [FeW ₁₂ O ₄₀ ], H ₅ [BW ₁₂ O ₄₀ ], H ₃ [VW ₁₂ O ₄₀ ], H ₆ [BeW ₉ O ₃₁ ], H ₆ [TeW ₆ O ₂₄ ], H ₅ [IW ₆ O ₂₄ ], H ₄ [NiW ₆ O ₂₄ H ₆ ], H ₃ [GaW ₆ O ₂₄ H ₆ ], H ₆ [P ₂ W ₁₈ O ₆₂ ], H Examples thereof include ₆ [As ₂ W ₁₈ O ₆₂ ] and H ₇ [PW ₁₁ O ₃₃ ].

The heteroatoms in the molybdic acid heteropolyacid include P, As, Si, Ge, Ti, Ce, Th, Mn, Ni, Te,
I, Co, Cr, Fe, Ga and the like are exemplified. Specific examples of the heteropoly acid of molybdic acid include the following structural formulas, H ₃ [PWo ₁₂ O ₄₀ ], H ₃ [AsMo ₁₂ O ₄₀ ], H ₄ [SiMo ₁₂ O ₄₀ ], H ₄ [GeMo ₁₂ O _40]. ], H ₄ [TiMo ₁₂ O _40], H ₈ [Cemo ₁₂ O _42], H ₈ [ThMo ₁₂ O _42], H ₇ [PMo ₁₁ O _39], H ₇ [ASMO ₁₁ O _39], H ₈ [ GeMo ₁₁ O ₃₉ ], H ₆ [MnMo ₉ O ₃₂ ], H ₆ [NiMo ₉ O ₃₂ ], H ₆ [TeMo ₆ O ₂₄ ], H ₅ [IMo ₆ O ₂₄ ], H ₃ [CoMo ₆ O ₂₄ H ₆ ], H ₃ [CrMo ₆ O ₂₄ H ₆ ], H ₃ [FeMo ₆ O ₂₄ H ₆ ], H ₃ [GaMo ₆ O ₂₄ H ₆ ], H ₄ [NiMo ₆ O ₂₄ H ₆ ], H ₆ [ Examples thereof include P ₂ Mo ₁₈ O ₆₂ ], H ₆ [As ₂ Mo ₁₈ O ₆₂ ].

Furthermore, a mixed coordination heteropolyacid in which two or more kinds of each atom are coordinated, for example, H ₄ PMoW ₁₁ O ₄₀ , H ₄ PReW ₁₁ O ₄₀ , H ₄ PVMo ₁₁ O ₄₀ , H ₅ PV ₂ Mo ₁₀ O ₄₀ , H ₃ PMo ₆ W ₆ O ₄₀ etc. can also be used. All of these heteropolyacids exemplified above are known. From the viewpoint of ease of synthesis or availability, a heteropoly acid containing P or Si as a hetero atom is preferable, and particularly 12-tungstophosphoric acid (H ₃ PW ₁₂ O ₄₀ ), 12-tungstosilicic acid (H ₃ SiW ₁₂ O ₄₀ ), 12-molybdophosphoric acid (H ₃ PMo ₁₂ O ₄₀ ) and the like are more preferable.

In addition, the tungstic acid, molybdic acid or heteropolyacid thereof used as the catalyst may be a hydrate, and further, a compound capable of producing the tungstic acid, molybdic acid or heteropolyacid thereof in the reaction system. It may be in the form of. Such compounds include MO ₃ , M
Examples are oxides, chlorides and sulfides represented by Cl ₆ and MS ₃ (M = W or Mo).

When such an oxide, chloride or sulfide is used, it is preferable to add a mineral acid such as phosphoric acid, hydrochloric acid or sulfuric acid into the reaction system and carry out the reaction under acidic conditions of pH 4 or less. It is also possible to add the catalyst in the acid form and further use mineral acids.

The catalysts exemplified above may be used alone or in combination of two or more kinds.

From the viewpoint of reactivity, heteropolyacid is preferable, and from the viewpoint of the balance between reactivity and cost, tungstic acid is preferable.

The manufacturing method according to the present invention is generally performed as follows. That is, olefins as raw materials and a catalyst are charged into a reactor, hydrogen peroxide is added, and the reaction is carried out in a solvent with heating and stirring.

The concentration of olefins during the reaction is not particularly limited. However, when the reaction mixture is cooled after completion of the reaction to crystallize the produced carboxylic acid for isolation, the concentration of the olefins is set to about 2 to 70% by weight from the viewpoint of the amount of precipitated crystals and quality. Is preferred, and more preferably 15 to 60% by weight.

