Synthesis of a New Class of Fused Cyclotetraphosphazene Ring Systems

Abstract

Octachlorocyclotetraphosphazene (1) was reacted with butylamines [n-butyl, i-butyl, sec-butyl, and t-butyl] in a 1:0.8 mol ratio in THF to obtain cyclotetraphosphazenes bearing a P-NH group, N4P4Cl7(NHR) [R = n-butyl (2a), i-butyl (2b), sec-butyl (2c), t-butyl (2d)](2a-d). The cyclotetraphosphazene derivatives 2a, 2b, and 2c were treated with sodium hydride giving rise to a new type of cyclophosphazene compounds (P8N8 ring) consisting of three fused tetramer rings (3a-c). Whereas reaction of sodium hydride with the t-butylaminocyclophosphazene derivative (2d) gave a P-O-P bridged compound (4) presumably as a result of hydrolysis reaction associated with moisture in the solvent. It is likely that the 16-membered cyclooctaphosphazene derivatives (3a-c) are formed by a proton abstraction/chloride ion elimination, intramolecular nucleophilic attack, ring opening and intermolecular condensation processes, respectively.

Phosphorus–nitrogen compounds: Part 31. Syntheses, structural and stereogenic properties, in vitro cytotoxic and antimicrobial activities, and DNA interactions of bicyclotetraphosphazenes containing bulky side group

“…The Fourier transform infrared (FTIR) spectra were recorded on a Jasco FT/IR-430 spectrometer in KBr discs and reported in cm -1 units. One-dimensional (1D) 1 H, 13 C and 31 P NMR and two-dimensional (2D) heteronuclear single quantum coherence (HSQC), and heteronuclear multiple-bond correlation (HMBC) spectra were recorded on a Bruker DPX FT-NMR (500 MHz) spectrometer (SiMe 4 as internal and 85% H 3 PO 4 as external standards). The spectrometer was equipped with a 5mm PABBO BB inverse gradient probe.…”

“…To date, the studies about chiral cyclotetraphosphazenes are very limited in the literature [9]. In this study, the chiral cyclotetraphosphazene derivatives were synthesized using dipotassium salt (1a) of the tetradentate symmetric ligand (1). The choice of the ligand (1) is very important to this study, because this ligand causes restricted conformations of the cyclotetraphosphazene derivatives.…”

“…Phosphazene derivatives are hybrid molecules with an essentially linear and/or cyclic backbone of alternating phosphorous nitrogen atoms with the same and/or different organic side groups bonded to each phosphorous atom [1]. The chlorocyclophosphazenes, N 3 P 3 Cl 6 and N 4 P 4 Cl 8 , are the best-known starting compounds and as such they have been extensively studied in the field of phosphazene chemistry [2,3].…”

Synthesis of A Novel Cyclotriphosphazene and Its Enhancement of Anti‐aging and Flame Retardancy of Polyolefin

“…Cyclotriphosphazene, as a ring compound consisting of alternating phosphorus and nitrogen atoms with two substituents attached to the phosphorus atoms, exhibits unusual thermal properties such as flame retardancy and self‐extinguishability . Due to its chemical composition and structure,Hexachlorocyclotriphosphazene (HCCP) has the following characteristics: (1) structural stability: the alternating N=P bonds have great chemical‐bond energy, which minimizes the possibility of ring‐opening reaction and enables the skeleton structure to stay partially even after high‐temperature combustion; (2) Flame retardancy: The thermal decomposition of the HCCP is an endothermic process, and phosphate, metaphosphate, polyphosphate generated in the thermal decomposition form a nonvolatile protective film on the surface of the polymer to isolate it from the air; meanwhile, the inflammable gases released such as CO 2 , NH 3 and N 2 cut off the supply of oxygen so as to achieve the aims of synergistic flame retardancy; (3) Chemical activity: The six chemically active chlorine atoms in HCCP can be substituted by multiple kinds of nucleophiles such as alkoxides, aryloxides, amines to synthesize the cyclotriphosphazene‐based flame retardants . Many reactive flame retardant approaches incorporating cyclotriphosphazene units into the polymer network were developed by introducing oxiranes or active groups (amino, alkenyl et al.)…”

Novel Cyclomatrix-Type Polyphosphazene Microspheres Crosslinked With Octachlorocyclotetraphosphazene: Preparation and Characterization

“…It is the most popular and widely studied molecule in polyphosphazene studies [11][12][13][14][15]. However, there are very few studies about octachlorocyclotetraphosphazene (OCCP, N 4 P 4 Cl 8 ) eight-membered ring, has skeletal flexibility due to its K and T conformations [16][17][18][19][20]. OCCP has eight chlorine atoms which are bound to phosphorus atoms, can react with amine or hydroxyl groups by nucleophilic substitution reaction and it is more reactive than HCCP [21].…”