CN1155555C - Method for synthesizing 2,3,4-trifluoro phenyl formic acid - Google Patents
Method for synthesizing 2,3,4-trifluoro phenyl formic acid Download PDFInfo
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Abstract
The present invention relates to a synthesis method for preparing 2, 3, 4-trifluorobenzoic acid, which comprises the steps: 2, 3, 4-trifluoroaniline is used as raw material; by amido diazotization, 2, 3, 4-trifluorobenzonitrile is obtained after cyano is treated, and 2, 3, 4-trifluorobenzoic acid is prepared through acidic hydrolysis; or after the 2, 3, 4-trifluoroaniline is diazotized by amido, 1-bromo-2, 3, 4-trifluorobenzene is obtained through bromination, the 1-bromo-2, 3, 4-trifluorobenzene reacts with magnesium to prepare a Grignard reagent, and reacts with carbon dioxide, and the 2, 3, 4-trifluorobenzoic acid is synthesized through acidification and hydrolysis. The method has the advantages of easy acquirement of original raw materials, low cost, simple reaction operation and easy industrialization.
Description
Technical field
The present invention relates to two kinds and prepare 2,3, the synthetic method of 4-trifluoro-benzoic acid.
Background technology
2,3, the 4-trifluoro-benzoic acid is a kind of important medicine intermediate, because the sp act of fluorine in medicine, agricultural chemicals and bioactive molecules, so have application widely aspect medicine, the agricultural chemicals.In addition, in organic molecule, behind the introducing fluorine atom, the original rerum natura of molecule can be changed, its chemistry and thermostability can be increased, the birefringence of visbreaking and light.In the liquid crystal system,, make the liquid crystal habit of liquid crystal molecule and other rerum natura produce exciting variation with the alternative hydrogen wherein of fluorine atom, so 2,3,4-trifluoromethyl benzonitrile acid esters compound is a kind of good liquid crystal material (Chinese J.Chem.Vol.17, No.1,1999,69.).More widened 2,3 thus, the application prospect of 4-trifluoro-benzoic acid.Its structural formula is:
2,3, the 4-trifluoro-benzoic acid is synthetic by following method usually:
1) the 4-fluorobenzoic acid is fluoridized with fluorine gas and is prepared (J.Chem.Soc., Perkin Trans, 1,1996,605.), but that shortcoming is a yield is lower, and many other by products are arranged, and owing to adopt fluorine gas, and need special conversion unit, and make operation bother like this, at all can not industrialization.
2) by 1,2, the 3-trifluoro-benzene is that starting raw material prepares (Chinese J.Chem., 17 (1), 1999,69.).
Butyllithium is adopted in this reaction, and butyllithium preparation difficulty, and danger is bigger, and reaction needed carries out under anhydrous, anaerobic and cold condition, conversion unit is required also higher, is difficult to generally adopt, and is extended to suitability for industrialized production.
Summary of the invention
The purpose of this invention is to provide a kind of high-efficient simple Synthetic 2,3, the method for 4-trifluoro-benzoic acid, and also this method can industrialization.
Can comprise two kinds of synthetic methods in the method for the present invention, be respectively:
1, with 2,3, the 4-trifluoromethyl aniline is a raw material, and after the diazotization by amino, itrile groupization gets 2,3 again, the 4-trifluorobenzonitrile, and 2,3, the 4-trifluorobenzonitrile makes 2,3 by acidic hydrolysis, the 4-trifluoro-benzoic acid.Above-mentioned synthetic method can be represented with following formula:
2, also can 2,3, the 4-trifluoromethyl aniline is a raw material, by after the diazotization of amino again bromination obtain 1-bromo-2,3, the 4-trifluoro-benzene appoints with MAGNESIUM METAL to make Ge Shi (Grignard) reagent again, again with carbon dioxide reaction after the acidification hydrolization Synthetic 2,3, the 4-trifluoro-benzoic acid.
