Method for producing benzonitrile compounds from corresponding trichlorotoluene compounds

Abstract

The invention discloses a method for preparing a cyanobenzene compound of formula (I) from the corresponding trichlorotoluene compound of formula (II). # imgabs0 # and # imgabs1 #

Description

Technical Field

[0001] The present invention relates to a process for preparing benzonitrile compounds. More particularly, the present invention relates to a process for preparing benzonitrile compounds of formula (I) by nitrilation of the corresponding trichlorotoluene compounds of formula (II). Background Art

[0002] Benzonitrile is a product known in the art and is used, inter alia, as an intermediate in the preparation of dyes, pharmaceuticals and agrochemicals.

[0003] J. Am. Chem. Soc. 1930, 52, 7, 2951–2954 discloses a method for preparing o-chlorobenzonitrile from o-chlorobenzotrichloride using ammonium chloride. This method has the disadvantage that it requires a sealed tube and high temperatures of 210 to 220°C, making it energy-intensive. Furthermore, to consume all the ammonium chloride, an excess of at least 60% of o-chlorobenzotrichloride is used. Furthermore, this method results in polymerization of benzonitrile and the production of tetraphenylmethane as a byproduct.

[0004] EP 441004 discloses a process for preparing o-chlorobenzonitrile from o-chlorobenzotrichloride using copper(II) chloride or zinc chloride as a catalyst and ammonium chloride. A disadvantage associated with this process is that the reaction is carried out at elevated temperatures exceeding 210°C, making it energy-intensive. Furthermore, the use of metal salts such as copper(II) chloride or zinc chloride results in the generation of large amounts of unnecessary solid waste.

[0005] WO2022091014 discloses a method for preparing o-chlorobenzonitrile, which comprises reacting 2-chlorobenzotrichloride with ammonium chloride in the presence of water, sulfuric acid, and zinc acetate at room temperature. The reaction is carried out at 180°C to 200°C for 16 hours. Disadvantages associated with this method include the high temperature at which the reaction is carried out and the low purity of o-chlorobenzonitrile (96%).

[0006] JP2652563 discloses a method for preparing o-chlorobenzonitrile and o-chlorobenzoyl chloride from o-chlorobenzotrichloride and o-chlorobenzamide in the presence of o-chlorotoluene solvent using concentrated sulfuric acid as a catalyst. The reaction mixture is heated to 140°C. Furthermore, the reaction solution is treated with ammonia gas to convert the acyl chloride product into its corresponding amide. Typical reactions involve converting o-chlorobenzotrichloride to o-chlorobenzoyl chloride and o-chlorobenzamide to o-chlorobenzonitrile.

[0007] Therefore, there is a need to develop a process for preparing benzonitrile compounds that avoids at least one of the problems of prior art processes, such as impure benzonitrile, specific reaction setup, polymerization, and cost-effectiveness.

[0008] The inventors of the present invention have discovered a simple, industrially feasible and advantageous process which avoids the use of expensive jacketed reactors, application of high temperature conditions, generation of residues, shorter reaction times, formation of by-products such as benzonitrile polymers and tetraphenylmethane. Purpose of the Invention

[0009] Some objects of the present invention are described below:

[0010] It is an object of the present invention to ameliorate one or more problems of the prior art or at least provide a useful alternative.

[0011] The object of the present invention is to provide a simple process for preparing benzonitrile compounds of the formula (I) from the corresponding trichlorotoluene compounds of the formula (II).

[0012] Another object of the present invention is to provide a process for preparing benzonitrile compounds of the formula (I) from the corresponding trichlorotoluene compounds of the formula (II), which process at least partially reduces the energy requirement.

[0013] Yet another object of the present invention is to provide a method for preparing a benzonitrile compound of formula (I) from a corresponding trichlorotoluene compound of formula (II), which method requires relatively low or mild temperature conditions.

[0014] Yet another object of the present invention is to provide a process for preparing high-purity benzonitrile compounds of formula (I) from the corresponding trichlorotoluene compounds of formula (II), which process at least partially avoids polymerization and the formation of undesirable by-products.

[0015] Yet another object of the present invention is to provide a process for preparing a benzonitrile compound of formula (I) from a corresponding trichlorotoluene compound of formula (II), which process at least partially avoids the generation of solid waste and is therefore more environmentally friendly.

[0016] Yet another object of the present invention is to provide a process for preparing benzonitrile compounds of the formula (I) from the corresponding trichlorotoluene compounds of the formula (II), wherein the reaction time is at least partially reduced.

