TWI510468B - Process for preparing n-substituted cyclic imides - Google Patents

Description

Method for preparing N-substituted cyclic quinone imine compound

The present application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 61/165, 714, filed on Apr. 1, 2009, the content of which is hereby incorporated by reference.

The present invention relates to a process for the synthesis of N-substituted cyclic quinone imine compounds, and in particular to a process for the synthesis of N-hydroxyquinone imine.

Oxidation of hydrocarbons in industrial organic chemistry is an important reaction. Thus, for example, the oxidation of cyclohexane is commercially used to prepare cyclohexanol and cyclohexanone, which are important precursors in the manufacture of nylon, whereas the oxidation of alkyl aromatic hydrocarbons is used to prepare phenols. Class, a precursor in the manufacture of polycarbonates and epoxies.

In many free radical-based oxidation reactions, N-substituted cyclic quinone imine compounds can be used as free radical vehicles. In particular, the use of N-substituted quinones often results in improved reaction rates, selectivities, and/or yields. Certain N-substituted quinazones (especially N-hydroxyindoles) are a good catalyst for the oxidation of secondary butylbenzene (SBB) and cyclohexylbenzene (CHB) to their corresponding peroxides. Candidate. SBB peroxides are intermediates in the manufacture of phenols and MEKs, and CHB peroxides are intermediates in the manufacture of phenols and cyclohexanone.

Oxidation of hydrocarbons can be carried out using well-known oxidizing agents such as KMnO ₄ , CrO ₃ and HNO ₃ . However, the use of these oxidizing agents will be accompanied by the disadvantage of producing undesirable products that cause handling and contamination problems. Preferably, therefore, an oxidizing agent based on peroxide or N ₂ O is used. However, the cheapest oxidant is molecular oxygen, in the form of pure oxygen or atmospheric oxygen, or in diluted form. However, because of the insufficient reactivity of the O ₂ molecules, which occurs in an energetically advantageous triplet form, oxygen itself is generally not suitable for use in oxidizing hydrocarbons.

N-substituted cyclic quinone imine compounds which can be used to oxidize hydrocarbons suffer from the disadvantages that they are currently not available in large commercial quantities. As such, there is no large scale process for making N-substituted cyclic quinone imine compounds.

In accordance with the present invention, it is proposed to optimize the preparation of certain N-substituted cyclic quinone imine compounds wherein the N-substituted cyclic quinone imine compound is obtainable in acceptable yields.

General theory of invention

In one aspect, the invention pertains to a method of making an N-substituted cyclic quinone imine compound, the method comprising:

a cyclic carboxylic anhydride is contacted with hydroxylamine or a salt thereof in an aqueous solution to form a first mixture, wherein the first mixture has a pH of from about 2 to about 6, and wherein the first mixture is before the reaction The molar ratio of hydroxylamine to carboxylic anhydride is from about 0.8 to about 2.0;

b. The mixture is reacted to form an N-substituted cyclic quinone imine compound.

Typically, the method can further comprise:

a. adding an acid to the first mixture to lower the pH of the first mixture to form a second mixture;

b. removing at least a portion of the N-substituted cyclic quinone imine compound from the second mixture.

Generally, the method may even further comprise:

a. adding an additional acid to the second mixture to further reduce the pH of the second mixture;

b. Remove at least a portion of the N-substituted cyclic quinone imine compound.

Detailed description of specific examples

"Deprotonated base" means a base which is reacted with a hydroxylamine salt to produce sufficient hydroxylamine to react with a cyclic carboxylic anhydride. Non-limiting examples of deprotonating bases to be used in the synthesis of N-substituted cyclic quinone imine compounds are NaOH, Na ₂ CO ₃ and NH ₃ . "Aqueous solution" means any liquid or slurry containing water.

The present invention provides a process for making an N-substituted cyclic quinone imine compound. The method comprises contacting a cyclic carboxylic anhydride with hydroxylamine. The synthesis conditions of the N-substituted cyclic quinone imine compound have been determined to allow reproducibility and high yield to form high purity N- from an aqueous solution of hydroxylamine or a salt thereof (e.g., hydroxylamine sulfate and hydroxylamine hydrochloride) and a cyclic carboxylic anhydride. Substituted cyclic quinone imine compounds.

