4-Chloropicolinic acid

A carboxyl group usually hinders electrophilic attack. It is, therefore, at first sight surprising to note that picolinic acid hydrochloride reacts with thionyl chloride to give 4-chloropicolinic acid in yields of up to 55%.182-184 Under more severe conditions a 35% yield of 4,6-dichloropicolinic acid is obtained.182 Sulfur dioxide in the reaction mixture favors 4-chloropicolinic acid formation.183 This suggests that the chlorination may actually involve a nucleophilic attack by chloride ion upon a complexed pyridinium salt1 ... 

Vannelli T, AB Hooper (1992) Oxidation of nitrapyrin to 6-chloropicolinic acid by the ammonia-oxidizing bacterium Nitrosomonas europaea. Appl Environ Microbiol 58 2321-2325. 

Biological. 6-Chloropicolinic acid and carbon dioxide were reported as biodegradation products (quoted, Verschueren, 1983). 

Chlorophenylurea, see Diflubenzuron. Monuron 6-Chloropicolinic acid, see Nitrap3U in... 

Poth M, Focht DD (1985) 15N kinetic analysis of N20 production by Nitrosomonas europaea an examination nitrifier denitrification. Appl Environ Microbiol 49 1134-1141 Powell SJ, Prosser JI (1985) The effect of nitrapyrin and chloropicolinic acid on ammonium oxidation by Nitrosomonas europaea. FEMS Microbiol Lett 28 51-54 Prince RC, Hooper AB (1987) Resolution of the hemes of hydroxylamine oxidoreductase by redox potentiometry and electron spin resonance spectroscopy. Biochemistry 26 970-974 Probst I, Bruschi M, Pfennig N, LeGall J (1977) Cytochrome c-551.5(c7) from Desulfuromonas acetoxidans. Biochim Biophys Acta 460 58-64... 

The acute oral lDjq of nitrapyrin is 1072 mg/kg for rats. It is converted in the soil into 6-chloropicolinic acid, and it is essentially this that is taken up by the plants (Redemann et al., 1964). In the USA it has been introduced under the trade name N-Serve for the treatment of maize, cotton and wheat. 

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