The synthetic method reaction formula of foregoing invention can be expressed as:
Principal reaction step of the present invention is as follows:
Inventive method 1:
1) 2,3,4-trifluorobenzonitrile synthetic:
With 2,3, the 4-trifluoromethyl aniline is a raw material, generate diazonium salt by diazotization reaction after, generate 2,3 with the nitrilation reagent react, the 4-trifluorobenzonitrile, can by rectifying get content greater than 98% 2,3, the 4-trifluorobenzonitrile.
In the diazotization reaction 2,3, the reaction mol ratio of 4-trifluoromethyl aniline and nitrous acid reagent is 1: 0.8～3 ,-10～60 ℃ of reactions 0.1～3 hour down.Recommending mol ratio is 1: 1～2, and the recommendation response temperature is that 0～20 ℃, soaking time are 0.1～1 hour.Used acid mainly contains Glacial acetic acid, the vitriol oil, hydrochloric acid, Hydrogen bromide or nitric acid etc. in the doazo reaction, and used nitrous acid reagent mainly contains Sodium Nitrite, nitrous acid or nitrous acid ester, and wherein ester group comprises the C of butyl, ethyl, amyl group and isopentyl etc.
1-6Alkyl.
The diazonium salt that generates after the above-mentioned diazotization reaction generates 2,3 with the nitrilation reagent react again, the 4-trifluorobenzonitrile, and with 2,3, the 4-trifluoromethyl aniline calculates, and 2,3, the mol ratio of 4-trifluoromethyl aniline and nitrilation reagent is 1: 1～10, recommending mol ratio is 1: 3～6.Temperature of reaction is 20～80 ℃, is recommended as 40～60 ℃.Wherein nitrilation reagent has: NaCN, KCN or CuCN etc., and nitrilation reagent can use separately also and can mix usefulness.
2) 2,3,4-trifluorobenzonitrile hydrolysis preparation 2,3, the 4-trifluoro-benzoic acid:
2,3, after 4-trifluorobenzonitrile and the reaction of strong acid Hybrid Heating, extraction, the concentrated target product 2,3,4-trifluoro-benzoic acid of obtaining.Wherein used strong acid is hydrochloric acid, sulfuric acid, nitric acid or Hydrogen bromide etc.Raw material 2,3, the mol ratio of 4-trifluorobenzonitrile and strong acid are 1: 1～20, and recommending mol ratio is 1: 3～7.Temperature of reaction is 60 a ℃～reflux temperature, and the recommendation response temperature is a reflux temperature, prolongs the conversion that the reaction times helps reacting in the reaction.
Inventive method 2:
1) 2,3,4-trifluorobromobenzene synthetic:
With 2,3, the diazonium salt that the 4-trifluoromethyl aniline generates by diazotization reaction obtains 2,3 again with after the bromide reagent reaction, and the 4-trifluorobromobenzene obtains content＞90% colourless liquid by steam distillation or/and carry out rectification under vacuum again---and 2,3, the 4-trifluorobromobenzene.
The above-mentioned diazonium salt and the mol ratio of bromide reagent are 1: 1～15, be recommended as 1: 1～and 4.Temperature of reaction is 20～120 ℃, and the recommendation response temperature is 40～80 ℃.Reaction times is 1～20 hour.Wherein bromide reagent has liquid bromine, Hydrogen bromide, cuprous bromide, Potassium Bromide, cupric bromide or Sodium Bromide etc.Above-mentioned bromide reagent can use separately also can mix usefulness.
2) 2,3,4-trifluoro-benzoic acid synthetic:
In organic solvent, 2,3, Grignard reagent is made in 4-trifluorobromobenzene and MAGNESIUM METAL reaction, feeds through CO then
2, gas reaction, acidification hydrolization reaction again, reaction solution extract crude product, obtain＞98% product 2,3 the 4-trifluoro-benzoic acid behind the alkali-soluble acid analysis.
Recommendation is with reaction product acidifying again, the reaction solution purifying through extraction, alkali-soluble acid analysis.
Raw material 2,3 in the reaction, and the mol ratio of 4-trifluorobromobenzene and MAGNESIUM METAL is 1: 0.9～5, and recommending mol ratio is 1: 1～2.The dropping temperature of Grignard reaction is at 10～60 ℃, and dripping back insulation reaction temperature is 10～80 ℃.The insulation reaction time is 0.2～5 hour.
