33567-95-2Relevant articles and documents
Synthesis of 1,3-bis(chlorodiorganosilyl)-cyclodisilazane via dehydro-chlorination reaction of 1,3-dichloro-Tetraorgano-Disilazane in the presence of deacidification agent
Kong, Shuxuan,Li, Ning,Tan, Yongxia,Xie, Zemin,Zhang, Shuhao,Zhang, Xuezhong,Zhang, Zhijie
, (2020)
A novel convenient synthesis process for 1,3-bis(chlorodiorganosilyl)-cyclodisilazanes is developed via an intermolecular dehydrochlorination of 1,3-dichloro-tetraorgano-disilazane, in the presence of a strong organic alkaline deacidification agent 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). This procedure involves a one-step process under mild synthesis condition, with higher production efficiency and product purity as compared to those of the previously reported methods. The formation of 1,3-bis(chlorodiorganosilyl)-tetraorgano-cyclodisilazane occurs via the primary dehydrohalogenation of intermolecular 1,3-dichloro-tetraorgano-disilazanes to trisilylamine structure with a subsequent ring closure. The silicon atoms with different exocyclic or endocyclic substituents are closely related to the steric hindrance of the substituents. Dehydrochlorination reactions occur more readily on the chlorine atoms attached to the silicon atoms with substituents possessing relatively low steric hindrance. Four 1,3-dichloro-tetraorgano-disilazanes for the synthesis of 1,3-bis(chlorodiorganosilyl)-cyclodisilazanes are prepared. The investigation into the reaction mechanism shows that the equilibrium reaction of cyclosilazane with diorgano-dichlorosilane is a more straightforward and efficient method in the preparation of 1,3-dichloro-tetraorgano-disilazanes, as compared to the trans-silylation reaction of hexamethyl-disilazane with diorgano-dichlorosilane.
Polycyclodisilazane: a new polymeric precursor for silicon nitride-based ceramics
Bao, Xujin,Edirisinghe, Mohan J.
, p. 395 - 401 (2007/10/03)
Several new polycyclodisilazanes with different molecular structures were synthesized and characterized using gel permeation chromatography and Fourier-transform infrared spectroscopy. All the polymers synthesized were tractable. The pyrolysis of these polymers at 900 deg C in nitrogen in a thermal balance indicated that the ceramic yields were very dependent on the compositions of the precursors. The polycyclodisilazanes with reactable groups (Si-H, N-H) showed higher ceramic yields due to the cross-linked structures formed during pyrolysis. The pyrolyzed residues were crystallized by heating to >1500 deg C. X-Ray diffraction of the crystallized residues showed that they were mixtures containing silicon nitride and silicon carbide. Chemical analysis of one crystallized residue which gave the highest ceramic yield showed that it contained 70 wt percent Si3N4 and 25 wt percent SiC after heat treatment at 1600 deg C. The compositions of the ceramic residues produced depended on the compositions of the polymeric precursors. More silicon carbide was formed in the residues derived from the polymers with phenyl group substituents.
