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Crystallization of Phenmedipham from Aqueous Emulsions

Published online by Cambridge University Press:  12 June 2017

Robert F. Norris
Robert F. Norris*
Affiliation:
Dep. of Botany, Univ. of California, Davis, Ca. 95616
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Abstract

Crystallization of methyl m-hydroxycarbanilate m-methyl-carbanilate (phenmedipham) occurred from aqueous emulsions of the commercial formulation when dilutions exceeded one part of the formulation to 30 parts water. Dilutions greater than 1 to 30 accelerated crystallization and increased the quantity of phenmedipham that crystallized out. Mechanical agitation increased the rate of crystallization during the first 12 hr after initial mixing. Low water temperature increased the rate of crystallization and total amount of phenmedipham that crystallized out. Phenmedipham crystallization was not altered by water hardness or pH over the range 4.0 to 8.0. Simulated refilling of a partially empty spray tank before adding formulated phenmedipham produced considerable crystallization, whereas adding formulated phenmedipham before adding water minimized crystallization. The solvent used in the commercial formulation to dissolve phenmedipham is partially soluble in water. The partitioning of this solvent into the aqueous phase of the emulsion explains crystallization of phenmedipham.

Type
Research Article
Information
Weed Science , Volume 21 , Issue 1 , January 1973 , pp. 6 - 10
Copyright
Copyright © 1973 Weed Science Society of America 

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References

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