CN114127045B

CN114127045B - Method for producing diacyl peroxide

Info

Publication number: CN114127045B
Application number: CN202080043097.8A
Authority: CN
Inventors: M·C·塔默
Original assignee: Norion Chemicals International Ltd
Current assignee: Norion Chemicals International Ltd
Priority date: 2019-06-12
Filing date: 2020-06-11
Publication date: 2023-10-13
Anticipated expiration: 2040-06-11
Also published as: CN114127045A

Abstract

The present invention relates to a process for producing diacyl peroxide comprising reacting an anhydride with an aldehyde and oxygen, removing the carboxylic acid formed, producing an anhydride from the carboxylic acid, and recycling the anhydride in the process.

Description

Method for producing diacyl peroxide

Technical Field

The present invention relates to a process for preparing diacyl peroxide.

Background

The diacyl peroxide has the general formula

R-C(＝O)-O-O-C(＝O)-R

Wherein the R groups may be the same or different and are selected from aryl, arylalkyl, and linear, branched, or cyclic alkyl, optionally substituted with heteroatom-containing substituents.

Symmetrical diacyl peroxides, i.e. those in which the R groups are the same in the above formula, have been prepared by reacting an excess of anhydride or acid chloride with an alkaline solution of hydrogen peroxide as shown in the following formula: 2R-C (=o) -O-C (=o) -r+na ₂ O ₂ →R-C(＝O)-O-O-C(＝O)-R+2NaOC(＝O)R2R-C(＝O)Cl+Na ₂ O ₂ →R-C(＝O)-O-O-C(＝O)-R+2NaCl。

In this reaction scheme, na ₂ O ₂ Not meaning the isolated product Na ₂ O ₂ But means to contain H ₂ O ₂ And NaOOH.

US 3,580,955 discloses a process for preparing an asymmetric diacyl peroxide by reacting an acyl chloride with an aldehyde and oxygen in the presence of an acid acceptor.

US 3,502,701 produces an asymmetric diacyl peroxide by reacting an acyl chloride with a peroxyacid.

Acid chlorides are relatively expensive and produce a water layer containing chloride ions, which results in high salt concentrations in the wastewater.

Another process which allows the preparation of asymmetric diacyl peroxides has been described in GB 1,156,573, which involves the reaction between an organic anhydride, an aldehyde and oxygen in the presence of a catalyst comprising a lithium or magnesium salt of an organic acid.

GB 444,603 discloses the preparation of acetophenone peroxide by reacting benzaldehyde and acetic anhydride with an oxygen-containing gas in the presence of dibenzoyl peroxide.

However, anhydrides are even more expensive than acid chlorides and the waste stream of the process contains a high organic load, i.e. has a high Chemical Oxygen Demand (COD) value, due to the carboxylate salt formed, and is therefore not economically and environmentally attractive.

GB 901,041 discloses a process for preparing diacyl peroxides by reacting a peracid with an anhydride or acyl halide of an organic acid, wherein it is said that the use of acid chlorides is preferred.

Disclosure of Invention

It is an object of the present invention to provide a process for the production of diacyl peroxide which has a relatively low carboxylic acid (salt) content in its effluent and which does not require the use of acid chloride.

This object is achieved by a method comprising the steps of:

a) By bringing one or more compounds of formula R ¹ -C(＝O)-O-C(＝O)-R ² Anhydride of formula (I) and formula (R) ³ The aldehyde of C (=o) H reacts with oxygen to produce a mixture comprising diacyl peroxide and carboxylic acid,

wherein R is ¹ And R is ³ Selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 1 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents, and R ² Selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 2 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents,

b) Extracting or separating the carboxylic acid from the mixture in the form of its carboxylate salt or adduct,

c) Releasing the carboxylic acid from the salt or adduct,

d) Optionally by reacting a compound of formula R ² Reaction of an aldehyde of C (=O) H with oxygen to giveAn additional amount of a carboxylic acid is provided,

e) Allowing the carboxylic acid obtained in step c) and optionally an additional amount of a compound of formula R ² Carboxylic acids and anhydrides of-C (=o) OH or R ⁴ Independently selected from H and CH ₃ C (R) ⁴ ) ₂ Ketene, preferably with acetic anhydride, of formula R ¹ -C(＝O)-O-C(＝O)-R ² Said additional amount of carboxylic acid being obtained from step d) and/or obtained in another way,

f) Recycling at least a portion of the anhydride formed in step e) to step a).

The process produces a diacyl peroxide from an anhydride, which is at least partially obtained from a carboxylic acid by-product. This reuse of the carboxylic acid formed in step a) makes the route economically attractive and the COD of its effluent low.

