Studies of phosphazenes. Part 31. Kinetic studies of the reactions of hexachlorocyclotriphosphazene with aromatic primary amines: evidence for the intermediacy of a reactive three-co-ordinated phosphorus(V) species

Kinetic studies of the reactions of hexachlorocyclotriphosphazene with aromatic primary amines(aniline, p-toluidine, and p-anisidine) have been investigated with a view to developing 'model systems' for analogous reactions with aromatic diamines. The first and second stages of chlorine replacement proceed by an SN2(P) mechanism in both tetrahydrofuran (thf) and methyl cyanide. Kinetic evidence is obtained for a base-catalysed E1(c.b.) mechanism for the formation of geminal products in thf in the presence of an excess of tri-n-butylamine. The intermediacy of a three-co-ordinate PV species is established by trapping experiments with methanol and by the isolation of the unusual products [NHEt3][gem-N3P3CL4(NHR)(O)][R = Ph, C6H4Me-p, or C6H4(OMe)-p]. These triethylammonium salts on dimethylaminolysis afford the hydroxy derivatives gem-N3P3(NHR)(OH)(NMe2)4, which exist in their oxophosphazadiene tautomeric forms

Studies of Phosphazenes. Part 31. Kinetic Studies of the Reactions of Hexachlorocyclotriphosphazene with Aromatic Primary Amines: Evidence for the Intermediacy of a Reactive Three-co-ordinated Phosphorus(v) Species

Kinetic studies of the reactions of hexachlorocyclotriphosphazene with aromatic primary amines (aniline, p-toluidine, and p-anisidine) have been investigated with a view to developing 'model systems' for analogous reactions with aromatic diamines. The first and second stages of Chlorine replacement proceed by an $S_N2(P)$ mechanism in both tetrahydrofuran (thf) and methyl cyanide. Kinetic evidence is obtained for a base-catalyzed $E_1(c.b.)$ mechanism for the formation of geminal product in thf in the presence of an excess of tri-n-butylamine. The intermediacy of a three-coordinate $P^V$ species is established by trapping experiments with methanol and by the isolation of the unusual products $[NHEt_3]$ $[gem-N_3P_3Cl_4(NHR)(O)]$ $[R = P4, C_6H_4Me_{-p}$ or $C_6H_4{(OMe)}_{-p}]$. These triethylammonium salts on dimethylaminolysis afford the hydroxy derivatives ${gem-N}_3P_3$ $(NHR)(OH){(NMe_2)}_4$, which exist in their oxophosphazadiene tautomeric forms

New initiators for the ring-opening thermal polymerization of hexachlorocyclotriphosphazene: synthesis of linear poly(dichlorophosphazene) in high yields

Ring-opening thermal polymerization of hexachlorocyclotriphosphazene (N3P3C&h)a s been investigated at 250 "C and at 1.333-Pa pressure using chlorocyclotriphosphazenes N3P3C15(N=PPh3) and N3P3Cl,.,(NMe2), (n = 2-4), salt hydrates, triphenylphosphine, and benzoic acid as initiators. The linear poly (dich1orophosphazene) products are phenoxylated, and the phenoxy polymers are characterized by gel permeation chromatography and dilute solution viscometry. Among the various initiators investigated, CaS04.2H20b rings about a high conversion (>60%) of N3P3C&to the linear [NPC12], polymer which possesses a high molecular weight (>5 X lo6). The rationale for the choice of the initiators and possible mechanism(s) of polymerization is discussed. Several mixed substituent polymers, [NP(OPh),(OC6H4Me-p)2,1, and [NP(OPh),(OCHzCF3)2,]nh, ave been prepared and their thermal properties evaluated

Studies of phosphazenes. Part 30. Reactions of hexachlorocyclotriphosphazene with aromatic primary amines: interplay of geminal and nongeminal modes of chlorine replacement

The reactions of hexachlorocyclotriphosphazene, $N_3P_3CI_6$, with aromatic primary amines (aniline, \rho-toluidine, and \rho-anisidine) yield the derivatives $N_3P_3CI_{6-n}{( NHC_6H_4Y-\rho)}_n$, [Y = H, Me, or OMe, n = 1 or 2 (three isomers); Y = OMe, n = 3 (three isomers), 4 (geminal isomer only), 5, or 61. The structures of these derivatives and their isomeric compositions have been determined by ,$^{31}P$ n.m.r. spectroscopy and also by $^1H$ n.m.r. spectra of the corresponding methoxy and/or dimethylamino derivatives. When diethyl ether, tetrahydrofuran, or MeCN is used as the solvent, non-geminal products predominate at the bis stage of chlorine replacement. However, in the presence of triethylamine, the geminal product is formed exclusively. A t the tetrakis stage of chlorine replacement, the geminal isomer is the sole product irrespective of the reaction medium. The reaction of non-gem-$N_3P_3CI_6,{[NHC_6H_4(OMe)-\rho]}_3$, with \rho-anisidine yields only $N_3P_3{[NHC_6H_4(OMe)-\rho]}_6$; formation of non-geminal tetrakis derivatives could not be detected. The mechanistic implications of these results are discussed

Pathways in the nucleophilic substitution reactions of halogenocyclophosphazenes and subtle aspects of the mechanism of formation of bicyclic phosphazenes

Both associative [SN2(P)] and dissociative [SN1(P) and E1CB] mechanisms have been established for the amination reactions of haloenocyclophosphazenes from synthetic and kinetic studies. Several intricate details concerning the formation of bicyclic phosphazenes have been unravelled