DE2724645A1 - PROCESS FOR THE PRODUCTION OF FLUORONITROBENZENE - Google Patents

Description

PAWWANWAUl ^Ka BROSE ^DK * BROSE

D-8023 Munchen-Pullach, Wiener 3Ir 2; TJ (089) "" ¹ U 30 71; Telex 52i £ K7 biosd. Cables. · Palenlibus »Munich

Graduate engineer

Your reference: Your ret .:

June 1, 1977

ISC CHEMICALS LIMITED, Borax House, Carlisle Place, London SV /. 1, England

Ancestors of the production of fluoronitrobenzoiew

The invention relates to a method for producing Fluoronitrobenzenes and in particular an improvement and Modification of the method according to patent ... (= patent application P 25 27 W. 1-42 = GB patent 1 4-69 700).

In DT-OS 2 527 944 (GB-PS 1 469 700) a method for the preparation of 2-fluoronitrobenzene described in the 2-chloronitrobenzene with an alkali metal fluoride at a temperature in the range of 230 to 250 ° in the presence heated by sulpholane (tetrahydrothiophene-1,1-dioxide) will. The preferred molar ratio of sulpholane to organic starting material is 0.3: 1 to 0.9: 1.

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In the meantime it has been established that the procedure of the DT-OS 2 527 W (= GB-PS 1 469 700) can be used in the same way, if a chlorine substituent is in the para position with respect to the nitro group, even if other unaffected

flowed substituents, such as a chlorine substituent, are in the meta position.

Thus, the present invention relates to a modification of the j Procedure of the patent ... (= patent application P 25 27 944.1-4-2 j = GB patent 1,469,700), in which the starting material is polychloronitrobenzene or is fluorochloronitrobenzene, which is a chlorine atom j in the para position with respect to the nitro group on v / e.

In this context, the term "polychloronitrobenzene" should include an aromatic nitro compound with at least 2 chlorine atoms ^; Ringkohienstoffatomen are understood.

According to the invention a method for the preparation of fluorine _;

'nitrobenzene with a fluorine atom in para position with respect to! the Nitrognppe provided in which one polychloronitrobenzene or; Fluorochloronitrobenzene with a chlorine atom in the para position in j with respect to the nitro group with an alkali metal ^ luorid in the presence heated by sulpholane. j

The polychloronitrobenzene can have chlorine substituents as the starting material contained both in the ortho and in the meta position and in both positions with respect to the nitro group. However, if such a chlorine substituent is in the meta position, it is normally not subject to exchange for a fluorine atom in the process of the invention.

If the starting material contains chlorine atoms in both the ortho and para positions with respect to the nitro group, the starting material is somewhat more reactive than if only one chlorine atom is present in either the ortho or the para position; therefore the molar ratio of sulpholane to the organic starting material can be reduced somewhat. The preferred molar

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The ratio in this case is in the range from 0.1: 1 to 3.0: 1 (ie moles of sulpholane: moles of dichloronitrobenzene), in particular in the range from 0.1: 1 to 0.9: 1 and particularly preferably in the range of 0 , 1: 1 to 0.5: 1 The reaction temperature in this case is preferably 180 to 250 ^° C.

In general, there should be at least one mole of alkali metal fluoride per to be exchanged chlorine atom can be used in the polychloronitrobenzene substrate j.

! When the starting material is 3,4-dichloronitrobenzene, yields the fluorination reaction as the main product 3-chloro-4-fluoronitro-

benzene. This compound can easily be converted into 3-chloro-4-fluoroaniline ι

transferred v / earth, which is a valuable intermediate product for the production of certain herbicides, such as isopropyl ( ⁱ ) -2- (N-benzoyl-3-chloro- ^ l-fluoroaniline) propionate, ι the one under the trade name " BARNON "expelled v / ird (Wa- '

! ι

j renzeichen). i

!

j If the starting material is 2,4-dichloronitrobenzene, ' ι

the resulting difluoro compound is a useful intermediate

! for the production of certain drugs. For example ι the nitro compound can form 2,4-difluoroaniline j

j, which is an intermediate product in the production j of the flame-retardant compound 2 ¹ , 4'-difluoro-4-hydroxy- (1,1 · - biphenyl) -3-carboxylic acid, which is sold under the trade name

I "DIFLUNISAL" is marketed.

! ■ ■

The invention is explained in more detail below by means of examples. example 1
Production of 3-chloro- ^/ fluomitrobenzene.

