DE1593265A1 - Process for the preparation of 2,4-dichloro-3-nitrotoluene - Google Patents

Description

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DH. ING. F. "WUESTHOFF A CflOOCE SCHWEIOEHSTHASSE DIPL. ING. G. PULS NJJtWJ tmmok S3 οβ 51 DR.K.T.PKOHMANN umiuauiiiMn. PATENT LAWYERS PBOTJSOTPATKKT icüircHBX

1A - 32

Description of the patent application

Parke, Davis & Company, Law Department Joseph Campau Avenue at the River Detroit, Michigan 48 232, U.S.A

concerning

Process for the production of 2,4-dichloro -3-nitrotoluene

The invention relates to a new chemical compound 2,4-dichloro-3-nitrotoluene and to a process for its preparation in a good yield of 60 ^c / o or more.

The process of the invention consists in reacting 4-chloro-3-nitrotoluene with a chlorinating agent in the presence of a chlorination catalyst. * The preparation of 2,4-dichloro-3- iitrotoluol by the present process surprisingly in view of the classical theory of substitution for aromatics, which was to be expected that the formation

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just this product would be unlikely in good yield. A deactivation of the ortho and para positions and a directing of the substitution mainly into the meta position EU was to be expected from the presence of a nucleus-bound nitro group. Chlorine gas or antimony trichloride can be used as the chlorinating agent. The amount of chlorinating agent used in the reaction is subject to considerable variation, but generally at least one mole of chlorinating agent will be used for every mole of 4-chloro-3-nitrotoluene starting material. A moderate excess of chlorinating agent is preferred * Suitable chlorination catalysts are antimony dichloride, antimony pentachloride, iodine, ferrite chloride and aluminum chloride * Antimony chloride and antimony pentachloride are preferred catalysts. The amount of catalyst for the reaction can be varied widely and is not critical 08 to 0.15 moles for antimony pentachloride for every mole of 4-chloro-3-nitrotoluene as starting material. With smaller amounts of catalyst, the reaction rate can be too slow, while larger amounts can be uneconomical! can * The [temperature range for the reaction can also vary considerably. Temperatures in the range from 10 to 100 ^° C

are satisfactory, the preferred range is 30

/ bia 50 ⁰ C · The reaction is usually left in about 5 hours. bleed to completeness. In the implementation

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gas is the completeness conveniently determined by periodic measurement until the calculated amount of chlorine is added to yield an excess of dissolved example up to about 10 io unreacted chlorine in the reaction mixture or otherwise do not participate directly in the reaction. Although a solvent is unnecessary for the reaction, any of a number of suitable non-reactive solvents can be used, among which halogenated carbons such as tetrachloroethane, chloroform and carbon tetrachloride are preferred.

The product according to the invention 2,4-dichloro-3-nitrotluol is valuable as an intermediate for the production of anthranilic acid compounds, which have valuable anti-inflammatory properties. In particular, the product can through Reduction converted into the corresponding 2,6-drichloro-3-methylaniline which in turn with potassium orthobromobenzoate to the anaetic compound F- (2,6-dichloro-m-tolyl) antranilic acid can be condensed. The latter connection is.t known e.g. from British patent specification 989 951.

The invention is illustrated by the following examples:

Example:

Chlorine gas is allowed in 500 g of 4-chloro-3-nitrotoluene and bubbled 30 g of antimony trichloride, keeping the temperature between 40 and 45 ⁰ C. The reaction is continued and the conversion of A _r Chlorgae maintained to 10 $ Chlorübersohuß

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are absorbed. The reaction mixture is then purified of gaseous compounds by blowing nitrogen through the mixture and diluted with ether and treated with concentrated hydrochloric acid. The acid layer is then removed and the remaining organic phase is dried and concentrated in vacuo. The residue is left to ^{stand at 0} ° C. and the resulting crystalline product 2,4-dichloro-3-nitrotoluene is weighed by filtration and it is recrystallized from ethanol; F. 84 - 85.5 ⁰ O.