Used organic solvent can be ether, kerosene, benzene, tetrahydrofuran (THF) or toluene etc. in the preparation Grignard reagent, or their mixed solvent.Recommend to use toluene-THF mixed solvent in the present invention, its proportioning is that 1: 0.1～10 (v/v) are for good with toluene: THF.
Feed CO
2Temperature of reaction be-30～50 ℃, aeration time is 1-40 hour.CO
2CO with drying, anaerobic, no alcohol
2For good.
Temperature of reaction when acid hydrolysis is-10～60 ℃.Wherein acid is mineral acids such as hydrochloric acid, Hydrogen bromide or sulfuric acid.
Product 2,3, the 4-trifluoro-benzoic acid can be used the alcohol-water system recrystallization, and the volume ratio of pure water is 1: 0.2～1.0.Wherein Chun kind mainly contains methyl alcohol, ethanol, propyl alcohol or Virahol etc.Above-mentioned two kinds of Synthetic 2s among the present invention, 3,4-trifluoro-benzoic acid method remarkable advantage arranged:
Starting raw material is easy to get, low price, and the operation process is simple, is easy to industrialization.
The invention 1, with 2,3, the 4-trifluoromethyl aniline carries out doazo reaction, operation is succinct, industrialization operation comparative maturity, though nitrilation reagent has the deficiency of hypertoxicity, nitrilation reagent is more cheap, and because it is in industrial use also comparative maturity, so use nitrilation reagent among the present invention, simplify operation, improve yield.
Invention 2, with 2,3, the 4-trifluoromethyl aniline carries out that bromination prepares 2,3 behind the doazo reaction, the 4-trifluorobromobenzene is a kind of more satisfactory suitability for industrialized production 2,3, the method for 4-trifluorobromobenzene.Then prepare Grignard reagent and carbon dioxide reaction generation acid and can access yield preferably.
Two kinds of Synthetic 2s among the present invention, 3, the method of 4-trifluoro-benzoic acid, the common synthetic method of comparing, advantage is to have improved yield, simplified operation, used that (for example: diazotization reaction), or by test, proving can industrialized reagent or method (for example: nitrilation reagent, Grignard reaction etc.) in industrial feasible method, so synthetic method of the present invention is a kind of method that is suitable for suitability for industrialized production.
Embodiment
The present invention will be helped to understand by following embodiment, but content of the present invention can not be limited.
Embodiment 1
1,2,3,4-trifluoro-benzene formonitrile HCN synthetic
With 14.7 grams 2,3,4-trifluoromethyl aniline, 38ml water and 47ml glacial acetic acid are put into the 250ml reaction flask, and cooling adds the 15ml vitriol oil down, under 0～10 ℃, add 7.6 gram NaNO
2Be dissolved in the solution of 26ml water, insulation 15min.
Other gets a 1L there-necked flask, adds 80ml water, adds 108 gram NaHCO again
311.6 gram CuCN and 17.6 gram NaCN, add toluene 80ml again, prepared diazonium salt solution is splashed into gradually, be heated to 45～55 ℃ of reactions 2～3 hours, cooling, isolate organic layer, water, 10%NaOH respectively wash once, dry then, concentrate 18.7 grams, crude product purity: 93% (GC), it is 98% colourless liquid that underpressure distillation gets 10.3 gram purity.
Theoretical yield: 15.7 grams,
Actual output: 10.1 grams,
Actual recovery: 64.3%.
IRν(cm
-1)3322，2976，2100，1750，1502，1169，1126
1H?NMR(CDCl
3)δ7.13(m，1H)，7.37(m，1H)ppm
19F?NMR(TFA)δ55.0，57.9，85.7ppm
MS(70eV)，m/e(relative?intensity)157(M
+)
C
7H
2F
3N calculated value: C53.52, H1.28
157.10 measured value: C53.28, H1.01
2,2,3,4-trifluoro-benzene formonitrile HCN hydrolysis preparation 2,3,4-trifluoro-benzoic acid
Add the mixed solution of 7.9 gram benzene nitriles, the 110mL vitriol oil and 110ml water in the 250ml three-necked bottle, be heated to backflow, back flow reaction 4～6 hours, cooling, with 1,2-ethylene dichloride extracting twice, wash once NaOH extraction with aqueous solution, hcl acidifying again with water, use 1 again, the extraction of 2-ethylene dichloride, drying, concentrating under reduced pressure gets 3.9 gram white solids, content＞98%, the survey fusing point is: 132-134 ℃.