Preferably, hydroxylamine salts such as hydroxylamine sulfate and hydroxylamine hydrochloride are used. Free hydroxylamine can be used, but free hydroxylamine may be more difficult to handle and dangerous than hydroxylamine salts. However, BASF It is indeed free hydroxylamine can be used for producing a process of the present invention, referred Hydroxylamine Free Base ^TM (50% aq).

The cyclic anhydrides useful in the process of the invention may comprise anhydrides of alicyclic, aromatic or heterocyclic dicarboxylic acids. Suitable anhydrides include, but are not limited to, 1,2,4,5-benzenetetracarboxylic anhydride, 1,2,4-benzene-tricarboxylic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride , phthalic anhydride, 4-methyl phthalic anhydride, tetrabromophthalic anhydride and tetrachlorophthalic anhydride, tetraphenyl phthalic anhydride, 3-nitrophthalic anhydride, cis-1,2,3,6-tetrahydrophthalic anhydride, etc. Wait. Preferably, the cyclic anhydrides useful in the process of the invention include phthalic anhydride and substituted phthalic anhydrides.

In one system, the phthalic anhydride is reacted with hydroxylamine to form N-hydroxyquinone imine ("NHPI" herein). The NHPI synthesis is described below. As described below, when phthalic anhydride is added to the aqueous hydroxylamine solution, the reaction rate in the NHPI synthesis facilitates the production of NHPI. Since the reaction rate constants k ₂ and k _{3 are} not conducive to this path to form NHPI, it is undesirable to drive the reaction through the tannic acid pathway (ie, k ₂ ).

The N-substituted cyclic quinone imine compound can be obtained by contacting a cyclic carboxylic anhydride with hydroxylamine or a salt thereof in an aqueous solution to form a first mixture. For example, the N-substituted cyclic quinone imine compound can be NHPI, the cyclic carboxylic anhydride can be phthalic anhydride, and the hydroxylamine can be a hydroxylamine salt.

When a hydroxylamine salt is used, it is preferred to deprotonate the hydroxylamine salt with a deprotonating base to form a hydroxylamine mixture. Preferably, the hydroxylamine mixture has a pH of from about 3 to about 10, from about 4 to about 9, from about 5 to about 8, from about 6 to about 8, or from about 6 to about 7.

For the case of synthetic NHPI, the reaction rate and yield are highest when starting with the complete deprotonation of hydroxylamine in aqueous solution. Increasing the hydroxylamine concentration and providing excess hydroxylamine can result in increased yield. For example, a 1.5 fold excess of hydroxylamine (see Example 2) can result in higher product purity.

The molar ratio of hydroxylamine to cyclic carboxylic anhydride prior to the reaction can be from about 0.8 to about 2.0, from about 1 to about 1.8, from about 1 to about 1.6, from about 1 to about 1.5, from about 1.1 to about 1.4, from about 1.2 to about 1.3. Preferably, the ratio of hydroxylamine to cyclic carboxylic anhydride is greater than 1.0.

Preferably, the pH of the first mixture is from about 2 to about 10, from about 2 to about 8, from about 3 to about 7, from about 2 to about 6, from about 3 to about 6, from about 4 to about 6, or about 5 to about 6. The first mixture can be subjected to a reaction to form an N-substituted cyclic quinone imine compound such as NHPI wherein all, substantially all, most, or at least a portion of the reaction is below about 100 ° C, or low Occurs at about 90 ° C, or below about 80 ° C, or below about 70 ° C. By "substantially all reactions" is meant that more than about 90% of the reactions occur at a given temperature, such as below about 100 °C, or below about 90 °C, or below about 80 °C, or below about 70 °C.

The recovery of N-substituted quinones depends on the final pH. For example, a pH between about 1 and about 2 allows for maximum NHPI recovery and minimizes NHPI decomposition. If the pH is lowered below about 1, the NHPI can be broken down into undesired tannic acid.

Thus, a make-up acid can be added to the first mixture to lower the pH of the first mixture to form a second mixture. Optionally, at least a portion of the N-substituted cyclic quinone imine compound can be removed from the first mixture prior to acid addition. Preferably, sulfuric acid or hydrochloric acid or other conventional acid which can be added to lower the pH of the solution and not directly participate in the reaction is used. The pH of the second mixture can be less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, or less than about 1. In another system, the pH of the second mixture can range from about 1 to about 7, from about 1 to about 4, from about 1 to about 3, from 1 to about 2, from about 2 to about 6, or from About 3 to about 6.