Detailed Description

Preferably, any additional amount of carboxylic acid required to form the amount of anhydride required in step a) is obtained by oxidation of the corresponding aldehyde. The oxidation can be carried out in the same apparatus as step a), which makes it very economical and further allows the production of diacyl peroxide starting from the corresponding aldehyde which is relatively inexpensive. It is therefore preferred to produce an additional amount of carboxylic acid in step d) and to react it with acetic anhydride or ketene in step e).

Since the process does not involve the use of corrosive or volatile reactants, the safety of production is improved and production is allowed at the site where the diacyl peroxide is ultimately used (e.g., polymerization facilities). Such on-site production allows on-demand production of peroxide, thereby minimizing storage capacity and corresponding safety measures.

Step a) involves reacting an aldehyde with a compound of formula R ¹ -C(＝O)-O-C(＝O)-R ² Is a reaction of an anhydride of (2).

In the formula R ¹ Selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 1 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents. Examples of suitable substituents are alkoxy, chloro and ester substituents. The number of carbon atoms is preferably 2 to 11, even more preferablySelected from 2 to 8 and most preferably 3 to 6 carbon atoms. In a further preferred embodiment, R ¹ Selected from linear or branched alkyl groups. Most preferably, R ¹ Selected from the group consisting of n-propyl, isopropyl, isobutyl, n-butyl and 2-butyl.

In the formula R ² Selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 2 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents. Examples of suitable substituents are alkoxy, chloro and ester substituents. The number of carbon atoms is preferably 2 to 11, even more preferably 2 to 8 and most preferably 3 to 6 carbon atoms. In a further preferred embodiment, R ² Selected from linear or branched alkyl groups. Most preferably, R ² Selected from the group consisting of n-propyl, isopropyl, isobutyl, n-butyl and 2-butyl.

The anhydride may be symmetrical, meaning R ¹ ＝R ² Or is asymmetric, meaning R ¹ ≠R ² 。

If the anhydride is symmetrical, the carboxylic acid formed in step a) and extracted or isolated in step b) will have the formula R ² -C (=o) OH. If the anhydride is asymmetric, the carboxylic acid will be R ² -C (=o) OH and R ¹ -a mixture of C (=o) OH.

Suitable symmetrical anhydrides are propionic anhydride, n-butyric anhydride, isobutyric anhydride, pivalic anhydride, valeric anhydride, isovaleric anhydride, 2-methylbutyric anhydride, 2-methylpentanoic anhydride, 2-methylhexanoic anhydride, 2-methylheptanoic anhydride, 2-ethylbutyric anhydride, hexanoic anhydride, octanoic anhydride, isohexanoic anhydride, n-heptanoic anhydride, nonanoic anhydride, isononyl anhydride, 2-propylheptanoic anhydride, decanoic anhydride, neodecanoic anhydride, undecanoic anhydride, neoheptanoic anhydride, isooctanoic anhydride, lauric anhydride, tridecanoic anhydride, 2-ethylhexanoic anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, phenylacetic anhydride, cyclohexane carboxylic anhydride, 3-methyl-cyclopentanecarboxylic anhydride, beta-methoxypropionic anhydride, methoxyacetic anhydride, ethoxyacetic anhydride, propoxyacetic anhydride, alpha-ethoxybutyric anhydride, benzoic anhydride, o-, m-and p-methylbenzoic anhydride, 2,4, 6-trimethylbenzoic anhydride, o-, m-and p-chlorobenzoic anhydride, o-, m-and p-bromobenzoic anhydride, o-, m-and p-nitrobenzoic anhydride, and mixtures of two or more of the foregoing.

Examples of suitable mixtures of symmetrical anhydrides are mixtures of isobutyric anhydride and 2-methylbutyric anhydride, mixtures of isobutyric anhydride and 2-methylpentanoic anhydride, mixtures of 2-methylbutyric anhydride and isovaleric anhydride and mixtures of 2-methylbutyric anhydride and valeric anhydride.

The asymmetric anhydride is generally obtained as a mixture of asymmetric and symmetric anhydrides. This is because the asymmetric anhydride is typically obtained by reacting a mixture of acids with, for example, acetic anhydride. This results in an anhydride mixture comprising an asymmetric anhydride and at least one symmetric anhydride. Such anhydride mixtures can be used in the process of the present invention. An example of a suitable asymmetric anhydride is isononyl methoxyacetate, which is preferably present as a mixture with methoxyacetic anhydride and isononyl anhydride; isononyl ethoxyacetate, preferably present as a mixture with ethoxyacetic anhydride and isononanoic anhydride; methoxy acetic anhydride, preferably as a mixture with methoxy acetic anhydride and n-nonanoic anhydride; ethoxylated nonanoic acid anhydride, which is preferably present as a mixture with ethoxylated acetic anhydride and n-nonanoic acid anhydride; isobutyric acid 2-methylbutyric anhydride, which is preferably present as a mixture with isobutyric anhydride and 2-methylbutyric anhydride; isobutyric acid acetic anhydride, preferably present as a mixture with isobutyric anhydride and acetic anhydride; isobutyric anhydride propionate, preferably present as a mixture with propionic anhydride and isobutyric anhydride; 2-methylbutyric anhydride valeric anhydride, which is preferably present as a mixture with 2-methylbutyric anhydride and valeric anhydride; and butyric anhydride, preferably as a mixture with butyric anhydride and valeric anhydride.

