Preparation method of asymmetric diaryl substituted p-phenylenediamine compounds

Abstract

The present invention provides a method for preparing an asymmetric diaryl-substituted p-phenylenediamine compound, wherein the compound has a structure as shown in the following formula A. The method comprises: (1) 3 Reacting hydroquinone with the compound of formula B in the presence of a catalyst to obtain a compound of formula C; and (2) in anhydrous FeCl 3 The compound of formula C and the compound of formula D are reacted in the presence of to obtain a compound of formula A; wherein each group is as defined herein. The method of the present invention can be used to efficiently and conveniently prepare asymmetric diaryl-substituted p-phenylenediamine compounds.

Description

Technical Field

[0001] The invention belongs to the field of rubber antioxidants, and specifically relates to asymmetric diaryl-substituted p-phenylenediamine compounds and a preparation method thereof. Background Art

[0002] Existing literature studies have shown that diaryl-substituted p-phenylenediamine has a long-lasting anti-aging effect. Compared with the widely used antioxidant 4020, diaryl p-phenylenediamine is not easy to volatilize, is resistant to extraction, and has a more lasting protective effect. For example, antioxidant H and antioxidant 3100 are typical late-effect long-term antioxidants, which can make up for the shortcomings of 4010 and 4020 antioxidants, which have good anti-aging effects in the early stage but slightly worse in the later stage.

[0003] However, antioxidant H is a symmetrical N,N'-diphenyl-p-phenylenediamine with strong crystallinity and poor compatibility with rubber. The amount used should not exceed 1 part, otherwise it is easy to precipitate and produce frosting, causing discoloration and pollution of the tread, and quickly loses the protection against rubber aging. Blooming is the phenomenon that liquid or solid compounding agents inside the rubber migrate to the surface and precipitate. Antioxidant 3100 is a mixture, of which about 45% is a symmetrical diaryl-p-phenylenediamine (23% N,N'-diphenyl-p-phenylenediamine and 22% N,N'-di(tolyl)-p-phenylenediamine), and the other 45% is an asymmetrical N-phenyl-N'-tolyl-p-phenylenediamine. Therefore, antioxidant 3100 is also prone to frosting, and the amount used generally does not exceed 1.5 parts.

[0004] US Patent Document US3432460 introduces a method for synthesizing diaryl-p-phenylenediamine antioxidants. The preparation of antioxidant H uses hydroquinone and aniline as reaction raw materials, Lewis acid such as anhydrous ferric chloride as catalyst, high temperature and slightly positive pressure toluene reflux with water, and the amount of water taken out is used as a sign of the end of the reaction. After the reaction is completed, the temperature is lowered and a saturated sodium carbonate aqueous solution is added to quench the reaction, the organic phase is filtered out, and the temperature is raised and the low-boiling substances are removed by vacuum distillation. The inorganic substances are removed by hot filtration and then cooled and solidified. If a mixture of aniline and o-toluidine is reacted with hydroquinone, a three-component mixture is obtained, namely antioxidant 3100. According to the reaction principle, it is impossible to obtain a single-component asymmetric diaryl-p-phenylenediamine according to this process.

[0005] European patent document EP0588060A2 adopts the method of synthesizing N-alkyl substituted phenyl-p-phenylenediamine first, and then condensing and dehydrogenating with cyclohexanone substituted with different alkyl groups to generate asymmetric diaryl substituted p-phenylenediamine. In this preparation method, alkyl substituted cyclohexanone is difficult to synthesize, the cost is relatively high, and it needs to consume hydrogen acceptors, and it is easy to generate a large amount of by-products.

[0006] US Patent Document US4804783A prepares the target product by first synthesizing N-alkyl-substituted phenyl-p-phenylenediamine and then condensing it with different alkyl-substituted phenols. This preparation method requires cyclohexanone as a hydrogen transfer reagent, and the reaction conditions are harsh and difficult to carry out, especially alkyl-substituted phenols are difficult to react, and almost no product is obtained.

[0007] Therefore, the art needs a method for preparing asymmetric diaryl-substituted p-phenylenediamine compounds with low cost, few side reactions, undemanding reaction conditions and high yield. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a novel method for preparing asymmetric diaryl-substituted p-phenylenediamine compounds. Asymmetric diaryl-substituted p-phenylenediamine compounds can be used as antioxidants for rubber products, especially rubber tires, to prevent rubber products or rubber tires from degradation due to light, heat, oxygen, fatigue, etc. during long-term use. Compared with the existing method for preparing asymmetric diaryl-substituted p-phenylenediamine compounds, the method of the present invention has the advantages of lower cost, less side reactions, less harsh reaction conditions, and higher yield.

[0009] Specifically, the present invention provides a method for preparing an asymmetric diaryl-substituted p-phenylenediamine compound, wherein the asymmetric diaryl-substituted p-phenylenediamine compound has a structure shown in the following formula A:

[0010]

[0011] In formula A, each R a independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5, each R b independently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0 to 5; the compound of formula A does not include (R a ) m Substituted phenyl and (R b ) n The same compounds with substituted phenyl groups;

[0012] The method comprises:

[0013] (1) reacting hydroquinone with a compound of formula B in the presence of a supported FeCl3 catalyst to obtain a compound of formula C:

[0014]

[0015] (2) reacting the compound of formula C with the compound of formula D in the presence of anhydrous FeCl3 to obtain a compound of formula A:

[0016]

[0017] Among them, in the compound of formula B, each R a are independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5; in the compound of formula D, each R b Independently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0-5; the compound of formula B is different from the compound of formula D.

[0018] In one or more embodiments, the supported FeCl3 catalyst is a catalyst in which FeCl3 is supported on a carrier.

[0019] In one or more embodiments, the reaction of step (1) is carried out in a non-polar solvent.

[0020] In one or more embodiments, the reaction temperature of step (1) is 200-240°C.

[0021] In one or more embodiments, the molar ratio of FeCl3 contained in the supported FeCl3 catalyst added in step (1) to the hydroquinone added in step (1) is (0.08-0.4):1.

[0022] In one or more embodiments, the molar ratio of the compound of formula B added in step (1) to the hydroquinone added in step (1) is (0.8-1.2):1.

[0023] In one or more embodiments, the reaction of step (1) is carried out in an inert gas atmosphere.

[0024] In one or more embodiments, the reaction of step (2) is carried out in a non-polar solvent.

[0025] In one or more embodiments, the reaction temperature of step (2) is 230-270°C.

[0026] In one or more embodiments, the molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is (0.1-0.5):1.

[0027] In one or more embodiments, the molar ratio of the compound of formula D added in step (2) to the hydroquinone added in step (1) is (1.0-1.8):1.

[0028] In one or more embodiments, the reaction of step (2) is carried out in an inert gas atmosphere.

[0029] In one or more embodiments, the carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieves, activated silicon oxide and activated aluminum oxide.

[0030] In one or more embodiments, in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10).

[0031] In one or more embodiments, the reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane.

[0032] In one or more embodiments, the reaction temperature of step (1) is 220-230°C.

