Abstract

L. N. Gupta, R. Singh and Shashi Prabha

The extreme stability of o-nitro-p-anisidine phosphoric diamide allowed its study to be conducted in 40% propionic acid-water system at 98°C ± 0.5°C. The various kinetic variables employed lead to the contribution of monoprotonated form only between 0.1-4.0 M-HCI, alongwith a constant contribution of the zwitterionic form (or the neutral species) in the entire (0.1-7.0 M, HCL) acid range examined. The optimum reactivity at 0.5 M HCL favours weakly basic character of the diamidate, due to abnormal short range interactions of the o-nitro-group with the reaction site. Bimolecular elimination with P-N cleavage is strengthened by various concepts and Arrhenius parameters etc. The diamidate was synthesized from phosphorous pentachloride rather than by POCL₃, the latter resulting in the formation of the famous Perkin's dye.

anisidine; zwitterionic; anisidine pentachloride

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