[0017] Other objects and advantages of the present invention will become more apparent from the following description, but the following description is not intended to limit the scope of the present invention. Summary of the Invention

[0018] In one aspect, the present invention provides a method for preparing a benzonitrile compound of formula (I);

[0019]

[0020] in,

[0021] R 1and R 2 are independently selected from hydrogen, X and cyano;

[0022] The condition is that R 1 and R 2 It cannot be cyano at the same time;

[0023] X is a halogen selected from fluorine and chlorine; and

[0024] n is an integer from 1 to 3;

[0025] The process comprises the steps of nitrilation of a trichlorotoluene compound of formula (II) using a suitable ammonium salt in the presence of a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200° C. to provide a benzonitrile compound of formula (I);

[0026]

[0027] in,

[0028] R 3 and R 4 are independently selected from hydrogen, X and trichloromethyl;

[0029] The condition is that R 3 and R 4 It cannot be trichloromethyl at the same time;

[0030] X is a halogen selected from fluorine and chlorine; and

[0031] n is an integer of 1 to 3.

[0032] In an exemplary embodiment, the present invention provides a method for preparing a benzonitrile compound of formula (III);

[0033]

[0034] Formula (III)

[0035] in,

[0036] X is a halogen selected from fluorine and chlorine; and

[0037] n is an integer from 1 to 5;

[0038] The process comprises the steps of nitriling a trichlorotoluene compound of formula (IV) using a suitable ammonium salt in the presence of a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200° C. to provide a benzonitrile compound of formula (IV);

[0039]

[0040] Formula (IV)

[0041] in,

[0042] X is a halogen selected from fluorine and chlorine; and

[0043] n is an integer of 1 to 5.

[0044] In a second aspect, the present invention provides a method for preparing a benzonitrile compound of formula (I);

[0045]

[0046] in,

[0047] R 1 and R 2 are independently selected from hydrogen, X and cyano;

[0048] The condition is that R 1 and R 2 It cannot be cyano at the same time;

[0049] X is a halogen selected from fluorine and chlorine; and

[0050] n is an integer from 1 to 3;

[0051] The process comprises the steps of nitriling a trichlorotoluene compound of formula (II) using a suitable ammonium salt in the presence of a suitable initiator, a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200°C to provide a benzonitrile compound of formula (I);

[0052]

[0053] in,

[0054] R 3 and R 4 are independently selected from hydrogen, X and trichloromethyl;

[0055] The condition is that R 3 and R 4 It cannot be trichloromethyl at the same time;

[0056] X is a halogen selected from fluorine and chlorine; and

[0057] n is an integer of 1 to 3.

[0058] In an exemplary embodiment, the present invention provides a method for preparing a benzonitrile compound of formula (III);

[0059]

[0060] Formula (III)

[0061] in,

[0062] X is a halogen selected from fluorine and chlorine; and

[0063] n is an integer from 1 to 5;

[0064] The process comprises the steps of nitriling a trichlorotoluene compound of formula (IV) using a suitable ammonium salt in the presence of a suitable initiator, a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200° C. to provide a benzonitrile compound of formula (IV);

[0065]

[0066] Formula (IV)

[0067] in,

[0068] X is a halogen selected from fluorine and chlorine; and

[0069] n is an integer of 1 to 5.

[0070] To the surprise of the present inventors, the amount of initiator and catalyst plays an important role in avoiding the use of expensive jacketed reactors, application of high temperature conditions and at least partially reducing or avoiding the formation of by-products such as benzonitrile polymers and tetraphenylmethane while leading to improved product purity. Detailed Description of the Invention

[0072] The terms used in the present disclosure are for the purpose of explaining particular embodiments only, and such terms should not be construed as limiting the scope of the present disclosure.

[0073] The use of the expression "at least" or "at least one" indicates the use of one or more elements or components or amounts, as such use may achieve one or more desired objectives or results in the embodiments of the present disclosure.

[0074] The numerical values ​​mentioned for various physical parameters, dimensions or amounts are approximations only, and values ​​above and below the numerical value assigned to the parameter, dimension or amount are contemplated to fall within the scope of the present disclosure unless expressly stated to the contrary in the specification.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. In the event of conflict, this document, including definitions, shall prevail. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used for the practice or testing of the present invention. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods and embodiments disclosed herein are illustrative only and are not intended to be restrictive.

[0076] As used herein, the terms "comprise(s)", "include(s)", "having", "has", "can", "contain(s)" and variations thereof are intended to be open-ended transitional phrases, terms or words that do not exclude the possibility of additional actions or structures.

[0077] The term "halogen" includes fluorine or chlorine.

[0078] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The present disclosure also encompasses other embodiments that "comprise," "consist of," and "consist essentially of": embodiments or elements presented herein, whether or not explicitly stated.