The amount of the catalyst used is selected from a wide range as long as it is an amount effective to exert the catalytic activity. However, from the viewpoint of reaction rate and catalyst cost, in terms of free acid (tungstic acid, molybdic acid or heteropolyacids thereof),
About 0.01 to 30% by weight, preferably 1
Advantageously, about 10% by weight.

The stoichiometric amount of hydrogen peroxide required for this reaction is 4 mols per 1 mol of olefins, but in practice it is desirable to use 10 to 50% excess thereof. The concentration of hydrogen peroxide in the reaction mixture can be selected from a wide range. The lower limit is a concentration sufficient for the catalyst that oxidizes olefins to recover its oxidizing ability by hydrogen peroxide, and the oxidation reaction proceeds even though the reaction rate is inevitable even if the catalyst is extremely dilute. Further, there is no particular upper limit, and the concentration may be considerably high. However, from the viewpoint of improving the reaction rate and reducing the production cost by using a low concentration of hydrogen peroxide, 0.1 mmol / -12 mol / about, preferably 10 mmol / -8 mol / about is advantageous. is there. Hydrogen peroxide is usually supplied in the form of an aqueous solution.

Water is suitable as the reaction solvent. Organic solvent miscible with water, for example, alcohol having 1 to 4 carbon atoms, 1 to 1 carbon atom
It is also possible to use the carboxylic acid of No. 4, dioxane, tetrahydrofuran, dimethylformamide, etc., alone or in combination with water within the range of maintaining a homogeneous phase.

From the viewpoint of reaction rate, the reaction temperature is usually in the range of about 20 to 100 ° C, but when the reaction is performed under pressure,
It is also possible to employ reaction temperatures up to about 150 ° C. From the viewpoint of reaction rate and the viewpoint of preventing or suppressing decomposition of hydrogen peroxide, it is preferable to carry out the reaction at about 50 to 130 ° C.

The reaction time may vary depending on the concentrations of olefins, catalyst and hydrogen peroxide, reaction temperature, etc., but is usually about 1 to 24 hours.

After completion of the reaction, the produced carboxylic acid can be separated from the reaction mixture by a method suitable for each physical property. For example, distillation may be carried out, or a reaction solvent may be topped and then recrystallized using an arbitrary solvent. In the method of slowly cooling the reaction mixture to crystallize the carboxylic acid, when a heteropolyacid, especially a heteropolyacid of tungstic acid, is used as a catalyst, a clear reaction mixture is obtained because these are well dissolved in water and other reaction solvents. Then, when the reaction mixture is gradually cooled, the produced carboxylic acid precipitates as crystals and can be separated very easily from the mother liquor in which the catalyst and unreacted olefins are dissolved by filtration. After the separation, the mother liquor can be reused for the reaction, and no deactivation of the catalyst is observed. The isolated crystals are dried as they are, or washed with water or the like if necessary, and recrystallized for purification. On the other hand, when tungstic acid or molybdic acid is used as the catalyst, when the hydrogen peroxide concentration in the reaction system decreases, the catalyst tends to precipitate, and the precipitated catalyst mixes with the generated carboxylic acid to reduce the purity of the target product. Invite. Therefore, when tungstic acid or molybdic acid is used as the catalyst, the hydrogen peroxide concentration is maintained at a concentration equal to or higher than the concentration at which these catalysts remain in the dissolved state even in the isolation step after the reaction, or immediately after the reaction, precipitation occurs. It is desirable to separate the catalyst by filtration before crystallization. By carrying out such an operation, the target carboxylic acid can be isolated with high purity and high yield equivalent to the case of using the heteropolyacid.

[Examples] The present invention will be described in detail below with reference to Examples.

Example 1 Cyclohexene 16.8 was added to a glass four-necked flask equipped with a stirrer.
g (0.2 mol), 60% hydrogen peroxide water 50 g (0.88 mol), and tungstic acid 0.74 g were added and heated to reflux with vigorous stirring. The reflux temperature increased from 74 ° C to 100 ° C with time. After reacting for 3 hours, the production rate of the corresponding carboxylic acid of the reaction solution was calculated by gas chromatography internal standard method. As a result, it was 95 mol% adipic acid and 3 mol% glutaric acid. The reaction solution was cooled and crystallized to obtain 24.5 g (yield 86 mol%) of adipic acid crystals.

