Process for the photocatalytic oxidation amination for the preparation of amides

Abstract

The application relates to the technical field of amide preparation, and discloses a method for preparing amide through photocatalytic oxidation and amination. The method comprises the following steps: under visible light irradiation, a nitrogen source is reacted with a hydrocarbon compound in the presence of a photocatalyst and an additive, and after post-treatment, amide is obtained; wherein the photocatalyst is a photoactive carbazole compound; the additive comprises alkaline substances and acidic substances; and the hydrocarbon compound is selected from one or more of C3-C11 chain alkanes, C3-C11 cycloalkanes and C3-C11 alkyl-substituted aromatic hydrocarbons. According to the method, a C-C bond in a low or medium hydrocarbon compound is directly oxidized and aminated to break and synthesize chain amide or lactam through photocatalysis. The method has mild reaction conditions, avoids the use of a high-pressure mercury lamp or other ultraviolet lamps, avoids the generation of tar and coke under ultraviolet conditions, and avoids the use of a large amount of alcohol additives such as t-butyl alcohol.

Description

Technical Field

[0001] This invention relates to the field of amide preparation technology, and more specifically to a method for preparing amides by photocatalytic oxidation and amination. Background Technology

[0002] Amides are organic compounds in which the hydroxyl group of a carboxylic acid is replaced by an amino or amine group. They are mainly used as industrial solvents. In addition, amides are important intermediates in organic synthesis, with wide applications in biology, medicine, food, and chemical industries. They can serve as precursors for the synthesis of other organic compounds and polymers. Nylon 6 is a well-known important chemical raw material, a translucent or milky-white thermoplastic resin with excellent self-lubricating properties, wear resistance, and solvent resistance. The monomer for the polymerization of nylon-6 is caprolactam.

[0003] Currently, the main methods for preparing amides are the condensation of carboxylic acids and amines, and the ketoxime rearrangement. A more traditional method uses ketones as starting materials, reacting them with hydroxylamine to generate the corresponding ketoximes, which are then subjected to a Beckmann rearrangement catalyzed by strong protic and Lewis acids to produce the corresponding amides. The protic and Lewis acids used are concentrated sulfuric acid, aluminum chloride, phosphorus pentoxide, etc., and the reaction conditions are harsh, typically requiring high temperatures. Although many scientists have subsequently improved this method, the results have been minimal. The primary source of ketoximes is the corresponding ketone, and ketone compounds are significantly more expensive than alkanes. Synthesizing the corresponding ketone from alkanes and then performing a Beckmann rearrangement to synthesize amides is not only costly and time-consuming, but also poses a high risk when conducting large-scale reactions in a reactor. Therefore, the direct synthesis of amides from alkanes is of great significance.

[0004] Currently, the existing technologies for preparing caprolactam mainly include the cyclohexanone-hydroxylamine method using benzene as raw material, the hexahydrobenzoic acid amidation method using toluene as raw material, and the cyclohexane photonitrosation method. Among them, 98% of caprolactam is prepared by the cyclohexanone-hydroxylamine method. The photonitrosation reaction inevitably produces dimers of nitroso compounds, affecting the yield of oximes and subsequent rearrangements. Furthermore, the photonitrosation step is particularly expensive; the mercury or sodium lamps used are fragile and have short lifespans. They also require considerable cooling and power supply (considering their high power consumption), making them costly. Moreover, the nitrosation reagent step (mainly nitrosyl chloride and trichloronitromethane-containing chlorinated reagents) produces 5%-10% chlorinated derivatives, forming chlorooxime hydrochlorides, which reduce the rearrangement yield in the subsequent Beckmann rearrangement. The presence of hydrochloric acid in the reaction necessitates particularly expensive safety materials and equipment, and the use of easily decomposable nitrosyl chloride makes scale-up difficult, resulting in a very low market share. Finally, the reaction produces a large amount of byproduct tar, leading to low product conversion rates. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of expensive raw materials, cumbersome preparation steps, and harsh reaction conditions in existing technologies, and to provide a method for photocatalytic oxidation and amination to prepare amides. This method features mild reaction conditions, avoiding the use of high-pressure mercury lamps or other ultraviolet lamps, preventing the generation of tar and coke under ultraviolet conditions, avoiding the use of large amounts of alcohol additives such as tert-butanol, avoiding the synthesis or use of ketone intermediates, and avoiding the formation of byproducts such as ketone oxime dimers. This method is highly efficient, reducing the reaction time from more than ten hours under ultraviolet irradiation conditions to less than one hour, enabling a one-pot, one-step synthesis of chain amides or lactams from low- to medium-grade (C3-C11) alkanes in high yield.

[0006] To achieve the above objectives, the present invention provides a method for preparing amides by photocatalytic oxidation and amination, the method comprising: reacting a nitrogen source with a hydrocarbon compound or its derivative under visible light irradiation in the presence of a photocatalyst and an additive, and obtaining an amide after post-treatment; wherein the photocatalyst is a photoactive carbazole compound, and the additive includes basic and acidic substances; the hydrocarbon compound is selected from one or more of cycloalkanes, chain alkanes, and alkyl-substituted aromatics.

[0007] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0008] This invention utilizes a method that, under visible light irradiation and in the presence of a photocatalyst and additives, directly breaks and rearranges the C-C bonds in C3-C11 hydrocarbons or their derivatives to synthesize chain amides or lactams via photocatalysis. The reaction conditions are mild, avoiding the use of high-pressure mercury lamps or other ultraviolet lamps, preventing the formation of tar and coke under ultraviolet conditions, avoiding the use of large amounts of alcohol additives such as tert-butanol, avoiding the synthesis or use of ketone intermediates, and avoiding the formation of byproducts such as ketone oxime dimers. This method is highly efficient, reducing the reaction time from over ten hours under ultraviolet irradiation to less than one hour, enabling a one-pot, one-step high-yield synthesis of chain amides or lactams from low- to medium-grade alkanes.

[0009] The method of this invention avoids the use of nitrosating agents (mainly nitrosyl chloride, trichloronitromethane chlorinated reagents), preventing the formation of chlorinated derivatives, which in turn form chlorooxime hydrochloride. Such chlorinated derivatives would reduce the yield of the rearrangement in the subsequent Beckmann rearrangement. Detailed Implementation

[0010] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0011] This invention provides a method for preparing amides by photocatalytic oxidation and amination. The method includes: reacting a nitrogen source with a hydrocarbon compound under visible light irradiation in the presence of a photocatalyst and an additive, followed by post-treatment to obtain an amide; wherein the photocatalyst is a photoactive carbazole compound; the additive includes basic and acidic substances; and the hydrocarbon compound is selected from one or more of C3-C11 chain alkanes, C3-C11 cycloalkanes, and C7-C11 alkyl-substituted aromatics.

[0012] In this invention, the additive can promote the transfer of hydrogen in the reaction and promote the formation of amide.

[0013] This invention enables the conversion from low to medium-grade alkanes to amides at low temperatures. The method of this invention can be used to prepare chain amides, cyclic amides, and aryl amides.

[0014] This invention obtains amides through photocatalysis. It can be achieved by direct heating and melting or by using hydrocarbon compounds themselves as solvents, eliminating the need for additional solvents such as tert-butanol. This ensures the sustainable use of raw materials and addresses the competitive influence of alcohols during subsequent rearrangement. This invention requires only a small amount of photocatalyst to achieve efficient conversion of alkanes to amides, significantly shortening the reaction time. Using a flow reactor will further shorten the reaction time and improve reaction efficiency and yield.

[0015] The method of this invention directly synthesizes amides by photocatalytically breaking and rearranging the C-C bonds of low and medium alkanes. The reaction avoids the use of nitrosating agents (mainly nitrosyl chloride, trichloronitromethane chlorinated reagents), preventing the formation of chlorinated derivatives, which in turn form chlorooxime hydrochloride. Such chlorinated derivatives will reduce the rearrangement yield in the subsequent Beckmann rearrangement.