[0079] In view of the above-defined purpose, the present invention provides a method for preparing a benzonitrile compound of formula (I)

[0080]

[0081] in,

[0082] R 1 and R 2 are independently selected from hydrogen, X and cyano;

[0083] The condition is that R 1 and R 2 It cannot be cyano at the same time;

[0084] X is a halogen selected from fluorine and chlorine; and

[0085] n is an integer from 1 to 3;

[0086] The method comprises the steps of nitriling a trichlorotoluene compound of formula (II) using a suitable ammonium salt in the presence of a suitable catalyst selected from the group consisting of p-toluenesulfonic acid, methanesulfonic acid, phosphonic acid, amberlyst, ion exchange resin, sulfuric acid, phosphoric acid, water and combinations thereof, optionally in the presence of a suitable initiator, and optionally in the presence of a suitable inert solvent at a temperature in the range of 150-200° C. to provide a benzonitrile compound of formula (I);

[0087]

[0088] in,

[0089] R 3 and R 4 are independently selected from hydrogen, X and trichloromethyl;

[0090] The condition is that R 3 and R4 It cannot be trichloromethyl at the same time;

[0091] X is a halogen selected from fluorine and chlorine; and

[0092] n is an integer of 1 to 3.

[0093] In a first aspect of the present invention, a process for preparing a benzonitrile compound of formula (I) by nitriling a trichlorotoluene compound of formula (II) is described in the following Scheme 1:

[0094]

[0095] Solution: 1

[0096] in,

[0097] R 1 and R 2 are independently selected from hydrogen, X and cyano;

[0098] The condition is that R 1 and R 2 It cannot be cyano at the same time;

[0099] R 3 and R 4 are independently selected from hydrogen, X and trichloromethyl;

[0100] The condition is that R 3 and R 4 It cannot be trichloromethyl at the same time;

[0101] X is a halogen selected from fluorine and chlorine; and

[0102] n is an integer from 1 to 3;

[0103] The process employs a suitable ammonium salt in the presence of a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200°C to provide the benzonitrile compound of formula (I).

[0104] Non-limiting examples of compounds of formula (I) according to the first aspect include o-chlorobenzonitrile, p-chlorobenzonitrile, m-chlorobenzonitrile, o-fluorobenzonitrile, p-fluorobenzonitrile, m-fluorobenzonitrile, 2,3-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 3,4-dichlorobenzonitrile, 3,5-dichlorobenzonitrile, 2,3-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,5-difluorobenzonitrile, 2,6-difluorobenzonitrile, 3,4-difluorobenzonitrile, 3,5-difluorobenzonitrile, 1,3-phthalonitrile, 1,4-phthalonitrile and 2-chloro-6-fluorobenzonitrile.

[0105] Preferably, the compound of formula (I) according to the first aspect is selected from o-chlorobenzonitrile, p-chlorobenzonitrile, 2,4-dichlorobenzonitrile, 1,3-phthalonitrile and 2-chloro-6-fluorobenzonitrile.

[0106] Non-limiting examples of compounds of formula (II) according to the first aspect include o-chlorobenzotrichloride, p-chlorobenzotrichloride, m-chlorobenzotrichloride, o-fluorobenzotrichloride, p-fluorobenzotrichloride, m-fluorobenzotrichloride, 2,3-dichlorobenzotrichloride, 2,4-dichlorobenzotrichloride, 2,5-dichlorobenzotrichloride, 2,6-dichlorobenzotrichloride, 3,4-dichlorobenzotrichloride, 3,5-dichlorobenzotrichloride, 2,3-difluorobenzotrichloride, 2,4-difluorobenzotrichloride, 2,5-difluorobenzotrichloride, 2,6-difluorobenzotrichloride, 3,4-difluorobenzotrichloride, 3,5-difluorobenzotrichloride, 1,3-bis(trichloromethyl)benzene, 1,4-bis(trichloromethyl)benzene and 2-chloro-6-fluorobenzotrichloride.

[0107] Preferably, the compound of formula (II) according to the first aspect is selected from o-chlorobenzotrichloride, p-chlorobenzotrichloride, 2,4-dichlorobenzotrichloride, 1,3-bis(trichloromethyl)benzene and 2-chloro-6-fluorobenzotrichloride.

[0108] Typically, suitable ammonium salts according to the first aspect are selected from ammonium chloride or ammonium bromide.

[0109] Non-limiting examples of catalysts suitable for the conversion as shown in Scheme 1 according to the first aspect include p-toluenesulfonic acid, methanesulfonic acid, phosphonic acid, amberlyst, ion exchange resins (e.g., Indion®), sulfuric acid, phosphoric acid, water, or combinations thereof.

[0110] By operating according to the first aspect of the present invention, the time required to complete or nearly complete the reaction is in the range of 8 hr to 30 hr. More preferably, the time required to complete the reaction is in the range of 12 to 28 hr.

[0111] By operating according to the first aspect of the present invention, the reaction can be carried out at a temperature of 1 to 10 kg / cm 2 More preferably, the reaction pressure can be in the range of 1 to 5 kg / cm 2 within the range.

[0112] By the operation according to the first aspect of the present invention, when the pressure of the reaction is between 1 and 5 kg / cm 2 When the reaction time is within the range of 12 to 28 hr, the reaction time can be reduced from 10 to 15 hr.

[0113] Typically, the amount of catalyst ranges from 0.1 to 1.0 wt.% relative to the compound of formula (II).

