Amides of the Hypophosphorous Acid: Some Properties and Application

Abstract

The interaction of 50% aqueous solution of hypophos-phorous acid (HPA) with some aromatic and aliphatic iso-cyanates (phenylisocyanate (PIC), 2,4-toluylenediisocyanate (TDI), butylisocyanate (BIC), and 1,6-hexamethylenediiso-cyanate (HMDI)) was investigated. PIC reacts only with water present in the system, yielding N,N-diphenylcarbamide. The interaction with TDI also leads to compounds possessing P-C bond. Their structure has been determined by IR- and NMR-spectroscopy. The interaction with aliphatic isocyana-tes proceeds mainly between the isocyanate groups and the acid P-OH group of HPA. Amides of HPA are obtained: N-butyk phosphamide and 1,6-N,N-hexamethylenediphosphamide. The structure of these compounds has been determined by IR-, ¹H-, and ³¹P-NMR-spectroscopy. 1,6-N,N-hexamethylenedi-phosphamide condenses with formaldehyde, yielding an olygo-meric product. The reaction proceeds mainly at the phosph-amide groups, but it has been established by ¹H- and ³¹P-NMR spectra, that the hydrogen atoms at the phosphorus also take part in the interaction. The prepared olygomer has also been characterized by gel-permeation-chromato-graphy. It possesses growth-regulating and cytokininic activity. 1,6-N,N-hexamethylenediphosphamide has also been tested as a fire retardant for rigid polyurethane foams.