AU616326B2 - Creation of Inventions and Patents with Artificial Intelligence

AU616326B2 – Preparation of difluorobenzenes containing electron withdrawing substituents
– Google Patents

AU616326B2 – Preparation of difluorobenzenes containing electron withdrawing substituents
– Google Patents
Preparation of difluorobenzenes containing electron withdrawing substituents

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Publication number
AU616326B2

AU616326B2
AU45572/89A
AU4557289A
AU616326B2
AU 616326 B2
AU616326 B2
AU 616326B2
AU 45572/89 A
AU45572/89 A
AU 45572/89A
AU 4557289 A
AU4557289 A
AU 4557289A
AU 616326 B2
AU616326 B2
AU 616326B2
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Australia
Prior art keywords
reaction
solvent
substituted benzene
nmp
temperature
Prior art date
1988-11-28
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Application number
AU45572/89A
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AU4557289A
(en

Inventor
James A. Gall
Jack C. Little
R. Garth Pews
Charles A. Wilson
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Dow Chemical Co

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Dow Chemical Co
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1988-11-28
Filing date
1989-11-27
Publication date
1991-10-24

1988-11-28
Priority claimed from US07/276,711
external-priority
patent/US4937396A/en

1989-11-27
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Dow Chemical Co

1990-05-31
Publication of AU4557289A
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patent/AU4557289A/en

1991-10-24
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1991-10-24
Publication of AU616326B2
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patent/AU616326B2/en

2009-11-27
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Classifications

C—CHEMISTRY; METALLURGY

C07—ORGANIC CHEMISTRY

C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS

C07C255/00—Carboxylic acid nitriles

C07C255/49—Carboxylic acid nitriles having cyano groups bound to carbon atoms of six-membered aromatic rings of a carbon skeleton

C07C255/50—Carboxylic acid nitriles having cyano groups bound to carbon atoms of six-membered aromatic rings of a carbon skeleton to carbon atoms of non-condensed six-membered aromatic rings

C—CHEMISTRY; METALLURGY

C07—ORGANIC CHEMISTRY

C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS

C07C17/00—Preparation of halogenated hydrocarbons

C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens

C07C17/20—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms

C07C17/202—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction

C07C17/208—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction the other compound being MX