Example 2 13.6 g (0.2 mol) of cyclopentene, 50 g of 60% hydrogen peroxide and 12-tungstophosphoric acid 29 were placed in a glass autoclave.
0.6 g of a hydrate was charged and reacted at 75 ° C for 7 hours. When the reaction solution was measured by a gas chromatography internal standard method, the production rate of carboxylic acid was 90 mol% of glutaric acid,
It was 2 mol% of succinic acid. The reaction solution was topped with water and recrystallized with benzene to give glutaric acid crystals.
22.6 g (yield 88 mol%) was obtained.

Example 3 16.8 g of cyclohexene, 30 g of tert-butanol, and 5.0 g of molybdic acid were charged into the reactor of Example 1, and 50 g of 60% hydrogen peroxide solution was added dropwise over 5 hours while heating under reflux. Then, the mixture was refluxed for 3 hours to complete the reaction. When the reaction solution was measured by a gas chromatography internal standard method, the production rates of the corresponding carboxylic acids were 86 mol% adipic acid and 2 mol% glutaric acid.

Example 4 The reaction was performed in the same manner as in Example 1 except that 3.0 g of 12-molybdophosphoric acid 29 hydrate was used as the catalyst. As a result of measurement by a gas chromatography internal standard method, the corresponding carboxylic acid production rates were 92 mol% adipic acid and 5 mol% glutaric acid.

Example 5 Isophorone 27.6 g (0.2 mol), water 30 in the reactor of Example 1
When 1.0 g of g, 12-dungstosilicic acid 24-hydrate was added and 140 g of 30% hydrogen peroxide solution was added dropwise over 3 hours while stirring at 80 ° C., vigorous foaming was observed. The reaction was continued for 8 hours until the bubbling stopped. When the reaction solution was measured by a gas chromatography internal standard method, the production rate of 3,3-dimethylglutaric acid was 50 mol%. No isophorone could be detected.

Example 6 The reactor of Example 1 was charged with 30 g (0.2 mol) of dicyclopentenol, 60 g of water, and 0.9 g of 12-tungstophosphoric acid 29 hydrate, and 50 g of 60% hydrogen peroxide solution while stirring at 90 ° C. Was added dropwise over 2 hours, and the reaction was continued for 4 hours. As a result of measuring this reaction solution by a gas chromatography internal standard method, the production rate of the corresponding carboxylic acid was 58 mol%, but when the neutralization value of this solution was measured, it was found to be 0.
44 mol of carboxyl groups had formed. So, further
When 50g of 60% hydrogen peroxide solution and 0.9g of catalyst were added and the reaction was continued for 10 hours, tricarboxylic clopentyl acetic acid was detected.
Obtained with a production rate of 60 mol% (by gas chromatography internal standard method). At this time, the amount of generated carboxyl groups calculated from the neutralization value was 0.73 mol.

Example 7 The reactor of Example 1 was charged with industrial oleic acid (iodine number 90.2).
Charge 28 g, 50 g of water, 2.0 g of 12-tungstophosphoric acid 29 hydrate, and while stirring vigorously at 90 ° C, 57 g of 60% hydrogen peroxide solution.
Was added dropwise over 5 hours, and then the reaction was carried out for 5 hours. The reaction solution was topped with water and then distilled under reduced pressure to obtain a monocarboxylic acid and a dicarboxylic acid. As a result of calculating the production rate of the corresponding carboxylic acid with respect to the unsaturated fatty acid contained in the industrial oleic acid from the weight of each fraction and gas chromatography, pelargonic acid 64 mol%, carbon chain 8 or less short-chain mono The content was 27 mol% of carboxylic acid, 79 mol% of azelaic acid, 11 mol% of long-chain dicarboxylic acid having 10 or more carbon atoms, and 5 mol% of short-chain dicarboxylic acid having 8 or less carbon atoms.

[Effect of the invention] Since the production method according to the present invention uses hydrogen peroxide, it is possible to produce carboxylic acid safely and inexpensively without using harmful metals. Moreover, the yield of the obtained carboxylic acid is high, and the produced carboxylic acid can be separated relatively easily to obtain a highly pure target product.

Therefore, the manufacturing method according to the present invention is an industrially excellent manufacturing method of carboxylic acid.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C07C 55/14 55/26 // B01J 23/28 23/30 23/85 23/88 27/188 C07B 61/00 300

Claims (1)

[Claims] 1. When producing a carboxylic acid by oxidatively cleaving an olefin, one or two selected from the group consisting of tungstic acid, molybdic acid and heteropolyacids thereof.
A method for producing a carboxylic acid, which comprises oxidatively cleaving with hydrogen peroxide in the presence of at least one catalyst.