[0016] The method of this invention features mild reaction conditions, avoiding the use of high-pressure mercury lamps or other ultraviolet lamps, thus preventing the formation of tar and coke under ultraviolet conditions, the use of large amounts of alcohol additives such as tert-butanol, the synthesis or use of ketone intermediates, and the formation of byproducts such as ketone oxime dimers. This method is highly efficient, reducing the reaction time from over ten hours under ultraviolet irradiation conditions to less than one hour, enabling a one-pot, one-step synthesis of chain amides or lactams from low- to medium-grade alkanes in high yield.

[0017] In some embodiments of the present invention, the photoactive carbazole compound is selected from one or more compounds with the structure shown in Formula II;

[0018]

[0019] In Equation II, R 1 and R 2 Ar 1 One or more substituents; R 1 and R 2 Each of the following groups can be independently represented as hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 alkyl or C 3-12 cycloalkyl; R 3 It is hydrogen, tert-butoxycarbonyl, p-toluenesulfonyl, methanesulfonyl, silyl, aryl, heteroaryl, C 1-12 alkyl or C 3-12 cycloalkyl;

[0020] R4, R5, R6, and R7 are each independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthraceneyl, phenanthryl, ester, cyano, or C. 1-12 Alkyl groups; wherein, R 4 -R 7 Adjacent groups can be independently or linked by chemical bonds to form five- or six-membered aromatic or heteroaromatic rings; dashed lines represent those that can form bonds or those that cannot. Ar 1 and Ar 2 Each is an aromatic ring or a 5-6 member heterocyclic aromatic ring.

[0021] In some embodiments of the present invention, the photoactive carbazole compound is selected from one or more compounds with structures shown in formulas IIA-IIG;

[0022]

[0023] Among them, R 1 and R 2 Ar 1 One or more substituents; R 1 and R 2 Each of the following groups can be independently represented as hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 alkyl or C 3-12 cycloalkyl; R 3 It is hydrogen, tert-butoxycarbonyl, p-toluenesulfonyl, methanesulfonyl, silyl, aryl, heteroaryl, C 1-12 alkyl or C 3-12 cycloalkyl; Ar1 Ar 2 and Ar 3 Each ring can be independently composed of naphthalene, anthracene, phenanthrene, or heteroaromatic rings.

[0024] In formula IIA, R 4 Ar 3 One or more substituents; R 5 Ar 2 One or more substituents; R 4 and R 5 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups;

[0025] In Equation IIB, R 4 R represents one or more substituents in the benzene ring. 5 Ar 2 One or more substituents; R 4 and R 5 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups;

[0026] In formula IIC, R 4 and R 5 Ar 2 One or more substituents; R 4 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl group; R 5 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl group; R 6 and R 7 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups;

[0027] In formula IID, R 4 and R 5 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl group; R 6 and R 7 Ar 2 One or more substituents; R 6It can be hydrogen, trihalomethyl, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, C 1-12 alkyl or C 3-12 cycloalkyl; R 7 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, acyl, phenyl, naphthyl, anthracene, phenanthrene, cyano, or C. 1-12 Alkyl groups;

[0028] In formula IIE, R 4 and R 5 Ar 2 One or more substituents; R 6 and R 7 Ar 3 One or more substituents; R 4 R 5 R 6 and R 7 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl group; R 8 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl groups;

[0029] In formula IIF, R 4 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, ester, cyano, or C. 1-12 Alkyl group; R 5 and R 6 Ar 2 One or more substituents; R 7 and R 8 Ar 3 One or more substituents; R 5 R 6 R 7 and R 8 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups;

[0030] In formula IIG, R 4 and R 5 Ar 2 One or more substituents; R 6 and R 7 Ar 3 One or more substituents; R 8 and R 9Ar 4 One or more substituents; R 4 R 5 R 6 R 7 R 8 and R 9 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups.

[0031] In this invention, the heteroaromatic rings include, but are not limited to: pyridine, thiophene, furan, pyrrole, indole, quinoline, pyrazine, thiazole, pyrimidine, or triazole.

[0032] In some embodiments of the present invention, the photocatalyst is a compound with the structure shown in Formula IIA and / or a compound with the structure shown in Formula IIB.

[0033] Preferably, in formula IIA, R 1 Hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, C 1-12 Acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, C 1-12 alkyl or C 3-12 cycloalkyl; R 2 It can be hydrogen, trihalomethyl, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, ester, cyano, C 1-12 alkyl or C 3-12 cycloalkyl; R 3 It can be hydrogen, B℃, Ts, Ms, silyl, aryl, heteroaryl, or C. 1-12 alkyl or C 3-10 cycloalkyl; R 4 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl group; R 5 It can be hydrogen, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, cyano, or C. 1-12 Alkyl groups.

[0034] Preferably, in formula IIB, R 1 It is a dialkylamine, alkoxy, or C 1-12 Alkyl group; R 2 For hydrogen, C 1-10 alkyl, phenyl, naphthyl, anthraceneyl, or phenanthrene; R 3 It is hydrogen, tert-butoxycarbonyl, silyl, aryl, heteroaryl, or C 1-10 alkyl, R 4 It can be an ester group, cyano group, formyl group, acetyl group, trihalomethyl group, or halogen; R5 It is phenyl, naphthyl, anthracene or C 1-12 Alkyl groups; Ar 1 and Ar 2 Each is independently a naphthalene ring, anthracene ring, or phenanthrene ring; Ar 3 It is selected from indole, quinoline, pyrazine, thiazole, pyrimidine, or triazole.

[0035] In this invention, the photocatalyst includes, but is not limited to, one or more compounds with structures shown in Formulas II-1 to II-26:

[0036]

[0037]

[0038] In some embodiments of the present invention, the alkaline substance is selected from one or more organic bases and inorganic bases.

[0039] In some embodiments of the present invention, the inorganic base is selected from one or more of ammonia, carboxylates, carbonates, bicarbonates, and hydroxides; more preferably, the inorganic base is selected from one or more of ammonia, lithium formate, lithium acetate, lithium propionate, sodium formate, sodium acetate, sodium propionate, potassium formate, potassium acetate, potassium propionate, cesium formate, cesium acetate, cesium propionate, sodium carbonate, sodium bicarbonate, cesium carbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

[0040] In some embodiments of the present invention, the organic base is selected from one or more organic amines and organic salts; wherein the organic salt is obtained by reacting an alcohol with an alkali metal or an alkaline earth metal.

[0041] In some embodiments of the present invention, the organic amine is selected from one or more of aliphatic amines, alcoholic amines, alicyclic amines, aromatic amines, naphthyl amines, and hydroxylamines.

[0042] In some embodiments of the present invention, the alcohol is selected from one or more of methanol, ethanol, n-butanol, isopropanol, tert-butanol, n-pentanol, isoamyl alcohol, and hexanol.

[0043] In some embodiments of the present invention, the alkali metal is selected from one or more of lithium, sodium, potassium, cesium, and francium.

[0044] In some embodiments of the present invention, the alkaline earth metal is selected from one or more of magnesium, calcium, and barium.

[0045] In some embodiments of the present invention, the aliphatic amines are selected from primary amines of C1 to C18, secondary amines of C1 to C18, or tertiary amines.

[0046] Preferably, the aliphatic amine is selected from one or more of methylamine, propylamine, butylamine, dimethylamine, diethylamine, diisopropylamine, diisopropylethyl, diisobutylamine, trimethylamine, triethylamine, tributylamine, triisopropylamine, triethylenediamine (which may also be named 1,4-diazabicyclo[2.2.2]octane or abbreviated as DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (or abbreviated as DBU), tetrabutylamine, tetramethylguanidine (TMG), and tert-butylamine.

[0047] In some embodiments of the present invention, the acidic substance is selected from at least one of acidified substances or acidified substitutes.

[0048] Preferably, the acid compound is selected from Lewis acids and / or Brønsted acids; more preferably, the Lewis acid is selected from one or more of boron trifluoride, aluminum trichloride, aluminum tribromide, ferric chloride, etc.; even more preferably, the Brønsted acid is selected from one or more of sulfuric acid, hydrochloric acid, acetic acid, formic acid, propionic acid, benzoic acid, substituted sulfonic acid and trichloroacetic acid; and even more preferably, the substituted sulfonic acid is selected from aminosulfonic acid or p-toluenesulfonic acid.