Description

PL-PI~~XXrlT”l~~’–‘~I-
AUSTRALIA
Patents Act COMPLETH SPECIFICATION
(ORIGINAL)
Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority 616326 Int. Class 09 4 0 Related Art: Applicant(s): The Dow Chemical Company 2030 Dow Center, Abbott Road, OF AMERICA Midland, Michigan 48640, UNITED STATES 9s 9 94 4s LV 9 09 O 0I Address for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: PREPARATION OF DIFLUOROBENZENES CONTAINING ELECTRON WITHDRAWING
SUBSTITUENTS
Our Ref 153959 POF Code: 1037/1037 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 1- 6006 i r -1A PREPARATION OF DIFLUOROBENZENES CONTAINING ELECTRON- -WITHDRAWING SUBSTITUENTS 04 6 0 o The present invention concerns a process for 0′ the preparation of ring-fluorinated benzonitriles and 0o benzotrifluorides from the corresponding ring- -chlorinated benzonitriles and benzotrifluorides. More 5 particularly, the present invention is directed to a process for the preparation of 3,4-difluorobenzonitrile and 3,4–difluorobenzotrifluoride using potassium fluoride (KF) as the o* 10 fluorinating agent.
0 4, 10 Difluorobenzotrifluorides and benzonitriles are useful intermediates for the manufacture of herbicides.
0° For example, U.S. Patent 4,642,338 discloses the use of 15 3,4-difluorobenzotrifluoride in the preparation of aryloxyphenoxy herbicides that control grassy weeds in the presence of broadleaf crops. Similarly, European 0 6 Patent Application Publication 302,203 discloses the use of 3,4-difluorobenzonitrile in the preparation of aryloxyphenoxy herbicides that control grassy weeds in the presence of broadleaf crops and in the presence of certain cereal grains. Furthermore, benzonitriles and benzotrifluorides can be interconverted by well-known organic reactions, as shown by the following scheme: 36.666A-F R \7 I
^L
r lit -2-
CF
3 COOH CONH 2 Conventional methods of preparing fluorinated aromatic compounds are based primarily on diazotization routes involving a number of steps. In U.S. Patent 4,6142,338, for example, 3,4-difluorobenzotrifluoride was prepared by reacting 4-chloro-3-nitrobenzotrifluoride with KF, reducing the nitro group to an amine, diazotizing and preparing the fluoroborate salt and decomposing to the desired product, as 15 shown by the following scheme: 00 0 0 0 0 0 co 00 0 r~ 0 0 ,o 00 0 0 0 Oo 00 0 000 0 0000 0000 00 0 00 00 0 0 00 00 0 o os 0 “~4 0 0 0o~0.*0 0 a N0 2 b
NO
2 NH 2 00 o 000 40 4 O 0 0 0 00 CF 3 d 0 1
F
36 ,666A-F r -3- A similar scheme was employed by Schaefer et al. in Can.
J.Chem., 57, 802 (1979).
Although highly fluorinated aromatic compounds can be prepared from perhalogenated aromatic compounds or perhalogenated aromatic compounds containing one or more electron-wiihdrawing substituents by the action of alkali metal fluorides, it was believed that this reaction was of preparative interest only for producing completely halogenated compounds and that reactions between incompletely halogenated aromatic compounds and 0oo 0 KF were accompanied by numerous side reactions and poor yields. (See, for’ example, Yokobson et al. in Synthesis, 0 652, October 1976).
1e i o;”b now been found that incompletely ring-flu-i ed benzotrifluorides and benzoni.tr dan be prepared in good yield by the ac KF or CsF on the correspond ng-chlorinated benzotrifluorides and O’ -Iges. The present invention is directed to a process for preparing a 3,4-difluoro substituted benzene of the formula S 3F a o (II i
F
F
,36,666A-F -3- -4wherein: Z is -CF 3 or -CN which comprises reacting a 3,4-dihalo substituted benzene of the formula
(III)
o R 0 0 0a e s s a oo a Sa A 0:o 0 6 r 6 wherein: X is -F or -Cl; and Z is as defined before; with an effective amount of KF in a cyclic carboxamide or urea solvent, the reaction medium containing less than 500 parts per million water, at a temperature from 220 to 295 0 C, and recovering the 3,4-difluoro substituted benzene from the reaction mixture.