[0114] Non-limiting examples of inert solvents suitable for use in the transformation as shown in Scheme 1 according to the first aspect include compounds of formula (I), xylene, monochlorobenzene, dichlorobenzene, sulfolane, o-chlorobenzonitrile, toluene, or combinations thereof.

[0115] In an exemplary embodiment of the first aspect, the present invention provides a method for preparing a benzonitrile compound of formula (IV) by nitriling a trichlorotoluene compound of formula (III), which is described in Scheme 2 below:

[0116]

[0117] Option: 2

[0118] in,

[0119] X is a halogen selected from fluorine and chlorine; and

[0120] n is an integer from 1 to 5;

[0121] The process employs a suitable ammonium salt in the presence of a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200°C to provide benzonitrile compounds of formula (IV).

[0122] Generally, the suitable catalyst, inert solvent, temperature range, pressure conditions and time required for the transformation as shown in Scheme 2 are the same as those described for the first aspect.

[0123] In a specific exemplary embodiment of the first aspect, the method for preparing o-chlorobenzonitrile from o-chlorotrichlorotoluene as disclosed in the present invention is depicted in the following Scheme 3:

[0124]

[0125] Option: 3

[0126] o-Chlorotrichlorobenzonitrilation using an ammonium salt in the presence of a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200°C provides o-chlorobenzonitrile.

[0127] Generally, the suitable catalyst, inert solvent, temperature range, pressure conditions and time required for the transformation as shown in Scheme 3 are the same as those described for the first aspect.

[0128] In a second aspect of the present invention, a process for preparing a benzonitrile compound of formula (I) by nitrilation of a trichlorotoluene compound of formula (II) is depicted in Scheme 1 below:

[0129]

[0130] Solution: 1

[0131] in,

[0132] R 1 and R 2 are independently selected from hydrogen, X and cyano;

[0133] The condition is that R 1 and R 2 It cannot be cyano at the same time;

[0134] R 3 and R 4 are independently selected from hydrogen, X and trichloromethyl;

[0135] The condition is that R 3 and R 4 It cannot be trichloromethyl at the same time;

[0136] X is a halogen selected from fluorine and chlorine; and

[0137] n is an integer from 1 to 3;

[0138] The process employs a suitable ammonium salt in the presence of a suitable initiator, a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200°C to provide benzonitrile compounds of formula (I).

[0139] Non-limiting examples of compounds of formula (I) according to the second aspect include o-chlorobenzonitrile, p-chlorobenzonitrile, m-chlorobenzonitrile, o-fluorobenzonitrile, p-fluorobenzonitrile, m-fluorobenzonitrile, 2,3-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 3,4-dichlorobenzonitrile, 3,5-dichlorobenzonitrile, 2,3-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,5-difluorobenzonitrile, 2,6-difluorobenzonitrile, 3,4-difluorobenzonitrile, 3,5-difluorobenzonitrile, 1,3-phthalonitrile, 1,4-phthalonitrile and 2-chloro-6-fluorobenzonitrile.

[0140] Preferably, the compound of formula (I) according to the second aspect is selected from o-chlorobenzonitrile, p-chlorobenzonitrile, 2,4-dichlorobenzonitrile, 1,3-phthalonitrile and 2-chloro-6-fluorobenzonitrile.

[0141] Non-limiting examples of compounds of formula (II) according to the second aspect include o-chlorobenzotrichloride, p-chlorobenzotrichloride, m-chlorobenzotrichloride, o-fluorobenzotrichloride, p-fluorobenzotrichloride, m-fluorobenzotrichloride, 2,3-dichlorobenzotrichloride, 2,4-dichlorobenzotrichloride, 2,5-dichlorobenzotrichloride, 2,6-dichlorobenzotrichloride, 3,4-dichlorobenzotrichloride, 3,5-dichlorobenzotrichloride, 2,3-difluorobenzotrichloride, 2,4-difluorobenzotrichloride, 2,5-difluorobenzotrichloride, 2,6-difluorobenzotrichloride, 3,4-difluorobenzotrichloride, 3,5-difluorobenzotrichloride, 1,3-bis(trichloromethyl)benzene, 1,4-bis(trichloromethyl)benzene and 2-chloro-6-fluorobenzotrichloride.

[0142] Preferably, the compound of formula (II) according to the second aspect is selected from o-chlorobenzotrichloride, p-chlorobenzotrichloride, 2,4-dichlorobenzotrichloride, 1,3-bis(trichloromethyl)benzene and 2-chloro-6-fluorobenzotrichloride.

[0143] Typically, suitable ammonium salts according to the second aspect are selected from ammonium chloride or ammonium bromide.