Theoretical yield: 8.8 grams,
Actual output: 3.9 grams,
Actual recovery: 44.3%.
IRν(cm
-1)3322(N-H)，2976，1750，1502，1169，1126
1H?NMR(CDCl
3)δ7.04(m，1H)，7.52(m，1H)，11.42(s，1H)ppm
19F?NMR(TFA)δ55.0，57.9，85.7ppm
MS(70eV)，m/e(relative?intensity)176(M
+)
C
7H
3F
3O
2Calculated value: C47.75, H1.72
176.10 measured value: C47.63, H1.58
Embodiment 2
1,2,3,4-trifluoro-benzene formonitrile HCN synthetic
With 14.7 grams 2,3,4-trifluoromethyl aniline, 38ml water and 47ml glacial acetic acid join in the 250ml Erlenmeyer flask, and cooling slowly drips the 15ml vitriol oil down, is chilled to 0-5 ℃ after adding, and add 7.6 gram NaNO
2Be dissolved in the solution of 26ml water, insulation 15～30min.
In the 250ml Erlenmeyer flask, add 80ml water, 108 gram NaHCO
3, 11.6 gram CuCN and 80ml toluene, be heated to 50～60 ℃ of reactions 3～5 hours, organic layer is told in cooling, water, the NaOH aqueous solution, water are respectively washed once, and is dry, concentrate, underpressure distillation gets 9.0 gram colourless liquids, content＞98%.
Theoretical yield: 15.7 grams,
Actual output: 9.0 grams,
Actual recovery: 57.3%.
IRν(cm
-1)3322，2976，1750，1502，1169，1126
1H?NMR(CDCl
3)δ7.13(m，1H)，7.37(m，1H)ppm
19F?NMR(TFA)δ-11.0(s，CF
3)ppm
MS(70eV)，m/e(relative?intensity)157(M
+)
C
7H
2F
3N calculated value: C53.52, H1.28
157.10 measured value: C53.28, H1.01
2,2,3,4-trifluoro-benzene formonitrile HCN hydrolysis preparation 2,3,4-trifluoro-benzoic acid
Add 8.7 gram cyanobenzenes in the 500ml three-necked bottle, stir the mixed solution that splashes into 300ml concentrated hydrochloric acid and 110ml water down, reacted 6～7 hours, cooling, with 1,2-ethylene dichloride extracting twice, extraction liquid washes with water once again, the NaOH extraction with aqueous solution, 36%HCl acidifying, 1, the extraction of 2-ethylene dichloride, drying, concentrating under reduced pressure get 4.5 gram white solids, content＞98%.
The survey fusing point is: 131.5-134 ℃.
Theoretical yield: 9.7 grams,
Actual output: 4.5 grams,
Actual recovery: 46.4%.
IRν(cm
-1)3322(N-H)，2976，1750，1502，1169，1126
1H?NMR(CDCl
3)δ7.04(m，1H)，7.52(m，1H)，11.42(s，1H)ppm
19F?NMR(TFA)δ54.0，56.4，85.5ppm
MS(70eV)，m/e(relative?intensity)176(M
+)
C
7H
3F
3O
2Calculated value: C47.75, H1.72
176.10 measured value: C47.93, H1.88
Embodiment 3
1,2,3,4-trifluorobromobenzene synthetic
Add Glacial acetic acid 220 grams in the 1L there-necked flask, water 160 grams, cooling adds the 128 gram vitriol oils down lentamente, and temperature is lower than 50 ℃ in the control.Add 67 grams 2,3 in the dropping funnel, the 4-trifluoromethyl aniline begins to drip, and temperature is lower than 50 ℃ in keeping, and finishes, and system is chilled to-1～4 ℃.