r -It 1>r The conversion of a 3,4-dichloro substituted benzene (formula I in the following scheme) to 3,4 -difluoro substituted benzene (formula II in the following scheme) is a stepwise process which involves the intermediacy of a singularly fluorine-exchanged compound (formula III in the following scheme), either 3–fluoro-4-chloro substituted benzene and/or 3-chloro- 4 fluoro substituted benzene.
o ao o 0 0 0 0 0 a 06 0a a o Q a 0 a .0 0 0Q 0 0 4o o ova a o oa 0 0 0 a 0
III
Optionally, the reaction can be conducted in a fashion so that the singularly fluorine-exchanged fluorochloro substituted benzene is obtained as the 25 major product.
in the present reaction and are commercially ilable compounds. Substantially anhydrous finely-divided KF or CsF are preferred. A ous or spray-dried forms are particularly pr red. Substantially anhydrous KF and CsF ca bprepared, for example, by drying invacuo a S36,666A-F “Alz Ha I -6t a a. jt a a.
S t 4 oo t tr a,.
taa a a a a It a a Sa 6 6a a KF, the fluorinating agent employed in the present reaction, is commercially available. Substantially anhydrous and finely-divided KF is preferred. Amorphous or spray-dried forms are particularly preferred. Substantially anhydrous KF can be prepared, for example, by drying in vacuo at 140-250 C for several hours.
3,4-Dichlorobenzotrifluoride and 3,4-dichlorobenzonitrile are also commercially available compounds.
Cyclic carboxamide or urea diluents are employed as the reaction medium in the present process. These include N-methyl pyrrolidinone (NMP), N-cyclohexyl pyrrolidinone (NCHP), 1,3-dimethyl-2-imidazolidinone (DMI) and l,3-dimethyl-3,4,5,6-tetrahydro-2-(lH)pyrimidone (DMTHP).
Optionally, the reaction may be conducted in the 15 presence of an acid scavenger, such as, an alkali metal carbonate, and/or a phase-transfer catalyst.
The present reaction is conducted under substantially 20 anhydrous conditions at elevated temperatures. Preferred temperature ranges for 3,4-difluorobenzotrifluoride are from 240 to 295 C, Preferred temperature ranges for 3,4-difluorobenzonitrile are from 220 to 275 C.
Pressures of from atmospheric to greater than atmospheric are typically employed. Although it is possible to operate at atmospheric pressure, it is sometimes advantageous to operate at the autogenous pressure generated by the diluent, starting material and product in a sealed reactor at the preferred reaction temperatures. Such pressures typically range from slightly above atmospheric to about 500 pounds per square inch (psi) [about 3,450 kilopascals (kPA)] and depend upon the volume of the reactor. Optionally, the reaction can be run under pressure in a suitably designed reactor equipped with a distillation column so the product can be removed as formed.
Water is detrimental to the reaction and substantially anhydrous reaction conditions are preferred. By substantially anhydrous is meant that the reaction medium §61 contains less than about 500 parts per million (ppm) of
,JM
&s’Ar iA’ ~rii ~2L 3,a r f~% r ju m iIII IT T T _l1 ii iiIimiiinji ir ‘i^i’ii i rr-~ i water. Preferably the reaction medium contains less than about 150 ppm of water. Substantially anhydrous conditions may be achieved employing standard drying techniques. For example, a typical laboratory reactor can be dried by distilling the cyclic carboxamide or urea under a vacuum before addition of the reactants. Optionally, a small amount (5 to 10 percent by weight of the polar aprotic solvent) of a non-polar solvent such as an aromatic hydrocarbon (for example, toluene or xylene) may be added to the cyclic carboxamide or urea to aid in the removal of water by azeotropic distillation. Residual water in the reactor system is also often removed by azeotrop.c distillation.
The amount of solvent is not critical, but it is advantageous to employ enough solvent to keep the starting material in solution at t ri I r t t I Ao
JNM