[0049] Preferably, the acidification substitute is selected from one or more of formyl chloride, acetyl chloride, propionyl chloride, butyryl chloride, cyanuric chloride, trifluoromethanesulfonyl chloride, p-toluenesulfonyl chloride, formyl bromide, acetyl bromide, propionyl bromide, butyryl bromide, cyanuric bromide, trifluoromethanesulfonyl bromide, p-toluenesulfonyl bromide, and elemental iodine.

[0050] The additives in this invention, consisting of alkaline and acidic substances, can work together to maintain the reaction system in a neutral state, thereby promoting efficient reaction.

[0051] In some embodiments of the present invention, the hydrocarbon compound or its derivative has the structure shown in Formula I, wherein Formula I contains at least one methylene group; wherein, R a and R b Same or different, R a H, halogen, nitro, C 1-10 alkyl, C 1-10 Alkoxy, acyl, cyano, aryl, C 1-10 Substituted ester or nitro group, R b To replace or not be replaced by C 2-10 Alkyl, aryl, benzyl, or ester group; R a and R b Optional cyclic or non-cyclic, R a and R b Each can form an independent loop, or R a and R b They are linked together in a ring by chemical bonds;

[0052]

[0053] In some embodiments of the present invention, the cycloalkane is selected from one or more alkanes having 3-11 carbon atoms on the ring; preferably, the cycloalkane is selected from one or more of cyclopropane, cyclobutane, cyclopentane, methylcyclopentanecyclohexane, methylcyclohexane, cycloheptane, cyclooctane, cyclononane, and cyclodecane.

[0054] In some embodiments of the present invention, the chain alkane is selected from C10. 3-11 straight-chain alkanes and C 3-11 The branched alkane is selected from one or more of n-propane, n-butane, n-pentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, 2-methyldecane, and 5-methylnonane.

[0055] In some embodiments of the present invention, the alkyl-substituted aromatic hydrocarbon has the structure shown in Formula III; wherein, R c Selected from H, halogen, nitro, C 1-4 Substituted or unsubstituted alkyl, C 1-4 Substituted or unsubstituted alkoxy, acyl, cyano, aryl, C-containing 1-4 Substituted ester group, R d Selected from substituted or unsubstituted alkanes, R c and R d Cyclic or non-cyclic formation is optional;

[0056]

[0057] Preferably, the alkyl-substituted aromatic hydrocarbon is selected from one or more of ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 4-chloroethylbenzene, p-ethylacetophenone, p-ethylbenzonitrile, methyl p-ethylbenzoate, p-ethylbenzeneboronic acid pinacol ester, and 4-ethylbiphenyl.

[0058] In some embodiments of the present invention, the derivative of the hydrocarbon compound is selected from one or more of n-hexanol, n-heptanol, chlorocyclohexane, methyl cyclohexane, n-octane bromo, 1-heptadecanol, 1-methoxy-hexane, 1,6-dimethoxyhexane, and hexyl acetate.

[0059] In some embodiments of the present invention, the nitrogen source is selected from one or more of alkyl nitrites, aryl nitrites, and alternatives to nitrites.

[0060] Preferably, the alkyl nitrite is an ester formed by nitrous acid and an alcohol, and more preferably one or more of the following: an ester formed by a C1 to C20 n-alcohol and nitrous acid, an ester formed by a C1 to C20 iso-alcohol and nitrous acid, methyl nitrite, ethyl nitrite, propyl nitrite, isopropyl nitrite, isobutyl nitrite, tert-butyl nitrite, pentyl nitrite, isopentyl nitrite, neopentyl nitrite, 2-methoxyethyl nitrite, and 1-methoxypropyl-2-yl nitrite.

[0061] Preferably, the aryl nitrite is selected from one or more esters formed by nitrite and phenol or substituted phenol.

[0062] Preferably, the substitute for the nitrite is (1) a product generated by the reaction of NO, O2 with alcohol and / or phenol; (2) a product generated by the reaction of NO2, NO with alcohol or phenol; or (3) a product generated by the reaction of NaNO2 with alcohol and / or phenol; more preferably, the alcohol has a structure of C1 to C20; more preferably, the phenol has a structure of phenol and one or more phenols with one or more of the ortho, meta, and para positions of the aromatic ring.

[0063] The method of the present invention uses nitrite or its substitute (a mixture of nitric oxide, oxygen and alcohol or phenol, a mixture of nitric oxide, nitrogen dioxide and alcohol or phenol, or a mixture of sodium nitrite and alcohol or phenol) as a nitrogen source, and under the action of a photocatalyst and additives, the C-C bonds in alkanes are directly broken and rearranged to synthesize amides.

[0064] In some embodiments of the present invention, the molar ratio of the nitrogen source to the hydrocarbon compound or its derivative is 1:20-200, preferably 1:20-100.

[0065] In some embodiments of the present invention, the molar ratio of the photocatalyst to the nitrogen source is 1:50-200, preferably 1:50-100.

[0066] In some embodiments of the present invention, the molar ratio of the photocatalyst to the additive is 1:20-200, preferably 1:20-100.

[0067] In some embodiments of the present invention, the molar ratio of the alkaline substance to the acidic substance is 1:2-50, preferably 1:2-10.

[0068] The hydrocarbon compounds or their derivatives in this invention do not require drying, reducing operational steps and energy consumption.

[0069] In some embodiments of the present invention, the light is light that can be obtained from any light source.

[0070] Preferably, the light is visible light with a wavelength of 390-760nm, more preferably 400-500nm.

[0071] This invention allows the reaction to occur under visible light irradiation, using an LED light source in the visible light region of 400-500nm. This greatly improves the heat dissipation and energy consumption of the system, avoiding the tar problem that occurs during the reaction (caused by insufficient heat dissipation and numerous byproducts).

[0072] In some embodiments of the present invention, the reaction is carried out in a flow reactor or a batch reactor.

[0073] In some embodiments, the method includes: S1A, adding a hydrocarbon compound or its derivative, a nitrogen source, a photocatalyst and an additive in a flow reactor under visible light irradiation at a temperature of 0-200°C, and reacting for 0.1-24 h.

[0074] In other embodiments, the method includes: S1B, adding a hydrocarbon compound or its derivative, a nitrogen source, a photocatalyst, and an additive in a batch reactor under visible light irradiation at a temperature of 0-200°C, and reacting for 0.1-24 hours.

[0075] The reaction provided by this invention, which involves the direct oxidation-amination cleavage and rearrangement of C-C bonds in low- to medium-grade (C3-C11) hydrocarbons or their derivatives via photocatalysis, can be carried out in a batch reactor or a flow reactor. Carrying it in a flow reactor can significantly shorten the reaction time and easily scale up the reaction.

[0076] In some embodiments of the present invention, the method further includes:

[0077] S2. Filter the reaction solution obtained in step S1A or S1B to remove solid waste.

[0078] S3. Distill the filtrate obtained in step S2 to collect the unreacted raw materials;

[0079] S4. The remaining solid from step S3 is recrystallized, filtered, and separated to obtain the amide product;

[0080] S5. The filtrate from step S4 is concentrated and separated to obtain the amide product, and the photocatalyst is recovered at the same time.

[0081] In this invention, the photocatalyst is recyclable and reusable. Under laboratory-scale conditions, residual reactants are recovered by distillation. In industrial production, alkanes are evaporated and recovered for reuse via flash evaporation, and most of the cyclic amide product is obtained by recrystallization, after which the photocatalyst is reused. The photocatalyst recovery rate is high, even exceeding 99%.

[0082] The method of this invention uses inexpensive raw materials, is simple and easy to operate, operates under mild reaction conditions, and yields high output, making it a green synthesis method. After the reaction, the photocatalyst can be recovered and reused with a yield of >99%, and the hydrocarbon compounds can also be recovered and reused.