[0033] In one or more embodiments, the molar ratio of FeCl3 contained in the supported FeCl3 catalyst added in step (1) to the hydroquinone added in step (1) is (0.1-0.25):1.

[0034] In one or more embodiments, the molar ratio of the compound of formula B added in step (1) to the hydroquinone added in step (1) is (0.9-1.1):1.

[0035] In one or more embodiments, the reaction of step (1) is carried out in a nitrogen atmosphere.

[0036] In one or more embodiments, the reaction of step (2) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane.

[0037] In one or more embodiments, the reaction temperature of step (2) is 240-260°C.

[0038] In one or more embodiments, the molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is (0.2-0.3):1.

[0039] In one or more embodiments, the molar ratio of the compound of formula D added in step (2) to the hydroquinone added in step (1) is (1.2-1.5):1.

[0040] In one or more embodiments, the reaction of step (2) is carried out in a nitrogen atmosphere.

[0041] In one or more embodiments, the carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieve, activated silicon oxide and activated alumina; in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10); the reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (1) is 220-230°C; in the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.1-0.25):1, and the compound of formula B and hydroquinone are The molar ratio of the hydroquinone to the anhydrous FeCl3 added in the step (2) is (0.2-0.3):1; the molar ratio of the compound of formula D added in the step (2) to the hydroquinone added in the step (1) is (1.2-1.5):1; and the reaction in the step (2) is carried out in a nitrogen atmosphere. The reaction in the step (2) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane. The reaction temperature in the step (2) is 240-260° C.; the molar ratio of the anhydrous FeCl3 added in the step (2) to the hydroquinone added in the step (1) is (0.2-0.3):1; the molar ratio of the compound of formula D added in the step (2) to the hydroquinone added in the step (1) is (1.2-1.5):1; and the reaction in the step (2) is carried out in a nitrogen atmosphere.

[0042] The present invention also provides a method for preparing the compound of formula I:

[0043]

[0044] In Formula I, R1 and R3 are independently hydrogen or C1-C6 alkyl; R2 is C1-C6 alkyl; the compound of Formula I does not include a compound in which the phenyl substituted by R1 and R2 is the same as the phenyl substituted by R3;

[0045] The method comprises:

[0046] (1) reacting hydroquinone with the compound of formula II in the presence of a supported FeCl3 catalyst to obtain a compound of formula III:

[0047]

[0048] (2) reacting the compound of formula III with the compound of formula IV in the presence of anhydrous FeCl3 to obtain a compound of formula I:

[0049]

[0050] Wherein, in the compound of formula II, R1 and R2 are independently hydrogen or C1-C6 alkyl; in the compound of formula IV, R3 is C1-C6 alkyl; the compound of formula II and the compound of formula IV are not the same; or

[0051] The method comprises:

[0052] (1) reacting hydroquinone with a compound of formula IV in the presence of a supported FeCl3 catalyst to obtain a compound of formula III':

[0053]

[0054] (2) reacting the compound of formula III' with the compound of formula II in the presence of anhydrous FeCl3 to obtain a compound of formula I:

[0055]

[0056] Wherein, in the compound of formula II, R1 and R2 are independently hydrogen or C1-C6 alkyl; in the compound of formula IV, R3 is C1-C6 alkyl; the compound of formula II and the compound of formula IV are not the same.

[0057] In one or more embodiments of the method for preparing the compound of formula I, the supported FeCl3 catalyst is a catalyst obtained by supporting FeCl3 on a carrier.

[0058] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (1) is carried out in a non-polar solvent.

[0059] In one or more embodiments of the method for preparing the compound of formula I, the reaction temperature of step (1) is 200-240°C.

[0060] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of FeCl3 contained in the supported FeCl3 catalyst added in step (1) to the hydroquinone added in step (1) is (0.08-0.4):1.

[0061] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of the compound of formula II or the compound of formula IV added in step (1) to the hydroquinone added in step (1) is (0.8-1.2):1.

[0062] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (1) is carried out under an inert gas atmosphere.

[0063] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (2) is carried out in a non-polar solvent.

[0064] In one or more embodiments of the method for preparing the compound of formula I, the reaction temperature of step (2) is 230-270°C.

[0065] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is (0.1-0.5):1.

[0066] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of the compound of formula IV or the compound of formula II added in step (2) to the hydroquinone added in step (1) is (1.0-1.8):1.

[0067] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (2) is carried out under an inert gas atmosphere.

[0068] In one or more embodiments of the method for preparing the compound of formula I, the carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieves, activated silicon oxide and activated aluminum oxide.

[0069] In one or more embodiments of the method for preparing the compound of formula I, in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10).

[0070] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane.

[0071] In one or more embodiments of the method for preparing the compound of formula I, the reaction temperature of step (1) is 220-230°C.

[0072] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of FeCl3 contained in the supported FeCl3 catalyst added in step (1) to the hydroquinone added in step (1) is (0.1-0.25):1.

[0073] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of the compound of formula II or the compound of formula IV added in step (1) to the hydroquinone added in step (1) is (0.9-1.1):1.

[0074] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (1) is carried out under a nitrogen atmosphere.

[0075] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (2) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane.

[0076] In one or more embodiments of the method for preparing the compound of formula I, the reaction temperature of step (2) is 240-260°C.

[0077] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is (0.2-0.3):1.

[0078] In one or more embodiments of the method for preparing the compound of formula I, the molar ratio of the compound of formula IV or the compound of formula II added in step (2) to the hydroquinone added in step (1) is (1.2-1.5):1.

[0079] In one or more embodiments of the method for preparing the compound of formula I, the reaction of step (2) is carried out under a nitrogen atmosphere.

[0080] In one or more embodiments of the method for preparing the compound of formula I, the carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieve, activated silicon oxide and activated alumina; in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10); the reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (1) is 220-230°C; in the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.1-0.25):1, the compound of formula II or formula IV The molar ratio of the compound to hydroquinone is (0.9-1.1):1; the reaction of step (1) is carried out in a nitrogen atmosphere; the reaction of step (2) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (2) is 240-260° C.; the molar ratio of anhydrous FeCl3 added in step (2) to the hydroquinone added in step (1) is (0.2-0.3):1; the molar ratio of the compound of formula IV or the compound of formula II added in step (2) to the hydroquinone added in step (1) is (1.2-1.5):1; and the reaction of step (2) is carried out in a nitrogen atmosphere.

[0081] In one or more embodiments of the method for preparing a compound of formula I, in formula I, R1 is hydrogen, R2 and R3 are each independently C1-C6 alkyl; or R3 is hydrogen, R1 and R2 are each independently C1-C6 alkyl; or R1, R2 and R3 are each independently C1-C6 alkyl.

[0082] In one or more embodiments of the process for preparing the compound of formula I, the C1-C6 alkyl group is selected from methyl, ethyl, propyl and butyl.

[0083] In one or more embodiments of the process for preparing the compound of formula I, the C1-C6 alkyl group is selected from methyl and isobutyl.

