METHOD AND CATALYST FOR PREPARING ANILINE COMPOUNDS AND USE THEREOF

Abstract

The present invention provides a method for preparing aniline compounds, and also provides a kind of catalyst and use thereof. This method for synthesizing an aniline compound in the invention includes following steps: use molybdenum oxide and activated carbon as catalyst, hydrazine hydrate as reducing agent, then reduce aromatic nitro compounds to aniline compounds. This method is green and high efficiency, and easy to be applied in industry.

Claims

1. A method for preparing aniline compounds, wherein the method comprising: use molybdenum oxide, activated carbon, and hydrazine to transform aromatic nitro compounds into aniline compounds.

2. The method according to claim 1, wherein the weight ratio of molybdenum oxide to activated carbon is from 1:1 to 1:10, preferably, from 1:2 to 1:5.

3. The method according to claim 1, wherein the molar ratio of molybdenum oxide to aromatic nitro compounds is from 0.001:1 to 0.1:1, preferably, from 0.01:1 to 0.03:1.

4. The method according to claim 1, wherein the molybdenum oxide includes one or more compounds which have the formula: MoO.sub.x (x=23). When x=2 or 3, it represents MoO.sub.2 or MoO.sub.3. When x=23 (non-integer), it represents molybdenum oxide whose average valence is between +4 and +6 or MoO.sub.3 partially reduced; preferably, the mentioned molybdenum oxide is MoO.sub.2.

5. The method according to claim 1, wherein the molybdenum oxide and activated carbon should be premixed before being charged into the reaction system, or be charged into reaction system respectively.

6. The method according to claim 1, wherein the molar ratio of hydrazine hydrate and aromatic nitro compounds is from 1.5:1 to 10:1, preferably, from 2:1 to 4:1.

7. The method according to claim 1, wherein the temperature of the reduction reaction is 25 C. to reflux, preferably, 2535 C.

8. The method according to claim 1, wherein the method comprising: reducing aromatic nitro compounds of the formula I: ##STR00002## to aniline compounds of the formula II: ##STR00003## Wherein R.sub.1-R.sub.5 are the same or different from each other and each represents an optionally hydrogen atom, halogen atom, C1-C6 alkyl, phenyl or its substituents, benzyl or its substituents, SR.sub.6, OR.sub.7, COOR.sub.8, CONR.sub.9R.sub.10 or CN; wherein R.sub.6, R.sub.7, R.sub.8, R.sub.9 and R.sub.10 each represent an optionally hydrogen atom, C1-C6 alkyl, phenyl or its substituents, benzyl or its substituents, R.sub.9 and R.sub.10 are the same or different.

9. The method according to claim 1, wherein the reaction is carried out in the presence of solvent. The solvent is protic solvent, preferably, one or more than one selected from H.sub.2O, methanol, ethyl alcohol or isopropanol, more preferably, ethyl alcohol.

10. The method according to claim 1, wherein hydrazine hydrate is selected from hydrazine hydrate aqueous solution with mass concentration of 40-80%.

11. The method according to claim 1, wherein the method comprising: filter the reaction mixture after reaction, then filter residue is used as recycled catalyst for recycling.

12. A kind of catalyst, wherein it includes molybdenum oxide and activated carbon, preferably, the weight ratio of molybdenum oxide to activated carbon is from 1:1 to 1:10, more preferably, from 1:2 to 1:5.

13. The catalyst according to claim 12, wherein the molybdenum oxide includes one or more compounds which have the formula: MoO.sub.x (x=23). When x=2 or 3, it represents MoO.sub.2 or MoO.sub.3. When x=23 (non-integer), it represents molybdenum oxide whose average valence is between +4 and +6 or MoO.sub.3 partially reduced; preferably, the molybdenum oxide is MoO.sub.2.

14. The use of catalyst according to claim 12, wherein the catalyst is applied to catalyze aromatic nitro compounds into aniline compounds, preferably, the reducing agent is hydrazine hydrate in reaction system; preferably, the catalyst molybdenum oxide and activated carbon should be premixed before being charged into the reaction system, or be charged into reaction system respectively.

15. The use of catalyst according to claim 14, wherein, after reaction, filter reaction mixture, recovery filter residue as recycled catalyst.

Description

EXAMPLES

[0030] In order to better understand the technical solution of the invention, the content of the invention is further expounded with the examples below, but the content of the invention is not limited to the following examples only.

[0031] Both the examples and comparative examples involve %, if not specifically stated, refer to quality percentages.