[0144] Typically, initiators suitable for use in the transformation as shown in Scheme 1 according to the second aspect of the present invention are represented by formula (V);

[0145]

[0146] in,

[0147] R 6 and R 7 are independently selected from hydrogen, X and -CO-R 5 ;

[0148] R 5 independently selected from -OH, -NH2 and -Cl;

[0149] The condition is that R 6 and R 7 Cannot be -CO-R at the same time 5 ;

[0150] X is a halogen selected from fluorine and chlorine; and

[0151] n is an integer of 1 to 3.

[0152] Non-limiting examples of the initiator of formula (V) according to the second aspect include benzoic acid, such as o-chlorobenzoic acid, p-chlorobenzoic acid, m-chlorobenzoic acid, o-fluorobenzoic acid, p-fluorobenzoic acid, m-fluorobenzoic acid; halogen-substituted or unsubstituted 1,4-phthalic acid, halogen-substituted or unsubstituted 1,3-phthalic acid; benzoyl chloride, such as o-chlorobenzoyl chloride, p-chlorobenzoyl chloride, m-chlorobenzoyl chloride, o-fluorobenzoyl chloride, p-fluorobenzoyl chloride; Acyl chloride, m-fluorobenzoyl chloride; halogen-substituted or unsubstituted 1,4-phthaloyl dichloride, halogen-substituted or unsubstituted 1,3-phthaloyl dichloride; benzamide, such as o-chlorobenzamide, p-chlorobenzamide, m-chlorobenzamide, o-fluorobenzamide, p-fluorobenzamide, m-fluorobenzamide, halogen-substituted or unsubstituted 1,4-phthaloyl dichloride, halogen-substituted or unsubstituted 1,3-phthaloyl dichloride, or a combination thereof.

[0153] Non-limiting examples of catalysts suitable for the conversion as shown in Scheme 1 according to the second aspect include p-toluenesulfonic acid, methanesulfonic acid, phosphonic acid, amberlyst, ion exchange resins (e.g., Indion®), sulfuric acid, phosphoric acid, water, and combinations thereof.

[0154] By operating according to the second aspect of the present invention, the time required to complete or nearly complete the reaction is in the range of 8 hr to 30 hr. More preferably, the time required to complete the reaction is in the range of 12 to 28 hr.

[0155] According to the operation of the second aspect of the present invention, the pressure of the reaction is 1 to 10 kg / cm 2 More preferably, the reaction pressure is between 1 and 5 kg / cm 2 within the range.

[0156] According to the operation of the second aspect of the present invention, the pressure of the reaction is 1 to 5 kg / cm 2 , wherein the reaction time is reduced from 12 to 28 hr to 10 to 15 hr.

[0157] Typically, the amount of initiator ranges from 1.0 to 10.0 wt.% relative to the amount of the compound of formula (II).

[0158] Typically, the amount of catalyst ranges from 0.1 to 1.0 wt.% relative to the amount of the compound of formula (II).

[0159] Non-limiting examples of inert solvents suitable for the transformation as shown in Scheme I according to the second aspect include compounds of formula (I), xylene, monochlorobenzene, dichlorobenzene, sulfolane, o-chlorobenzonitrile, toluene, and combinations thereof.

[0160] In an exemplary embodiment of the second aspect, the present invention provides a method for preparing a benzonitrile compound of formula (IV) by nitriling a trichlorotoluene compound of formula (III), which is depicted in Scheme 2 below:

[0161]

[0162] Option: 2

[0163] in,

[0164] X is a halogen selected from fluorine and chlorine; and

[0165] n is an integer from 1 to 5;

[0166] The process employs a suitable ammonium salt in the presence of a suitable initiator, a suitable catalyst and optionally in the presence of a suitable inert solvent at a temperature in the range of 150 to 200°C to provide the benzonitrile compound of formula (IV).

[0167] Generally, the suitable catalyst, inert solvent, temperature range, pressure conditions and time required for the transformation as shown in Scheme 2 are the same as those described for the second aspect.

[0168] In a specific exemplary embodiment of the second aspect, the method for preparing o-chlorobenzonitrile from o-chlorotrichlorotoluene as disclosed in the present invention is depicted in the following Scheme 3:

[0169]

[0170] Option: 3

[0171] o-Chlorotrichlorobenzoyl cyanide is cyanated using an ammonium salt in the presence of o-chlorobenzoic acid as an initiator, a suitable catalyst, and optionally a suitable inert solvent at a temperature in the range of 150 to 200°C to provide o-chlorobenzonitrile.

[0172] Generally, the suitable catalyst, inert solvent, temperature range, pressure conditions and time required for the transformation as shown in Scheme 3 are the same as those described for the second aspect.

[0173] In an alternative specific exemplary embodiment of the second aspect, o-chlorotrichlorobenzoyl chloride as an initiator, a suitable catalyst, and optionally a suitable inert solvent are used to cyanate o-chlorobenzoyl chloride using an ammonium salt at a temperature in the range of 150 to 200° C. to provide o-chlorobenzonitrile.

[0174] According to the present invention, the compound of formula (I) is obtained in a yield ranging from 70-95%.