After the acid is added to the first mixture to form the second mixture, the desired product is precipitated in the second mixture. In a system, the first mixture can be heated to a temperature below about 100 °C. In another system, the temperature of the first mixture can be less than about 90 ° C, less than about 80 ° C, or less than about 70 ° C. In another system, the temperature of the reaction can range from about 100 ° C to about 90 ° C, from about 90 ° C to about 80 ° C, from about 80 ° C to about 70 ° C. The pH of the second mixture can be reduced to less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, or less than about 2.

Optionally, lowering the pH of the first mixture can occur in a series of steps, wherein (i) the acid is added to the first mixture to form a second mixture, and (ii) at least a portion of the N-substituted cyclic oxime is removed. An imine compound, (iii) after removing the N-substituted cyclic quinone imine compound, adding an acid to the second mixture to lower the pH of the second mixture, (iv) removing at least a portion of the N from the second mixture a substituted cyclic quinone imine compound, (v) adding an additional acid to the second mixture; (vi) removing at least a portion of the N-substituted cyclic quinone imine compound from the second mixture; At the end of each acid addition step, the pH of the second mixture can be reduced to less than about 7, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, or less than about 1. In this system, the temperature of the reaction can be less than about 90 ° C, less than about 80 ° C, or less than about 70 ° C. Further, the temperature of the reaction may be from about 100 ° C to about 90 ° C, from about 90 ° C to about 80 ° C, from about 80 ° C to about 70 ° C.

In addition, the synthesis of NHPI from hydroxylamine salts (hydroxylamine sulfate and hydroxylamine hydrochloride) and phthalic anhydride has been demonstrated in alcohols (such as 2-butanol and methanol), or in two-phase media containing alcohol and water (eg 2-butanol/water) )in. The sequence using methanol and hydroxylamine hydrochloride allows for single phase reaction conditions and promotes the removal of inorganic salts formed during the reaction. The use of biphasic conditions allows for simple removal of organic products.

Catalysts prepared by the present invention can be used to oxidize hydrocarbons to the corresponding hydroperoxides, alcohols, ketones, carboxylic acids or dicarboxylic acids. The oxidizing process comprises contacting a reaction medium comprising a hydrocarbon feed with an oxygen-containing gas in a reaction zone and in the presence of a catalyst comprising a cyclic quinone imine compound prepared by the process of the invention. The general methods of hydrocarbon feed and oxidation reactions are described below.

Hydrocarbon feed

The use of an N-substituted cyclic quinone imine compound prepared by the disclosed method selectively oxidizes a broad group of substituted or unsubstituted saturated or unsaturated hydrocarbons (such as alkanes, naphthenes, Alkene, cycloolefin and aromatic). However, in particular, the method has been utilized for the selective oxidation of isobutylene to tributyl butyl hydroperoxide and tertiary butanol, the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone, and the general formula (II) The alkyl aromatic compound is selectively oxidized to the corresponding hydroperoxide:

Wherein R ⁴ and R ⁵ each independently represent hydrogen or an alkyl group having from 1 to 4 carbon atoms, provided that R ⁴ and R ⁵ are bondable to form a cyclic group having 4 to 10 carbon atoms And the cyclic group is optionally substituted, and R ⁶ represents hydrogen, one or more alkyl groups having from 1 to 4 carbon atoms or a cyclohexyl group. In one system, R ⁴ and R ^{5 are} bonded to form a cyclic group having from 4 to 10 carbon atoms, usually a hexyl group, via one or more alkyl groups having from 1 to 4 carbon atoms Or substituted by one or more phenyl groups. Examples of suitable alkyl aromatic compounds are ethylbenzene, cumene, secondary-butylbenzene, secondary-pentylbenzene, p-methyl-secondary-butylbenzene, 1,4-diphenylcyclohexane, Di-hexylbenzene and cyclohexylbenzene, and secondary-butylbenzene and cyclohexylbenzene are preferred. It is also understood that in the case where R ⁴ and R ^{5 are} bonded to form a cyclic group, the carbon number forming the ring is from 4 to 10. However, the ring itself may have one or more substituents such as one or more alkyl groups having from 1 to 4 carbon atoms or one or more phenyl groups, such as in 1,4-diphenyl. The case of cyclohexane.