More preferred anhydrides are isobutyric anhydride, n-butyric anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2-methylhexanoic anhydride, 2-methylpentanoic anhydride, 2-propylheptanoic anhydride, n-nonanoic anhydride, isononyl anhydride, cyclohexane-carboxylic anhydride, 2-ethylhexanoic anhydride, n-pentanoic anhydride and isopentanoic anhydride. Most preferred is isobutyric anhydride.

In step a), the anhydride is reacted with the reaction product of the aldehyde and oxygen.

The aldehyde has the formula R ³ -C (=o) H, wherein R ³ Selected from linear and branched alkyl, cycloalkyl, aryl or aralkyl groups having 1 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents.

Examples of suitable substituents are alkoxy, chloro and ester substituents.

The number of carbon atoms is preferably 1 to 11, more preferably 3 to 9 and most preferably 3 to 6.

In a further preferred embodiment, R ³ Is a linear or branched alkyl group.

Most preferred R ³ The radicals are n-propyl and isopropyl, which means that most preferred are those of the formula R ³ The aldehydes of C (=o) H are isobutyraldehyde, n-valeraldehyde and n-butyraldehyde.

Suitable aldehydes include acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, 2-dimethylpropionaldehyde, n-valeraldehyde, 3-methylbutyraldehyde, 2-ethylbutyraldehyde, 2-propylheptanal, n-hexanal, n-octanal, 4-methylpentanal, n-heptanal, 6-methylheptanal, n-octanal, n-nonanal, isononanal, n-decanal, undecanal, tridecanol, 2-ethylhexanal, tetradecanal, octadecanol, phenylacetaldehyde, cyclohexane formaldehyde, 3-methyl-cyclopentanal, β -methoxypropionaldehyde, α -ethoxybutyraldehyde, benzaldehyde, o-, m-and p-methylbenzaldehyde, 2,4, 6-trimethylbenzaldehyde, o-, m-and p-chlorobenzaldehyde, o-, m-and p-bromobenzaldehyde, o-, m-and p-nitrobenzaldehyde, o-, m-and p-acetoxybenzaldehyde, and o-, m-and p-methoxybenzaldehyde.

Preferred aldehydes are n-butyraldehyde, iso-butyraldehyde, 2-dimethylpropionaldehyde, 3-methylbutyraldehyde, 2-methylpentanal, 2-ethylhexanal, n-heptanal, n-valeraldehyde, isononanal and 2-propylheptanal.

More preferred aldehydes are n-butyraldehyde, iso-butyraldehyde, 3-methylbutyraldehyde, n-valeraldehyde, n-heptanal and isononaldehyde.

Most preferred aldehydes are isobutyraldehyde, n-valeraldehyde, and n-butyraldehyde.

A suitable oxygen source is air, but pure oxygen, oxygen enriched or oxygen depleted air may also be used. The oxygen source may preferably be added to the reaction mixture using a sparger by feeding it as a gas to the reactor.

The oxygen source and aldehyde are preferably fed to the anhydride-containing reactor in such a way that the losses due to evaporation are small and the reaction rate is sufficiently high.

The reaction of step a) is preferably carried out at a temperature in the range of-10 to 60 ℃, more preferably in the range of 0 to 50 ℃, even more preferably in the range of 0 to 40 ℃ and most preferably in the range of 5 to 40 ℃.

Atmospheric pressure is preferably used. At lower pressures, less oxygen is dissolved in the reaction mixture and more aldehyde may evaporate. Some overpressure may be used to increase the reaction rate, but high pressures are generally not desirable for concentrated peroxide systems.

The molar ratio of aldehyde to anhydride is preferably in the range of 0.8-2.5, more preferably 1.0-2.0 and most preferably 1.1-1.7.