32 gram Sodium Nitrites are dissolved in the 51 gram water, splash in the reaction flask, temperature is at-5～10 ℃ in the control.Dropwise, be incubated 30 minutes stand-by.
Other gets a 1L there-necked flask, adds 124 grams, 50% Hydrogen bromide, adds 102 gram cuprous bromides, is warming up to 55～65 ℃, drips the diazonium salt solution of above-mentioned preparation, and temperature of reaction is controlled between 65～80 ℃.
Reinforced finishing do not emitted to there being nitrogen 70～80 ℃ of insulations.Reaction is cooled to 20～30 ℃, filtering reacting liquid then, filter cake is with about 20 gram washings, collect liquid phase, pack in the 500ml there-necked flask, add 20 gram water, stirring heating, connect water trap, the beginning steam distillation is collected lower floor's oil phase in the water trap, carries out rectification under vacuum after the drying, get 43.6 gram colourless liquids, content＞90%.
Theoretical yield: 94.9 grams,
Actual output: 43.6 grams,
Yield: 45.9%.
IR?ν(cm
-1)3322(N-H)，2976，1650，1502，1169，1126，1670
1H?NMR(CDCl
3)δ6.81(m，1H)，7.03(m，1H)ppm
19F?NMR(TFA)δ33.0，45.2，55.9ppm
MS(70eV)，m/e(relative?intensity)212(M
+)
C
6H
2BrF
3Calculated value: C34.16, H0.96
210.98 measured value: C34.30, H0.20
2,2,3,4-trifluoro-benzoic acid synthetic
250 milliliters of three-necked bottle configurations thermometer, magnetic stirring apparatus and dropping funnels, add 6.0 gram magnesium chips, 37 milliliters of tetrahydrofuran (THF)s and several iodine, add 40.0 grams 2 in the dropping funnel, 3,4-trifluorobromobenzene and 61 milliliters of toluene, the control temperature in the kettle is 1-25 ℃, splash into 2,3,4-trifluorobromobenzene solution, temperature in the kettle slowly raise and represent the reaction beginning.If do not react then heating, question response begin slowly to splash into again all the other 2,3, the toluene solution of 4-trifluorobromobenzene.After finishing, 40～50 ℃ of insulations 30 minutes.
Regulating temperature in the kettle is-12～10 ℃, and the carbonic acid gas that feeds drying, deoxygenation is to not absorbing.
Regulating temperature in the kettle is 25～35 ℃, and stirring adds 242 grams, 25% sulfuric acid, back ethyl acetate extraction three times down.Merge organic layer, 2.6%NaOH extraction with aqueous solution three times, water layer with ethyl acetate extraction is once used 24 milliliter of 25% sulfuric acid acidation then, gets faint yellow solid 22.7 grams, content＞98%.
Theoretical yield: 37 grams,
Actual output: 22.7 grams,
Yield: 61.4%.
IPν(cm
-1)3322(N-H)，2976，1750，1502，1169，1126
1H?NMR(CDCl
3)δ7.04(m，1H)，7.52(m，1H)，11.42(s，1H)ppm
19F?NMR(TFA)δ55.0，57.5，85.8ppm
MS(70eV)，m/e(relative?intensity)176(M
+)
C
7H
3F
3O
2Calculated value: C47.75, H1.72
176.10 measured value: C47.93, H1.88
Claims (10)
1, a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that by following method syntheticly, it is characterized in that with 2,3, the 4-trifluoromethyl aniline is a raw material, by the diazotization of amino, gets 2,3 after the itrile groupization, the 4-trifluorobenzonitrile makes 2,3 through acidic hydrolysis again, the 4-trifluoro-benzoic acid; Perhaps 2,3, the 4-trifluoromethyl aniline by the diazotization of amino after again bromination obtain 1-bromo-2,3, the 4-trifluoro-benzene makes Grignard reagent with MAGNESIUM METAL again, with carbon dioxide reaction after acidification hydrolization makes 2,3, the 4-trifluoro-benzoic acid; Promptly by following (1), (2) and (3), perhaps (1), (4) and (5) prepare respectively:
(1), in the presence of acid and under-10～60 ℃, 2,3, the reaction mol ratio of 4-trifluoromethyl aniline and nitrous acid reagent is reaction in 1: 0.8～3 o'clock 0.1～3 hour, described acid is Glacial acetic acid, sulfuric acid, hydrochloric acid, Hydrogen bromide or nitric acid, used nitrous acid reagent is Sodium Nitrite, nitrous acid or alkyl nitrite, and wherein alkyl is C