In a practical system, the alkylaromatic compound of the formula (II) is a secondary-butene benzene and is obtained by alkylation conditions and in a heterogeneous phase catalyst such as zeolite beta or more preferably at least one MCM-22 family molecular sieve (as defined below)) with the presence of at least C ₄ alkylating agent of benzene to alkylating prepared.

In another practical system, the alkyl aromatic compound of the formula (II) is cyclohexylbenzene and is obtained by reacting benzene with hydrogen in a heterogeneous phase comprising at least one metal having hydrogenation activity (usually Selected from the group consisting of palladium, rhodium, nickel and cobalt) and a crystalline inorganic oxide material having an alkylation activity (usually at least one molecular sieve of the MCM-22 family (as defined below)) Got it.

Hydrocarbon oxidation

The terms "group", "radical" and "substituent" are used interchangeably in this document. For the purposes of this disclosure, a "hydrocarbyl group" is defined as a group containing a hydrogen atom and up to 20 carbon atoms and which may be linear, branched or cyclic, and when cyclic, aromatic or non-aromatic Family. The "substituted hydrocarbyl group" is a group in which at least one hydrogen atom in the hydrocarbyl group has been substituted with at least one functional group or at least one non-hydrocarbon atom or group has been inserted in the hydrocarbyl group.

The oxidation step in the process of the invention is produced by contacting a hydrocarbon substrate with an oxygen-containing gas in the reaction zone and in the presence of an N-substituted cyclic quinone imine catalyst.

Generally, a cyclic quinone imine which can be used as an oxidation catalyst is as follows:

Wherein R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently selected from a hydrocarbon group having 1 to 20 carbon atoms and a substituted hydrocarbyl group, or a group SO ₃ H, NH ₂ , OH and NO ₂ , or Atoms H, F, Cl, Br and I; X and Z are each independently selected from C, S, CH ₂ , N, P and Group 4 elements of the periodic table; Y is O or OH; k is 0, 1 Or 2, and l is 0, 1, or 2. Typically, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently selected from the group consisting of aliphatic alkoxy or aromatic alkoxy groups, carboxyl groups, alkoxy-carbonyl groups and hydrocarbon groups, each having 1 to 20 carbon atoms.

The desired product from the process of the invention will be encompassed within the scope of the cyclic quinone imines of the above formula. Thus, various cyclic carboxylic acids, including but not limited to phthalic anhydride, can be used as an intermediate with hydroxylamine or a salt thereof to obtain a cyclic quinone imine of the above formula.

In a practical system, the cyclic quinone imine catalyst comprises N-hydroxyquinone imine (NHPI), and preferably between about 0.0001% by weight and about 5% by weight, such as between about 0.1% by weight. An amount of hydrocarbon reactant between about 1% by weight is present in the reaction zone.

The oxidation of the hydrocarbon reactant is typically at a temperature between about 20 ° C and about 300 ° C, more specifically between about 50 ° C and about 130 ° C, and/or a pressure between about 100 kPa and about 7000 kPa. More preferably, more than 500 kPa to about 5000 kPa, and/or a concentration of oxygen in the oxygen-containing gas is from 0.1 to 100% by volume, typically from about 2 to about 10% by volume.

Oxidation product

The nature of the product of the oxidation process of the invention depends on the oxidized hydrocarbon substrate, but is typically a hydroperoxide, alcohol, ketone, carboxylic acid or dicarboxylic acid, especially a hydroperoxide.

In the case where the hydrocarbon substrate is an alkyl aromatic compound of the formula (II), the product of the oxidation reaction comprises a hydroperoxide of the formula (IV):

Wherein R ⁴ , R ⁵ and R ⁶ have the same meanings as in the formula (II). Preferably, the hydroperoxide is hydrogen peroxide-di-butylbenzene or cyclohexyl hydroperoxide. The hydroperoxide can then be converted to a phenol or substituted phenol and an aldehyde or ketone of the formula R ⁴ COCH ₂ R ⁵ (V) by acid cleavage, wherein R ⁴ and R ⁵ have the formula (II) The same meaning.

