Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfur containing
Patent
1987-02-05
1989-07-18
Terapane, John F.
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfur containing
568938, C07C 7912
Patent
active
048495522
DESCRIPTION:
BRIEF SUMMARY
Fluoronitrobenzene compounds such as 2-fluoronitrobenzene, 4-fluoronitrobenzene, and 2,4-difluoronitrobenzene, are useful as intermediates for the synthesis of various herbicidal compounds, dyes, and the like. Such compounds have been prepared from corresponding chloronitrobenzene compounds by so-called halogen exchange reactions, illustrated as follows: ##STR1## wherein MF represents an alkali metal fluoride salt. The reaction is generally conducted in an aprotic, polar, organic solvent, such as dimethylsulfoxide, dimethylformamide, tetramethylenesulfone (sulfolane), and the like.
Alkali metal fluoride salts are not soluble in such solvents. Therefore, the reaction mixtures usually contain two phases, i.e., solid and liquid phases or two immiscible liquid phases. Finger, et al., J. Am. Chem Soc., 78, 6034 (1956) and Duesel, et al., U.S. Pat. No. 3,064,058 (1962), describe the reaction of chloronitrobenzene compounds with finely-divided, solid potassium fluoride in aprotic polar solvents to produce corresponding fluoronitrobenzene compounds. Boudakian, et al., U.S. Pat. No. 3,240,824 (1966), describe the reaction of o-chloronitrobenzene with solid potassium fluoride at elevated temperatures, without any solvent or diluents, to produce o-fluoronitrobenzene. Napier and Starks, U.S. Pat. No. 3,992,432 (1976), describe a reaction involving two liquid phases. In the Napier and Starks reaction, the inorganic fluoride salt is dissolved in an aqueous phase, and the chloronitrobenzene compound is dissolved in a water-immiscible, organic phase. The reaction is catalyzed by a quaternary salt, which reportedly transfers ions across the phase interface.
Use of quaternary salt phase-transfer catalysts in solid-liquid, two phase reactions also has been known. For instance, Kunz, U.S. Pat. No. 4,069,262 (1978), describes the production of 2-fluoronitrobenzene by reacting 2-chloronitrobenzene with ultrafine particulate potassium fluoride in tetramethylenesulfone solvent using a macrocyclic ether (crown ether) or a quaternary ammonium halide (such as tetrabutylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium fluoride or benzyltriethylammonium chloride) as the catalyst.
Tull, et al., U.S. Pat. No. 4,140,719 (1979), describes the production of 2,4-difluoro-5-chloronitrobenzene by reacting 2,4,5-trichloronitrobenzene with a solid fluorinating agent selected from NaF, KF, CsF, and C.sub.1-4 alkyl quaternary ammonium fluoride, and mixtures thereof under substantially anhydrous conditions in the presence of a quaternary compound solid-liquid phase transfer catalyst. The liquid phase comprises an organic solvent in which the trichloro compound is soluble and the fluorinating agent is essentially insoluble.
Starks, "Selecting a Phase Transfer Catalyst," Chemtech (February 1980), pages 110-117, describes patterns that purportedly enable prediction of catalysts for anion transfer from aqueous or solid inorganic phases to organic phases.
North U.S. Pat. No. 4,287,374 (1981) discloses a proces for the production of a monofluoronitrobenzene in which a monochloronitrobenzene is heated with an alkali metal fluoride and a phase transfer catalyst at a temperature of no more than 200.degree. C., preferably 125.degree.-170.degree. C., especially 140.degree.-150.degree. C. North discloses, as examples of such catalysts which may be used, long chain alkylammonium halides.
In general, halide-exchange reactions for preparing fluoronitrobenzene compounds by reacting chloronitrobenzene compounds with fluoride salts in aprotic, polar organic solvents in the presence of quaternary ammonium salt phase-transfer catalysts proceed at faster rates when conducted at elevated temperature relative to rates obtainable at lower temperature. However, quaternary ammonium phase-transfer catalysts employed in heretofore known methods are less stable at higher temperature and have been found to decompose or lose their catalytic activity at elevated reaction temperatures. Moreover, U.S. Pat. No. 4,418,229 (to White), incorporated herein b
REFERENCES:
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patent: 3240824 (1966-03-01), Boudakian et al.
patent: 3480667 (1969-11-01), Siegart et al.
patent: 4069262 (1978-01-01), Kunz
patent: 4140719 (1979-02-01), Tull et al.
patent: 4164517 (1979-08-01), Fuller
patent: 4226811 (1980-10-01), Oeser et al.
patent: 4229365 (1980-10-01), Oeser et al.
patent: 4287374 (1981-09-01), North
patent: 4294988 (1981-10-01), Tull et al.
patent: 4418229 (1983-11-01), White
patent: 4642399 (1987-02-01), White
patent: 4684734 (1987-08-01), Kareda et al.
Finger et al., Journal of the American Chemical Society, 78, 6034-6037 (1956), p. 6035.
Mallinckrodt Inc.
Terapane John F.
Wolffe Susan
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