1-6Alkyl;
(2), above-mentioned 2,3, product and the nitrilation reagent react of 4-trifluoromethyl aniline behind product after the diazotization and nitrilation reagent react gets 2,3, the 4-trifluorobenzonitrile is with 2,3, the 4-trifluoromethyl aniline calculates, and 2,3, the mol ratio of 4-trifluoromethyl aniline and nitrilation reagent is 1: 1～10, temperature of reaction is 20～80 ℃, and wherein nitrilation reagent is NaCN, KCN or CuCN, and nitrilation reagent can use separately also can mix usefulness;
(3), under 60 ℃～reflux temperature, 2,3, be prepared into 2,3 after 4-trifluorobenzonitrile and the strong acid reacting by heating, the 4-trifluoro-benzoic acid, 2,3, the mol ratio of 4-trifluorobenzonitrile and strong acid is 1: 1～20, described strong acid is hydrochloric acid, sulfuric acid, nitric acid or Hydrogen bromide;
(4), above-mentioned 2,3, after reacting with bromide reagent, the diazonium salt that 4-trifluoromethyl aniline and nitrous acid reagent generate by diazotization reaction obtains, the mol ratio of described diazonium salt and bromide reagent is 1: 1～15 o'clock, in temperature of reaction is that 20～120 ℃ of reactions obtained 2,3, the 4-trifluorobromobenzene in 1～20 hour, wherein bromide reagent is liquid bromine, Hydrogen bromide, cuprous bromide, Potassium Bromide, cupric bromide or Sodium Bromide, and above-mentioned bromide reagent can use separately also can mix usefulness;
(5), in organic solvent, 2,3, the mol ratio of 4-trifluorobromobenzene and MAGNESIUM METAL is 1: 0.9～5 o'clock, is 0.2～5 hour 10～80 ℃ of reaction times, feeds down CO at-30～50 ℃ then
2Reaction in gas 1-40 hour obtains 2,3 with mineral acid hydrolysis again, the 4-trifluoro-benzoic acid, and acid-hydrolyzed temperature of reaction is-10～60 ℃;
2, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that in the reaction (1) 2,3, and the reaction mol ratio of 4-trifluoromethyl aniline and nitrous acid reagent is 1: 1～2, and temperature of reaction is that 0～20 ℃, reaction times are 0.1～1 hour;
3, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that in the reaction (2) that with 2,3, the 4-trifluoromethyl aniline calculates, 2,3, and the mol ratio of 4-trifluoromethyl aniline and nitrilation reagent is 1: 3～6, temperature of reaction is 40～60 ℃.
4, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that in the reaction (4), reaction product by steam distillation or/and rectification under vacuum.
5, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that the mol ratio of described diazonium salt and bromide reagent is 1: 1～4 in the reaction (4), and temperature of reaction is 40～80 ℃.
6, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that in the reaction (5) CO
2Gas is the CO of drying, anaerobic, no alcohol
2Gas.
7, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that 2,3,4-trifluoro-benzoic acid alcohol-water system recrystallization, and the volume ratio of pure water is 1: 0.2～1.0, wherein alcohol is methyl alcohol, ethanol, propyl alcohol or Virahol.
8, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that in (5) 2,3, and the mol ratio of 4-trifluorobromobenzene and MAGNESIUM METAL is 1: 1～2.
9, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid is characterized in that in (5) that used organic solvent is ether, kerosene, benzene, tetrahydrofuran (THF) or toluene in grignard reaction, or their mixed solvent.
10, as claimed in claim 1 a kind of 2,3, the synthetic method of 4-trifluoro-benzoic acid, the reaction product acidifying again of its feature (5), reaction solution are through the purifying of extraction, alkali-soluble acid analysis.
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2001
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