In one system, the oxidized alkyl aromatic compound is cyclohexylbenzene, the oxidation product is cyclohexyl hydroperoxide, and the cleavage product comprises phenol and cyclohexanone. The crude cyclohexanone and crude phenol from the cleavage step can be further purified to yield purified cyclohexanone and phenol. Suitable purification methods include, but are not limited to, a series of distillation columns to separate cyclohexanone and phenol from other materials. The crude or purified cyclohexanone itself can be hydrogenated for conversion to phenol. This hydrogenation can be carried out, for example, on a catalyst such as platinum, nickel or palladium.

The invention will now be described more specifically with reference to the following non-limiting examples.

The hydroxylamine sulfate, phthalic anhydride and N-hydroxyquinone imide used in the following non-limiting examples were supplied by Sigma-Aldrich.

Example 1 (present invention)

6.7 g (40.9 mmol; 1.25 equivalents) of hydroxylamine sulfate [(NH ₂ OH) ₂ SO ₄ ] was dissolved in 13.4 ml of deionized water, and 4.3 ml of 50 wt% in 7.3 ml of water was slowly added ( 81.8 millimoles of NaOH to deprotonate hydroxylamine sulfate. 10.9 g (73.6 mmol) of phthalic anhydride flakes were added to react with hydroxylamine to form a mixture. Thus, the molar ratio of hydroxylamine to phthalic anhydride is about 1.25. After the addition of the phthalic anhydride, the mixture was heated to 90 °C. After 9 minutes the mixture turned cloudy (67 ° C); at this point the phthalic anhydride did not completely dissolve. Once the mixture became cloudy, add 25 ml of DI water. The mixture was heated and kept at 90 ° C for 15 minutes. Heating and stirring were stopped after a total of 30 minutes of reaction time. Allow to cool to room temperature. After 16 hours, the white solid was filtered off and dried at 75 ° C for 3 hours. The mother liquor has a pH of about 4-5.

The first filtration produced 8.9 grams of N-hydroxyindoleimine (NHPI) in 98% purity. The yield is about 72%.

1 ml of 30% by volume (6.2 mmol) of H ₂ SO _{4 was} added to the mother liquor until the pH dropped to 2. No precipitation. Heat to 75 ° C for 5 minutes and then allow to cool to room temperature. The needle formed after 24 hours. The solid was filtered off and the solid was dried at 75 ° C for 3 hours.

The second filtration produced 1.1 grams of additional NHPI in 98% purity with a yield of 9%.

After filtration, it was further precipitated from the mother liquor at room temperature. Needle-like and "blobby" crystals were filtered off.

The third filtration produced 0.3 grams of additional NHPI; however, the purity of this NHPI was only about 62%.

Example 2 (present invention)

9.84 grams (60 millimoles; 1.5 equivalents) of hydroxylamine sulfate (HAS) was dissolved in a solution of 54 milliliters of deionized water. Slowly add 6.3 ml of a 50% by weight NaOH solution. No gas evolution was observed. 11.84 grams (80 millimoles) of phthalic anhydride (PA) flakes were added. Therefore, the molar ratio of hydroxylamine to phthalic anhydride is 1.5. Heating was started to 90 ° C after the addition. PA dissolves completely and rapidly (pH = 3-4). The orange mixture became cloudy after 10 minutes at 80 °C. Heating was stopped after 15 minutes at 90 °C. The mother liquor has a pH of about 6-7. Allow to cool to room temperature. After 1 hour, the pale yellow solid was filtered off and dried at 75 ° C for 3 hours. The mother liquor has a pH of about 6.

The first filtration yielded 6.64 grams of NHPI in 100% purity with a yield of about 50.9%.

Slowly add 30% by volume of H ₂ SO ₄ to the mother liquor:

(i) 1 ml of H ₂ SO _{4 was added} to lower the pH to about 4, and the solution turned pale orange and more turbid.

(ii) Further adding 1 ml of H ₂ SO ₄ to lower the pH to about 3 and increasing the temperature of the mother liquor to about 90 °C. The suspension became thicker.

(iii) Further adding 1 ml of H ₂ SO ₄ to lower the pH to about 2 to 3. The suspension became very clear (white) and allowed to cool to room temperature. The white solid was filtered off and dried at 75 ° C for 3 hours.

An additional 3 ml of H ₂ SO _{4 was added to} yield 5.04 g of additional NHPI in 100% purity.

The total solids recovery was 11.68 grams and the total yield was about 89.7%.