The reaction does not require the presence of a solvent. However, if the final product (i.e., the diacyl peroxide) needs to be diluted in a solvent, the solvent and the aldehyde may be preloaded or dosed into the reaction mixture during the reaction. Suitable solvents are alkanes, esters, ethers, amides and ketones. Preferred solvents are (mixtures of) alkanes, such as isododecane,Mineral oil; esters such as ethyl acetate, methyl acetate, ethylene dibenzoate, dibutyl maleate, diisononyl 1, 2-cyclohexanedicarboxylate (DINCH) or 2, 4-trimethylpentanediol diisobutyrate (TXIB); and phthalic acid esters such as dimethyl phthalate or dioctyl terephthalate.

A basic catalyst may optionally be used. Examples of suitable catalysts are magnesium, lithium, sodium, potassium or calcium oxides, hydroxides, bicarbonates, carbonates, phosphoric (hydro) acid salts and carboxylates.

The catalyst may be added in an amount of 0 to 30 mole%, more preferably 0 to 10 mole% and most preferably 0 to 5 mole% with respect to the acid anhydride.

According to step b), the carboxylic acid is extracted or separated from the mixture produced in step a) in the form of its carboxylate salt or adduct. The formation of the salt or adduct requires the presence of a base. If no base is present during step a), or if the amount of base added during step a) is insufficient to convert most of the carboxylic acid to the corresponding salt or adduct, then a base or additional amount of base may be added in step b). If the amount of base present in the mixture resulting from step a) is sufficient to convert the majority of the carboxylic acid to the corresponding salt or adduct, no additional amount of base need be added in step b).

Suitable bases are alkylated amines, oxides, hydroxides, bicarbonates, carbonates and carboxylates of magnesium, lithium, sodium, potassium or calcium. These bases will deprotonate the carboxylic acid, forming a water-soluble salt that eventually enters the aqueous phase. The organic and aqueous phases were then separated.

Other suitable bases are solid materials having basic functional groups capable of capturing carboxylic acids to form adducts. Examples of such solid materials are basic ion exchange resins such as poly (styrene-co-vinylbenzylamine-co-divinylbenzene), N- {2- [ bis (2-aminoethyl) amino ] ethyl } -aminomethyl-polystyrene, diethylaminomethyl-polystyrene, dimethylaminomethylated copolymers of styrene and divinylbenzene, polymer-bound morpholines, poly (4-vinylpyridines), zeolites or mesoporous silica containing alkyl amine groups such as 3-aminopropylsilyl-functionalized SBA-15 silica, polymeric amines and mixtures of one or more of these. The adduct formed can be removed from the reaction mixture by filtration.

By using solvents and/or anhydrides, preferably of formula R ¹ -C(＝O)-O-C(＝O)-R ² The aqueous phase may be washed with the anhydride to remove any remaining peroxide compound in the aqueous phase.

After removal of the carboxylic acid, the organic phase containing the diacyl peroxide may be purified and/or dried. Purification can be carried out by washing with water optionally containing salts, bases or acids and/or filtration through, for example, carbon black or diatomaceous earth. By using dry salts such as MgSO ₄ Or Na (or) ₂ SO ₄ Or by makingDrying is performed with air or vacuum drying steps. If the diacyl peroxide is to be emulsified in water, the drying step may be omitted.

In step c), the carboxylic acid is released, for example, by,

(i) The aqueous phase containing the carboxylate salt is acidified,

(ii) Separating the adducts (split) (e.g. by heating or acidification) and physically separating the carboxylic acids from the solid material with basic functional groups (e.g. distillation), or

(iii) Salts are separated via electrochemical membrane separation, such as bipolar membrane electrodialysis (BPM).

The preferred acid for acidifying and protonating the carboxylic acid is pK _a Acids below 3 such as H ₂ SO ₄ 、HCl、NaHSO ₄ 、KHSO ₄ Etc. Most preferably H is used ₂ SO ₄ . If H is used ₂ SO ₄ It is preferably added as a 90-96% by weight solution. Acidification is preferably carried out to a pH below 6, more preferably below 4.5 and most preferably below 3. The pH value obtained is preferably not less than 1.

In addition to the acid, a small amount of reducing agent such as sulfite and/or iodide may be added to the aqueous phase to decompose any peroxide residues. A heat treatment (e.g., at 20-80 ℃) may be applied to decompose any diacyl peroxide residues.

The organic layer containing the carboxylic acid is then separated from any aqueous layer containing salt. The separation may be performed by gravity using conventional separation equipment such as liquid/liquid separators, centrifuges, (pulsed and/or packed) countercurrent columns, mixer-settlers (combinations) or continuous (plate) separators.

In some embodiments, the salt may be prepared by using a concentrated salt solution, e.g., 20-30 wt% NaCl, naHSO ₄ 、KHSO ₄ 、Na ₂ SO ₄ Or K ₂ SO ₄ The solution salted out the organic liquid phase to facilitate separation. The salts reduce the solubility of the carboxylic acid in the aqueous liquid phase. Such extraction may be performed in any suitable device such as a reactor, centrifuge or mixer-settler.