[0084] In one or more embodiments of the method for preparing a compound of formula I, the compound of formula I is selected from:

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] The present invention also provides a supported FeCl3 catalyst, wherein the carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieve, activated silicon oxide and activated aluminum oxide, and in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10).

[0092] In one or more embodiments, the carrier of the supported FeCl3 catalyst is prepared by heating anhydrous FeCl3 and a carrier in an alcohol solvent. DETAILED DESCRIPTION

[0093] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0094] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0095] Herein, all features such as quantity, content and concentration defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0096] Herein, unless otherwise specified, ratio refers to mass ratio and percentage refers to mass percentage.

[0097] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0098] Herein, the terms "comprising", "including" or "comprising" indicate that various components can be applied together in the mixture or composition of the present invention. Therefore, the terms "consisting mainly of" and "consisting of" are included in the terms "comprising", "including" or "comprising".

[0099] As used herein, an alkyl group refers to a linear or branched monovalent saturated hydrocarbon group, typically containing 1 to 16 carbon atoms (C1 to C16 alkyl), such as 3 to 16 carbon atoms (C3 to C16 alkyl). Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 1,4-dimethylpentyl, and tert-octyl.

[0100] Herein, the asymmetric diaryl-substituted p-phenylenediamine compound refers to a compound that can be regarded as a compound obtained by substituting two different aryl groups for the hydrogen atoms on the two amino groups on p-phenylenediamine. For example, the asymmetric diaryl-substituted p-phenylenediamine compound may have a structure shown in the following formula A:

[0101]

[0102] In formula A, each R a independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5, each R b are independently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0 to 5; and (R a ) m Substituted phenyl and (R b ) n The substituted phenyl groups are not the same.

[0103] Herein, the substituted phenyl groups are identical means that the number of substituents on the phenyl groups, the positions of the substituents, and the substituent groups at the corresponding positions are identical.

[0104] In the present invention, as R a or R b The C1-C6 alkyl groups include, but are not limited to, methyl, ethyl, propyl and butyl, wherein the propyl group includes n-propyl and isopropyl, and the butyl group includes n-butyl, isobutyl and tert-butyl. a and R bcan be independently selected from hydrogen, methyl, ethyl, propyl and butyl. a or R b The C1-C6 alkyl group is a methyl group or a tert-butyl group, that is, each R a and R b Each is independently selected from hydrogen, methyl and tert-butyl.

[0105] In Formula A, m is preferably an integer selected from 0 to 3, and more preferably an integer selected from 0 to 2. In Formula A, n is preferably an integer selected from 0 to 3, and more preferably an integer selected from 0 to 2.

[0106] The inventors of the present invention have found that an asymmetric diaryl-substituted p-phenylenediamine compound having the following formula I (referred to as compound I or compound of formula I) can not only provide long-term anti-aging performance similar to antioxidant H or antioxidant 3100, but also improve blooming properties:

[0107]

[0108] Wherein, R1 and R3 are each independently hydrogen or C1-C6 alkyl; R2 is C1-C6 alkyl; and the phenyl substituted by R1 and R2 is different from the phenyl substituted by R3.

[0109] In the present invention, the C1-C6 alkyl group as R1, R2 or R3 includes, but is not limited to, methyl, ethyl, propyl and butyl, wherein the propyl group includes n-propyl and isopropyl, and the butyl group includes n-butyl, isobutyl and tert-butyl, i.e., each R1, R2 and R3 can be independently selected from hydrogen, methyl, ethyl, propyl and butyl. In some embodiments, the C1-C6 alkyl group as R1, R2 or R3 is methyl or tert-butyl, i.e., each R1, R2 and R3 is independently selected from hydrogen, methyl and tert-butyl.

[0110] In some embodiments, in Formula I, when R1 is hydrogen, the groups represented by R2 and R3 are different, or the groups represented by R2 and R3 are the same but in different positions on the respective substituted phenyl groups.

[0111] In some embodiments, in Formula I, when R1 is hydrogen, the groups represented by R2 and R3 are different.

[0112] In some embodiments, in Formula I, R1 and R3 are not both hydrogen.

[0113] In some embodiments, in Formula I, R1 is hydrogen, R2 and R3 are each independently C1-C6 alkyl, and R2 and R3 are different.

[0114] In some embodiments, in Formula I, R3 is hydrogen, and R1 and R2 are each independently C1-C6 alkyl.

[0115] In some embodiments, in Formula I, R1, R2, and R3 are each independently C1-C6 alkyl.

[0116] In some embodiments, Compound I has a structure as shown in any one of Formula I-1 to Formula I-6:

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123] The present invention provides a method for preparing an asymmetric diaryl-substituted p-phenylenediamine compound having a structure shown in the following formula A (referred to as the compound of formula A):

[0124]

[0125] In formula A, each R a independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5, each R b independently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0 to 5; the compound of formula A does not include (R a ) m Substituted phenyl and (R b ) n The same compounds with substituted phenyl groups;

[0126] The method comprises the following steps:

[0127] (1) reacting hydroquinone with the compound of formula B in the presence of a supported FeCl3 catalyst (FeCl3 / support) to obtain a compound of formula C:

[0128]

[0129] (2) reacting the compound of formula C with the compound of formula D in the presence of anhydrous FeCl3 to obtain a compound of formula A:

[0130]

[0131] Among them, in the compound of formula B, each R a are independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5; in the compound of formula D, each R bIndependently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0-5; the compound of formula B is different from the compound of formula D.

[0132] In the preparation method of the compound of formula A of the present invention, preferably each R in compound B is a , preferred m, preferred R in compound D b , the preferred n may be as described in any embodiment herein.

[0133] The method for preparing the compound of formula A is also applicable to the preparation of the compound of formula I described in any of the embodiments herein.

[0134] The method for preparing the compound of formula I may comprise the following steps:

[0135] (1) reacting hydroquinone with the compound of formula II in the presence of a supported FeCl3 catalyst to obtain a compound of formula III:

[0136]

[0137] (2) reacting the compound of formula III with the compound of formula IV in the presence of anhydrous FeCl3 to obtain a compound of formula I:

[0138]

[0139] Wherein, in the compound of formula II, R1 and R2 are independently hydrogen or C1-C6 alkyl; in the compound of formula IV, R3 is C1-C6 alkyl; the compound of formula II and the compound of formula IV are not the same.

[0140] The method for preparing the compound of formula I may also comprise the following steps:

[0141] (1) reacting hydroquinone with a compound of formula IV in the presence of a supported FeCl3 catalyst to obtain a compound of formula III':

[0142]

[0143] (2) reacting the compound of formula III' with the compound of formula II in the presence of anhydrous FeCl3 to obtain a compound of formula I:

[0144]

[0145] Wherein, in the compound of formula II, R1 and R2 are independently hydrogen or C1-C6 alkyl; in the compound of formula IV, R3 is C1-C6 alkyl; the compound of formula II and the compound of formula IV are not the same.

