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, comprising reacting aromatic nitro compounds with hydrazine hydrate in the presence of molybdenum oxide and activated carbon at a molar ratio of the molybdenum oxide to the aromatic nitro compounds from 0.005:1 to 0.05:1 to reduce the aromatic nitro compounds into aniline compounds, wherein the weight ratio of the molybdenum oxide to the activated carbon is from 1:2 to 1:8, whereby a reaction mixture comprising the aniline compounds is obtained.

2. The method according to claim 1, wherein the molybdenum oxide comprises one or more compounds having the formula MoO.sub.x, wherein x is a number between 2 and 3, inclusive wherein when x=2 or 3, the molybdenum oxide is MoO.sub.2 or MoO.sub.3, and respectively, when x is a non-integer between 2 and 3, the molybdenum oxide has an average valence between +4 and +6.

3. The method according to claim 1, wherein the molybdenum oxide and the activated carbon are premixed before the reaction.

4. The method according to claim 1, wherein the molar ratio of the hydrazine hydrate to the aromatic nitro compounds is from 2:1 to 8:1.

5. The method according to claim 1, wherein the temperature of the reaction is 25 C. to reflux.

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

7. The method according to claim 1, wherein the reaction is carried out in the presence of a protic solvent.

8. The method according to claim 1, wherein the hydrazine hydrate is a hydrazine hydrate aqueous solution with a mass concentration of 40-80%.

9. The method according to claim 1, further comprising filtering the reaction mixture after reaction, recovering a filter residue from the filtered reaction mixture, and adding the recovered filter residue to the reaction as a recycled catalyst.

10. The method according to claim 7, wherein the protic solvent is selected from the group consisting of water, methanol, ethyl alcohol, isopropanol, and a combination thereof.

Description

EXAMPLES

(1) 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.

(2) Both the examples and comparative examples involve %, if not specifically stated, refer to quality percentages.

(3) The following describes test instruments and part of experimental materials used in examples and comparative examples:

(4) 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.

(5) High performance liquid chromatography: Agilent 1206.

(6) 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

(7) 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%.

(8) .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

(9) 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%.

(10) .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

(11) 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%.

(12) .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

(13) 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%.

(14) .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

(15) 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%.

(16) .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

(17) 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%.

(18) .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

(19) 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%.

(20) .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

(21) 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%.

(22) .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

(23) 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%.

(24) .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

(25) 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%.

(26) .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

(27) 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%.

(28) .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

(29) 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%.

(30) .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

(31) 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%.

(32) .sup.1HNMR data: .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

(33) 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%.

(34) .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

(35) 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%.

(36) .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

(37) 3.2 g (10 mmol) of 2-nitro-4-methoxy-5-(3-morpholinylisopropyl) 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 2.65 g of light yellow solid, the molar yield was 91%, HPLC purity was 99.3%.

(38) .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

(39) 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:

(40) 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

(41) 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:

(42) 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

(43) Compare with Example 1, experiment is carried out to prepare aniline without activated carbon, and the process is as below:

(44) 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

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

(46) 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

(47) 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:

(48) 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

(49) 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:

(50) 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%.

(51) .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).

(52) 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