In particular for lower molecular weight acids such as butyric acid, isobutyric acid, valeric acid and methyl or ethyl branched valeric acid, the residual amount of acid will remain dissolved in the aqueous layer. The residual amount may be recovered by adsorption, (azeotropic) distillation or extraction. Optionally, a salt (e.g., sodium sulfate) may be added to the aqueous layer to reduce the solubility of the carboxylic acid.

In another embodiment, the release of carboxylic acid is achieved by electrochemical membrane separation. Examples of electrochemical membrane separation techniques are membrane electrolysis and bipolar membrane electrodialysis (BPM). BPM is the preferred electrochemical membrane separation method.

Electrochemical membrane separation results in the separation of metal carboxylates and the separation of these two species in carboxylic acids and metal hydroxides (e.g., naOH or KOH). Thus, a membrane separated (i) carboxylic acid-containing mixture and (ii) NaOH or KOH solution is produced. The NaOH or KOH solution can be reused in the process of the invention, for example in step a).

Depending on the temperature, salt concentration and solubility of the carboxylic acid in water, the carboxylic acid-containing mixture may be a biphasic mixture or a homogeneous mixture of two liquid phases. If a homogeneous mixture is formed under electrochemical membrane separation conditions (typically 40-50 ℃), cooling the mixture to a temperature below about 30 ℃ and/or adding salt will ensure that a biphasic mixture is formed. The organic liquid layer of this biphasic carboxylic acid-containing mixture may then be separated from the aqueous layer by gravity or using a device such as a centrifuge.

The carboxylic acid-containing organic phase is optionally purified to remove volatiles such as alcohols, ketones, olefins and water prior to use in step e). These volatiles may be removed by adsorption, distillation or drying with salts, molecular sieves, etc. Distillation is the preferred purification mode. The distillation preferably comprises two product collection stages, one to collect impurities such as alcohols and the other to collect the remaining water, optionally as an azeotrope with the carboxylic acid.

According to steps e) and f), followed by reacting the carboxylic acid with an anhydride or a compound of formula C (R) ⁴ ) ₂ Ketene reaction of =c=o, each R ⁴ Independently selected from H and CH ₃ Preferably with acetic anhydride to form a compound having the formula R ¹ -C(＝O)-O-C(＝O)-R ² Is then reacted with the acidThe anhydride is at least partially recycled to step a) and is used again for the production of diacyl peroxide.

The reaction of step e), in particular with acetic anhydride, is advantageously carried out in a reactive distillation column fed with carboxylic acid and acetic anhydride in the middle. The product anhydride is withdrawn from the bottom of the column, and the product acetic acid is collected from the top of the column. An alternative method is to produce the anhydride in a stirred reactor with a distillation column at the top. This allows acetic acid to be distilled off as it is formed to shift the equilibrium. US 2005/014974 discloses a process for preparing isobutyric anhydride by reacting acetic anhydride with isobutyric acid, the process comprising the step of distilling acetic acid just formed. The distillation column is preferably effective enough to obtain high purity acetic acid. The efficiency of the column is preferably at least 8 theoretical plates. High purity acetic acid may be sold and/or used for various purposes.

As disclosed in US 2,589,112, with formula C (R ⁴ ) ₂ The reaction of ketene=c=o is preferably carried out in a countercurrent adsorption apparatus. Preferred ketenes have the formula CH ₂ ＝C＝O。

In step e) a catalyst may be used, but the reaction is preferably carried out in the absence of a catalyst. Examples of suitable catalysts are oxides, hydroxides, bicarbonates, carbonates and carboxylates of magnesium, lithium, sodium, potassium or calcium.

The molar ratio of carboxylic acid to acetic anhydride is preferably in the range of 0.5:1 to 5:1, more preferably 1.5:1 to 2.2:1, most preferably 1.8:1 to 2.2:1. A slight excess of carboxylic acid relative to acetic anhydride may be used.

The reaction is preferably carried out at a temperature of from 70 to 200 ℃, preferably from 100 to 170 ℃, most preferably from 120 to 160 ℃. The temperature can be maintained at a desired value by adjusting the pressure in the reactor. The pressure is preferably in the range of 1 to 100kPa, more preferably 5 to 70 kPa.

After the reaction is completed, any excess acetic anhydride which may be present may be distilled off to purify formula R ¹ -C(＝O)-O-C(＝O)-R ² Is an acid anhydride of (2).

The anhydride can then be used again in step a).