r It -8reaction temperatures, generally from 2 to 25 parts by weight of the solvent per part by weight of the substituted benzene starting material. The relative proportions of reactants to be employed are not critical because some of the product will be formed when employing any proportion of reactants. The reaction consumes the reactants, however, in the ratio of one mole of fluorinating agent per mole of exchangeable chlorine atoms present in the starting material. For 1 example, with 3, 4 -dichlorobenzonitrile as the starting 0 0 10 oO material, 2 molar equivalents of KF -fS per mole of starting material are consumed. Usually from 1.0 to moles of KF me GF are employed per mole of exchangeable chlorine in the starting material.
The present reaction is typically conducted in the presence of agitation sufficient to maintain an o a essentially uniform dispersion of the reactants in the So solvent.
Catalysts are optionally employed to increase the reaction rate. Suitable catalysts include phase- -transfer catalysts. The catalyst is added to the °o present reaction mixture in an amount of from 0.0001 to o 25 0.1 mole per mole of starting material. Advantageously from 0.001 to 0.075 molar equivalents and preferably from 0.01 to 0.05 molar equivalents of catalyst are employed.
Phase-transfer catalysts are well-known compounds and include quaternary phosphonium salts containing 10 or more carbon atoms and macrocyclic polyethers commonly known as crown ethers. Suitable c crown ether catalysts include 18-crown-6; dicyclohexano- -18-crown-6; dibenzo-18-crown-6; 15-crown-5. A related 36,666A-F -8- ‘I j”^ -9catalyst species, tris(3,6-dioxa-heptyl)-amine, is also efficacious. Suitable quaternary phosphonium salts include the tetra-n-alkylphosphonium salts. The anion of the phosphonium salts is Fe, which may be derived from any anion which readily converts to Fe, such as, for example, Cle, Bre, Ie, OHe or OAce, under the reaction conditions.
Acid scavengers are optionally employed in the present reaction to consume or inactivate traces of HC1 10 or HF which may be present or generated during the reaction. Suitable acid scavengers include alkali metal 0 carbonates such as anhydrous K 2 C0 3 and anhydrous Na 2 C0 3 A preferred acid scavenger is anhydrous K 2
CO
3 The acid scavengers are added to the present reaction mixture in an amount of from 0.001 to 0.1 mole per mole of benzonitrile or benzotrifluoride starting material.
°o Preferably, from 0.03 to 0.05 molar equivalents are 4 employed.
The 3,4-difluorobenzonitrile or 3,4-difluorobenzotrifluoride can be recovered from the reaction 4 O mixture by conventional techniques such as extraction and/or distillation. Preferably, the product is removed S 25 from the reaction mixture as it is formed. Optionally, the reactant compound may be added as the product is removed.
The product may be separated from starting material and/or intermediate fluorochloro substituted benzenes by fractional distillation.
In carrying out the present reaction, neither the rate nor the order of addition of the reactants is critical. Usually, the solvent and fluorinating agent 36,666A-F -9are added to an appropriate reaction vessel and the reaction is dried by distilling a small portion of the solvent. ~t.L.iting material or precursor compound is then added to the reaction vessel. The reaction mixture is then h- ted to a temperature high enough to maintain S a satisfactory reaction rate. The product may be recovered from the reaction mixture after completion of the reaction by extraction and or distillation.
o “0 Alternatively, the product may be removed from the 10 reaction mixture by fractional distillation as it is ros 10 o° oformed. If an acid scavenger, a non-polar solvent, or o catalyst is employed in the reaction, then they are advantageously added to the solvent/fluorinating agent mixture prior to drying the reactor vessel.
The following examples illustrate the process of the present invention and should not be construed as limiting.
S 20 In the following examples, the fluorinating agents were dried in a vacuum oven at 150 0 C for at least 24 hours Solvents were dried by distillation from Scalcium hydride. Also, the following terms are used:
QQ
25 DCBCN 3,4-dichlorobenoni trile o o 25 DFBCN 3,4-difluorobenzoni trile FCBCN fluorochlorobenzonitrile NMP N-methyl pyrrolidinone DMI 1,3-dimethyl-2-imidazolinone DMTHP 1,3-dimethyl-3,4,5,6-tetrahydro-2- (1H) pyrimldone, and 36,666A-F itk -11- Example 1 A 600 milliliter (mL) Hastelloy” C pressure reactor was charged with 28.35 grams of KF, 150 mL of NMP, 20.5 g of DCBCN and 10.06 g of naphthalene (internal standard). The reactor was sealed and pressure tested. The reaction mixture was stirred at 235°C for 40 hr. After cooling and venting the reactor, the reaction mixture was analyzed by gas chromatography.
The analysis indicated a 21 percent yield of DFBCN.
Example 2 o ~A 300 mL stainless steel pressure reactor was charged with 34.8 g (0.6 mol) of KF, 120 mL of DMI and 34.8 g (0.2 mol) of DCBCN. The reactor was sealed and pressure tested. The reaction mixture was stirred a.
250°C for 24 hr. After cooling and venting, the product was isolated by extraction with ethyl acetate. A gas *.chromatographic analysis of the extract with biphenyl added to the extract as an internal standard indicated a 14 percent yield of fluorochlorobenzonitrile FCBCN and a 46 percent yield of DFBCN.
i r
I
II- Y I- Is~ V* 4 a 15 o e 9 fr) SO PI -12– Example 3 A 250 mL round bottom flask was equipped with a concentric tube distillation column, thermometer, magnetic stirrer and a distillation head with a nitrogen purge. The distillation column and head were wrapped with electrical tape and controlled at 160 and 130 0
C
respectively. The flask was charged with 34.8 g (0-.6 mol) of KF, 120 mL of DMTHP and 34 g (0.2 mol) of DCBCN.
The reaction mixture was heated with stirring at 240 0
C
for 23 hr and 8.71 g of distillate was collected. The temperature was increased to 245°C for an additional 2 1/4 hr and additional distillate was collected.
Analysis of the combined distillate indicated a 26 percent yield of FCBCN and a 39 percent yield of
DFBCN.
Example 4 DMI solvent (300 mL) and KF (70 g; 1.2 mol) were charged into a 500 mL 4-necked glass round bottom flank. The flask was equipped with a Oldershaw”‘ column, mechanical stirrer, thermowell and powder addition funnel. N 2 was purged through the flask and distillation system. The distillation system was vacuum-jacketed. The system was dried under a vacuum of 100 mm Hg (13.3 kilopascali) and the pot temperature was 160°C. About 25 mL of 3MI and water were removed. The vacuum was released, the N 2 puige and powder addition funnel were installed and the reactor temperature was increased to 220°C. The starting material DCBCN (62 g; 0.36 mol) was added slowly in order to maintain a concentration of DCBCN and FCBCN at about 5 percent.
The product DFBCN was distilled overhead. The distillate was 140 g of DMI and DFBCN. Gas chromatographic analysis of the distillate indicates that DFBCN was 25 percent 35 g (70 percent yield). The FCBCN intermediate was 1 percent, 1.4 g. The distillate was redistilled to yield 14 g of pure DFBCN.
U -13- Example DMI solvent (300 mL) and KF (70 g; 1.2 mol) were charged to a 500 mL 4-necked glass round bottom flask. The flask was equipped with a Oldershaw column, mechanical stirrer, thermowell and powder addition funnel. N 2 was purged through the flask and distillation system. The distillation system was vacuum-jacketed. The system was dried under a vacuum of 100 mm Hg (13.3 kilopaenals) and pot temperature of 1600C. A total of 25 mL of DMI and water, were removed.
The vacuum was released, the N 2 purge and powder addition funnel were installed. The reactor temperature was increased to 2270C. The starting material DCBCN (62 g; 0.36 mol) was added slowly in order to maintain a 15 concentration of starting material and intermediate at about 10 percent. The product DFBCN was distilled overhead. The distillate, cut was 25.8 g, containing 83 percent, 21.4 g DFBCN. Cut #2 was 52.6 g of DMI and DFBCN 65 percent, 34 g; total moles of DFBCN 20 were (0.3999 m) 80.0 percent. The FCBCN intermediate :a-x was 4.2 g (0.027 m) 5,4%.