Example 3 (NHPI synthesis in 2-butanol)

In a three-necked flask equipped with a reflux condenser and a stir bar, 20 ml of 2-butanol was added to 3.07 g (18.3 mmol) of hydroxylammonium sulfate (HAS) and heated to 100 °C. No dissolution of HAS was observed. Add 5.42 grams (36.6 millimoles) of phthalic anhydride (PA) and increase the temperature to 120 ° C (boiling point). The PA completely dissolves and the HAS only partially dissolves. The dispersion turned pale yellow. Stirring was continued at 120 °C. The HAS is still not completely dissolved. About 0.5 ml of deionized water was added to promote mass transport and stirring was continued under reflux for a total of 3.5 hours. The yellow organic phase was removed and the white needles were filtered to give a first organic portion. The solvent is evaporated from the mother liquor to obtain a second organic portion. 2-butanol was added to the white crystals and heated to reflux, but the crystals did not dissolve. About 4 ml of deionized water was added to the 2-butanol/white crystal suspension to form a solvent portion, at which time the white crystals dissolved at about 120 °C. When the suspension is cooled, transparent crystals are formed in the aqueous phase. Dry all parts in a N ₂ ventilated oven.

1.14 grams of solid was recovered in the first organic fraction, which contained 78% NHPI, 18% ester, and 3% citric acid.

5.17 grams of solids were recovered in the second organic fraction comprising 5% NHPI, 77% ester and 18% decanoic acid.

A solid of 1.00 g was recovered in a solvent portion not containing NHPI, ester or citric acid.

Example 4 (NHPI synthesis in methanol)

5.42 grams (36.6 millimoles) of phthalic anhydride (PA) was added to 15 milliliters of methanol and the temperature was increased to about 80 °C until the solids dissolved. 2.55 g (36.7 mmol) of NH ₂ OH (HCl) was added and stirring was continued until hydroxylamine hydrochloride [NH ₂ OH (HCl)] dissolved. No reaction was seen at this time. Add 1.9 grams (18.3 millimoles) of Na ₂ CO ₃ and see CO ₂ release. Stirring was continued for a total of 3 hours. The heating was stopped and allowed to cool to room temperature. The solvent was evaporated but only a yellow oil with a dispersed white solid was obtained. 20 ml of deionized water was added and the oil was completely dissolved. At a pH of about 6 to 7 overnight, no solid precipitated. Concentrated sulfuric acid (H ₂ SO ₄ ) was added dropwise. Upon becoming an acid, a solid is produced which slowly dissolves in the aqueous phase. The acid is added until the pH reaches about 3 to 4 and the precipitate never dissolves. The temperature was increased to 80 ° C for 10 minutes at which time the solid dissolved. Allow to cool to room temperature. The solid (fine needles) was filtered and dried at 75 ° C for 3 hours.

The first filtration produced 0.93 grams of precipitate (96% NHPI and 4% citric acid).

The solvent was removed from the mother liquor and attempted to recrystallize by the addition of 30 mL of deionized water. The solid is not completely dissolved. Allow to cool to room temperature. The solid (fine needles) was filtered and dried at 75 ° C for 3 hours.

The second filtration produced 2.72 grams of precipitate (86% NHPI, 14% ester).

Example 5 (NHPI synthesis under two-phase conditions)

In a three-necked flask equipped with a reflux condenser and a stir bar, 10 ml of 2-butanol was added to 5.42 g (36.6 mmol) of phthalic anhydride (PA) and heated to 75 °C. Add 2 ml of deionized water and increase the temperature to 105 °C. PA is not completely dissolved. Add 5 ml of 2-butanol and increase the temperature until the boiling point is reached. After adding 1 ml of deionized water, a clear solution was formed (ie, no aqueous phase was seen). 3.07 g of hydroxylammonium sulfate (HAS) was slowly added. After the addition is completed, the second phase appears. The solution turned yellowish after about 1 hour. Stir under reflux for a total of 4 hours, then reduce the temperature to room temperature and stop stirring for several hours. A transparent crystal is formed in the aqueous layer; the organic layer contains pale yellow needles and "drop-like spots" of broccoli crystals. The temperature was increased to 120 ° C and all needles were dissolved in the organic layer at 60 ° C. However, "droplet spot" crystals are still present, indicating that NHPI is more soluble in 2-butanol than phthalic anhydride. The crystals in all the water layers are also dissolved. The organic and aqueous phases were separated at 120 ° C and allowed to cool to room temperature. A clear crystal is formed in water and a yellow precipitate forms in the organic phase. The crystals were filtered and dried at 50 ° C for 4 hours in a N ₂ oven.