[0146] In the preparation method of the compound of formula I of the present invention, the preferred R1 and R2 in compound II and the preferred R3 in compound IV can be as described in any embodiment herein.

[0147] The present invention adopts a two-step method to prepare asymmetric diaryl-substituted p-phenylenediamine. In the first step, supported FeCl3 is used as a catalyst. Since trivalent iron is stably bonded to the surface of the carrier and has weaker catalytic activity than free FeCl3, the target product arylaminophenol is restricted from further reacting with aromatic amine to generate symmetrical diaryl p-phenylenediamine. In addition, the pore structure of the carrier further spatially restricts the generation of diaryl p-phenylenediamine.

[0148] The reaction of step (1) is carried out in a non-polar solvent; the non-polar solvent may be, for example, toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, etc., preferably toluene or xylene. The reaction of step (1) is carried out under conditions of reflux azeotropy and dehydration. The reaction temperature of step (1) is preferably 200-240° C., more preferably 220-230° C. The dehydration method may be conventional in the art, for example, a water separator may be used for dehydration. The reaction of step (1) is preferably carried out in an inert gas (e.g., nitrogen) atmosphere.

[0149] The present invention finds that in the first step of the reaction of preparing asymmetric diaryl-substituted p-phenylenediamine, using supported FeCl3 as a catalyst, aromatic aminophenol can be prepared, and the aromatic aminophenol is restricted from further reacting with aromatic amine to generate symmetrical diaryl p-phenylenediamine. In the present invention, the supported FeCl3 catalyst refers to a catalyst obtained by loading FeCl3 onto a carrier. In the supported FeCl3 catalyst, trivalent iron is stably bonded to the carrier, and the mass ratio of FeCl3 to the carrier is preferably 1: (5-10). The carrier of the supported FeCl3 catalyst can be a hydrogen-type molecular sieve, activated silicon oxide or activated alumina. Herein, activated alumina and activated silicon oxide refer to solid silicon oxide and solid alumina containing hydroxyl groups on the inner and outer surfaces and being porous. The hydrogen-type molecular sieve can be, for example, GENERAL-REAGENT, 4A of Shanghai Titan Chemical Co., Ltd. The activated silicon oxide can be, for example, GENERAL-REAGENT, G72651A of Shanghai Titan Chemical Co., Ltd. The activated alumina may be, for example, GENERAL-REAGENT, G21116K produced by Shanghai Titan Chemical Co., Ltd.

[0150] The supported FeCl3 catalyst used in the present invention can be prepared by heating anhydrous FeCl3 and a carrier in a solvent. The solvent used in preparing the supported FeCl3 catalyst can be an alcohol solvent, preferably a C1-C3 monohydric alcohol, such as methanol. The mass ratio of FeCl3 to the solvent in the reaction system is generally 1:5 to 1:20, for example, 1:9 to 1:19. The mass ratio of FeCl3 to the carrier in the reaction system is generally 1:(5-10). The reaction is generally carried out under stirring and refluxing conditions. The reaction time is generally 5-10 hours, preferably 7-8 hours. After the reaction is completed, the solvent is removed to obtain a supported FeCl3 catalyst. The method for removing the solvent can be, for example, distilling the solvent under heating and vacuum conditions.

[0151] In some embodiments, the supported FeCl3 catalyst is prepared by the following method:

[0152] Weigh a certain amount of anhydrous FeCl3, prepare a solution with a concentration of 5-10wt% with methanol, add it to a four-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, add a certain amount of dried carrier, the mass ratio of FeCl3 to carrier is 1:(5-10), start mechanical stirring, gradually increase the temperature to methanol reflux, maintain reflux for 7-8h, then evaporate the methanol, increase the temperature to 140-150℃ and evacuate to an absolute pressure of about 10kPa, maintain for 5-6h, cool down and quickly pour into a clean and dry reagent bottle, and store in a desiccator.

[0153] In step (1), the molar ratio of FeCl3 contained in the added supported FeCl3 catalyst to the added hydroquinone is preferably (0.08-0.4):1, more preferably (0.1-0.25):1. In step (1), the molar ratio of the added compound of formula B (e.g., the compound of formula II or the compound of formula IV) to the added hydroquinone is preferably (0.8-1.2):1, more preferably (0.9-1.1):1.

[0154] Whether the reaction of step (1) is completed can be determined by detecting whether water is generated. When no water is generated, the reaction is completed. After the reaction of step (1) is completed, the catalyst is filtered out while hot, and the solvent and unreacted compound of formula B (such as compound of formula II or compound of formula IV) are distilled out under reduced pressure to obtain a compound of formula C (such as compound of formula III or compound of formula III'); filtration and reduced pressure distillation are preferably carried out at the reaction temperature of step (1); the vacuum degree of reduced pressure distillation is preferably less than 5 mmHg.

[0155] The reaction of step (2) is carried out in a non-polar solvent; the non-polar solvent may be, for example, toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, etc., preferably toluene or xylene. The reaction of step (2) is carried out under the conditions of heating to reflux azeotropy and dehydration. The reaction temperature of step (2) is preferably 230 to 270° C., preferably 240 to 260° C. The dehydration method may be conventional in the art, for example, a water separator may be used for dehydration. The reaction of step (2) is preferably carried out in an inert gas (e.g., nitrogen) atmosphere.

[0156] The molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is preferably (0.1-0.5):1, more preferably (0.2-0.3):1. The molar ratio of the compound of formula D (e.g., compound of formula IV or compound of formula II) added in step (2) to hydroquinone added in step (1) is preferably (1.0-1.8):1, more preferably (1.2-1.5):1.

[0157] Whether the reaction of step (2) is completed can be determined by detecting whether water is generated. When no water is generated, the reaction is completed. After the reaction of step (2) is completed, the temperature is lowered to about 80-100°C, an appropriate amount of alkali solution is added for neutralization, the temperature is increased and the reduced pressure is distilled to remove water, solvent and unreacted compound of formula D (e.g. compound of formula IV or compound of formula II), and the mixture is filtered while hot, and the filtrate is cooled and solidified to obtain compound of formula A (e.g. compound of formula I); the neutralization time is preferably 0.5-1.5h; the alkali solution can be, for example, an aqueous solution of a weak alkaline salt; the weak alkaline salt can be sodium carbonate, potassium carbonate, sodium phosphate, potassium phosphate, etc.; the vacuum degree of the reduced pressure distillation is preferably less than 5 mmHg; the temperature of the reduced pressure distillation is preferably 250-300°C; the temperature of the filtration is preferably 130-160°C.

[0158] The method of the present invention has the following advantages:

[0159] (1) The method of the present invention can prepare a single-component asymmetric diaryl-substituted p-phenylenediamine compound, while it is difficult to prepare a single-component asymmetric diaryl p-phenylenediamine in the prior art;

[0160] (2) Low cost: no need to use expensive substituted cyclohexanone as a reaction raw material;

[0161] (3) Few side reactions and high yield: The reaction does not require the addition of hydrogen acceptors, has few side reactions, and the yield can reach more than 80%, and the product purity can reach more than 85%;

[0162] (4) The reaction conditions are not harsh: the reaction can be carried out under heating and the catalysis of supported FeCl3 catalyst or anhydrous FeCl3.

