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Hydrogen Chloride (hydrogen + chloride)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Predicting HCl concentrations in fire enclosures using an HCl decay model coupled to a CFD-based fire field model

FIRE AND MATERIALS, Issue 7 2007
Z. Wang
Abstract The amount of atmospheric hydrogen chloride (HCl) within fire enclosures produced from the combustion of chloride-based materials tends to decay as the fire effluent is transported through the enclosure due to mixing with fresh air and absorption by solids. This paper describes an HCl decay model, typically used in zone models, which has been modified and applied to a computational fluid dynamics (CFD)-based fire field model. While the modified model still makes use of some empirical formulations to represent the deposition mechanisms, these have been reduced from the original three to two through the use of the CFD framework. Furthermore, the effect of HCl flow to the wall surfaces on the time to reach equilibrium between HCl in the boundary layer and on wall surfaces is addressed by the modified model. Simulation results using the modified HCl decay model are compared with data from three experiments. The model is found to be able to reproduce the experimental trends and the predicted HCl levels are in good agreement with measured values. Copyright © 2006 John Wiley & Sons, Ltd. [source]

TEMPO and Carboxylic Acid Functionalized Imidazolium Salts/Sodium Nitrite: An Efficient, Reusable, Transition Metal-Free Catalytic System for Aerobic Oxidation of Alcohols

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009
Cheng-Xia Miao
Abstract An effective catalytic system comprising a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) functionalized imidazolium salt ([Imim-TEMPO]+,X,), a carboxylic acid substituted imidazolium salt ([Imim-COOH]+,X,), and sodium nitrite (NaNO2) was developed for the aerobic oxidation of aliphatic, allylic, heterocyclic and benzylic alcohols to the respective carbonyl compounds with excellent selectivity up to >99%, even at ambient conditions. Notably, the catalyst system could preferentially oxidize a primary alcohol to the aldehyde rather than a secondary alcohol to the ketone. Moreover, the reaction rate is greatly enhanced when a proper amount of water is present. And a high turnover number (TON 5000) is achieved in the present transition metal-free aerobic catalytic system. Additionally, the functionalized imidazolium salts are successfully reused at least four times. This process thus represents a greener pathway for the aerobic oxidation of alcohols into carbonyl compounds by using the present task-specific ionic liquids in place of the toxic and volatile additive, such as hydrogen bromide, bromine, or hydrogen chloride (HBr, Br2 or HCl), which is commonly required for the transition metal-free aerobic oxidation of alcohols. [source]

Effect of cyanoguanidine-metal and urea-metal complexes on the thermal degradation of poly(vinyl chloride)

JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2010
Abir S. Abdel-Naby
Tin, nickel, cobalt, zinc, and copper complexes of cyanoguanidine and urea were synthesized and investigated as thermal stabilizers for rigid poly(vinyl chloride) at 180°C in air. Their stabilizing efficiencies were evaluated by measuring the induction period (the period during which no evolved hydrogen chloride could be detected) and the rate of dehydrochlorination as determined by continuous potentiometric measurements, in addition to the extent of discoloration. The results clearly revealed the greater efficiency of all of the investigated metal complexes as compared to those of well-recognized reference stabilizers. The tin complex always exhibited the highest efficiency irrespective of the type of ligand used. The nickel and cobalt complexes also possessed high stabilizing efficiencies. The order of the stabilizing potency of the various metal complexes was Sn , Co, Ni , Zn, Cu. Combining the ligand itself with dimethyltin- s,s,-bis (isooctyl thioglycolate), as a reference stabilizer containing a tin atom, led to a true synergism. This synergistic effect might be attributed to the formation in situ of a complex between the ligand and the tin atom. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers [source]

Synthesis and Functionalization of Isotactic Poly(propylene) Containing Pendant Styrene Groups

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 20 2004
Junfeng Zou
Abstract Summary: Copolymerization of propylene and 1,4-divinylbenzene was successfully performed by a MgCl2 -supported TiCl4 catalyst, yielding isotactic poly(propylene) (i -PP) polymers containing a few pendant styrene groups. With a metalation reaction with butyllithium and a hydrochlorination reaction with dry hydrogen chloride, the pendant styrene groups were quantitatively transformed into benzyllithium and 1-chloroethylbenzene groups, respectively, which allowed the synthesis of i -PP-based graft copolymers by living anionic and atom transfer radical (ATRP) polymerization mechanisms. The incorporation of styrene pendant groups into isotactic poly(propylene) using a Zeigler,Natta catalyst gave functionalized polymers able to undergo living anionic and atom transfer radical (ATRP) polymerizations. [source]