A mixture of 3,4-dichloronitrobenzene (76.8 g, 0.4 mol) and previously dried KF (25.5 g, 0.44 mol) in sulpholane (35 g) was stirred at 240 ° 24 in a 500 ml -Drfiihwip ^ oi ^ «·» -erfahrt,

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which was provided with a Polytetrafluorä!, ethylene stirrer, a thermometer pocket and a reflux condenser. The cold reaction mixture was transferred to a rotating film evaporator flask and the volatile portion of the product was recovered under reduced pressure with the oil bath temperature recorded during the distillation. Fraction 1 (41.02 g) was distilled at 30 mm from an oil bath at 190 to 200 ⁰ C and containing a mixture of 83.2% 3-Chlorf 4-fluoronitrobenzene, 3,2% 3, ^ - dichloronitrobenzene and 11% sulpholane , while fraction 2 (34.58 g) distilled at 5 mm from an oil bath at 180 to 200 ⁰ C and a mixture of 41 % 3-chloro-4-fluoronitrobenzene, 6 % 3,4-dichloronitrobenzene and 52 %

ι contained sulpholane.

!

The dichloronitrobenzene and sulpholane contents of the distillate;

Lated fractions were determined and the yields calculated. There were 48.3 g of 3-chloro-4-fluoronitrobenzene (conversion ' j

68.8 %) and 3.3 g of 3,4-dichloronitrobenzene (conversion 2.5 #): obtained and recovered 22.7 g of sulpholane (65 % of the material used).

Example 2 I.

The following table I gives the reaction conditions for five:

Try again the ones for the implementation of ^, ^ - dichloronitrobenzene (abbreviated 2,4-DOINB) with previously dried potassium fluoride were carried out.

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Tabcli3 I.

KP and 2,4-DClNB / sulpholane (quantities of the reactants and Conditions)

Attempt KP attempt

2,4-DClNB sulpholane temp / time molar ratio

Sulpholane / 2,4-DClNB

I. 38.3 g
(O.66m) 57.6
(0.3 S) 30 g
(0.25 m) 240/6 0.83 II 66.1 g
(1.14 m) 102.6
(0.53 m) nothing 240/30 nothing III 65.8 ε
(1.14 m) 96.8
(0.5 r;
m) 16.1 g
(0.14 m) 240-218 / 53 0.26 IV 65.0 g
(1.12m) 97.0
(0.5 r:
m) 16.2 r:
(0.14 m) 240-256 / 24 0.28 V 127-6 rc
(2.2 m) 192.0
(1.0 m) 12.0 fr
(0.1 m) 238-240 / 24 0.10

Note: m = mole

In each case, the reaction was carried out in a 250 m] three-necked flask carried out with a stirrer with a polytetrafluoroethylene sheet, a thermometer pocket and a single surface reflux condenser was provided. During the conversion, samples were taken at certain intervals; the conversion of 2,4-dichloronitrobenzene to 2,4-difluoronitrobenzene was calculated from gas / liquid chromatographic analyzes of the samples according to the following relationship:

Conversion to 2,4-DFNB

^'10 °

2,4-DFNB + 2 Cl 4 PNB + 2,4-DClKB

2,4-DFNB = 2,4-difluoronitrobenzene

2 Cl 4 FNB = mixture of 2-chloro-4-fluoronitrobenzene and

4-chloro-2-fluoronitrobenzene 2,4-DClNB = 2,4-dichloronitrobenzene

In experiment II (without ulpholan) the conversion was about 20 % in 30 hours.

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Using a molar ratio of sulpholane: 2, chloronitrobenzene = 0.1: 1 (experiment V), the conversion was 38.4 % in 24 hours, while at a molar ratio of 0.83: (experiment I) a 94 percent conversion into only 6 h was reached. In Run III the conversion was 63 % in 24 hours. In Run IV the conversion was 52 % in 24 hours.

In summary it can be said that the sulpholane

rate is increased and is preferably used in a molar ratio in the range from 0.1: 1 to 0.5: 1 with respect to the dichloronitrobenzene ' . ί

[ The following Table II shows the reaction conditions and the

! Product analyzes for a further six trials at different

j Sulpholane: dichloronitrobenzene molar ratios and reaction

'Conditions with the 2,4-dichloro compound as starting material.j

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Table II

Try KP

2,4-DClNB Sulpholane Time Temp. Molver product analysis (- '$)

(h) ( ⁰ C) ratio

Sulpholane /

2,4-DClNB DFITB ClPIiB DClITB

exploited
tes KP (#

Yl 220.5 g.
(3.8 m) 333.6 g.
(1.74 a) 68.7 g.
(O _r 57 m) 22nd 226-
240 0.33 75.2 22.8 0.4 59 TII 351.3 g.
(6.06 m) 666.1 g.
. (3.47 m) 237.7 g.
(1.98 n) 9 208-
240 0.57 50.8 37.3 4.1 57.6 VIII 351.2 g.
(6 _; 06 m) 666.1 g.
(3.47 a) 238.6 g.
(1.99 m) 9 230-
240 0.57 67.8 29.3 0.7 68.0 ΊΧ 262.7 g.
(4.53 m) 498.1 g.
(2.59 m) 177.8 g.
(1 _; 48 a) 13th 229-
240 0.57 57.3 37.0 1.8 75.7 X 40.0 g.
(0.69 m) 96.8 g.
(0.50 m) 34.6 g.
(0.29 n) 20th 232-
240 0.58 48.0 43.1 4.1 66.6 el 283.8 g.
(4 _- 89 m) 668.1 g.
(3.48 m) 242.2 g.
(2.02 m) 15.5 240-
243 0.58 17.3 47.5 25.7 41.5

ISJ ISJ

xn

Note: In the table above, '· used KF (#) "means the fluorine content of the fluoronitrobenzenes in the product, expressed in % of the fluorine in the potassium fluoride used.