[0163] Compound I of the present invention can be used as a rubber antioxidant, providing more durable protection than conventional antioxidants, and does not produce blooming. Therefore, the present invention provides a rubber composition, which contains one or more of Compound I of the present invention. The raw materials of the rubber composition generally include diene elastomers, reinforcing fillers, antioxidants and crosslinking agents. The amounts of diene elastomers, reinforcing fillers, antioxidants and crosslinking agents can be conventional amounts in the art. Based on 100 parts by mass of diene elastomers, the amount of Compound I in the rubber composition can be 0.1-5 parts by mass, such as 0.5-5 parts by mass, 1-3 parts by mass, 1-2 parts by mass. Herein, the rubber composition includes unvulcanized rubber and vulcanized rubber. Unvulcanized rubber can be obtained by vulcanization (curing) to obtain vulcanized rubber.

[0164] Diene elastomer refers to an elastomer whose monomers contain dienes (such as butadiene, isoprene). Diene elastomers suitable for the present invention can be various diene elastomers known in the art, including but not limited to one or more selected from natural rubber (NR), butadiene rubber (BR), isoprene rubber, styrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), isoprene / butadiene copolymer, isoprene / styrene copolymer and isoprene / butadiene / styrene copolymer. In certain embodiments, in the rubber composition of the present invention, the diene elastomer is composed of natural rubber (such as SCR5) and butadiene rubber (such as BR9000); the mass ratio of natural rubber and butadiene rubber is not particularly limited, for example, 1:9 to 9:1, 2:8 to 8:2, 3:7 to 7:3, 4:6 to 6:4, or about 1:1.

[0165] The reinforcing filler may be a reinforcing filler conventionally used for rubber, including but not limited to one or more selected from carbon black, titanium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay and talc. The reinforcing filler may be used in an amount of 40-60 parts by mass of the reinforcing filler per 100 parts by mass of the diene elastomer.

[0166] The crosslinking agent may be sulfur. The amount of crosslinking agent used may be 1 to 3 parts by mass per 100 parts by mass of diene elastomer.

[0167] The amount of the antioxidant may be 0.1-5, 0.5-5, 1-3 or 1-2 parts by mass per 100 parts by mass of the diene elastomer. In the rubber composition of the present invention, the antioxidant may be compound I or a combination of compound I and a conventional antioxidant.

[0168] The raw materials of the rubber composition may also include other ingredients commonly used in rubber, including but not limited to additives and accelerators, etc. The amounts of the additives and accelerators may be conventional amounts in the art.

[0169] Auxiliary agent can include the softener used to improve processability. Softener can be petroleum softener such as aromatic oil, process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and vaseline etc., and can also be fatty oil softener such as castor oil, linseed oil, rapeseed oil, coconut oil, wax (such as beeswax, carnauba wax and lanolin), tall oil, linoleic acid, palmitic acid, stearic acid and lauric acid etc. Auxiliary agent can also include activating agent, such as zinc oxide, can play the effect such as accelerating vulcanization speed, improving rubber thermal conductivity, wear resistance, tear resistance. Usually, every 100 mass parts of diene elastomer uses the auxiliary agent of 5-20 mass parts in total, for example, 2-8 mass parts of aromatic oil, 2-8 mass parts of zinc oxide and 1-4 mass parts of stearic acid can be used.

[0170] The accelerator is usually a vulcanization accelerator, which can be at least one of sulfonamides, thiazoles, thiurams, thioureas, guanidines, dithiocarbamates, aldehyde amines, aldehyde amines, imidazolines and xanthate vulcanization accelerators. For example, the accelerator can be accelerator NS (N-tert-butyl-2-benzothiazole sulfenamide). Typically, 0.5-1.5 parts by mass of the accelerator are used per 100 parts by mass of the diene elastomer.

[0171] In addition, when necessary, the rubber composition may also contain plasticizers such as DMP (dimethyl phthalate), DEP (diethyl phthalate), DBP (dibutyl phthalate), DHP (diheptyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DIDP (diisodecyl phthalate), BBP (butyl benzyl phthalate), DWP (dilauryl phthalate), and DCHP (dicyclohexyl phthalate), etc. The amount of the plasticizer used is the conventional amount in the art.

[0172] The unvulcanized rubber of the present invention can be prepared by a conventional rubber mixing method, for example, by a two-stage mixing method: a first stage of mixing in an internal mixer, mixing the diene elastomer, reinforcing filler, auxiliary agent and antioxidant, with a rubber discharge temperature of 110°C or above; a second stage of mixing in an open mixer, mixing the rubber obtained in the first stage with a crosslinking agent and an accelerator. Usually, a diene elastomer is first added to a thermomechanical mixer (such as an internal mixer), and after kneading for a certain period of time, reinforcing fillers, auxiliary agents and antioxidants are added, and kneading is continued until the mixture is uniform. The reinforcing fillers, auxiliary agents and antioxidants can be added in batches, and the temperature during kneading is controlled between 110°C and 190°C, preferably between 150°C and 160°C; then, the mixture is cooled to below 100°C, a crosslinking agent and an accelerator are added, and kneading is performed again, and the temperature during kneading is controlled below 110°C, such as about 70°C, to obtain an unvulcanized rubber.

[0173] The unvulcanized rubber of the present invention can be vulcanized by conventional vulcanization methods to obtain vulcanized rubber; the vulcanization temperature is usually 130°C-200°C, such as about 145°C; the vulcanization time depends on the vulcanization temperature, the vulcanization system and the vulcanization kinetics, and is usually 15-60 minutes, such as about 30 minutes. Before vulcanization, the kneaded unvulcanized rubber can be conventionally sheeted.

[0174] Compound I and rubber composition of the present invention are used in rubber products, especially rubber tires, and can give rubber products or rubber tires more durable anti-aging properties, and do not produce frost. Therefore, the present invention also provides a rubber product, which uses the rubber composition of the present invention as its rubber component. The rubber product can be a tire, a rubber shoe, a sealing strip, a soundproofing board, a shockproof pad, etc. In certain embodiments, the rubber product is a tire, such as a tread, a belt layer and a sidewall of a tire. The belt layer of the tire, in addition to the rubber composition of the present invention, can also contain a reinforcing material conventionally used in the art.

[0175] The asymmetric diaryl-substituted p-phenylenediamine compounds of the present invention can prevent rubber products from blooming during use. The present invention also provides the use of the compound I of the present invention in improving the anti-aging performance and / or blooming property of rubber or rubber products.

[0176] The present invention will be described below in the form of specific examples, the purpose of which is to better understand the content of the present invention. It should be understood that these examples are merely illustrative and non-restrictive. The raw materials and reagents used in the examples are conventionally purchased from the market unless otherwise specified. The experimental methods, preparation methods and detection methods used in the examples are conventional methods unless otherwise specified. The instruments and equipment used in the examples are conventional instruments and equipment in the art unless otherwise specified. In the examples, unless otherwise specified, percentages refer to mass percentages.