[0032] The following describes test instruments and part of experimental materials used in examples and comparative examples:

[0033] Materials, reagents and solvents: purchased commercially. Reagents such as hydrazine hydrate solution with quality concentration of 50% and 80%, and molybdenum dioxide, were purchased from Sinopharm Chemical Reagent Co., Ltd., and activated carbon was purchased from the Activated Carbon Branch of Hangzhou Wood Co., Ltd. All the solvents used were domestic analytical pure reagent without any treatment before used, and purchased from Sinopharm Chemical Reagent Co., Ltd.

[0034] High performance liquid chromatography: Agilent 1206.

[0035] Nuclear Magnetic Resonance Spectrometer: Bruker DRX-400FT (Germany), .sup.1HNMR is detected in CDCl.sub.3, DMSO-d.sub.6 and D.sub.2O, and the chemical shift was measured using tetramethylsilane (TMS) as the reference, unit ppm.

Example 1

Preparation of Aniline

[0036] 1.58 g (10 mmol) of nitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 2 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.22 g of light brown liquid, the molar yield was 100%, HPLC purity was 99.8%.

[0037] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.10-7.14 (m, 2H), 6.78-6.73 (m, 3H).

Example 2

Preparation of 4-methylaniline

[0038] 1.37 g (10 mmol) of 4-methylnitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 2 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.05 g of colorless solid, the molar yield was 98%, HPLC purity was 99.8%.

[0039] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.13-7.17 (m, 2H), 6.74-6.69 (m, 2H), 2.3 (s, 3H).

Example 3

Preparation of p-methoxylaniline

[0040] 1.53 g (10 mmol) of 4-nitroanisole, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 1.5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.2 g of colorless solid, the molar yield was 97.6%, HPLC purity was 99.6%.

[0041] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.11-7.14 (m, 2H), 6.75-6.71 (m, 2H), 3.65 (s, 3H).

Example 4

Preparation of o-chloroaniline

[0042] 1.58 g (10 mmol) of o-chloronitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 3 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.22 g of light brown liquid, the molar yield was 95.3%, HPLC purity was 99.7%.

[0043] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.31-7.34 (m, 1H), 7.13-7.16 (m, 1H), 6.83-6.86 (m, 1H), 6.71-6.73 (m, 1H), 5.28 (s, 2H).

Example 5

Preparation of o-fluoroaniline

[0044] 1.41 g (10 mmol) of o-fluoronitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.92 g (20 mmol) of hydrazine hydrate (50%) was added dropwise at room temperature and reacted at room temperature for 4.5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.22 g of light brown liquid, the molar yield was 94.6%, HPLC purity was 99%.

[0045] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.30-7.33 (m, 1H), 7.13-7.16 (m, 1H), 6.82-6.85 (m, 1H), 6.75-6.78 (m, 1H), 5.29 (s, 2H).

Example 6

Preparation of m-chloroaniline

[0046] 1.58 g (10 mmol) of m-chloronitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.25 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.21 g of light brown liquid, the molar yield was 94.5%, HPLC purity was 98.7%.

[0047] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.15-7.18 (m, 1H), 7.09-7.13 (m, 1H), 6.83-6.86 (m, 1H), 6.64-6.67 (m, 1H), 5.34 (s, 2H).

Example 7

Preparation of m-fluoroaniline

[0048] 1.41 g (10 mmol) of m-nitrofluorobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 1.92 g (20 mmol) of hydrazine hydrate (50%) was added dropwise at room temperature and reacted at room temperature for 4.5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.05 g of light yellow liquid, the molar yield was 94.6%, HPLC purity was 98.9%.

[0049] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.10-7.13 (m, 1H), 7.93-7.96 (m, 1H), 6.65-6.68 (m, 1H), 6.54-6.57 (m, 1H), 5.30 (s, 2H).

Example 8

Preparation of p-chloroaniline

[0050] 1.58 g (10 mmol) of p-chloronitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.24 g of light yellow crystals, the molar yield was 96.9%, HPLC purity was 99.5%.

[0051] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.14-7.17 (m, 2H), 6.61-6.58 (m, 2H), 5.49 (s, 2H).

Example 9

Preparation of p-fluoroaniline

[0052] 1.41 g (10 mmol) of p-fluoronitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 1.25 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 4.5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.08 g of light yellow liquid, the molar yield was 97.3%, HPLC purity was 99.4%.

[0053] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.04-7.01 (m, 2H), 6.71-6.68 (m, 2H), 5.45 (s, 2H).

Example 10

Preparation of 2-(2,4-dimethylphenylthio)benzenamine

[0054] 2.00 g (7.70 mmol) of 2-(2,4-dimethyl phenyl sulfide) nitrobenzene, 0.01 g (0.077 mmol) of MoO.sub.2, 0.05 g of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 0.92 g (15.0 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 6 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.64 g of white solid, the molar yield was 93%, HPLC purity was 99.5%.

