Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1997-06-18
1999-08-17
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C07C 5948
Patent
active
059395842
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for preparing solid, free-flowing water-soluble salts of aryloxy-C.sub.1 -C.sub.4 -alkanecarboxylic acids.
The aryloxyalkanecarboxylic acids, in particular the aryloxyacetic acids, 2-aryloxypropanoic acids and 4-aryloxybutanoic acids, substance class, in which an aryl radical is in particular to be understood as meaning a phenyl radical substituted by halogen, such as bromine or chlorine, and/or C.sub.1 -C.sub.4 -alkyl, in particular methyl, has been known for a long time for its herbicidal action. A compilation is found eg. in K. H. Buchel: Pflanzenschutz und Schadlingsbekampfung (Crop Protection and Pest Control), Georg Thieme Verlag, Stuttgart 1977, pp. 173-175. The following active compounds eg.: 2,4-dichlorophenyoxyacetic acid (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2-(2-methyl-4-chlorophenoxy)-propionic acid (mecoprop, MCPP), 2-(2,4-dichlorophenoxy)propionic acid (dichlorprop, 2,4-DP), 2-(2,4,5-trichlorophenoxy)propionic acid (fenoprop), 4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB) and 4-(2-methyl-4-chlorophenoxy)butanoic acid (MCPB) and their salts, in particular those of sodium, potassium, ethylammonium and dimethylammonium, found commercial use (cf. also The Pesticide Manual, 9th ed., published by the British Crop Protection Council, 1991).
The marketing of the aryloxycarboxylic acids, also called phenoxycarboxylic acids in the following, mainly took place in the form of their salts as liquid concentrates. Aqueous solutions of phenoxycarboxylic acid salts are disclosed eg. in U.S. Pat. No. 2,694,625, U.S. Pat. No. 2,992,913 and U.S. Pat. No. 3,284,186. These salt solutions are handled in plastic or metal containers whose disposal or cleaning caused public discussions.
There was therefore a need to make these compounds available in solid and, at the same time, readily water-soluble form.
Even in 1950, granulated formulations of halogenated phenoxyacetic acids were published in which, to avoid dust contents, auxiliaries such as clay, chalk, gypsum or artificial fertilizer were added (U.S. Pat. No. 2,792,295).
Solid, free-flowing, water-soluble lithium salts of phenoxycarboxylic acids were also described (U.S. Pat. No. 3,208,843). U.S. Pat. No. 3,023,096 describes the preparation of the potassium and lithium salts of dichlorophenoxyacetic acid.
In U.S. Pat. No. 5,266,553, the prior art is discussed in detail, and for the preparation of solid salts it is proposed to neutralize the corresponding aryloxycarboxylic acids with a base and to convert the resulting aqueous solution or mash into the solid salts by evaporating water under controlled conditions. The solid salts can also be prepared by evaporating water from the corresponding commercially available aryloxy salt solutions.
Publications on the preparation of solid, free-flowing salts of optically active phenoxypropionic acids were hitherto unknown.
The optically active phenoxypropionic acids are liberated by acidifying the neutral reaction solutions obtained from the synthesis with acids, isolating and converting them into the salts (DE-A 30 24 265).
According to EP-A 0 009 285, an oily phase is separated at pH 4 from the neutral reaction solution partly prepared with hydrochloric acid, which is extracted with ether. After evaporating the ether, the corresponding optically acid phenoxypropionic acids are obtained.
It is an object of the present invention to make available a process for preparing solid, free-flowing and readily water-soluble salts of aryloxycarboxylic acids, which is also suitable, in particular, for preparing optically active propionates, of which, as is known, the D-(+)-enantiomers are exclusively biologically active (cf. K. H. Buchel, loc. cit. and Kgl. Lantbruks-Hogskolans, Anm. 20 (1953) 241-295).
We have found that this object is achieved by a process for preparing solid, free-flowing, water-soluble salts of aryloxy-C.sub.1 -C.sub.4 -alkanecarboxylic acids, which comprises reacting the aryloxy-C.sub.1 -C.sub.4 -alkanecarboxylic acids with a salt-forming base, the salt f
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Brenner Karl Siegfried
Fretschner Erich
Merkle Hans Rupert
Schonherr Michael
van Gastel Anne
BASF - Aktiengesellschaft
Killos Paul J.
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