Filtration of the organic layer resulted in 840 mg of precipitate (24% NHPI, 65% decanoic acid, 11% ester).

Filtration of the aqueous layer produced 2.58 grams of precipitate (no organic compound).

The NHPI product fraction was shown by ¹³ C NMR in all examples.

Although the invention has been described and illustrated by reference to the specific embodiments thereof, it will be understood by those skilled in the art For this reason, the purpose of determining the true scope of the invention is to refer only to the scope of the appended claims.

Claims (17)

A process for the preparation of an N-substituted cyclic quinone imine compound comprising the steps of: a. contacting a cyclic carboxylic anhydride with hydroxylamine or a salt thereof in an aqueous solution to form a first mixture, wherein the first mixture The pH is from about 2 to about 6, and wherein the molar ratio of hydroxylamine to carboxylic anhydride in the first mixture is from about 0.8 to about 2.0 prior to the reaction; and b. reacting the mixture to form N- A substituted cyclic quinone imine compound, wherein the N-substituted cyclic quinone imine compound is as shown in the following formula: Wherein R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently selected from a hydrocarbon group having 1 to 20 carbon atoms and a substituted hydrocarbyl group, or a group SO ₃ H, NH ₂ , OH and NO ₂ , or Atoms H, F, Cl, Br and I; X and Z are each independently selected from C, S, CH ₂ , N, P and Group 4 elements of the periodic table; Y is O or OH; k is 0, 1 or 2 And 1 is 0, 1 or 2; and wherein the cyclic carboxylic anhydride is phthalic anhydride, substituted phthalic anhydride, or a combination thereof. The method of claim 1, further comprising the steps of: a. adding an acid to the first mixture to lower the pH of the first mixture to form a second mixture; and b. from the first The two mixtures remove at least a portion of the N-substituted cyclic quinone imine compound. The method of claim 2, further comprising the steps of: a. adding an acid to the second mixture to lower the pH of the second mixture; and b. removing at least a portion of the N-substituted ring A quinone imine compound. The method of claim 2, wherein the at least a portion of the N-substituted cyclic quinone imine compound is removed from the first mixture prior to the acid addition. The method of any one of claims 1 to 3, wherein the N-substituted cyclic quinone imine compound is N-hydroxyimine. The method of any one of claims 1 to 3 wherein the hydroxylamine is derived from the group consisting of hydroxylamine sulfate and hydroxylamine hydrochloride. The method of any one of claims 1 to 3, wherein prior to the contacting (a), the hydroxylamine salt is contacted with a deprotonating base to convert at least a portion of the hydroxylamine salt to a deprotonated hydroxylamine. And a hydroxylamine mixture is formed. The method of claim 7, wherein the hydroxylamine mixture has a pH of from about 6 to about 8. The method of any one of claims 1 to 3 wherein the pH of the first mixture is from about 4 to about 6. The method of any one of claims 1 to 3 wherein the pH of the second mixture is from about 1 to about 3. The method of any one of claims 1 to 3 wherein the pH of the second mixture is from about 1 to about 2. The method of any one of claims 1 to 3 wherein at least a portion of the reaction occurs at a temperature below about 100 °C. The method of any one of claims 1 to 3 wherein at least a portion of the reaction occurs at a temperature below about 90 °C. The method of any one of claims 1 to 3 wherein the molar ratio of hydroxylamine to carboxylic anhydride in the first mixture prior to the reaction is from about 1 to about 1.8. The method of any one of claims 1 to 3 wherein the molar ratio of hydroxylamine to carboxylic anhydride in the first mixture prior to the reaction is from about 1 to about 1.5. The method of any one of claims 1 to 3 wherein the molar ratio of hydroxylamine to carboxylic anhydride in the first mixture prior to the reaction is from about 1.1 to about 1.4. The method of any one of claims 1 to 3 wherein the molar ratio of hydroxylamine to carboxylic anhydride in the first mixture prior to the reaction is from about 1.2 to about 1.3.