[0175] Preferably, the compound of formula (I) is obtained in a yield ranging from 85 to 95%.

[0176] By operating the process according to the invention, an almost complete conversion of the compound of formula (II) is achieved with high selectivity.

[0177] The benzonitrile obtained according to the invention can be easily separated from the reaction mixture, and in particular from the catalyst and excess ammonium salt, by known techniques such as distillation, separation and solvent work-up.

[0178] Specifically, benzonitrile may be directly distilled from the reaction mixture, or may be extracted by dissolving in a suitable organic solvent.

[0179] In any event, the catalyst, initiator, or ammonium salt can be readily recovered and recycled into subsequent reaction cycles, a feature which is desirable and an intended result of the present invention.

[0180] Various features and embodiments of the invention are illustrated in the following representative examples, which are intended to be illustrative rather than limiting. Example

[0181] Example 1: Preparation of o-chlorobenzonitrile

[0182] 195 g of o-chlorobenzotrichloride, 10 g of o-chlorobenzoyl chloride, 0.5 g of p-toluenesulfonic acid, and 55.8 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content reached <0.2%, the reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 86.0%; purity: >99.0%).

[0183] Example 2: Preparation of o-chlorobenzonitrile

[0184] 20 g of o-chlorobenzotrichloride and 50 g of o-chlorobenzonitrile were added to the reactor at room temperature, and the reaction mass was heated. 1.4 g of aqueous sulfuric acid was added to the reaction mixture for 20 minutes, followed by the addition of 55.8 g of ammonium chloride. The reaction mass was heated to 170-175 ° C. Further, 190 g of o-chlorobenzotrichloride was added to the reaction mixture dropwise at 170-175 ° C for 16 hours. After the reaction was completed, when the content of o-chlorobenzotrichloride was <0.2%, the reaction mass was cooled to 110 ° C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 90.26%, purity: >99.5%).

[0185] Example 3: Preparation of o-chlorobenzonitrile

[0186] 195 g of o-chlorobenzotrichloride, 10 g of o-chlorobenzoyl chloride, 0.4 g of phosphoric acid, and 55.8 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content reached <0.2%, the reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 85.0%; purity: >99.0%).

[0187] Example 4: Preparation of o-chlorobenzonitrile

[0188] 100 g of o-chlorobenzotrichloride, 2.0 g of o-chlorobenzoic acid, 0.5 g of amberlyst, and 28.2 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. The reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 70%, purity: >99%).

[0189] Example 5: Preparation of o-chlorobenzonitrile

[0190] 100 g of o-chlorobenzotrichloride, 2.0 g of o-chlorobenzoic acid, 0.2 g of sulfuric acid, and 28.2 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content was less than 0.2%, the reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 90.0%; purity: >99.5%).

[0191] Example 6: Preparation of o-chlorobenzonitrile

[0192] 195 g of o-chlorobenzotrichloride, 10 g of o-chlorobenzoyl chloride, 0.4 g of sulfuric acid, and 55.8 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content was less than 0.2%, the reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 94.0%; purity: >99.5%).

[0193] Example 7: Preparation of o-chlorobenzonitrile in the presence of OCBN as a solvent

[0194] 100 g of o-chlorobenzotrichloride, 2.0 g of o-chlorobenzoic acid, 25 g of o-chlorobenzonitrile, 0.2 g of sulfuric acid, and 28.2 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content was less than 0.2%, the reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 90.0%; purity: >99.5%).

[0195] Example 8: Preparation of o-chlorobenzonitrile in the presence of sulfolane as a solvent

[0196] 100 g of o-chlorobenzotrichloride, 2.0 g of o-chlorobenzoic acid, 0.2 g of sulfuric acid, 25 g of sulfolane, and 28.2 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content was less than 0.2%, the reaction mixture was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 89.0%; purity: >99.5%).

[0197] Example 9: Preparation of o-chlorobenzonitrile

[0198] 200 g of o-chlorobenzotrichloride and 0.4 g of sulfuric acid were added to the reactor at room temperature, and the reaction mass was heated to 150-155°C. 1.0 g of water was added to the reaction mixture at 155-160°C for 20 minutes, followed by 55.8 g of ammonium chloride. The reaction mass was heated to 180-185°C. The resulting reaction mass was heated at 180-185°C for 25 hours. After the reaction was complete, when the o-chlorobenzotrichloride content was <0.2%, the reaction mass was cooled to 110°C. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 89.5%; purity: >99.5%).

[0199] Example 10: Preparation of p-chlorobenzonitrile

[0200] 195 g of p-chlorobenzotrichloride, 10 g of p-chlorobenzoyl chloride, 0.2 g of sulfuric acid, and 55.8 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C and held for 25 hours. When the o-chlorobenzotrichloride content reached <0.2%, the reaction mixture was cooled to 110°C. The crude p-chlorobenzonitrile obtained was purified by distillation (yield: 94.0%; purity: >99.5%).