In a preferred embodiment, the carboxylic acid used in step e) is obtained from two or three sources. The first source is the carboxylic acid released in step c). The second source is the carboxylic acid obtained by oxidizing the corresponding aldehyde according to step d), as described below. The third source is the additional amount of carboxylic acid obtained in any other way.

The oxidation of the aldehyde in step d) can be carried out in the same equipment as in step a), which makes it very economical and further allows the production of diacyl peroxide starting from the corresponding aldehyde, which is relatively inexpensive.

As oxygen source for step d) air is preferably used, but pure oxygen or oxygen enriched or depleted air may also be used. The oxygen source may preferably be added to the reaction mixture using a sparger by feeding it as a gas to the reactor.

The reaction of step d) is preferably carried out at a temperature in the range of 0-70 ℃, more preferably in the range of 10-60 ℃ and most preferably in the range of 20-55 ℃.

Atmospheric pressure is preferably used; at lower pressures, aldehydes may evaporate, which is undesirable.

Optionally, a catalyst may be used. Platinum black and iron salts are very good catalysts, not only to accelerate oxidation, but also to increase acid yield. Cerium, nickel, lead, copper and cobalt salts are also useful, particularly carboxylate salts thereof.

The catalyst may be added in an amount of 0 to 20 mole%, more preferably 0 to 5 mole%, most preferably 0 to 2 mole%, with respect to the aldehyde.

Both symmetrical and asymmetrical diacyl peroxides can be produced by the process of the present invention. However, symmetrical diacyl peroxides are preferred. If R in the above formula ¹ 、R ² And R is ³ The same, symmetrical diacyl peroxide is produced. Examples of symmetrical diacyl peroxides for which the process is particularly applicable are di-n-butyryl peroxide, di-n-pentanoyl peroxide, di-2-methylbutyryl peroxide, di-3-methylbutyryl peroxide, di-2-methylpentanoyl peroxide, dicyclohexylformyl peroxide, di-n-nonanoyl peroxide, diisononanoyl peroxide and diisobutanoyl peroxide. Most preferred are di-2-methylbutanoyl peroxide, di-2-methylpentanoyl peroxide and diisobutyryl peroxide.

Examples of asymmetric diacyl peroxides for which the process is particularly applicable are isononyl isobutyryl, isononyl butyryl peroxide, isononyl 2-ethylhexyl peroxide, isononyl 2-methylbutyl peroxide, isononyl 3-methylbutyl peroxide, isononyl pivaloyl peroxide, isononyl cyclohexylformyl peroxide, isononyl heptanoyl peroxide, isononyl 2-propylheptanoyl peroxide, 3-methyl Ding Xianyi butyryl peroxide, 3-methyl Ding Xianzheng butyryl peroxide, 3-methylbutyl 2-ethylhexyl peroxide, 3-methylbutyl 2-methylbutyl peroxide, 3-methyl Ding Xiante pentanoyl peroxide, 3-methylbutyl cyclohexylformyl peroxide, 3-methyl Ding Xiangeng acyl peroxide, 3-methyl Ding Xianyi nonanoyl peroxide 3-methylbutyryl 2-propylheptanoyl peroxide, iso-Ding Xianding acyl peroxide, iso-butyryl 2-ethylhexanoyl peroxide, iso-butyryl 2-methylbutanoyl peroxide, iso-butyryl 3-methylbutanoyl peroxide, iso-butyrylcyclohexylacyl peroxide, iso-Ding Xiangeng acyl peroxide, iso-butyryl 2-propylheptanoyl peroxide, n-Ding Xianyi butyryl peroxide, n-butyryl 2-ethylhexanoyl peroxide, n-butyryl 2-methylbutanoyl peroxide, n-butyryl 3-methylbutanoyl peroxide, n-Ding Xiante pentanoyl peroxide, n-butyrylcyclohexylacyl peroxide, n-Ding Xiangeng acyl peroxide, n-butyryl 2-propylheptanoyl peroxide, 2-methyl Ding Xianyi butyryl peroxide, 2-methyl Ding Xianding acyl peroxide, 2-methylbutanoyl 2-ethylhexanoyl peroxide, 2-methylbutyryl 3-methylbutyryl peroxide, 2-methylbutyryl cyclohexylformyl peroxide, 2-methyl Ding Xiangeng acyl peroxide, 2-methylbutyryl 2-propylheptanoyl peroxide, 2-methylpentanoyl isobutyryl peroxide, 2-methylpentanoyl butyryl peroxide, 2-methylpentanoyl cyclohexylformyl peroxide, 2-methylpentanoyl heptanoyl peroxide, 2-propylheptanoyl heptanoyl peroxide, nonanoyl isobutyryl peroxide, nonanoyl butanoyl peroxide, nonanoyl 2-ethylhexanoyl peroxide, nonanoyl 2-methylbutyryl peroxide, nonanoyl 3-methylbutyryl peroxide, nonanoyl pivaloyl peroxide, nonanoyl cyclohexylformyl peroxide, nonanoyl heptanoyl peroxide, nonanoyl 2-propylheptanoyl peroxide, methoxyacetyl isononyl peroxide and ethoxyacetyl nonanoyl peroxide.