[0055] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.15-7.20 (m, 2H), 7.02 (s, 6.81-6.85 (m, 2H), 6.58-6.65 (m, 2H), 5.28 (s, 2H), 2.31 (s, 3H), 2.20 (s, 3H).

Example 11

Preparation of 3-(2,4-dimethylphenylthio)benzenamine

[0056] 2.00 g (7.70 mmol) of 3-(2,4-dimethyl phenyl sulfide) nitrobenzene, 0.01 g (0.077 mmol) of MoO.sub.2, 0.05 g of activated carbon and 20 mL of ethyl alcohol were added into a 50 mL flask. Then 1.47 g (15.0 mmol) of hydrazine hydrate (50%) was added dropwise at room temperature and reacted at room temperature for 5.5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.6 g of white solid, the molar yield was 90.4%, HPLC purity was 99.1%.

[0057] .sup.1HNMR data: .sup.1HNMR (400 MHz, DMSO-d.sub.6) : 7.35-7.38(m, 1H), 7.17-7.24 (m, 2H), 7.09-7.15 (m, 1H), 7.04 (s, 1H), 6.92-6.98 (m, 2H), 6.58-6.65 (m, 1H), 5.20 (s, 2H), 2.30 (s, 3H), 2.21 (s, 3H).

Example 12

Preparation of 4-(2,4-dimethylphenyithio)benzenamine

[0058] 2.00 g (7.70 mmol) of 4-(2,4-dimethyl phenyl sulfide) nitrobenzene, 0.01 g (0.077 mmol) of MoO.sub.2, 0.05 g of activated carbon and 20 mL of ethyl alcohol were added into a 50 mL flask. Then 1.47 g (15.0 mmol) of hydrazine hydrate (50%) was added dropwise at room temperature and reacted at room temperature for 6.5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.67 g of white solid, the molar yield was 94.4%, HPLC purity was 99.3%.

[0059] .sup.1HNMR data: .sup.1HNMR (400 MHz, DMSO-d.sub.6) : 7.18-7.23 (m, 1H), 7.02 (s, 1H), 6.80-6.87 (m, 3H), 6.60-6.66 (m, 2H), 5.28 (s, 2H), 2.31 (s, 3H), 2.20 (s, 3H).

Example 13

Preparation of 4-aminobenzonitrile

[0060] 1.48 g (10 mmol) of 1-cyano-4-nitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 20 mL of ethyl alcohol were added into a 50 mL flask. Then 1.25 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.1 g of solid, the molar yield was 93%, HPLC purity was 99%.

[0061] .sup.1HNMR d.sub.ata: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.23-7.27 (m, 2H), 6.81-6.87 (m, 2H), 5.63 (s, 2H).

Example 14

Preparation of 2-amino-6-fluorobenzoic acid

[0062] 1.85 g (10 mmol) of 6-fluoro-2-nitrobenzoic acid, 25.6 mg (0.2 mmol) of MoO.sub.2, 76.8 mg of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.25 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 7 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.5 g of light yellow solid, the molar yield was 96.8%, HPLC purity was 99.6%.

[0063] .sup.1HNMR data: .sup.1HNMR (400 MHz, D.sub.2O) : 7.45-7.40 (m, 1H), 6.86-6.95 (m, 2H).

Example 15

Preparation of 2-Amino-4,5-bis(2-methoxyethoxy)benzonitrile

[0064] 2.96 g (10 mmol) of 2-nitro-4,5-bis (2-methoxyethoxy) benzonitrile, 38.4 mg (0.3 mmol) of MoO.sub.2, 0.12 g of activated carbon and 30 mL of ethyl alcohol were added into a 50 mL flask. Then 1.88 g (30 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 7 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated to near dry, slurryed with petroleum ether, finally, get 2.4 g of light yellow solid, the molar yield was 90.2%, HPLC purity was 99%.

[0065] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.41 (s, 1H), 7.04 (s, 1H), 3.61-3.66 (m, 4H), 2.47-2.55 (m, 4H), 3.24 (s, 3H), 3.21 (s, 3H).

Example 16

Preparation of 2-amino-4-methoxy-5-(3-morpholinylisopropyl)benzonitrile

[0066] 3.2 g (10 mmol) of 2-nitro-4-methoxy-5-(3-morpholinylisopropyl) benzonitrile, 38.4 mg (0.3 mmol) of is MoO.sub.2, 0.12 g of activated carbon and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 1.88 g (30 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 7 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated to near dry, slurryed with petroleum ether, finally, get 2.65 g of light yellow solid, the molar yield was 91%, HPLC purity was 99.3%.