Example 2:

Chlorine gas is bubbled into 40 g of 4-chloro-3-nitrtoluene and 2.4 g of antimony trichloride in 50 ecm of tetrachloroethane, up to 10 g of chlorine are absorbed. After degassing the reaction mixture with nitrogen, the Gemisoh is diluted with ether and stirred with 20 ecm 10 η sodium hydroxide solution for two hours. Then filtered the organic layer and the product 2,4-dichloro-3-nitrotoluene is isolated in the same way as in Example 1. The same reaction can be carried out using aluminum chloride or ferric chloride as a catalyst in excess instead of antimony trichloride.

Example 3:

A solution of 6 g of iodine and 40 g of 4-chloro-3-nitrotoluene is introduced at 40 ° until the exothermic reaction ceases. After removing the volatile halogen compounds by rinsing

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len the reaction mixture with nitrogen is cooled, wherein the product 2,4-dichloro-3-nitrotoluene crystallizes, and then isolates the product and purifies as in Example 1.

Example 4:

The mixture is allowed chlorine into a solution of 40 g of 4-chloro-3-nitrotoluene and 7 g Antimonpenatachlorid bubbled, keeping the temperature between 40 and 45 ⁰ C until the amount of the absorbed chlorine of the molar amount of toluene exceeds the starting material 10 $. The reaction mixture is then worked up in the same way as in Example 1; the resulting product is 2,4-dichloro-3-nitrotoluene.

The product can be converted into N- (2,6-dichloro-m-tolyl) anthranilic acid by reduction to 2,6-dichloro-3-methylaniline and condensation with potassium o-bromobenzoate according to the following as Example given method of operation can be converted:

A solution of 225 g of stannous chloride dihydrate in 325 ecm of ethanol and 215 com of concentrated hydrochloric acid is prepared. To this is added 42.4 g of 2,4-dichloro-3-nitrotoluene in portions, keeping the temperature below 35 ⁰ C. The solution is allowed to stir for about 15 hours and then the ethanol, which contains suspended solids, is removed under reduced pressure. The aqueous residue is neutralized with sodium hydroxide and the ethereal basic solution is drawn off

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with ether out. The extracts are combined, dried and the ether is removed under reduced pressure, being used as 2,6-Diohlor-3-methylaniline residue is obtained. This product 34 »2 g is kept together with 47.7 g of potassium o-bromobenzoate, 23 g N-ethylmorpholine and 2 g cuplibromide in 120 ecm diglyme (Diethylene glycol dimethyl ether) 3 hours with stirring at 150-160 ° C. under nitrogen. The mixture is then diluted one after the other with 120 ecm diglyme and 25 ecm more concentrated Hydrochloric acid and 100 ecm of water. The remaining oil, which is N- (2,6-dichloro-m-tolyl) anthranyl acid, is treated one with cold ethanol and the resulting crystals are collected; F. 254 - 255 ° C with decomposition after recrystallization from acetone-water.

Claims

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Claims (5)

»» .LLr.PBCnMl.lfA ^ 1A-32 561 PATxirTAX patent claims 1. Process for the preparation of 2,4-dichloro-3-nitrotoluene, gekenneichnet thereby that 4-chloro-3-nitrotoluene treated with a chlorinating agent in the presence of a chlorination catalyst. 2. The method according to claim 1, .d As a result g e k e η nz e i without t that chlorine gas is used as the chlorinating agent. 3. The method according to claim 1, characterized that antimony pentachloride is used as the chlorinating agent. 4. The method according to claim 1, characterized in that the catalyst used is antimony trichloride, Antimony pentachloride, iodine or aluminum chloride are used. 5. The method according to claim 1, characterized in that the reaction is carried out at temperatures of about 30-50 ^° C. in the presence of a non-reacting solvent. 009834/2123