[0083] The reaction of this invention can be scaled up with minimal impact on yield and reaction time, enabling large-scale preparation of amides. The method of this invention is simple to operate, operates under mild conditions, and yields high amounts, making it a green synthetic method.

[0084] The photocatalyst of this invention has excellent catalytic effect, can complete the reaction well, and obtain the final amide product in high yield.

[0085] The method of this invention achieves excellent results without the need for tert-butanol as a solvent, as the reaction is carried out under the action of a photocatalyst. In existing technologies, tert-butanol is indispensable, as it participates in the reaction and stabilizes the generated nitric oxide free radicals. However, through in-depth research, the inventors discovered that the reaction can proceed well without the addition of tert-butanol. Moreover, omitting tert-butanol avoids the following drawbacks: the addition of large amounts of tert-butanol can significantly affect the subsequent rearrangement (competing with the active intermediate of the rearrangement), and subsequent removal processes need to be considered; the reaction time is very long, indicating low reaction efficiency, which is difficult to implement in industrial applications.

[0086] The reaction of this invention can be carried out simultaneously in a batch reactor and a flow reactor. However, carrying out the reaction in a flow reactor can minimize the reaction time and has virtually no impact on subsequent scale-up of the reaction. In contrast, existing amide preparations can only be carried out in a batch reactor, which poses a high risk and lacks reproducibility when scaling up the reaction.

[0087] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0088] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents and instruments used without a specified manufacturer are all commercially available products.

[0089] Example 1

[0090] Synthesis of 2-azhexanecycloone:

[0091] Isopropyl nitrite (0.3 mol) was pumped into a flow reactor at a constant rate over one hour. The compound with the structure shown in Formula II-1, DABCO, cyclopentane, and acetic acid were mixed in a specific molar ratio (compound with the structure shown in Formula II-1:DABCO = 1:5; nitrite:the sum of the compound with the structure shown in Formula II-1 and DABCO = 1:0.08; nitrite:cyclopentane = 1:20; nitrite:acetic acid = 2:1) and simultaneously pumped into the flow reactor. The mixture was then irradiated with 50W LEDs and reacted at 40°C for 0.5 h. After the reaction was complete, the reaction solution was filtered to remove solid waste. The filtrate was then acidified, cooled, and crystallized to obtain the final amide product. The unreacted raw material was then obtained by distillation. The remaining liquid after recrystallization was evaporated to dryness for further recrystallization to recover the photocatalyst. Finally, the target product, 2-azhexanecycloone, was obtained with a yield of 97% (28.8 g). The photocatalyst was recovered with a yield greater than 99%.

[0092] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting by C NMR confirmed that the compound was 2-azhexane ketone.

[0093] 1 H NMR (CDCl3, 400MHz): δ7.49 (brs, 1H), 3.27-3.18 (m, 2H), 2.30-2.20 (m, 2H), 1.75-1.63 (m, 4H). 13 C NMR (CDCl3, 100MHz): 173.1, 42.2, 31.6, 22.4, 21.0.

[0094] Example 2

[0095] Synthesis of caprolactam:

[0096] Methyl nitrite (0.3 mol) was reacted and post-treated according to the procedures and post-treatment steps in Example 1, wherein the proportions of various compounds were: methyl nitrite: the sum of the compound with the structure shown in Formula II-18 and K2CO3 = 1:0.25, the compound with the structure shown in Formula II-18: K2CO3 = 1:5; methyl nitrite: cyclohexane = 1:200; methyl nitrite: formic acid = 1:0.4, the pumping time was 1.5 h, the reaction was carried out under 50 W LEDs illumination at 0 °C for 1.5 h; finally, the target product caprolactam was obtained in a yield of 98%, 33.2 g. The photocatalyst was recovered in a yield greater than 99%.

[0097] By nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13The structure of the product was determined by chemical shift and coupled splitting analysis using C NMR.

[0098] 1 H NMR (CDCl3, 400MHz): δ7.16 (brs, 1H), 3.18-3.11 (m, 2H), 2.42-2.37 (m, 2H), 1.69-1.57 (m, 6H). 13 C NMR (CDCl3, 100MHz): 179.73, 42.99, 36.99, 30.85, 29.94, 23.46.

[0099] Example 3

[0100] Synthesis of 2-azacyclooctone:

[0101] Isobutyl nitrite (0.2 mol) was reacted and post-treated according to the procedures and post-treatment steps in Example 1, wherein the proportions of various compounds were as follows: Isobutyl nitrite: the sum of compound II-13 (structure shown in Formula II) and 1,8-diazabicyclo[5.4.0]undec-7-ene = 1:0.25, compound II-13 (structure shown in Formula II): 1,8-diazabicyclo[5.4.0]undec-7-ene = 1:5; Isobutyl nitrite: cycloheptane = 1:50; Isobutyl nitrite: p-toluenesulfonyl chloride: cycloheptane = 1:0.4:20, with a pumping time of 1.5 h, irradiated by 70 W LEDs, and reacted at 10 °C for 1 h; finally, the target product 2-azacyclooctanone was obtained in a yield of 97%, 24.6 g. The photocatalyst was recovered in a yield greater than 99%.

[0102] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting by C NMR confirmed that the compound was 2-azacyclooctanone.

[0103] 1 H NMR (CDCl3, 400MHz): δ6.16 (brs, 1H), 3.33-3.28 (m, 2H), 2.40 (t, J = 6.4Hz, 2H), 1.82-1.76 (m, 2H), 1.61-1.51 (m, 6H). 13 C NMR (CDCl3, 100MHz): 178.3, 42.1, 32.5, 32.3, 28.3, 26.0, 24.7.

[0104] Example 4

[0105] Synthesis of N-hexylacetamide:

[0106] 0.2 mol of isoamyl nitrite was reacted and post-treated according to the procedures and post-treatment steps in Example 1, wherein the ratios of various compounds were: isoamyl nitrite: the sum of compound II-4 (structure II) and CH3COONa (formula II) = 1:0.45, compound II-4 (structure II) : CH3COONa = 1:8; isoamyl nitrite : n-octane = 1:20; isoamyl nitrite : propionic acid = 1:0.8, the pumping time was 1.5 h, the reaction was carried out under 100 W LEDs illumination at 30 °C for 0.75 h; finally, the target product amide was obtained with a total yield of 91%, 26.1 g. The photocatalyst was recovered with a yield greater than 99%.

[0107] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting by C NMR confirmed that the compound was N-hexylacetamide.

[0108] 1 H NMR (CDCl3, 400MHz): δ5.49 (brs, 1H), 3.22 (q, J = 6.2Hz, 2H), 1.97 (s, 3H), 1.52-1.44 (m, 2H), 1.34-1.26 (m, 6H), 0.87 (t, J = 6.9Hz, 3H). 13 CNMR(CDCl3,100MHz):170.4,40.0,31.8,29.9,26.9,23.7,22.9,14.3.

[0109] Example 5

[0110] Synthesis of N-(5-hydroxypentyl)acetamide

[0111] Isoamyl nitrite (0.2 mol) was reacted and post-treated according to the procedures and post-treatment steps in Example 1, wherein the proportions of various compounds were: isoamyl nitrite: the sum of compound II-15 (structure shown in Formula II) and CH3COONa = 1:0.55, compound II-15 (structure shown in Formula II): CH3COONa = 1:10; isoamyl nitrite: n-heptane = 1:30; isoamyl nitrite: propionic acid = 1:1; the pumping time was 1 h, the reaction was carried out under 150 W LEDs illumination, and the reaction was carried out at 40 °C for 0.5 h; finally, the target product N-(5-hydroxypentyl)acetamide was obtained in a yield of 87%, 25.3 g. The photocatalyst was recovered in a yield greater than 99%.

[0112] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13Chemical shift and coupling splitting by C NMR confirmed that the compound was N-(5-hydroxypentyl)acetamide.

