Ciba-geigy Corporation

Robert Hassig

Gottfried Seifert

Urs Siegrist

(3-Fluoropyridin-2-yloxy)phenoxypropionic acids of formula I ##STR1## wherein X is hydrogen, fluoro, chloro, bromo or trifluoromethyl and Y is hydrogen, sodium or potassium, are prepared by reacting a compound of formula II ##STR2## wherein X and Y are as defined for formula I, in an anhydrous mixture of hydrogen fluoride, dimethylsulfoxide and a diazotising agent under normal pressure, and converting the diazonium fluoride so produced by thermal decomposition into the (3-fluoropyridin-2-yloxy)phenoxypropionic acid of formula I.

Process for the preparation of (3-fluoropyridin-2-yloxy)phenoxypropionic

There is disclosed a process for the preparation of isothiocyanates of formula ##STR1## wherein R.sub.1 and R.sub.2 are each independently of the other C.sub.1 -C.sub.6 alkyl and R.sub.3, R.sub.4 and R.sub.5 are each independently of the other hydrogen, halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, trifluoromethyl or nitro, which process comprises an amine of formula ##STR2## with ammonium thiocyanate or an alkali metal thiocyanate, in the presence of acid and an inert solvent, to the thiourea of formula ##STR3## and cleaving said thiourea by heating. The essential feature of this process consists in carrying out the reaction of the amine of the above formula with ammonium thiocyanate or an alkali metal thiocyanate in the presence of 0.5-5% by weight of water, based on the total weight of the reaction mixture. The isothiocyanates of the above formula are intermediates for the synthesis of pesticidal compounds.

Process for the preparation of isothiocyanates

4-Bromoaniline hydrobromides of formula I ##STR1## wherein R.sup.1 and R.sup.2 are each independently of the other C.sub.1 -C.sub.10 alkyl or C.sub.3 -C.sub.7 cycloalkyl, are prepared by brominating an aniline hydrohalide of formula II ##STR2## wherein X is chlorine or bromine and R.sup.1 and R.sup.2 are as defined above, in the presence of an inert organic solvent.

Process for the preparation 4-bromoaniline hydrobromides

4,6-Bis(difluoromethoxy)pyrimidines of formula I ##STR1## wherein R is C.sub.1 -C.sub.4 alkyl or unsubstituted or substituted phenyl or benzyl, are prepared by reacting a 4,6-dihydroxypyrimidine dialkali metal salt of formula II ##STR2## wherein R is as defined for formula I and Me is an alkali metal, with chlorodifluoromethane in a solvent selected from the group consisting of ketones and alkyl cyanides, in the presence of 0.05 to 1.1 mol of water per mol of dialkali metal salt of formula II.

Process for the preparation of pyrimidine derivatives

The present invention relates to a process for the preparation of 2-mercapto-4,6-bis-fluoroalkoxypyrimidines of the formula ##STR1## wherein R.sub.1 is C.sub.1 -C.sub.4 alkyl, phenyl or benzyl and each of T.sub.1 and T.sub.2 independently of the other is hydrogen or a --CHX.sub.1 X.sub.2 group, wherein each of X.sub.1 and X.sub.2 independently of the other is trifluoromethyl, fluorine, chlorine or bromine. In accordance with this process, 2-mercapto-4-halo-6-hydroxy-pyrimidines of the formula ##STR2## wherein R.sub.1 is as defined above and Y is chlorine or bromine, are reacted with chlorodifluoromethane or a 1,1-difluoroalkene of the formula ##STR3## wherein each of the X.sub.1 and X.sub.2 independently of the other is trifluoromethyl, fluorine, chlorine or bromine, in an inert solvent and in the presence of a strong base, to give a 2-mercapto-4-halo-6-fluoro-alkoxypyrimidine of the formula ##STR4## wherein R.sub.1, Y and T.sub.1 are as defined above, said 2-mercapto-4-halo-6-fluoroalkoxypyrimidine is converted by subsequent reaction with an alkali metal nitrite or an alkaline earth metal nitrite into a 2-mercapto-4-hydroxy-6-fluoroalkoxypyrimidine of the formula ##STR5## wherein R.sub.1 and T.sub.1 are as defined above, and then said 2-mercapto-4-hydroxy-6-fluoroalkoxypyrimidine is converted by reaction with chlorodifluoromethane or a 1,1-difluoroalkene of the above formula into a 2-mercapto-4,6-bix-fluoroalkoxypyrimidine of the above formula. The 2-mercapto-4,6-bis-fluoroalkoxypyrimidines of the above formula are intermediates for the preparation of herbicidally effective sulfonylureas.

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Gipf-Oberfrick, Switzerland

Robert Hassig