[0177] The supported FeCl3 catalyst used in the examples was prepared by the following method:

[0178] Weigh a certain amount of anhydrous FeCl3, prepare a methanol solution of FeCl3 with methanol at a concentration of 8wt%, add it to a four-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, add a certain amount of dried carrier, the mass ratio of FeCl3 to carrier is 1:8, start mechanical stirring, gradually increase the temperature to methanol reflux, maintain reflux for 8h, then evaporate the methanol, increase the temperature to 150℃ and evacuate to an absolute pressure of 10kPa, maintain for 6h, cool down and quickly pour into a clean and dry reagent bottle, and store in a desiccator. In Examples 1-11, a supported FeCl3 catalyst prepared with a hydrogen molecular sieve (Shanghai Titan Chemical Co., Ltd., GENERAL-REAGENT, 4A) as a carrier was used, in Example 12, a supported FeCl3 catalyst prepared with an activated silicon oxide (Shanghai Titan Chemical Co., Ltd., GENERAL-REAGENT, G72651A) as a carrier was used, and in Example 13, a supported FeCl3 catalyst prepared with an activated alumina (Shanghai Titan Chemical Co., Ltd., GENERAL-REAGENT, G21116K) as a carrier was used.

[0179] Example 1: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0180]

[0181] (1) Add 96.8 g (0.8 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 12.96 g (0.08 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 200° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0182] (2) Add 16.2 g (0.1 mol) of anhydrous FeCl3, 111.6 g (1.2 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, heat to 230 °C and react until no water is discharged from the water separator, and the reaction is completed;

[0183] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 212 g (yield 81.0%). The content of the product was measured by GC analysis and the mass spectrometer was 88%. The molecular weight was 288.

[0184] Example 2: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0185] (1) Add 121 g (1 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 12.96 g (0.08 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, start stirring, heat to 220° C., react until no water is discharged from the water separator, filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0186] (2) Add 32.4 g (0.2 mol) of anhydrous FeCl3, 93 g (1 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 230°C and react until no water is discharged from the water separator, and the reaction is completed;

[0187] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 277 g (yield 85.6%). The content of the product was measured by GC analysis and the mass spectrometer was 89%. The molecular weight was 288.

[0188] Example 3: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0189] (1) Add 121 g (1 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 16.2 g (0.1 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 230° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0190] (2) Add 48.6 g (0.3 mol) of anhydrous FeCl3, 93 g (1 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 240°C and react until no water is discharged from the water separator, and the reaction is completed;

[0191] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 278 g (yield 89.8%). The content of the product was measured by GC analysis and the mass spectrometer was 93%. The molecular weight was 288.

[0192] Example 4: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0193] (1) Add 133.1 g (1.1 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 16.2 g (0.1 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 230° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0194] (2) Add 48.6 g (0.3 mol) of anhydrous FeCl3, 111.6 g (1.2 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0195] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 280 g (yield 91.4%). The content of the product was measured by GC analysis and the mass spectrometer was 94%. The molecular weight was 288.

[0196] Example 5: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0197] (1) Add 133.1 g (1.1 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 32.4 g (0.2 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, start stirring, heat to 220° C., react until no water is discharged from the water separator, filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0198] (2) Add 48.6 g (0.3 mol) of anhydrous FeCl3, 139.5 g (1.5 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0199] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 281 g (yield 91.7%). The content of the product was measured by GC analysis and the mass spectrometer was 94%. The molecular weight was 288.

[0200] Example 6: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0201] (1) Add 133.1 g (1.1 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 64.8 g (0.4 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, start stirring, heat to 230° C., react until no water is discharged from the water separator, filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0202] (2) Add 64.8 g (0.4 mol) of anhydrous FeCl3, 139.5 g (1.5 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0203] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 280 g (yield 88.5%). The content of the product was measured by GC analysis and the mass spectrometer was 91%. The molecular weight was 288.

[0204] Example 7: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0205] (1) Add 145.2 g (1.2 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 64.8 g (0.4 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 230° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0206] (2) Add 81 g (0.5 mol) of anhydrous FeCl3, 111.6 g (1.2 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 260°C and react until no water is discharged from the water separator, and the reaction is completed;

[0207] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 289 g (yield 85.3%). The content of the product was measured by GC analysis and the mass spectrometer was 85%. The molecular weight was 288.

[0208] Example 8: Preparation of N-phenyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-1)

[0209] (1) Add 145.2 g (1.2 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 32.4 g (0.2 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 230° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0210] (2) Add 64.8 g (0.4 mol) of anhydrous FeCl3, 167.4 g (1.8 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, heat to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0211] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 276 g (yield 83.3%). The content of the product was measured by GC analysis and the mass spectrometer was 87%. The molecular weight was 288.

[0212] In Examples 1-8, the amount of hydroquinone added was 1 mol. The differences in other conditions and experimental results are shown in Table 1.

[0213] Table 1: Experimental conditions and experimental results of Examples 1-8

[0214]

[0215] Example 9: N-phenyl-N'-(2,6-dimethyl)phenyl-p-phenylenediamine (Compound I-2)

[0216]

[0217] (1) Add 133.1 g (1.1 mol) of 2,6-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 16.2 g (0.1 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, start stirring, heat to 230° C., react until no water is discharged from the water separator, filter out the catalyst while hot, and distill off toluene and unreacted 2,6-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0218] (2) Add 48.6 g (0.1 mol) of anhydrous FeCl3, 111.6 g (1.2 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0219] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 275 g (yield 90.7%). The content of the product was measured by GC analysis and the mass spectrometer was 95%. The molecular weight was 288.

[0220] Preparation Example 10: N-phenyl-N'-(2-tert-butyl-4-methyl)phenyl-p-phenylenediamine (Compound I-3)

[0221]

[0222] (1) Add 179.3 g (1.1 mol) of 2-tert-butyl-4-methylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 16.2 g (0.1 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stirring is started, and the temperature is raised to 240° C. to react until no water is discharged from the water separator, and the catalyst is filtered out while hot. At this temperature, toluene and unreacted 2-tert-butyl-4-methylaniline are distilled off under reduced pressure to complete the first step of the reaction;

[0223] (2) Add 48.6 g (0.1 mol) of anhydrous FeCl3, 111.6 g (1.2 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0224] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 311 g (yield 87.6%). The content of the product was measured by HPLC analysis and the molecular weight was 330 by mass spectrometry.

[0225] Preparation Example 11: N-o-tolyl-N'-(2,3-dimethyl)phenyl-p-phenylenediamine (Compound I-4)

[0226]

[0227] (1) Add 133.1 g (1.1 mol) of 2,3-dimethylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 16.2 g (0.1 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 230° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,3-dimethylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0228] (2) Add 48.6 g (0.1 mol) of anhydrous FeCl3, 128.4 g (1.2 mol) of o-toluidine and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0229] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 290 g (yield 90.3%). The content of the sample was measured by GC analysis and the molecular weight was 302 by mass spectrometry.

