The Dow Chemical Company

Dowelanco

Charles A. Wilson

R. Garth Pews

James A. Gall

Jack C. Little

Charles A Wilson

Craig E Mixan

George A Burk

Alexander P Fung

John A Werner

John C Little

Charles E Reineke

R Garth Pews

Duane R Romer

Ravi B Shankar

Laura J Dietsche

Karl L Krumel

James A Gall

Kent D Campbell

Jack C Little

Thad S Hormel

Brian G Witt

George K Tyson

Janice E Gatlin

Mark A Van Dort

Kurt W Swogger

Keith D Hovda

Lee B Crampton

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Substituted 5,6-dihydro-5-oxo-1,4-dithiino-(2,3-d)-pyridazine-2,3-dicarbonitriles are prepared which correspond to the formula: ##STR1## wherein R represents ##STR2## wherein X.sup.1 is Cl, Br, NO.sub.2 or CH.sub.3, y is 0 or 1 and n is 0, 1 or 2. These compounds have been found to exhibit antimicrobial and marine antifouling activity in industrial and commercial applications and compositions containing these compounds are so employed.

Substituted

2,3-Difluoro-5-(trifluoromethyl)pyridine is prepared by contacting a 2,3-dihalo-5-(trifluoromethyl) pyridine with an effective amount of KF or CsF in a polar aprotic solvent (diluent) at an elevated temperature under substantially anhydrous conditions with removal of the difluoropyridine products essentially as they are formed. The starting material may optionally be added as the reaction proceeds to minimize decomposition. The reaction is also optionally conducted in the presence of an acid scavenger and/or a crown ether or other phase-transfer catalyst.

Preparation of 2,3-difluoro-5-(trifluoromethyl)pyridine

Finely divided potassium chloride is removed from mixtures with polar, aprotic solvents, such as N-methyl-2-pyrrolidinone, by combining the mixture with sufficient water to dissolve a significant portion, but not all of the potassium chloride present, removing the added water by distillation, and subsequently separating the larger crystals of the salt that form by filtration or centrifugation. The amount of water employed is in the same general range as the amount of polar, aprotic solvent present.

Removal of potassium chloride from solvents

Alpha, beta-difluoropyridine compounds are prepared by contacting a 2,3-dihalopyridine compound or suitable precursor thereof with an effective amount of KF or CsF in a polar aprotic solvent (diluent) at an elevated temperature under substantially anhydrous conditions with removal of the difluoropyridine products essentially as they are formed. The starting material may optionally be added as the reaction proceeds to minimize decomposition. The reaction is also optionally conducted in the presence of an acid scavenger and/or a crown ether or other phase-transfer catalyst.

Preparation of difluoropyridine compounds

The preparation of 3,5-dichloro-2,4,6-trifluoropyridine from pentachloropyridine and potassium fluoride was found to proceed in high yield and at a rapid rate with little tar formation when the reaction is conducted under essentially anhydrous conditions in N-methylpyrrolidone solvent at temperatures below 170.degree. C. High yields of this intermediate for herbicides are obtained.

Method of preparation of 3,5-dichloro-2,4,6-trifluoropyridine

The components of aqueous ammonium fluoride solutions are recovered as ammonia and potassium fluoride by adding potassium hydroxide, distilling to remove and secure the ammonia, concentrating the remaining solution and combining it with a water soluble, dipolar, aprotic solvent, such as N-methylpyrrolidone, and distilling to remove the remaining water to obtain the potassium fluoride as a slurry in the solvent. Slurries of potassium fluoride are useful in the replacement of chloride in heterocyclyl and aryl chlorides by fluoride.

Process for the recovery of ammonia and fluoride values from ammonium

Preparation of 2,3-dichloro-5-trichloromethylpyridine in high yields and purity by chlorinating 2-chloro-5-trichloromethylpyridine at 70.degree. to 250.degree. C. with chlorine in the presence of a catalyst containing one or more molybdenum, tungsten or ruthenium compounds.

Preparation of 2,3-dichloro-5-trichloromethylpyridine

(Trifluoromethyl)pyridine compounds are prepared by contacting (trichloromethyl)pyridine compounds with hydrogen fluoride in the presence of a catalytic amount of a catalyst selected from the group consisting of FeCl.sub.2, FeF.sub.2 and mixtures thereof under liquid phase conditions. The (trifluoromethyl)pyridine compounds are useful as intermediates for the preparation of agricultural chemicals.

Preparation of (trifluoromethyl)pyridines under liquid phase conditions

A method of exchanging a chlorine atom for a fluorine atom at the 2-position of a 2-fluoropyridine compound which comprises contacting a 2-fluoropyridine compound with a substituted or unsubstituted trichloromethyl or dichlorofluoromethyl alpha, beta or gamma picoline compound at a temperature of 50.degree.-250.degree. C. and a pressure of atmospheric to about 100 psig.

Chlorine exchange for fluorine in 2-fluoropyridine compounds

An alkyl .alpha.-cyanoacetate is reacted with ammonia in a glycol solvent medium to form cyanoacetamide. Advantageously and without requirement of separation of the formed cyanoacetamide in glycol solvent (even though the next step and entire procedure can optionally commence with pre-formed cyanoacetamide), 2,2-dibromo-3-nitrilopropionamide is formed in situ by treating the cyanoacetamide in glycol with an appropriate mixture of bromine and an alkali metal bromate at about 10.degree. C-40.degree. C. Excellent and stable antimicrobial compositions may then be prepared, as part of an overall integrated process by incorporating in the resultant 2,2-dibromo-3-nitrilopropionamide-containing reaction mass an appropriate quantity of paraformaldehyde or equivalent satisfactory stabilizer at a suitably adjusted pH level.

Preparation of cyanoacetamide and 2,2-dibromo-3-nitrilopropionamide

2,3-Dichloro-5-trichloromethylpyridine is produced by selective liquid phase chlorination of 2-chloro-5-trichloromethylpyridine.

Chlorination of 2-chloro-5-trichloromethylpyridine

Substituted benzylidene methylhydrazides of haloacetic acid corresponding to the formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 each independently represent hydrogen, chloro or bromo with the proviso that at least one of R.sup.1, R.sup.2 and R.sup.3 is always chloro or bromo; Y represents hydrogen, chloro, bromo, nitro, or cyano. The compounds' use as antimicrobials and the method of preparing the same are also disclosed.

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Pittsburg, CA, United States of America

Charles A Wilson