Phospha-Mannich reactions of PH₃ and its analogs

The easiest route to form compounds with P–Csp3–N linkage(s) is phosphorus-based Mannich-type reactions (phospha-Mannich reactions) between phosphines (R3P, R2PH, RPH2, PH3), carbonyl (mainly CH2O) and amines (R2NH, RNH2, NH3). Because of toxicity inflammability, applications PH3 its liquid analog (Me3Si)3P in such are rare. Stable, less toxic, non-pyrophoric adducts CH2O, i.e., tris(hydroxymethyl)phosphine (HOCH2)3P tetrakis(hydroxymethyl)phosphonium (HOCH2)4P+ salts, often used as both P- C-sources phospha-Mannich reactions, providing many acyclic cyclic P,N-ligands, among which 1,3,5-triaza-7-phosphaadamantane (PTA) most known. Phospha-Mannich salts urea condensation products that impart fire retardance cotton materials, the important oldest area application salts. use cross-linking agents protein-based hydrogel manufacturing, enzyme immobilization on NH2-containing supports, leather tanning, also based ability P–CH2–N linkages amino acids residues. Mechanistic aspects discussed.