Example 3

Fluorination of 2,4-dichloronitrobenzene with KF / sulpholane 200 °.

Four tests were carried out in which different Approaches of 2,4-dichloronitrobonzene, a mixture of 2-chloro-4-fluoronitrobenzene and 4-chloro-2-fluoronitrobenzene and from KF /; j sulpholane were placed in a reaction vessel, which in 'each case' was heated to 200 ° in about 4 h (see. Table III). When the j

"η '

When the temperature reached 200, the contents were collected and analyzed by gas / liquid chromatography (designated "g.l.c."; see Table IV). The increase in the difluoronitrobenzene content and the corresponding decrease in the 2,4-dichloronitrobenzene content showed that considerable fluorination had occurred at this stage.

Table III

Approach used in the KF / sulpholane reaction (parts by weight) Use Trial 1 Trial 2 Trial 3 Trial 4

Theatrical Version 125 • 150 150 X1% ) ⁺ 150 Sulpholane 254 425 290 , 6 (26 ,8th%) 265 2,4-DFNB 6.2 (2.3%) ⁺ - 4.3 , 0 (72 , 3%) 8.7 (2.3%) 2C14FNB 171 .8 (64.0%) - 119 143.8 (38.4S 2,4-DCINB 90, 5 (33.7%) 225 (100%) 323 222 (59.3%)

Note: = percentage of the total content of nitro compounds

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Table IV

Gas / liquid chromatography analysis of the product after 4 hours

Heat to 200

Connection attempt 1

attempt

Attempt 3

Attempt 4

2,4-DFNB

! 2C14FNB

! 2,4-DCINB

'Sulpholanes

7.48% (14.5%) 30.87% (60.0%)

7 ₇ 64% (16 _; 1%)

31%

46.32% -

Notes: ⁺ = percentage of the total organic composition

= percentage of the nitro compounds alone without sulpholane content

Keys for Tables III and IV:

2,4-DFNB = 2,4-difluoronitrobenzene 2C14FNB = mixture of 2-chloro-4-fluoronitrobenzene and

4-chloro-2-fluoronitrobenzene 2,4-DClNB = 2,4-dichloronitrobenzene

j Example 3 shows that considerable fluorination in the er-! heating the reaction mixture to 200 ⁰ G takes place in the course of 4 h.

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Claims (1)

PATENT CLAIMS subsequently changed f Ί. , Process for the preparation of fluoronitrobenzene by heating of chloronitrobenzene with an alkali metal fluoride in the presence of sulpholane (addendum to patent ... = patent application P 25 27 944-1-Ί-2), characterized in that a polychloronitrobenzene or chlorofluoronitrobenzene with a chlorine atom in the para-position with respect to the nitro group as chloronitrobenzene output uses and produces a fluoronene trobenzene with einnm fluorine atom in para position with respect to the nitro group. ι 2. The method according to claim 1, characterized in that one a chloronitrobenzene uses, in which chlorine atoms in the meta- j ι and are in the para position with respect to the nitro group. 3. The method according to claim 1 or 2, characterized in that; that the sulpholane: dichloronitrobenzene molar ratio in the range i
j is from 0.3: 1 to 0.9: 1. 4-, Process according to one of the preceding claims, characterized in that a Henktionstomneratur of 230 to 250 ⁰ C is used. 5 «The method according to claim 1, characterized in that one 'a chloronitrobenzene uses, in which chlorine atoms in the ortho-' x are in the para position with respect to the nitro group. i [ 6. The method according to claim S, characterized in that j is a sulpholane: dichloronitrobenzene molar ratio in the range of 0.1: 1 to 3.0: 1 applies. 7 · The method according to claim 6, characterized in that a sulpholane: dichloronitrobenzene fiol ratio in the range of! 0.1: 1 to 0.9: 1 applies. 8. The method according to claim 7, characterized in that one a sulpholane: dichloronitrobenzene molar ratio in the range of 709850/1030 ORIGINAL INSPECTED 0.1: 1 to 0.5: 1 applies. 9. Process according to one of the preceding claims, characterized in that a reaction temperature of 180 to 250 ⁰ C is used. 10. The method according to any one of the preceding claims, characterized in that potassium fluoride is used as AJ kaLimetallfluorid! used. 709850/1030