[0113] 1 H NMR (CDCl3, 300MHz): δ3.70 (t, 2H, J = 6.0Hz), 3.26 (m, 2H), 2.71 (s, 3H), 1.49-1.67 (m, 4H), 1.32-1.48 (m, 2H); 13 C NMR (CDCl3, 75MHz): δ170.5, 62.3, 39.5, 32.0, 29.2, 23.2, 23.0.

[0114] Example 6

[0115] Synthesis of N-phenylacetamide:

[0116] Ethyl nitrite (0.2 mol) was reacted and post-treated according to the procedures and post-treatment steps in Example 1, wherein the ratios of various compounds were: ethyl nitrite: the sum of compound II-9 (structure shown in Formula II) and cesium formate (HCOOCs) = 1:0.35, compound II-9 (structure shown in Formula II): HCOOCs = 1:6; ethyl nitrite: ethylbenzene = 1:20; ethyl nitrite: acetic acid = 1:0.6, the pumping time was 1 h, the reaction was carried out under 100 W LEDs illumination at 50 °C for 0.4 h; finally, the target product N-phenylacetamide was obtained in a yield of 85%, 23.0 g. The photocatalyst was recovered in a yield greater than 99%.

[0117] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting by C NMR confirmed that the compound was N-phenylacetamide.

[0118] 1 H NMR (CDCl3, 400MHz): δ7.60 (brs, 1H), 7.49 (d, J = 7.9Hz, 2H), 7.30 (t, J = 7.7Hz, 2H), 7.10 (t, J = 7.4Hz, 1H), 2.16 (s, 3H).

[0119] 13 C NMR (CDCl3, 100MHz): 168.9, 138.2, 129.3, 124.6, 120.3, 24.8.

[0120] Example 7

[0121] Synthesis of N-phenyloctamide:

[0122] 0.2 mol of phenyl nitrite was reacted and post-treated according to the procedures and post-treatment steps in Example 1, wherein the proportions of various compounds were: phenyl nitrite: the sum of compound II-10 (structure shown in Formula II) and HCOOK = 1:0.45, compound II-10 (structure shown in Formula II): HCOOK = 1:8; phenyl nitrite: 1-phenyloctane = 1:30, phenyl nitrite: p-toluenesulfonyl chloride: 1-phenyloctane = 1:0.8:20, the pumping time was 1 h, the reaction was carried out under 150 W LEDs illumination, and the reaction was carried out at 60 °C for 0.3 h; finally, the target product N-phenylacetamide was obtained in a yield of 88%, 38.6 g. The photocatalyst was recovered in a yield greater than 99%.

[0123] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting by C NMR confirmed that the compound was N-phenyloctamide.

[0124] 1 H NMR (CDCl3, 400MHz): δ7.65 (brs, 1H), 7.52 (d, J = 8.1Hz, 2H), 7.29 (t, J = 7.4Hz, 2H), 7.08 (t, J = 7.3Hz,1H),2.34(t,J=7.5Hz,2H),1.75-1.67(m,2H),1.31-1.27(m,8H),0.88(t,J=6.6Hz,3H).

[0125] 13 C NMR (CDCl3, 100MHz): 172.2, 138.4, 129.2, 124.4, 120.25, 38.1, 32.0, 29.6, 29.4, 26.0, 22.9, 14.4.

[0126] Example 8

[0127] Synthesis of (1S,2R,5S)-2-isopropyl-5-methylcyclohexyl-4-acetaminobenzoate:

[0128] Isopropyl nitrite (0.1 mol) was reacted and post-treated according to the operating and post-treatment steps in Example 1, wherein the ratios of various compounds were as follows: Isopropyl nitrite: Compound II-21 of Formula II and HCOOK = 1:0.35, Compound II-21 of Formula II: HCOOK = 1:6; Isopropyl nitrite: (1S,2R,5S)-2-isopropyl-5-methylcyclohexyl-4-ethylbenzoate = 1:30; Isopropyl nitrite: p-toluenesulfonyl chloride: (1S,2R,5S)-2-isopropyl-5-methylcyclohexyl-4-ethylbenzoate = 1:0.6:20, with a pumping time of 1 h, irradiated by 150 W LEDs, and reacted at 80 °C for 0.2 h; Finally, the target product (1S,2R,5S)-2-isopropyl-5-methylcyclohexyl-4-acetaminobenzoate was obtained with a yield of 84% and 26.7 g. The photocatalyst was recovered in a yield of more than 99%.

[0129] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting analysis by C NMR confirmed that the compound was (1S,2R,5S)-2-isopropyl-5-methylcyclohexyl-4-acetaminobenzoate.

[0130] 1 H NMR (CDCl3, 500MHz): δ8.00(d,J=8.5Hz,2H),7.88(brs,1H),7.58(d,J=8.5Hz,2H),7.30(brs,1H),4.93-4.88(m,1H),2.21(s,3H),2.11(d,J =12.3Hz,1H),2.00-1.91(m,1H),1.72(d,J=11.4Hz,2H),1.57-1.52(m,2H),1.16-1.05(m,2H),0.91(t,J=6.2Hz,7H),0.78(d,J=7.0Hz,3H).

[0131] 13 C NMR (CDCl3, 125MHz): 169.1, 166.1, 142.4, 131.1, 126.5, 119.1, 75.1, 47.5, 41.3, 34.6, 31.8, 26.8, 25.0, 24.0, 22.4, 21.1, 16.9.

[0132] Example 9

[0133] Synthesis of 1,3,3-trimethylbicyclo[2.2.1]heptyl-2-yl-4-acetaminobenzoate:

[0134] Benzyl nitrite (0.1 mol) was reacted and post-treated according to the operating and post-treatment steps in Example 1, wherein the ratio of various compounds was as follows: benzyl nitrite: the sum of compound II-23 and DABCO with the structure shown in Formula II = 1:0.55, compound II-23 with the structure shown in Formula II: DABCO = 1:10; benzyl nitrite: 1,3,3-trimethylbicyclo[2.2.1]heptyl-2-yl-4-ethylbenzoate = 1:40; benzyl nitrite: p-toluenesulfonyl chloride: 1,3,3-trimethylbicyclo[2.2.1]heptyl-2-yl-4-ethylbenzoate = 1:1:10, the pumping time was 1.5 h, the reaction was carried out under 200 W LEDs, and the reaction was carried out at 100 °C for 0.1 h; finally, the target product 1,3,3-trimethylbicyclo[2.2.1]heptyl-2-yl-4-acetaminobenzoate was obtained with a yield of 87% and 27.4 g. The photocatalyst was recovered in a yield of more than 99%.

[0135] by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and carbon nuclear magnetic resonance (NMR) 13 Chemical shift and coupling splitting by C NMR confirmed that the compound was 1,3,3-trimethylbicyclo[2.2.1]heptyl-2-yl-4-acetaminobenzoate.

[0136] 1 H NMR (CDCl3, 400MHz): δ8.01(d,J=8.4Hz,2H),7.92(brs,1H),7.62(d,J=8.0Hz,2H),4.59(d,J=1.6Hz,1H),2.20(s,3H),1.9 5-1.88(m,1H),1.80-1.73(m,2H),1.64(d,J=10.0Hz,1H),1.55-1.46(m,1H),1.25-1.16(m,5H),1.09(s,3H),0.82(s,3H).

[0137] 13 C NMR (CDCl3, 100MHz): 169.7, 167.0, 142.7, 130.9, 126.1, 119.4, 86.9, 48.8, 48.6, 41.7, 40.1, 30.0, 27.1, 26.1, 24.8, 20.6, 19.7.

[0138] Example 10

[0139] Synthesis of 2-azhexanecycloone:

[0140] 0.3 mol of isopropyl nitrite was rapidly and uniformly pumped into a flow reactor. Compound II-1 (of Formula II), DABCO, cyclopentane, and acetic acid were mixed in a specific molar ratio (isopropyl nitrite: compound II-1 + DABCO = 1:0.08, compound II-1:DABCO = 1:5; isopropyl nitrite:cyclopentane = 1:20; isopropyl nitrite:acetic acid = 2:1) and simultaneously pumped into the flow reactor. The reaction was carried out under 50 W LED illumination at 30 °C for 1 h. After the reaction was complete, the reaction solution was filtered to remove solid waste. The filtrate was then acidified, cooled, and crystallized to obtain the final amide product. Unreacted raw materials were then obtained by distillation. The remaining liquid was evaporated to dryness for further recrystallization to recover the photocatalyst. Finally, the target product, 2-azhexanecycloone, was obtained in 96% yield (28.6 g). The photocatalyst was recovered in a yield greater than 99%.