[0230] Preparation Example 12: N-o-tolyl-N'-(4-tert-butyl)phenyl-p-phenylenediamine (Compound I-5)

[0231]

[0232] (1) Add 163.9 g (1.1 mol) of 4-tert-butylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 16.2 g (0.1 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 240° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 4-tert-butylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0233] (2) Add 48.6 g (0.1 mol) of anhydrous FeCl3, 128.4 g (1.2 mol) of o-toluidine and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0234] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 308 g (yield 87.8%). The content of the product was measured by HPLC analysis and the molecular weight was 330 by mass spectrometry.

[0235] Preparation Example 13: N-phenyl-N'-(2,4-di-tert-butyl)phenyl-p-phenylenediamine (Compound I-6)

[0236]

[0237] (1) Add 225.5 g (1.1 mol) of 2,4-di-tert-butylaniline, 110.0 g (1 mol) of hydroquinone, and a supported FeCl3 catalyst containing 32.4 g (0.2 mol) of FeCl3 to a 1 L stainless steel reactor equipped with a condenser and a water separator, and then add 20 ml of toluene. After nitrogen substitution, stir and heat to 240° C. to react until no water is discharged from the water separator. Filter out the catalyst while hot, and distill off toluene and unreacted 2,4-di-tert-butylaniline under reduced pressure at this temperature to complete the first step of the reaction;

[0238] (2) Add 48.6 g (0.1 mol) of anhydrous FeCl3, 111.6 g (1.2 mol) of aniline and 20 mL of xylene, start stirring after nitrogen replacement, raise the temperature to 250°C and react until no water is discharged from the water separator, and the reaction is completed;

[0239] (3) The temperature was lowered to 90° C., an aqueous solution containing 0.3 mol of sodium carbonate was added, the mixture was stirred for 1 h, the temperature was raised and the light component was distilled off under reduced pressure, and then filtered while hot. The filtrate was cooled and solidified into a block product of 330 g (yield 82.5%). The content of the product was measured by HPLC analysis and the molecular weight was 372 by mass spectrometry.

[0240] Test example:

[0241] The rubber compositions of Test Examples 1-4 were prepared according to the formulations shown in Table 2, specifically comprising the following steps:

[0242] 1. Add natural rubber SCR5 and synthetic rubber BR to an internal mixer, knead for a period of time, then add carbon black N550, aromatic oil, zinc oxide, stearic acid and antioxidants (antioxidant H, compound I-1, antioxidant 3100, compound I-6), and continue kneading until the mixture is uniform; during the kneading period, the temperature is controlled between 150°C and 160°C;

[0243] 2. Cool the entire mixture to below 100°C, then add the crosslinking system (sulfur S and accelerator NS), and knead the entire mixture; during kneading, control the temperature not to exceed 110°C;

[0244] 3. The obtained rubber composition was rolled into a sheet (thickness of 2-3 mm) and vulcanized at a vulcanization temperature of 145° C. for 30 minutes.

[0245] The sources of the ingredients in Table 2 are as follows:

[0246] SCR5: Xishuangbanna Sinochem Rubber Co., Ltd., natural rubber SCR5;

[0247] BR: Nanjing Yangzi Petrochemical Rubber Co., Ltd., synthetic rubber BR9000;

[0248] N550: Cabot Corporation, carbon black N550;

[0249] Aromatic oil: Shanghai Titan Technology Co., Ltd., general reagent;

[0250] Stearic acid: Shanghai Titan Technology Co., Ltd., general reagent, stearic acid (AR);

[0251] Zinc oxide: Shanghai Titan Technology Co., Ltd., general reagent, zinc oxide (AR);

[0252] NS: Shengao Chemical Technology Co., Ltd., vulcanization accelerator NS;

[0253] S: Sinopharm Chemical Reagent Company, sublimated sulfur (AR);

[0254] Antioxidant H: Shengao Chemical Technology Co., Ltd.;

[0255] Compound I-1: the compound synthesized in Example 4;

[0256] Antioxidant 3100: Acmechem Limited, India;

[0257] Compound I-6: the compound synthesized in Example 13.

[0258] Table 2: Formulation of rubber composition (unit: mass parts)

[0259]

[0260]

[0261] Ozone aging resistance performance evaluation:

[0262] Test pieces of various rubber compositions were subjected to ozone degradation tests at a temperature of 40°C, an ozone concentration of 50 pphm, and an elongation of 20%. The time for the appearance of cracks of grade 1c to 4c was recorded. The longer the time for the formation of cracks of the same grade, the better the anti-ozone aging performance. The experimental results are shown in Table 3. In Table 3, the numbers in "1c~4c" represent the crack width grade, and the letters represent the crack number grade; 1 means that the crack width is greater than 0mm and less than 0.1mm, 2 means that the crack width is greater than or equal to 0.1mm and less than 0.2mm, 3 means that the crack width is greater than or equal to 0.2mm and less than 0.4mm, and 4 means that the crack width is greater than or equal to 0.4mm; c means that the number of cracks per centimeter is greater than or equal to 40.

[0263] Table 3: Film ozone aging results

[0264] Test Example 1 Test Example 2 Test Example 3 Test Example 4 1c crack 3h 3h 3h 3h 2c crack 6h 6h 6h 6h 3c crack 22h 21h 21h 22h 4c crack 50h 60h 54h 62h

[0265] It can be seen from Table 3 that the time for the four test films to develop primary cracks is almost the same, and the time for the two films of Test Example 2 and Test Example 4 to develop 4c-level cracks is the longest, indicating that the anti-ozone aging performance of the homemade compounds I-1 and I-6 is better than that of antioxidant H and antioxidant 3100.

[0266] Evaluation of spray frosting performance:

[0267] The surface conditions of the films were observed one week and two weeks after the films were made. The results are shown in Table 4.

[0268] Table 4: Blooming performance test results

[0269] Test Example 1 Test Example 2 Test Example 3 Test Example 4 1 week Obvious frost phenomenon No change on the surface Slight frost No change on the surface 2 weeks Large area of ​​white frost No change on the surface Large area of ​​white frost No change on the surface

[0270] As can be seen from Table 4, the two films to which antioxidant H (Test Example 1) and antioxidant 3100 (Test Example 3) were added showed obvious blooming after being left for a period of time, while the two films to which homemade compound I-1 (Test Example 2) and homemade compound I-6 (Test Example 4) were added showed no blooming after being left for two weeks, indicating that the compounds of the present invention can improve the blooming properties.

