The present invention relates to an improved process for the synthesis and purification of 3-chloro-N-(3-chloro-5-trifluoromethyl-2-pyridyl)-a,a,a-trifluoro-2,6-dinitro-p-toluidine (fluazinam) and other pyridinamines, which implements methyl isobutyl ketone (MIBK) as the reaction solvent. The process of the invention overcomes the drawbacks of prior art methods, by reducing the side reactions such as hydrolysis, eliminating the need for difficult and labor-intensive purification methods, and providing pure products in higher yields. The present invention relates to novel crystalline polymorphic forms fluazinam, and to mixtures of the polymorphs. The present invention also provides methods for preparing the novel polymorphs, as well as pharmaceutical compositions comprising same, and methods of using the polymorphs as pesticidal agents for combating noxious living organisms on agricultural and horticultural crops.