[0141] Example 11

[0142] Synthesis of 2-azhexanecycloone:

[0143] Nitric oxide (0.3 mol), oxygen (0.15 mol), and isopropanol (0.3 mol) were rapidly pumped into a flow reactor. Compound II-1 (of Formula II), DABCO, cyclopentane, and acetic acid were mixed in a specific molar ratio (isopropyl nitrite: compound II-1 + DABCO = 1:0.08, compound II-1: DABCO = 1:5; isopropyl nitrite: cyclopentane = 1:20; isopropyl nitrite: acetic acid = 2:1) and simultaneously pumped into the flow reactor. The mixture was irradiated with 70 W LEDs and reacted at 80 °C for 0.5 h. After the reaction was complete, the reaction solution was filtered to remove solid waste. The filtrate was then acidified, cooled, and crystallized to obtain the final amide product. Unreacted raw material was then obtained by distillation. The remaining liquid was evaporated to dryness for further recrystallization to recover the photocatalyst. Finally, the target product, 2-azhexanecycloone, was obtained with a yield of 96% and a weight of 28.6 g. The photocatalyst was recovered in a yield of more than 99%.

[0144] Example 12

[0145] Synthesis of 2-azhexanecycloone:

[0146] Nitric oxide (0.3 mol), nitrogen dioxide (0.3 mol), and isopropanol (10 mol) were rapidly pumped into a flow reactor. Compound II-1 (of Formula II), DABCO, cyclopentane, and acetic acid were mixed in a specific molar ratio (nitrite: compound II-1 + DABCO = 1:0.08, compound II-1:DABCO = 1:5; nitrite:cyclopentane = 1:20; nitrite:acetic acid = 2:1) and simultaneously pumped into the flow reactor. The reaction was carried out under 100W LED illumination at 30°C for 0.75 h. After the reaction was complete, the reaction solution was filtered to remove solid waste. The filtrate was then acidified, cooled, and crystallized to obtain the final amide product. Unreacted raw material was then obtained by distillation. The remaining liquid was evaporated to dryness for further recrystallization to recover the photocatalyst. Finally, the target product, 2-azhexanecycloone, was obtained with a yield of 96% and a volume of 428.6 g. The photocatalyst was recovered in a yield of more than 99%.

[0147] Example 13

[0148] Synthesis of 2-azhexanecycloone:

[0149] Sodium nitrite (0.3 mol) and isopropanol (0.33 mol) were rapidly pumped into a flow reactor. Compound II-1 (of Formula II), DABCO, cyclopentane, and acetic acid were mixed in a specific molar ratio (isopropyl nitrite: compound II-1 + DABCO = 1:0.08, compound II-1:DABCO = 1:5; isopropyl nitrite: cyclopentane = 1:20; isopropyl nitrite: acetic acid = 2:1) and simultaneously pumped into the flow reactor. The mixture was irradiated with 120W LEDs and reacted at 80°C for 0.2 h. After the reaction was complete, the reaction solution was filtered to remove solid waste. The filtrate was then acidified, cooled, and crystallized to obtain the final amide product. The unreacted raw material was then obtained by distillation. The remaining liquid was evaporated to dryness for further recrystallization to recover the photocatalyst. Finally, the target product, 2-azhexanecycloone, was obtained with a yield of 95% and a volume of 28.3 g. The photocatalyst was recovered in a yield of more than 99%.

[0150] Example 14

[0151] Nitric oxide (0.3 mol), nitrogen dioxide (0.3 mol), and tert-butanol (0.6 mol) were rapidly pumped into a flow reactor. Compound II-1 (with the structure shown in Formula II), DABCO, acetic acid, and acetonitrile were mixed in a certain molar ratio (tert-butyl nitrite: compound II-1 + DABCO (with the structure shown in Formula II) = 1:0.08, compound II-1: DABCO (with the structure shown in Formula II) = 1:5; tert-butyl nitrite: acetonitrile = 1:30, tert-butyl nitrite: acetic acid = 2:1) and simultaneously pumped into the flow reactor. Cyclopropane was slowly bubbled into the flow reactor as a gas. The reaction was carried out under 50W LEDs at 25°C for 1.2 h. After the reaction was completed, the reaction solution was filtered to remove solid waste. The filtrate was then acidified, cooled, and crystallized to obtain the final amide product. The product was then distilled to obtain unreacted acetonitrile. The remaining liquid was evaporated to dryness for further recrystallization to recover the photocatalyst. Finally, the target product, 2-pyrrolidone, was obtained in 90% yield, totaling 26.7 g. The photocatalyst was recovered in a yield greater than 99%.

[0152] Example 15

[0153] 2-azacyclobutanone was synthesized according to the method of Example 14, except that tert-butyl nitrite was replaced with an equimolar amount of isopropyl nitrite, and the yield of 2-azacyclobutanone was 80%.

[0154] Example 16

[0155] Caprolactam was synthesized according to the method of Example 2, except that methyl nitrite was replaced with phenol nitrite in equal molar amounts, and the yield of caprolactam was 89%.

[0156] Example 17

[0157] Caprolactam was synthesized according to the method of Example 2, except that methyl nitrite was replaced by 2-methoxyethyl nitrite in equal molar amounts, and the yield of caprolactam was 91%.

[0158] Example 18

[0159] Caprolactam was synthesized according to the method in Example 2, except that the ratio of methyl nitrite:cyclohexane:DMSO was 1:40:70, and the yield of caprolactam was 90%.

[0160] Example 19

[0161] Caprolactam was synthesized according to the method in Example 2, except that the ratio of methyl nitrite:cyclohexane:DMSO was 1:200:90, and the yield of caprolactam was 95%.

[0162] Example 20

[0163] Caprolactam was synthesized according to the method of Example 2, except that the sum of methyl nitrite, the compound with the structure shown in II-1, and DABCO was 1:0.25, and the yield of caprolactam was 97%.

[0164] Example 21

[0165] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-3 and CH3COOK were used in a molar ratio of 1:1, and the yield of caprolactam was 90%.

[0166] Example 22

[0167] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-3 and CH3COOK were used in a molar ratio of 1:20, and the yield of caprolactam was 86%.

[0168] Example 23

[0169] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-3 and CH3COOK were used in a molar ratio of 1:50, and the yield of caprolactam was 83%.

[0170] Example 24

[0171] Caprolactam was synthesized according to the method of Example 2, except that the ratio of methyl nitrite to p-toluenesulfonyl chloride was 1:1, and the yield of caprolactam was 90%.

[0172] Example 25

[0173] Caprolactam was synthesized according to the method in Example 2, except that the ratio of methyl nitrite to sulfamic acid was 1:0.5, and the yield of caprolactam was 94%.

[0174] Example 26

[0175] Caprolactam was synthesized according to the method in Example 2, except that the ratio of methyl nitrite to p-toluenesulfonic acid was 1:0.3, and the yield of caprolactam was 95%.

[0176] Example 27

[0177] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-18 and K2CO3 were replaced with the compound with the structure shown in Formula II-12 and CH3COOK in a molar ratio of 1:10, and the yield of caprolactam was 88%.

[0178] Example 28

[0179] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-18 and K2CO3 were replaced with the compound with the structure shown in Formula II-24 and CH3COOK in a molar ratio of 1:10, and the yield of caprolactam was 90%.

[0180] Example 29

[0181] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-18 and K2CO3 were replaced with the compound with the structure shown in Formula II-27 and CH3COOK in a molar ratio of 1:10, and the yield of caprolactam was 35%.