Example .6 A series of experiments were conducted under pressure in either a 300 mL or 600 mL Hastelloy” “C” pressure reactor. The fluorinating agents were dried in a vacuum oven at 150°C for at least 24 hr. Solvents were dried by distillation from calcium hydride. The starting material, fluorinating agent and diluent were introduced into the pressure reactor with a known amount of 1,3-diethylbenzene which served as an internal standard. The reactor was sealed and pressure tested.
After the indicated times and temperatures, the reactor was cooled and vented and the reaction mixture was analyzed by gas chromatography. The experimental conditions and the results of these experiments are summarized in Table Ig .4^
I
_Y
r 4 4 4, 0 ar a p p 00 0O o a.
O *00 p0Q bg 0 000 O P l a p B 0 CO Table I q CF 3 Cl
I
Fluorine-Exchange on 3,4-Dichlorobenzotrifluoride
KF
solvent CF3 3 C 1 3
I
Temp Time KF I II III Mat Mol I mL E C hr (Hal) (Mol) (I1ol) (Hol) Bal. solvent Left Solvent No 1 275 24.25 0.4 0.2 2 0 074 0.096 0.77 85% NHP 0 250 2 275 24.25 0.8 0.2 4 0 092 0.059 1.55 76% NMP 0 250 3 275 24.33 0.8 0.2 4 0.098 0.068 1.44 83% NMP 0 250 4 275 24 0 .8 0.2 4 0.09 0.06 1.50 75% NMP 0 250 275 8 0.8 0.2 4 0.055 0.132 0.41 99% NMP 0.011 250 6 275 24 1 0.8 0 2 4 0.081 0.062 1.30 71.5% NMP a 250 7 275 24 0 Z 0.2 3 0.088 0.065 1.35 76.5% NMP 0 250 a 275 24 0 6 0.2 3 0.088 0.055 1.60 71 5% NMP 0 250 9 275 24 0 4 0 2 2 0.097 0.05 1.73 76 5% NMP 0 250 1O 275 24 0.8 Q2 4 0.052 0.133 0.46 82.5% NMP 0 250 folane ~-p
.X
:-CI-
‘i’
L
r_ i I -r 3-fi 3 LI tc~ i -1 ;Y c r Fw 0ra 0e 0 0 0 a a 0 O 00 S-_i 0 0 Table I (continued) Fluorine-Exchange on 3,4-Dichlorobenzotrifluoride ci CF 3
KF
solvent Cl CF 3 F CF 3 +F CF 3 F Cl F -aP
V\I
Temp Time KF I 1 III Mol I mL Exp, KC F/I II/III Mat. Bal. Solvent x C hr (Mol) (Mol) (Mol) (Mol) Left Solvent No.
13 275 24 0.2 0.1 2 0.033 0.046 0.71 79% NMP C 125
MFBTF
14 275 24 0.2 0.1 2 0.019 0.039 0.48 58% NMP 0 125
MFBTF
285 24 0.8 0.2 4 0.087 0.061 1.42 74% NMP 0 250 16 265 24 0,8 0.2 4 0.074 0.098 0.75 36% NMP 0 250 17 260 24 P.8 0.2 4 0.054 0.12 0.45 87% NMP 0 250 18 225 24 0.8 0.2 4 0.013 0.157 0.08 94.5% NMP 0.019 250 19 250 24 0.8 0.4 4 0.047 0.156 0.30 101.5% NMP 0 250 275 24 0.8 0.2 4 0.083 0.031 2.67 57% DMTHP 0 250 21 275 24 0.8 0,2 4 0.011 0.109 0.10 70% NCHP 0.02 250 22 260 24 0.8 0.2 4 0.053 0.083 0.63 68% DMTHP 0 250 23 240 24 0.8 0.2 4 0.026 0.109 0.23 70.7% DMTHP 0 250 24 250 24 0.4 0.1 4 0.02 0.056 0.35 76% DMTHP 0 125
U”
‘I
01 aI
ON
r c.
x^, 00 0 0 0 0 0 000 000 0 a a 0 a 00 0 0 00 *0 0 0 0 0 0 a 000 Table I (continued) Fluorine-Exchange on 3, 4-Dichlorobenzotrifluoride C1 CF 3 Ko 0C1 Q CF 3 F CF 3 F CF 3 solvent F C1 FC 4 ‘ii Y Y Exp.
No.
Temp 0C Time hr KF I (o4) (Mol}
KF/I
II
(Mol)
III
(Mol)
ITI/III
Mat. Bal. Solvent Mol I Left mL Solvent 260 24 0.4 0.1 4 0.026 0.057 0.45 85% DMI 0.002 125 26 275 12 0.4 0.1 4 0 0.026 103% NMP 0.077 125 27 275 12 V&4 0.1 4 0.042 0.041 1.02 83% DMI 0 125 28 275 12 0.4 0.1 4 0.05 0.037 1.35 87% DMI 0 125 29 260 12 0.4 0.1 4 0.027 0.06 0.45 87% DMI 0 125 260 12 0.4 0.1 4 0.028 0.061 0.45 89% DMI 0 125 31 260 24 0.4 0.1 4 0.04 0.044 0.90 88% DMI 0 125 32 260 24 0.4 0.1 4 0.047 0.042 1.11 89% DMI 0 125
I.
0.? 0″ 0 *o 0 0 f* 0 C C C C 000 060O
C
C 0 0 *g C o CC 000a 000 00* C C CC 00 0400 0 ~J Table I (continued) Fluorine-Exchange on 3,4-Dichlorobenzotrifluoride C ll
CF
3 Cl
KF
solvent C- CF 3 +F CF 3 F CF 3
F
F Cl SIII
II
Temp Tire KF I IM III Mt.I m Exp. KF/I 11,111 Solvent HlIm C hr (Hal) (Mol) (Mol) (Mol) Bal. Left Solvent No.
33 275 24 0.4 0.1 4 0.057 0.023 2.47 80% DM1 0 125 34 275 24 0.4 0.1 4 0.067 0.017 3.94 84% DM1 0 125
F
F
37 275 12 0.4 0.1 4 0.034 0.048 0.70 82% NMP 0 125 38 275 12 0.4 0.1 4 0.036 0.051 0.50 87% NMP 0 125
F
275 12 0.4 0.1 4 0.021 0.066 0.31 87% NMP 0 125 41 275 12 0.4 0.1 4 0.047 0.04 1.17 87% DM1 0 125 1

