Dissertation > Excellent graduate degree dissertation topics show

Density Functional Theoretical Study on Reaction Mechanism of Hexachlorocyclotriphosphazene

Author: TianZuoZuo
Tutor: LiuYaQing
School: University of North
Course: Materials Science
Keywords: Hexachlorocyclotriphosphazene polymerization reaction reaction mechanism density functional theory transition state
CLC: O643.12
Type: Master's thesis
Year: 2011
Downloads: 59
Quote: 0
Read: Download Dissertation

Abstract


Hexachlorocyclotriphosphazene was one of the most important compounds of polyphosphazenes. It played a pivotal role in the development of polyphosphazenes. At present, the researches were mainly focused on the raw materials, the choice of catalysts and how to separate the product efficiently. The report has not been seen of theoretical study on reaction mechanism of this kind of reaction to this day.The mechanism of hexachlorocyclotriphosphazene which was synthesized by phosphorus pentachloride and ammonium chloride was investigated by using the density functional theory （DFT） of quantum chemistry. All of the possible reaction pathways were discussed. At the GGA–HCTH/DND level, the geometry optimizations of reactants, intermediates, the transition states and the products were performed. All of the transition states were verified by the frequency analysis method. Reaction energy barriers of all elementary processes were also calculated.Firstly, the chain initiation reaction mechanism of hexachlorocyclotri- phosphazene was studied. Results showed that the chain initiation reaction was a very complex procedure so there were various intermediates and transition states along reaction paths and the product was [Cl3P---N---PCl3]+PCl6– which was agreed well with experiment results. This reaction was an endothermal process, and it only took place when heated. For this reaction pathway, IM2→TS2→IM3+HCl had the lowest energy barrier, only 12.18 kJ/mol; while the fifth procedure （IM5+PCl5→TS5→IM6+HCl） was the rate-controlling step, had the highest energy barrier 174.83 kJ/mol.Secondly, the chain propagation reaction mechanism of hexachlorocyclotri- phosphazene was investigated. Results showed that the chain propagation reaction was a very complex procedure,there were four different reaction pathways and three different products were obtained. The product obtained by pathway three and four was [Cl3P---N---PCl2---N--- PCl2---N---PCl3]+Cl–, which was agreed well with experiment results. Pathway four was the main reaction channel for its lower reaction barriers of each step. For reaction pathway four, IM16→TS17→IM17 had the lowest energy barrier 39.02 kJ/mol; while the last procedure （IM17+Cl3P=NH→TS（P3）→P3+HCl） had the highest energy barrier 154.79 kJ/mol, was the rate-controlling step.Finally, the chain termination reaction mechanism of hexachlorocyclotri- phosphazene was considered. Results showed that there were two steps of elementary processes and the product obtained by theory was N3P3Cl6 which was agreed well with experimental result. Each elementary process had a higher energy barrier and this reaction was an endothermal process, and it only took place when heated.

Related Dissertations

  1. Quinoline ring substituted camptothecin QSAR Studies,R914
  2. Ir surface NH 3 catalytic decomposition and oxidation reaction mechanism studies,X131.1
  3. Containing pyridyl group metal complexes Synthesis and Structure,O627
  4. N-heptane HCCI combustion process temperature thermodynamics and kinetics theory,O643.21
  5. WC / graphene composite electronic structure and electron transport properties,O613.71
  6. Density Functional Theory Calculation on Principle Vitamin Eliminating Free Radicals,TS201
  7. A Density Functional Theory Study for Wn C0,± （n=1-6） Clusters,O641.1
  8. Influence of Doping Effect on Zinc Oxide by First Principles Studies,O614.241
  9. First-principles Study on Magnetic and Optical Properties of Rutile TiO2,O614.411
  10. Synthesis of Ag / Al 2 O 3 powder composites research,TB383.3
  11. Theoretical Studies on I-V Properties of Organic Molecular Junctions,O561
  12. Density Functional Theoretical Research on Adsorption of Heavy Metal Cadmium and Zine Ions and PFOS and PFOA on Rutile(110),O647.31
  13. Theoretical Study on the Substitutions of Platinum Complexes with Nonplanar Heterocyclic Piperidine Ligands Binding to Biological Targets,R96
  14. Density Functional Theory Study of Hydrogen Adsorption on Ti(0001) Surface,O485
  15. First-principles study YBaCo_4O_7 oxygen absorption performance,O469
  16. Study on Forming Mechanism of the Fe-Al2O3-FeAl2O4 Composite Coating by Reactive Plasma Spraying,TG174.442
  17. Synthesis and Characterization for the Polyphosphazenes,O634.51
  18. Theoretical Studies on the Mechanism of CO Catalytic Oxidation on Au Surfaces,O643.32
  19. The Study of Salary System of the State-owned Enterprises in Transition Based on the Benefit Plans Incentive Perspective,F272.92
  20. First-principles Study of Hydrogen Adsorption, Dissociation and Diffusion on Thin Mg(0001)Films Supported by Mo(110) Substrate,O484
  21. Modulation of the Transport Properties of One-dimensional Carbon Based Nanostructures,TB383.1

CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Chemical kinetics > The mechanism and kinetics of chemical reactions
© 2012 www.DissertationTopic.Net  Mobile