[0182]

[0183] Comparative Example 1

[0184] Caprolactam was synthesized according to the method of Example 2, except that eosin Y was used as an equimolar substitute for the compound with the structure shown in Formula II-18 as a catalyst, and phenolic nitrite was used as an equimolar substitute for methyl nitrite. The yield of caprolactam was 14%.

[0185] Comparative Example 2

[0186] Caprolactam was synthesized according to the method of Example 2, except that rhodamine B was used as an equimolar substitute for the compound with the structure shown in Formula II-18 as a catalyst, and methyl nitrite was used as an equimolar substitute for 2-methoxyethyl nitrite. The yield of caprolactam was 10%.

[0187] Comparative Example 3

[0188] Caprolactam was synthesized according to the method of Example 2, except that a compound with the structure shown in formula II-18 was replaced equimolarly with tris(2-phenylpyridine)iridium as the catalyst. The yield of caprolactam was 14%.

[0189] Comparative Example 4

[0190] Caprolactam was synthesized according to the method of Example 2, except that the compound with the structure shown in Formula II-18 was replaced as a catalyst with 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile (4CzIPN), and the yield of caprolactam was 8%.

[0191] Comparative Example 5

[0192] Caprolactam was synthesized according to the method of Example 2, except that the catalyst was replaced by PTH (10-phenyl-10H-phenothiazine) with the structure shown in Formula II-18. The yield of caprolactam was 5%.

[0193]

[0194] Comparative Example 6

[0195] Caprolactam was synthesized according to the method of Example 2, except that formic acid and p-toluenesulfonyl chloride were not added, and the yield of caprolactam was 15%.

[0196] Comparative Example 7

[0197] Caprolactam was synthesized according to the method of Example 2, except that K2CO3 was not added, and the yield of caprolactam was 6%.

[0198] As can be seen from the above, the method of the present invention has mild reaction conditions, avoiding the use of high-pressure mercury lamps or other ultraviolet lamps, avoiding the generation of tar and coke caused by ultraviolet conditions, avoiding the use of large amounts of alcohol additives such as tert-butanol, avoiding the synthesis or use of ketone intermediates, and avoiding the generation of byproducts such as ketone oxime dimers. This method is highly efficient, shortening the reaction time from more than ten hours under ultraviolet irradiation conditions to less than one hour, and synthesizing chain amides or lactams from low and medium alkanes in a high yield in one pot and one step.

[0199] This invention synthesizes amides by directly oxidizing and rearranging the C-C bonds of low- to medium-grade C3-C11 hydrocarbons or their derivatives using a photocatalyst. The reaction conditions are mild, while significantly improving reaction efficiency and yield. In current literature, photocatalytic reactions generally require the addition of a photocatalyst to occur. We compared commonly used ruthenium and iridium complexes as photosensitizers, as well as common organic photocatalysts such as rhodamine B, rhodamine 6G, eosin Y, 4CzIPN, PTH, DPZ, and pyridine salts. While all showed catalytic activity, their yields were relatively poor.

[0200] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing amides by photocatalytic oxidation and amination, characterized in that, The method includes: reacting a nitrogen source with a hydrocarbon compound under visible light irradiation in the presence of a photocatalyst and additives, followed by post-treatment to obtain an amide; wherein the photocatalyst is a photoactive carbazole compound; the additives include basic and acidic substances; and the hydrocarbon compound is selected from one or more of C3-C11 chain alkanes, C3-C11 cycloalkanes, and C7-C11 alkyl-substituted aromatics.

2. The method according to claim 1, wherein, The photoactive carbazole compound is selected from one or more compounds with the structure shown in Formula II; In Equation II, R 1 and R 2 Ar 1 One or more substituents; R 1 and R 2 Each of the following groups can be independently represented as hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 alkyl or C 3-12 cycloalkyl; R 3 It is hydrogen, tert-butoxycarbonyl, p-toluenesulfonyl, methanesulfonyl, silyl, aryl, heteroaryl, C 1-12 alkyl or C 3-12 Cycloalkyl; R4, R5, R6, and R7 are each independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthraceneyl, phenanthryl, ester, cyano, or C. 1-12 Alkyl groups; wherein, R 4 -R 7 Adjacent groups can be independently or linked by chemical bonds to form five- or six-membered aromatic or heteroaromatic rings; dashed lines represent those that can form bonds or those that cannot. Ar 1 and Ar 2 Each is an aromatic ring or a 5-6 member heterocyclic aromatic ring.

3. The method according to claim 2, wherein, The photoactive carbazole compounds are selected from one or more compounds with structures shown in formulas IIA-IIG; Among them, R 1 and R 2 Ar 1 One or more substituents; R 1 and R 2 Each of the following groups can be independently represented as hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 alkyl or C 3-12 cycloalkyl; R 3 It is hydrogen, tert-butoxycarbonyl, p-toluenesulfonyl, methanesulfonyl, silyl, aryl, heteroaryl, C 1-12 alkyl or C 3-12 cycloalkyl; Ar 1 Ar 2 and Ar 3 Each ring can be independently composed of naphthalene, anthracene, phenanthrene, or heteroaromatic rings. In formula IIA, R 4 Ar 3 One or more substituents; R 5 Ar 2 One or more substituents; R 4 and R 5 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups; In Equation IIB, R 4 R represents one or more substituents in the benzene ring. 5 Ar 2 One or more substituents; R 4 and R 5 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups; In formula IIC, R 4 and R 5 Ar 2 One or more substituents; R 4 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl group; R 5 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl group; R 6 and R 7 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups; In formula IID, R 4 and R 5 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl group; R 6 and R 7 Ar 2 One or more substituents; R 6 It can be hydrogen, trihalomethyl, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, C 1-12 alkyl or C 3-12 cycloalkyl; R 7 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, acyl, phenyl, naphthyl, anthracene, phenanthrene, cyano, or C. 1-12 Alkyl groups; In formula IIE, R 4 and R 5 Ar 2 One or more substituents; R 6 and R 7 Ar 3 One or more substituents; R 4 R 5 R 6 and R 7 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl group; R 8 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl groups; In formula IIF, R 4 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, ester, cyano, or C. 1-12 Alkyl group; R 5 and R 6 Ar 2 One or more substituents; R 7 and R 8 Ar 3 One or more substituents; R 5 R 6 R 7 and R 8 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups; In formula IIG, R 4 and R 5 Ar 2 One or more substituents; R 6 and R 7 Ar 3 One or more substituents; R 8 and R 9 Ar 4 One or more substituents; R 4 R 5 R 6 R 7 R 8 and R 9 Each group can be independently hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, or C. 1-12 Alkyl groups.

4. The method according to claim 3, wherein, The photocatalyst is a compound with the structure shown in Formula IIA and / or a compound with the structure shown in Formula IIB; Preferably, in formula IIA, R 1 Hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, C 1-12 Acyl, phenyl, naphthyl, anthracene, phenanthrene, ester, cyano, C 1-12 alkyl or C 3-12 cycloalkyl; R 2 It can be hydrogen, trihalomethyl, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, ester, cyano, C 1-12 alkyl or C 3-12 cycloalkyl; R 3 It can be hydrogen, B℃, Ts, Ms, silyl, aryl, heteroaryl, or C. 1-12 alkyl or C 3-10 cycloalkyl; R 4 It can be hydrogen, trihalomethyl, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthryl, ester, cyano, or C. 1-12 Alkyl group; R 5 It can be hydrogen, halogen, nitro, dialkylamine, alkoxy, acyl, phenyl, naphthyl, anthracene, phenanthrene, cyano, or C. 1-12 Alkyl groups; Preferably, in formula IIB, R 1 It is a dialkylamine, alkoxy, or C 1-12 Alkyl group; R 2 For hydrogen, C 1-10 alkyl, phenyl, naphthyl, anthraceneyl, or phenanthrene; R 3 It is hydrogen, tert-butoxycarbonyl, silyl, aryl, heteroaryl, or C 1-10 alkyl, R 4 It can be an ester group, cyano group, formyl group, acetyl group, trihalomethyl group, or halogen; R 5 It is phenyl, naphthyl, anthracene or C 1-12 Alkyl groups; Ar 1 and Ar 2 Each is independently a naphthalene ring, anthracene ring, or phenanthrene ring; Ar 3 It is selected from indole, quinoline, pyrazine, thiazole, pyrimidine, or triazole.