[0201] Example 11: Preparation of 2,4-dichlorobenzonitrile

[0202] 195 g of 2,4-dichlorobenzotrichloride, 10 g of 2,4-dichlorobenzoyl chloride, 0.4 g of sulfuric acid, and 48.6 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 190-195°C and maintained for 26 hours. When the o-chlorobenzotrichloride content reached <0.2%, the reaction mixture was cooled to 110°C. The crude 2,4-dichlorobenzonitrile obtained was purified by distillation (yield: 90.0%; purity: >99.0%).

[0203] Example 12: Preparation of o-chlorobenzonitrile

[0204] 195 g o-chlorotoluene trichloride, 10 g o-chlorobenzoyl chloride, 0.4 g sulfuric acid and 55.8 g ammonium chloride were added to the reactor at room temperature. The reaction mass was heated to 180-185 °C and the reaction mixture was heated at 3 kg / cm 2 The pressure was maintained for 12 hours. The reaction mass was cooled to 110°C and the pressure was released when the o-chlorobenzotrichloride content reached <0.2%. The crude o-chlorobenzonitrile thus obtained was purified by distillation (yield: 93.0%; purity: >99.5%).

[0205] Example 13: Preparation of 1,3-phthalonitrile

[0206] 195 g of 1,3-bis(trichloromethyl)benzene, 15 g of 1,3-phthaloyl dichloride, 0.4 g of sulfuric acid, and 74 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 190-195°C and maintained for 25 hours. When the 1,3-bis(trichloromethyl)benzene content reached <0.2%, the reaction mixture was cooled to 110°C. The crude 1,3-phthalonitrile obtained was purified by distillation (yield: 90.0%; purity: >99.0%).

[0207] Example 14: Preparation of 2-chloro-6-fluorobenzonitrile

[0208] 195 g of 2-chloro-6-fluorobenzotrichloride, 10 g of 2-chloro-6-fluorobenzoyl chloride, 0.4 g of sulfuric acid, and 50.51 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 190-195°C and held for 28 hours. When the 2-chloro-6-fluorobenzotrichloride content reached <0.2%, the reaction mixture was cooled to 100°C. The crude 2-chloro-6-fluorobenzonitrile thus obtained was purified by distillation (yield: 89.0%; purity: >99.0%).

[0209] Comparative Example 1: Preparation of o-chlorobenzonitrile using metal salt as catalyst

[0210] 100 g of o-chlorobenzotrichloride, 2.0 g of o-chlorobenzoic acid, a ZnCl2 / CuO catalyst, and 28.2 g of ammonium chloride were added to a reactor at room temperature. The reaction mixture was heated to 180-185°C, and the reaction mixture was held for 25 hours. It was observed that the process for preparing o-chlorobenzonitrile using a metal salt as a catalyst was slow, and therefore, it was found that metal catalysts were not suitable for the process for preparing o-chlorobenzonitrile in the absence of sulfuric acid.

[0211] The above description of the present invention is only provided for the purpose of illustrating the present invention and is not intended to be limiting. Since those skilled in the art can conceive of modifying the disclosed embodiment in conjunction with the spirit and substance of the present invention, the present invention should be interpreted as including all contents within the scope of the present disclosure.

[0212] The embodiments herein and their various features and advantageous details are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted to avoid unnecessarily obscuring the embodiments herein. The examples used herein are only intended to facilitate understanding of the modes in which the embodiments herein can be put into practice, and further enable those skilled in the art to practice the embodiments. Therefore, the examples should not be construed as limiting the scope of the embodiments herein.

[0213] The description of the specific embodiments will fully reveal the general nature of the embodiments herein so that others can readily modify and / or adapt these specific embodiments for various applications by applying current knowledge without departing from the general concepts, and therefore, such adaptations and modifications should and are intended to be understood to be within the meaning and range of equivalents of the disclosed embodiments. It should be understood that the phraseology or terminology used herein is for the purpose of description and not limitation. Therefore, although the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

[0214] Although considerable emphasis has been placed on the specific features of the present invention, it will be appreciated that various modifications and numerous changes may be made to the preferred embodiments without departing from the principles of the present invention. These and other modifications to the nature of the present invention or the preferred embodiments will be apparent to those skilled in the art from the invention herein, and it will be clearly understood that the foregoing description is to be construed as merely illustrative of the present invention and not as limiting.

