Carl T. Redemann

A Picolinic Acid Derivative: A Plant Growth Regulator

4-Amino-3,5,6-trichloropicolinic acid is more toxic to many broad-leaved plants than 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. It is comparable in absorption by foliage, in translocation, and in soil-leaching characteristics; in soil, however, it retains its activity for a longer time.

The inhibition of several enzyme systems by 2,2-dichloropropionate

Abstract The effect of 2,2-dichloropropionate on three enzyme systems involving pyruvic acid as a substrate has been studied. Pyruvate oxidase from Streptococcus faecalis is inhibited in a complex manner somewhat resembling uncompetitive inhibition. Yeast carboxylase and pyruvate oxidase from Proteus vulgaris X-19 both appear to be competitively as well as uncompetitively inhibited.

The Hydrolysis and Photolysis Rates of Nitrapyrin in Dilute Aqueous Solution

The hydrolysis rate of nitrapyrin (2-chloro-6-(trichloromethyl)pyridine), the active ingredient of N-SERVE® nitrogen stabilizer (a registered trademark of The Dow Chemical Company, Midland, Michigan), in buffered, distilled water followed simple first-order kinetics over the concentration range, 6.2×10−7 to 8.7×10−5M. The only product of the reaction was 6-chloropicolinic acid. The rate of the reaction decreased with increasing buffer concentration at 35°C (M buffer concentration-half-life): 0.005M − 1.7 days, 0.02M−2.0 days, 0.067M−4.0 days. The ramifications of this negative salt effect are discussed. The hydrolysis rate was independent of pH over the range, 3.2 to 8.4. Additional data were obtained for rates at 25° and 45°C. The activation energy for the reaction under these conditions was 25.0 kcal/mole.Photolysis of nitrapyrin at 25°C in 0.005M phosphate buffers at pH 5.1, 7.1, 8.0, and in a natural water also followed simple first-order kinetics over the nitrapyrin concentration range, 7.1×10−6 to 7.5×10−6M. Again, there was no observable pH effect on the rate over the pH range investigated, nor was there a rate enhancement in the natural water. The half-life of the reaction under these conditions was 0.5 day. The products of this reaction were 6-chloropicolinic acid (6-C1PA), 6-hydroxypicolinic acid (6-OHPA), and unidentified polar material formed in that order in a series of sequential reactions. Simulation of the set of sequential reactions using determined first-order rate constants at 25°C and a starting concentration of 1.7 ppm predicts that nitrapyrin will be half gone in 0.5 day, that the concentration of 6-ClPA will peak at 1.3 ppm in 1.8 days, and that the concentration of 6-OHPA will peak at 0.2 ppm in 3.7 days.

A method of estimating 6-chloropicolinic acid in soil

In a study of the fate of 2-chloro-6-(trichloromethyl)pyridine, the active ingredient in N-SERVE~nutrient stabilizer, Redemann and co-workers (3) found that this compound underwent hydrolysis in soil to 6-chloropicolinic acid. In another study (2), it was shown that crop plants can absorb this hydrolysis product from soil and that 6-chloropicolinic acid is the residue most apt to be found following agricultural application of N-SERVE. Because of these facts, it is desirable to have a chemical method of estimating 6-chloropicolinic acid in soil.