5. The method according to any one of claims 1-4, wherein, The alkaline substance is selected from one or more organic bases and inorganic bases; Preferably, the inorganic base is selected from one or more of ammonia, carboxylates, carbonates, bicarbonates, and hydroxides; more preferably, the inorganic base is selected from one or more of ammonia, lithium formate, lithium acetate, lithium propionate, sodium formate, sodium acetate, sodium propionate, potassium formate, potassium acetate, potassium propionate, cesium formate, cesium acetate, cesium propionate, sodium carbonate, sodium bicarbonate, cesium carbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, and ammonium hydroxide. Preferably, the organic base is selected from one or more organic amines and organic salts; wherein the organic salt is obtained by reacting an alcohol with an alkali metal or an alkaline earth metal; More preferably, the organic amine is selected from one or more of aliphatic amines, alkanolamines, alicyclic amines, aromatic amines, naphthylamines, and hydroxylamines; More preferably, the alcohol is selected from one or more of methanol, ethanol, n-butanol, isopropanol, tert-butanol, n-pentanol, isoamyl alcohol, and hexanol; More preferably, the alkali metal is selected from one or more of lithium, sodium, potassium, cesium, and francium; More preferably, the alkaline earth metal is selected from one or more of magnesium, calcium, and barium.

6. The method according to claim 5, wherein, The aliphatic amines are selected from primary amines of C1 to C18, secondary amines of C1 to C18, or tertiary amines. Preferably, the aliphatic amine is selected from one or more of methylamine, propylamine, butylamine, dimethylamine, diethylamine, diisopropylamine, diisopropylethyl, diisobutylamine, trimethylamine, triethylamine, tributylamine, triisopropylamine, triethylenediamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, tetrabutylamine, tetramethylguanidine, and tert-butylamine.

7. The method according to any one of claims 1-6, wherein, The acidic substance is selected from at least one of acid compounds or acid substitutes; Preferably, the acid compound is selected from Lewis acids and / or Brønsted acids; more preferably, the Lewis acid is selected from one or more of boron trifluoride, aluminum trichloride, aluminum tribromide and ferric chloride; even more preferably, the Brønsted acid is selected from one or more of sulfuric acid, hydrochloric acid, acetic acid, formic acid, propionic acid, benzoic acid, substituted sulfonic acid and trichloroacetic acid; and even more preferably, the substituted sulfonic acid is selected from aminosulfonic acid or p-toluenesulfonic acid. Preferably, the acidification substitute is selected from one or more of formyl chloride, acetyl chloride, propionyl chloride, butyryl chloride, cyanuric chloride, trifluoromethanesulfonyl chloride, p-toluenesulfonyl chloride, formyl bromide, acetyl bromide, propionyl bromide, butyryl bromide, cyanuric bromide, trifluoromethanesulfonyl bromide, p-toluenesulfonyl bromide, and elemental iodine.

8. The method according to any one of claims 1-7, wherein, The hydrocarbon compound has the structure shown in Formula I, wherein Formula I contains at least one methylene group; wherein, R a and R b Same or different, R a H, halogen, nitro, C 1-10 alkyl, C 1-10 Alkoxy, acyl, cyano, aryl, C 1-10 Substituted ester or nitro group, R b To replace or not be replaced by C 2-10 Alkyl, aryl, benzyl, or ester group; R a and R b Optional cyclic or non-cyclic, R a and R b Each can form an independent loop, or R a and R b They are linked together in a ring by chemical bonds; 9. The method according to any one of claims 1-8, wherein, The cycloalkane is selected from one or more alkanes having 3-11 carbon atoms on the ring; preferably, the cycloalkane is selected from one or more of cyclopropane, cyclobutane, cyclopentane, methylcyclopentanecyclohexane, methylcyclohexane, cycloheptane, cyclooctane, and cyclononane. And / or, the chain alkane is selected from C 3-11 straight-chain alkanes and C 3-11 The branched alkanes are selected from one or more of n-propane, n-butane, n-pentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, 2-methyldecane, and 5-methylnonane. And / or, the alkyl-substituted aromatic hydrocarbon has the structure shown in Formula III; wherein, R c Selected from H, halogen, nitro, C 1-4 Substituted or unsubstituted alkyl, C 1-4 Substituted or unsubstituted alkoxy, acyl, cyano, aryl, C-containing 1-4 Substituted ester group, R d Selected from substituted or unsubstituted alkanes, R c and R d Cyclic or non-cyclic formation is optional; Preferably, the alkyl-substituted aromatic hydrocarbon is selected from one or more of ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 4-chloroethylbenzene, p-ethylacetophenone, p-ethylbenzonitrile, methyl p-ethylbenzoate, p-ethylbenzeneboronic acid pinacol ester, and 4-ethylbiphenyl.

10. The method according to any one of claims 1-9, wherein, The nitrogen source is selected from one or more of alkyl nitrites, aryl nitrites, and alternatives to nitrites; Preferably, the alkyl nitrite is an ester formed by nitrous acid and an alcohol, and more preferably one or more of the following: an ester formed by a C1 to C20 n-alcohol and nitrous acid, an ester formed by a C1 to C20 iso-alcohol and nitrous acid, methyl nitrite, ethyl nitrite, propyl nitrite, isopropyl nitrite, isobutyl nitrite, tert-butyl nitrite, amyl nitrite, isoamyl nitrite, neopentyl nitrite, 2-methoxyethyl nitrite, and 1-methoxypropyl-2-yl nitrite; Preferably, the aryl nitrite is selected from one or more esters formed by nitrite and phenol or substituted phenol; Preferably, the substitute for the nitrite is (1) a product generated by the reaction of NO, O2 with alcohol and / or phenol; (2) a product generated by the reaction of NO2, NO with alcohol or phenol; or (3) a product generated by the reaction of NaNO2 with alcohol and / or phenol; more preferably, the alcohol has a structure of C1 to C20; more preferably, the phenol has a structure of phenol and one or more phenols with one or more of the ortho, meta, and para positions of the aromatic ring.

11. The method according to any one of claims 1-10, wherein, The molar ratio of the nitrogen source to the hydrocarbon compound or its derivative is 1:20-200, preferably 1:20-100; And / or, the molar ratio of the photocatalyst to the nitrogen source is 1:50-200, preferably 1:50-100; And / or, the molar ratio of the photocatalyst to the additive is 1:20-200, preferably 1:20-100; And / or, the molar ratio of the alkaline substance to the acidic substance is 1:2-50, preferably 1:2-10.

12. The method according to any one of claims 1-11, wherein, The light mentioned is light that can be obtained from any light source; Preferably, the light is visible light with a wavelength of 390-760nm, more preferably 400-500nm.

13. The method according to any one of claims 1-12, wherein, The reaction is carried out in a flow reactor or a batch reactor; Preferably, the method includes: S1A, under visible light irradiation, in a flow reactor, in an air atmosphere, at a temperature of 0-200°C, adding a hydrocarbon compound or its derivative, a nitrogen source, a photocatalyst, and an additive, and reacting for 0.1-24 hours; Alternatively, the method may include: S1B, under visible light irradiation, in a batch reactor, in an air atmosphere, at a temperature of 0-200°C, adding a hydrocarbon compound or its derivative, a nitrogen source, a photocatalyst, and an additive, and reacting for 0.1-24 h.

14. The method according to claim 13, wherein, The method further includes: S2. Filter the reaction solution obtained in step S1A or S1B to remove solid waste. S3. Distill the filtrate obtained in step S2 to collect the unreacted raw materials; S4. The remaining solid from step S3 is recrystallized, filtered, and separated to obtain the amide product; S5. The filtrate from step S4 is concentrated and separated to obtain the amide product, and the photocatalyst is recovered at the same time.

Images