Claims

1. A method for preparing an asymmetric diaryl-substituted p-phenylenediamine compound, characterized in that: The asymmetric diaryl-substituted p-phenylenediamine compound has a structure shown in the following formula A: In formula A, each R a independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5, each R b independently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0 to 5; the compound of formula A does not include (R a ) m Substituted phenyl and (R b ) n The same compounds with substituted phenyl groups; The method comprises: (1) reacting hydroquinone with a compound of formula B in the presence of a supported FeCl3 catalyst to obtain a compound of formula C: (2) reacting the compound of formula C with the compound of formula D in the presence of anhydrous FeCl3 to obtain a compound of formula A: Among them, in the compound of formula B, each R a are independently selected from hydrogen and C1-C6 alkyl, m is an integer selected from 0 to 5; in the compound of formula D, each R b independently selected from hydrogen and C1-C6 alkyl, n is an integer selected from 0 to 5; the compound of formula B is different from the compound of formula D; The carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieve, activated silicon oxide and activated aluminum oxide; in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10).

2. The method according to claim 1, characterized in that The method has one or more of the following features: The reaction of step (1) is carried out in a non-polar solvent; The reaction temperature of step (1) is 200-240° C. In the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.08-0.4):1; In the reaction system of step (1), the molar ratio of the compound of formula B to hydroquinone is (0.8-1.2):1; The reaction of step (1) is carried out in an inert gas atmosphere; The reaction in step (2) is carried out in a non-polar solvent; The reaction temperature of step (2) is 230-270° C. The molar ratio of the anhydrous FeCl3 added in step (2) to the hydroquinone added in step (1) is (0.1-0.5):1; The molar ratio of the compound of formula D added in step (2) to the hydroquinone added in step (1) is (1.0-1.8):1; and The reaction in step (2) is carried out in an inert gas atmosphere.

3. The method according to claim 2, characterized in that The method has one or more of the following features: The reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; The reaction temperature of step (1) is 220-230° C. In the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.1-0.25):1; In the reaction system of step (1), the molar ratio of the compound of formula B to hydroquinone is (0.9-1.1):1; The reaction in step (1) is carried out in a nitrogen atmosphere; The reaction of step (2) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; The reaction temperature of step (2) is 240-260° C. The molar ratio of the anhydrous FeCl3 added in step (2) to the hydroquinone added in step (1) is (0.2-0.3):1; The molar ratio of the compound of formula D added in step (2) to the hydroquinone added in step (1) is (1.2-1.5):1; and The reaction in step (2) is carried out in a nitrogen atmosphere.

4. The method according to claim 1, characterized in that The reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (1) is 220-230° C.; in the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.1-0.25):1, and the molar ratio of the compound of formula B to hydroquinone is (0.9-1.1):1; the reaction of step (1) is carried out in a nitrogen atmosphere; step (2) The reaction is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (2) is 240-260° C.; the molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is (0.2-0.3):1; the molar ratio of the compound of formula D added in step (2) to hydroquinone added in step (1) is (1.2-1.5):1; and the reaction of step (2) is carried out in a nitrogen atmosphere.

5. A method for preparing the compound of formula I: In Formula I, R1 and R3 are independently hydrogen or C1-C6 alkyl; R2 is C1-C6 alkyl; the compound of Formula I does not include a compound in which the phenyl substituted by R1 and R2 is the same as the phenyl substituted by R3; The method comprises: (1) reacting hydroquinone with the compound of formula II in the presence of a supported FeCl3 catalyst to obtain a compound of formula III: (2) reacting the compound of formula III with the compound of formula IV in the presence of anhydrous FeCl3 to obtain a compound of formula I: Wherein, in the compound of formula II, R1 and R2 are independently hydrogen or C1-C6 alkyl; in the compound of formula IV, R3 is C1-C6 alkyl; the compound of formula II and the compound of formula IV are not the same; or The method comprises: (1) reacting hydroquinone with a compound of formula IV in the presence of a supported FeCl3 catalyst to obtain a compound of formula III': (2) reacting the compound of formula III' with the compound of formula II in the presence of anhydrous FeCl3 to obtain a compound of formula I: Wherein, in the compound of formula II, R1 and R2 are independently hydrogen or C1-C6 alkyl; in the compound of formula IV, R3 is C1-C6 alkyl; the compound of formula II and the compound of formula IV are not the same; The carrier of the supported FeCl3 catalyst is selected from hydrogen molecular sieve, activated silicon oxide and activated aluminum oxide; in the supported FeCl3 catalyst, the mass ratio of FeCl3 to the carrier is 1:(5-10).

6. The method according to claim 5, characterized in that The method has one or more of the following features: The reaction of step (1) is carried out in a non-polar solvent; The reaction temperature of step (1) is 200-240° C. In the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.08-0.4):1; In the reaction system of step (1), the molar ratio of the compound of formula II or the compound of formula IV to hydroquinone is (0.8-1.2):1; The reaction of step (1) is carried out in an inert gas atmosphere; The reaction of step (1) is carried out in a non-polar solvent; The reaction temperature of step (2) is 230-270° C. The molar ratio of the anhydrous FeCl3 added in step (2) to the hydroquinone added in step (1) is (0.1-0.5):1; The molar ratio of the compound of formula IV or the compound of formula II added in step (2) to the hydroquinone added in step (1) is (1.0-1.8):1; and The reaction in step (2) is carried out in an inert gas atmosphere.

7. The method according to claim 6, characterized in that The method has one or more of the following features: The reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; The reaction temperature of step (1) is 220-230° C. In the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.1-0.25):1; In the reaction system of step (1), the molar ratio of the compound of formula II or the compound of formula IV to hydroquinone is (0.9-1.1):1; The reaction in step (1) is carried out in a nitrogen atmosphere; The reaction of step (2) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; The reaction temperature of step (2) is 240-260° C. The molar ratio of the anhydrous FeCl3 added in step (2) to the hydroquinone added in step (1) is (0.2-0.3):1; The molar ratio of the compound of formula IV or formula II added in step (2) to the hydroquinone added in step (1) is (1.2-1.5):1; and The reaction in step (2) is carried out in a nitrogen atmosphere.

8. The method according to claim 5, characterized in that In formula I, R1 is hydrogen, R2 and R3 are each independently a C1-C6 alkyl group; or R3 is hydrogen, R1 and R2 are each independently a C1-C6 alkyl group; or R1, R2 and R3 are each independently a C1-C6 alkyl group.

9. The method according to claim 5, characterized in that The reaction of step (1) is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (1) is 220-230° C.; in the reaction system of step (1), the molar ratio of FeCl3 contained in the supported FeCl3 catalyst to hydroquinone is (0.1-0.25):1, and the molar ratio of the compound of formula II or the compound of formula IV to hydroquinone is (0.9-1.1):1; the reaction of step (1) is carried out in a nitrogen atmosphere; step (2) The reaction is carried out in toluene, xylene, trimethylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, methylcyclohexane, dimethylcyclohexane and / or trimethylcyclohexane; the reaction temperature of step (2) is 240-260° C.; the molar ratio of anhydrous FeCl3 added in step (2) to hydroquinone added in step (1) is (0.2-0.3):1; the molar ratio of the compound of formula IV or the compound of formula II added in step (2) to the hydroquinone added in step (1) is (1.2-1.5):1; and the reaction of step (2) is carried out in a nitrogen atmosphere.

10. The method according to claim 5, characterized in that The compound of formula I is selected from:

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