[0067] .sup.1HNMR data: .sup.1HNMR (400 MHz, CDCl.sub.3) : 7.45 (s, 1H), 7.02 (s, 1H), 4.81-4.85 (m, 2H), 3.58-3.65 (m, 4H), 3.28 (s, 3H), 2.41-2.48 (m, 2H), 2.31-3.38 (m, 2H), 1.87-1.91 (m, 2H).

Example 17

[0068] Filter the reaction mixture and get filter residue from example 8 as catalyst. Experiment is carried out using recovered catalyst without any treatment, and the process which used the 10th catalysts is as below:

[0069] 1.58 g (10 mmol) of p-chloronitrobenzene, MoO.sub.2 and activated carbon (recovered from 9.sup.th process) and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 5 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.24 g of light yellow crystals, the molar yield was 96.9%, HPLC purity was 99%.

Example 18

[0070] Filter the reaction mixture and get filter residue from example 10 as catalyst. Experiment is carried out using recovered catalyst without any treatment, and the process which used the 10th catalysts is as below:

[0071] 2.00 g (7.70 mmol) of 2-(2,4-dimethyl phenyl sulfide) nitrobenzene, MoO.sub.2 and activated carbon (recovered from 9.sup.th process) and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 0.92 g (15.0 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 6 hours until TLC analysis showed the raw materials were reacted completely and then filtered, concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, finally, get 1.64 g of white solid, the molar yield was 93%, HPLC purity was 99.4%.

Comparative Example 1

[0072] Compare with Example 1, experiment is carried out to prepare aniline without activated carbon, and the process is as below:

[0073] 1.58 g (10 mmol) of nitrobenzene, 25.6 mg (0.2 mmol) of MoO.sub.2 and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 1.2 g (20 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature. TLC analysis showed almost no products were produced, HPLC showed raw material nitrobenzene was left 99%, and aniline was only 0.8%.

Comparative Example 2

[0074] Compare with Example 10, experiment is carried out to prepare 2-(2,4-dimethylphenylthio) benzenamine without activated carbon, and the process is as below:

[0075] 2.00 g (7.70 mmol) of 2-(2,4-dimethyl phenyl sulfide) nitrobenzene, 0.01 g (0.077 mmol) of MoO.sub.2 and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 0.92 g (15.0 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 6 hours. TLC analysis showed almost no products were produced, HPLC showed raw material was left 99.3%, and product was only 0.3%.

Comparative Example 3

[0076] Compare with Example 10, experiment is carried out to prepare 2-(2,4-dimethylphenylthio) benzenamine without MoO.sub.2, and the process is as below:

[0077] 2.00 g (7.70 mmol) of 2-(2,4-dimethyl phenyl sulfide) nitrobenzene, 0.05 g activated carbon and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 0.92 g (15.0 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 6 hours. TLC analysis showed almost no products were produced, HPLC showed raw material was left 99.3%, and product was only 0.3%.

Example 19

[0078] Compare with Example 10, experiment is carried out to prepare 2-(2,4-dimethylphenylthio) benzenamine with MoO.sub.3, and the process is as below:

[0079] 2.00 g (7.70 mmol) of 2-(2,4-dimethyl phenyl sulfide) nitrobenzene, 11.1 mg (0.077 mmol) of MoO.sub.3, 0.05 g of activated carbon and 30 mL of ethyl alcohol were added into a 50 ml flask. Then 0.92 g (15.0 mmol) of hydrazine hydrate (80%) was added dropwise at room temperature and reacted at room temperature for 6 hours, TLC analysis showed there was still raw material left, then reacted at room temperature for another 6 hours until TLC analysis showed the raw materials were left less, filtered and concentrated filtrate, extracted with 20 mL of ethyl acetate and 10 mL of water, the obtained organic phase was washed and concentrated, slurryed with 10 mL of n-heptane for 1 hour, finally, get 1.42 g of white solid, the molar yield was 80.5%, HPLC purity was 98.5%.

[0080] .sup.1HNMR data: .sup.1HNMR (400 MHz, DMSO-d.sub.6) : 7.15-7.20 (m, 2H), 7.02 (s, 1H), 6.81-6.85 (m, 2H), 6.58-6.65 (m, 2H), 5.28 (s, 2H), 2.31 (s, 3H), 2.20 (s, 3H).

[0081] Technicians in this field may understand and under the instruction of this invention, some modifications or adjustments can be made to the invention. Such modifications or adjustments should also be within the scope of the claims of the invention