Kinetics and mechanism of the reaction between oligosiloxanes and P-trichloro-N-dichlorophosphoryl monophosphazene (Cl3P=N-POCl2)

Article abstract of DOI:10.1080/10426500008076550

³¹P NMR investigation has been made of the action of Cl₃P=N-POCl₂ (I) first on hexamethyldisiloxane (Me₃Si)₂O and then on oligosiloxanes Me₃Si-(OSiMe₂)_n-OSiMe₃ n = 2 and n=3. The reactions were carried out in bulk or in solution with molar ratios siloxane/(I) varying from 1 to 5. It was demonstrated that only the monosubstitution of a chlorine atom by the -(OSiMe₂)_n-OSiMe₃ species n = 0, 2, 3 with elimination of trimethylchlorosilane occurred leading to the derivatives Cl₂OP-N=PCl₂O-(SiMe₂-O)_nSiMe ₃ (II). For n=2, 3 the siloxane redistribution reactions were observed by ²⁹Si NMR analysis. A two steps mechanism is proposed, consisting in a nucleophilic substitution, involving a tricoordinate phosphazenium intermediate, followed by the formation of an active ionic centre probably an oxonium ion, arising from the solvatation by the siloxane of this phosphazenium ion and /or of (II) leading to the redistribution reactions. The influences of the solvent, of trimethylchlorosilane, of the temperature, and of the addition of a protonated species (MDH) were investigated.

Full text of DOI:10.1080/10426500008076550

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Phosphorus, Sulfur, and
Silicon and the Related
Elements
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KINETICS AND MECHANISM
OF THE REACTION
BETWEEN OLIGOSILOXANES
AND P-TRICHLORO-N-
DICHLOROPHOSPHORYL
MONOPHOSPHAZENE
(Cl3P[dbnd]N-POCl2)
Abdeslam Meliani a b , Yann Vaugeois a , Hamza
Bali a b , Ahmed Mazzah a , Roger de Jaeger a
Jean Habimana c
a Laboratoire de Spectrochimie lnfrarouge et
&
Roman , CNRS, UMR Université des Sciences et
Technologies de Lille , 8516, B[acaron]t. C5,
Villeneuve d'Ascq, France
b UFR Chimie des Matériaux, Luboratoire de
Chimie Minérale, Faculté des Sciences et
Techniques Fès-Saïss , Université Sidi Mohamed
Ben Abdellnh , Fès, Morocco
c Dow Corning S.A. Parc Industriel , Zone CB,
7180, Seneffe, Belgium
Published online: 19 Dec 2006.
To cite this article: Abdeslam Meliani , Yann Vaugeois , Hamza Bali ,
Ahmed Mazzah , Roger de Jaeger & Jean Habimana (2000) KINETICS AND
MECHANISM OF THE REACTION BETWEEN OLIGOSILOXANES AND P-TRICHLORO-
N-DICHLOROPHOSPHORYL MONOPHOSPHAZENE (Cl3P[dbnd]N-POCl2),

Phosphorus, Sulfur, and Silicon and the Related Elements, 166:1, 283-301, DOI:
10.1080/10426500008076550
To link to this article: http://dx.doi.org/10.1080/10426500008076550
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