Most preferred asymmetric diacyl peroxides are isononyl isobutyryl, nonanoyl isobutyryl peroxide, isononyl Ding Xiangeng acyl peroxide, pentanoyl 2-ethylhexyl peroxide, pentanoyl 2-propylheptanoyl peroxide, pentanoyl cyclohexylformyl peroxide, heptanoyl 3-methylbutyryl peroxide, nonanoyl 3-methylbutyryl peroxide, isononyl 3-methylbutyryl peroxide, pentanoyl 3-methylbutyryl peroxide, nonanoyl heptanoyl peroxide, isononyl heptanoyl peroxide, nonanoyl pentanoyl peroxide, isononyl pentanoyl peroxide, and isononyl peroxide.

The process according to the invention and its individual steps can be carried out batchwise or continuously. The steps which are preferably carried out in continuous mode are reactive distillation for preparing the anhydride in step e) and isolation and purification of the carboxylic acid in step c).

Furthermore, a combination of batch and continuous operations may be used. Examples of combinations are:

intermittent reaction in step a) to give diacyl peroxide, followed by batch separation and continuous purification of the carboxylic acid and continuous reactive distillation in step e) to give the anhydride,

continuous reaction to give diacyl peroxide and isolation and purification of the carboxylic acid, followed by batch mode distillation in step e) to give the anhydride, or

Batch reaction to give diacyl peroxide and isolation of the product, followed by purification of the carboxylic acid in continuous mode and continuous reactive distillation in step e) to give the anhydride.

Examples

Example 1

1.8g of isobutyraldehyde, 30.9g of isododecane, 39.9g of isobutyric anhydride and 0.42g of NaHCO are introduced into an empty reactor at 10 ℃ ₃ . Air was passed through the resulting mixture with rapid stirring. A mixture of 34.2g of isobutyraldehyde and 39g of isobutyric anhydride was added at 8-10℃over a period of 4.5 hours. Air dosing was maintained during 16.5 hours during which the temperature was reduced by 3 ℃.

After cooling the resulting mixture to 0 ℃, 24g of Na dissolved in 104g of water was slowly dispensed ₂ CO ₃ . The layers were separated at 0deg.C to give 117g of organic phase and 1474g of aqueous phase.

The diisobutyryl peroxide content of the organic phase was 47% by weight, calculated on aldehyde, corresponding to a yield of 63%. FTIR analysis of the product showed that the peroxide contained a small amount of anhydride (shoulder at 1750cm ^-1 )

The aqueous phase was extracted with 2.3g of isododecane to remove traces of peroxide and then with 20 wt% H ₂ SO ₄ The solution was acidified to pH 2. The phase separation yielded an organic layer with 20.9g wet isobutyric acid.

GC analysis of the organic compounds in the organic layer showed an isobutyric acid content of 97%, an isododecane content of 1% and a volatile component (excluding water) content of 1%.

After azeotropic distillation of the isobutyric acid containing layer, a bottom stream containing greater than 98% isobutyric acid and a small amount of water is obtained. The isobutyric acid was then mixed with isobutyric acid from other sources (in this case from Sigma Aldrich) and then with acetic anhydride at a molar ratio of isobutyric anhydride to acetic anhydride of 2:1.05 and the acetic acid was distilled at less than 400 mbar and 120 ℃ to give isobutyric anhydride as a residue. The isobutyric anhydride is then recycled to the first step, where it is reacted with isobutyraldehyde.

Claims

1. A process for producing diacyl peroxide comprising the steps of:

a) By bringing one or more compounds of formula R ¹ -C(=O)-O-C(=O)-R ² Anhydride of formula (I) and formula (R) ³ The aldehyde of C (=o) H reacts with oxygen to produce a mixture comprising diacyl peroxide and carboxylic acid,

wherein R is ¹ And R is ³ Independently selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 1 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents, and R ² Selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 2 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents,

c) Releasing the carboxylic acid from the salt or adduct,

d) Optionally by reacting a compound of formula R ² The reaction of the aldehyde of C (=o) H with oxygen produces an additional amount of carboxylic acid,

e) Allowing the carboxylic acid obtained in step c) and optionally an additional amount of a compound of formula R ² Carboxylic acids and anhydrides of-C (=o) OH or R ⁴ Independently selected from H and CH ₃ C (R) ⁴ ) ₂ Ketene reaction of =c=o to form one or more compounds having formula R ¹ -C(=O)-O-C(=O)-R ² Said additional amount of carboxylic acid being obtained from step d) and/or obtained in another way,

f) Recycling at least a portion of the anhydride formed in step e) to step a).