Claims (6)

1. A process for preparing a 3, 1

4-difluoro substituted benzene of the formula ~0 0 Q 00 @0 0 040 O 00 0 4 0i~ 0 to 04 0110 4440 0 0 0 00 4 00 0 0 0 0 04 (II) 10 wherein: Z is -CF 3 or -CN, which comprises reacting a 3,4-dihalo substituted benzene of the formula Li 01 Z 020 (III) 04 36,666A-F V r -*19- wherein; X is -F or -Cl; and Z is as defined before; with an effective amount of KF in a cyclic carboxamide or urea solvent, the reaction medium containing less than 500 parts per million water, at a temperature from 220 to 295 C, and recovering the 3,4-difluoro substituted benzene from the reaction mixture. 2. A process as claimed in Claim 1 in which X is -Cl. 3. A process as claimed in Claim 1 or 2 in which Z is -CN. 4. process as claimed in Claim 1 or 2 in which Z is -CF 3 I, 5. A process as claimed in Claim 3 in which the S .15 temperature is from 220 to 275°C.

6. A process as claimed in Claim 4 in which the I temperature is from 240 to 295°C

7. A process as claimed in any one of the preceding claims in which the cyclic carboxamide or urea solvent is 20 N-methyl pyrrolidinone, 1,3-dimethyl-2-imidazolidinone or 1,3-dimethyl-3,4,5,6-tetrahydro-2-(lH) pyrimidone.

8. A process as claimed in Claim 5, 6 or 7 in which from 1.0 to 3.0 molar equivalents of KF per exchangeable -Cl atom are employed. S* 25 9. A process as claimed in any one of the preceding claims in which the reaction is carried out in the presence of a phase transfer catalyst or an acid scavenger. A process as claimed in any one of the preceding claims in which the reaction is carried out at the autogenous pressure generated by the reaction mixture in a sealed reactor.

11. A process as claimed in Claim 1 substantially as hereinbefore described with reference to any one of the examples. DATED: 30 July, 1991 THE DOW CHEMICAL COMPANY By their Patent Attorneys: PHILLIPS ORMONDE FITZPATRICK

AU45572/89A
1988-11-28
1989-11-27
Preparation of difluorobenzenes containing electron withdrawing substituents

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US07/276,711

US4937396A
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1988-11-28
1988-11-28
Preparation of 3,4-difluorobenzotrifluoride

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Preparation of difluorobenzenes containing electron withdrawing substituents

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Title

US4937397A
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1988-11-28
1990-06-26
The Dow Chemical Company
Preparation of halofluorobenzenes

EP0497239A1
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1991-01-30
1992-08-05
Hoechst Aktiengesellschaft
2-Chloro-4,5-difluorobenzonitrile and process for preparation thereof

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1991-05-10
1991-07-03
Ici Plc

EP0944564B9
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1996-11-22
2005-01-19
Albemarle Corporation
Halogen exchange reactions and uses thereof

GB0407952D0
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2004-04-08
2004-05-12
Amersham Plc
Fluoridation method

JP4973143B2
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2005-12-08
2012-07-11
住友化学株式会社

Method for producing tetrafluoroterephthalic acid difluoride

HU0800492A2
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2005-12-08
2010-01-28
Sumitomo Chemical Co
Method for producing tartrafluoroterephthalic acid difluoride

JP6385845B2
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2014-03-27
2018-09-05
大阪ガスケミカル株式会社

Novel fluorene compound and process for producing the same

CN104387264B
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2014-11-11
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Priority date
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Assignee
Title

US4229365A
(en)

1977-05-28
1980-10-21

Basf Aktiengesellschaft

Manufacture of substituted fluorobenzenes

AU4557389A
(en)

1988-11-28
1990-05-31

Dow Chemical Company, The

Preparation of halofluorobenzenes

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1989-11-27
EP
EP19890203010
patent/EP0372621B1/en
not_active
Expired – Lifetime

1989-11-27
DE
DE1989617567
patent/DE68917567T2/en
not_active
Expired – Lifetime

1989-11-27
AU
AU45572/89A
patent/AU616326B2/en
not_active
Expired

1989-11-27
CA
CA 2003919
patent/CA2003919C/en
not_active
Expired – Lifetime

1989-11-27
JP
JP1304934A
patent/JP2667720B2/en
not_active
Expired – Lifetime

1989-11-27
FI
FI895662A
patent/FI92387C/en
not_active
IP Right Cessation

1989-11-28
BR
BR8906227A
patent/BR8906227A/en
not_active
IP Right Cessation

Patent Citations (2)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

US4229365A
(en)

1977-05-28
1980-10-21
Basf Aktiengesellschaft
Manufacture of substituted fluorobenzenes

AU4557389A
(en)

1988-11-28
1990-05-31
Dow Chemical Company, The
Preparation of halofluorobenzenes

Also Published As

Publication number
Publication date

JPH02218629A
(en)

1990-08-31

CA2003919A1
(en)

1990-05-28

DE68917567T2
(en)

1994-12-22

DE68917567D1
(en)

1994-09-22

BR8906227A
(en)

1990-06-26

EP0372621B1
(en)

1994-08-17

FI895662A0
(en)

1989-11-27

AU4557289A
(en)

1990-05-31

EP0372621A1
(en)

1990-06-13

FI92387B
(en)

1994-07-29

CA2003919C
(en)

2000-01-18

FI92387C
(en)

1994-11-10

JP2667720B2
(en)

1997-10-27

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