Claims

1. Method for preparing benzonitrile compounds of formula (I) in, R 1 and R 2 are independently selected from hydrogen, X and cyano; The condition is that R 1 and R 2 It cannot be cyano at the same time; X is halogen selected from fluorine and chlorine; and n is an integer from 1 to 3; The method comprises the steps of nitriling a trichlorotoluene compound of formula (II) using a suitable ammonium salt in the presence of a suitable catalyst selected from p-toluenesulfonic acid, methanesulfonic acid, phosphonic acid, amberlyst, ion exchange resin, sulfuric acid, phosphoric acid, water and combinations thereof, optionally in the presence of a suitable initiator, and optionally in the presence of a suitable inert solvent at a temperature in the range of 150-200° C. to provide the benzonitrile compound of formula (I); in, R 3 and R 4 are independently selected from hydrogen, X and trichloromethyl; The condition is that R 3 and R 4 It cannot be trichloromethyl at the same time; X is halogen selected from fluorine and chlorine; and n is an integer of 1 to 3.

2. The method of claim 1, wherein a) the suitable ammonium salt is selected from ammonium chloride or ammonium bromide; and b) The suitable inert solvent is selected from the group consisting of a compound of formula (I), xylene, monochlorobenzene, dichlorobenzene, sulfolane, o-chlorobenzonitrile, toluene, and combinations thereof.

3. The method of claim 1, wherein a) the amount of the catalyst is in the range of 0.1 to 1.0 wt.% relative to the compound of formula (II); and b) The amount of the initiator is in the range of 1.0 to 10.0 wt.% relative to the compound of formula (II).

4. The method of claim 1, wherein the reaction is carried out at a temperature of 1 to 10 kg / cm 2 The reaction is carried out at a pressure in the range of 100 to 200 hr, and the reaction time is in the range of 8 to 15 hr.

5. The method of claim 1, wherein the reaction is carried out at a temperature of 1 to 5 kg / cm 2 The reaction is carried out at a pressure in the range of 10 to 15 hr.

6. The process of claim 1, wherein the yield of the benzonitrile compound of formula (I) is in the range of 70 to 95%.

7. The method of claim 1, wherein the initiator is represented by a compound of formula (V); in, R 6 and R 7 are independently selected from hydrogen, X and -CO-R 5 ; R 5 independently selected from -OH, -NH2 and -Cl; The condition is that R 6 and R 7 Cannot be -CO-R at the same time 5 ; X is halogen selected from fluorine and chlorine; and n is an integer of 1 to 3.

8. The method of claim 7, wherein the suitable initiator of formula (V) is selected from benzoic acid, such as o-chlorobenzoic acid, p-chlorobenzoic acid, m-chlorobenzoic acid, o-fluorobenzoic acid, p-fluorobenzoic acid, m-fluorobenzoic acid, halogen (un) substituted 1,4-phthalic acid, halogen (un) substituted 1,3-phthalic acid; benzoyl chloride, such as o-chlorobenzoyl chloride, p-chlorobenzoyl chloride, m-chlorobenzoyl chloride, o-fluorobenzoyl chloride , p-fluorobenzoyl chloride, m-fluorobenzoyl chloride, halogen (un) substituted 1,4-phthaloyl dichloride, halogen (un) substituted 1,3-phthaloyl dichloride; benzamides, such as o-chlorobenzamide, p-chlorobenzamide, m-chlorobenzamide, o-fluorobenzamide, p-fluorobenzamide, m-fluorobenzamide, halogen (un) substituted 1,4-phthaloyl dichloride, halogen (un) substituted 1,3-phthaloyl dichloride, and combinations thereof.

9. The method of claim 1 , wherein the compound of formula (I) is selected from the group consisting of o-chlorobenzonitrile, p-chlorobenzonitrile, m-chlorobenzonitrile, o-fluorobenzonitrile, p-fluorobenzonitrile, m-fluorobenzonitrile, 2,3-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,6-dichlorobenzonitrile, 3,4-dichlorobenzonitrile, 3,5-dichlorobenzonitrile, 2,3-difluorobenzonitrile, 2,4-difluorobenzonitrile, 2,5-difluorobenzonitrile, 2,6-difluorobenzonitrile, 3,4-difluorobenzonitrile, 3,5-difluorobenzonitrile, 1,3-phthalonitrile, 1,4-phthalonitrile, and 2-chloro-6-fluorobenzonitrile.

10. The method of claim 1, wherein the compound of formula (II) is selected from the group consisting of o-chlorobenzotrichloride, p-chlorobenzotrichloride, m-chlorobenzotrichloride, o-fluorobenzotrichloride, p-fluorobenzotrichloride, m-fluorobenzotrichloride, 2,3-dichlorobenzotrichloride, 2,4-dichlorobenzotrichloride, 2,5-dichlorobenzotrichloride, 2,6-dichlorobenzotrichloride, 3,4-dichlorobenzotrichloride, 3,5-dichlorobenzotrichloride, 2,3-difluorobenzotrichloride, 2,4-difluorobenzotrichloride, 2,5-difluorobenzotrichloride, 2,6-difluorobenzotrichloride, 3,4-difluorobenzotrichloride, 3,5-difluorobenzotrichloride, 1,3-bis(trichloromethyl)benzene, 1,4-bis(trichloromethyl)benzene, and 2-chloro-6-fluorobenzotrichloride.

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