Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Patent
1998-04-27
2000-02-01
Richter, Johann
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
568812, 568814, C07C25500, C07C 3346, C07C 2700
Patent
active
060205172
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing fluorinated benzonitrile and fluorinated benzyl alcohol useful as intermediates for the production of cyclopropane carboxylic acid esters having superior insecticidal action, and other agrochemicals, drugs, etc.
BACKGROUND ART
It has been disclosed that a cyclopropane carboxylic acid ester of a fluorinated benzyl alcohol having the general formula: ##STR1## wherein a and b independently represent 1, 2, 3, or 4 and c represents 0, 1, or 2 has a high insecticidal activity (DE-A-2658074 etc.). In particular, it has been disclosed that a cyclopropane carboxylic acid ester of 2,3,5,6-tetrafluorobenzyl alcohol has a high insecticidal activity and that it has a lower toxicity to mammals compared with a cyclopropane carboxylic acid ester of pentafluorobenzyl alcohol, and therefore, is a superior insecticide (DE-A-3705224).
As a process for producing the fluorinated benzyl alcohol having the general formula (I), a process has been proposed of reducing a halogen substituted benzoic acid derivative with a metal hydrides such as NaBH.sub.4, LiAlH.sub.4. For example, DE-A-3714602 discloses a process for producing 2,3,5,6-tetrafluorobenzyl alcohol by reacting 2,3,5,6-tetrafluorobenzoic acid with NaBH.sub.4 followed by treating with an alkylation agent. Further, DE-A-2658074, 2714042, and 2661074 disclose processes for producing for reducing polyfluorobenzoyl fluoride with NaBH.sub.4 to produce polyfluorobenzyl alcohol and processes for reducing polyfluorobenzoyl fluoride with LiAlH.sub.4 to produce a polyfluorobenzyl alcohol wherein one or more fluorine substituted groups are defluorinated. EP-A-31199 discloses a process for reacting 1,2,4,5-tetrafluorobenzene and n-butyl lithium and then reacting with carbon dioxide to form 2,3,5,6-tetrafluorobenzoic acid, which is reduced with LiAlH.sub.4 to produce 2,3,5,6-tetrafluorobenzyl alcohol.
On the other hand, electrolytic reduction processes have also been proposed as processes for the production of a fluorinated benzyl alcohol having the general formula (I). For example, JP-A-1-119686 discloses a process for the production of 2,3,5,6-tetrafluorobenzaldehyde and 2,3,5,6-tetrafluorobenzyl alcohol by electrolytic reduction of pentafluorobenzoic acid using a solid metal or a solid alloy as a cathode and an aqueous solution of sulfuric acid, hydrochloric acid, phosphoric acid, or sulfonic acid as an electrolyte. Further, JP-A-63-206491 discloses production of 2,3,5,6-tetrafluorobenzyl alcohol as a mixture with pentafluorobenzyl alcohol so as to electrolytically reduce pentafluorobenzoic acid using a solid metal or solid alloy as a cathode and an aqueous sulfuric acid solution as an electrolyte. There are many reports on processes for production of a fluorinated benzyl alcohol by electrolytic reduction, but in the same way as above, a benzyl alcohol is produced as a mixture in each case ("J. Electroanal. Chem.", 1991, p. 215; "J. Electroanal. Chem.", 1987, p. 315; "J. Chem. Soc. Perkin Trans I", 1972, p. 189; "J. Appl. Electrochem.", 1992, p. 1082; "Denkikagaku oyobi Kogyobutsurikagaku", 1990, p. 83; etc.)
DISCLOSURE OF INVENTION
The object of the present invention is to produce a fluorinated benzyl alcohol having the general formula (I) and the intermediates thereof, the fluorinated benzonitrile having the general formula (III), by an industrially advantageous process at a high yield, more particularly, to produce 2,3,5,6-tetrafluorobenzonitrile and 2,3,5,6-tetrafluorobenzyl alcohol at a high purity and a high yield, which are useful as production intermediates of pyrethroids having a high insecticidal activity and a low toxicity to the human body.
In accordance with the present invention, there is provided a process for producing a fluorinated benzonitrile comprising the step of:
hydrogenolyzing a fluorinated dicyanobenzene substituted with 1 to 4 fluorine atoms and having the remainder which may be substituted with a chlorine atom in the presence of a catalyst so as to cause hydrodecyanation of onl
REFERENCES:
patent: 4889872 (1989-12-01), Naumann et al.
(Abstract), Weigert, et al, "Hydrodecyanation", J. Mol. Cat., V. 75, N. 2, pp. 209-218, 1992.
Ito Haruaki
Miyata Hideo
Monzen Hiroyuki
Morikawa Kohei
Morinaka Katsutoshi
Murray Joseph
Richter Johann
Showa Denko K.K.
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