2. The process of claim 1 wherein the carboxylic acid is reacted with acetic anhydride in step e).

3. The method of claim 1 or 2, wherein R ¹ And each R ² The same applies.

4. The method of claim 1 or 2, wherein R ¹ 、R ³ And each R ² The same applies.

5. The process according to any one of claims 1-2, wherein an additional amount of carboxylic acid is produced in step d) and reacted in step e).

6. The process according to any one of claims 1-2, wherein the carboxylic acid is extracted with an aqueous solution of a base in step b) to form a carboxylate salt and wherein the carboxylic acid is released from its salt in step c) by acidifying the extract.

7. The process according to any one of claims 1-2, wherein the carboxylic acid is extracted with an aqueous solution of a base in step b) to form a carboxylate salt and wherein the carboxylic acid is released from its salt in step c) by electrodialysis.

8. The method of claim 7, wherein the carboxylic acid is released from its salt in step c) by polar membrane electrodialysis (BPM).

9. The process of any one of claims 1-2, wherein acetic acid is removed from the reaction mixture during step e).

10. The process according to any one of claims 1-2, wherein step e) is performed in a reactive distillation column.

11. The method of any one of claims 1-2, wherein the one or more is of formula R ¹ -C(=O)-O-C(=O)-R ² Is a symmetrical anhydride, wherein R ¹ And R is ² Selected from the group consisting of linear and branched alkyl, cycloalkyl, aryl and arylalkyl groups having from 2 to 17 carbon atoms, optionally substituted with oxygen-containing and/or halogen-containing substituents.

12. The method of any one of claims 1-2, wherein R ¹ And each R ² Independently selected from linear and branched alkyl groups having 2 to 8 carbon atoms.

13. The method of claim 11, wherein the one or more formulae R ¹ -C(=O)-O-C(=O)-R ² The anhydride of (2) is selected from the group consisting of isobutyric anhydride, n-butyric anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2-methylhexanoic anhydride, 2-methylpentanoic anhydride, 2-propylheptanoic anhydride, n-nonanoic anhydride, isononyl anhydride, cyclohexane-acetic anhydride, 2-ethylhexanoic anhydride, n-pentanoic anhydride and isopentanoic anhydride.

14. The method of claim 12, wherein the one or more formulae R ¹ -C(=O)-O-C(=O)-R ² The anhydride of (2) is selected from the group consisting of isobutyric anhydride, n-butyric anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2-methylhexanoic anhydride, 2-methylpentanoic anhydride, 2-propyl groupHeptanoic acid anhydride, n-nonanoic acid anhydride, isononanoic acid anhydride, cyclohexane acetic acid anhydride, 2-ethylhexanoic acid anhydride, n-valeric acid anhydride, and isovaleric acid anhydride.

15. The method of any one of claims 1-2, wherein formula R ³ The aldehyde of C (=o) H is selected from n-butyraldehyde, iso-butyraldehyde, 2-dimethylpropionaldehyde, 3-methylbutyraldehyde, 2-methylpentanal, 2-ethylhexanal, n-heptanal, n-pentanal, isononanal and 2-propylheptanal.

16. A method according to claim 3, wherein the diacyl peroxide is selected from di-n-butyryl peroxide, di-2-methylbutyl peroxide, di-3-methylbutyl peroxide, diisopentanoyl peroxide, di-n-pentanoyl peroxide, di-2-methylpentanoyl peroxide, dicyclohexyl formyl peroxide, di-n-nonanoyl peroxide, diisononanoyl peroxide and diisobutyryl peroxide.

17. The method of any one of claims 1-2, wherein the diacyl peroxide is selected from isononyl isobutyryl peroxide, nonanoyl isobutyryl peroxide, isononyl Ding Xiangeng acyl peroxide, pentanoyl 2-ethylhexanoyl peroxide, pentanoyl 2-propylheptanoyl peroxide, pentanoyl cyclohexylformyl peroxide, heptanoyl 3-methylbutyl peroxide, nonanoyl 3-methylbutyl peroxide, isononyl 3-methylbutyl peroxide, pentanoyl 3-methylbutyl peroxide, nonanoyl heptanoyl peroxide, isononyl heptanoyl peroxide, nonanoyl pentanoyl peroxide, isononyl pentanoyl peroxide, and isononyl peroxide.

18. The method according to any one of claims 1-2, wherein step d) is performed in the same apparatus as step a).