Mathematical Modeling of Chemical Reactors—Development and Implementation of Novel Technologies

Mathematical modeling is an important tool for rapid and reliable reactor development and design. The models are built up from basic studies of the reaction mechanism and kinetics, the transfer processes, and the interactions within the system. A detailed understanding of the elementary processes enables the construction of powerful and complex models for dynamic and steady-state simulation. With the aid of experimentally determined parameter values one can develop new processes or improve existing ones. Excellent results obtained in experimental work under idealized laboratory conditions can seldom be fully realized in practice. This is due to factors such as transfer resistances, local gradients, fluctuating conditions, and constructional and other limitations which lead to unsatisfactory parameter values and higher costs to compensate for these shortcomings. Some recommendations are made for circumventing these deficiencies.     

Yuri Alexeev,Theresa L. Windus,Chang‐Guo Zhan,David A. Dixon,Erratum to “Accurate heats of formation and acidities for H3PO4, H2SO4, and H2CO3 from ab initio electronic structure calculations,” International Journal of Quantum Chemistry (2005) 102(5) 775–784

The original article to which this Erratum refers was published in International Journal of Quantum Chemistry (2005) 102(5) 775–784     

Silyl-titanation of acetylenes and 1,3-dienes

A Ti^IIISi active species, Cp₂TiSiMe₂Ph, is formed either by the reaction of Cp₂TiCl₂ with two equivalents of PhMe₂SiLi or by the reaction of Cp₂TiCl with one equivalent of PhMe₂SiLi. Highly regio- and stereo-selective silyltitanation by this species has been observed with acetylenes and 1,3-dienes.     

Organofluorosilicates in organic synthesis: XV. Reaction of exo- and endo-5-norbornen-2-ylsilyl derivatives with n-bromosuccinimide. Difference in reactivity between hexacoordinate and tetracoordinate silicon compounds

The reactions of potassium 5-norbornen-2-ylpentafluorosilicate (I) and 5-norbornen-2-yltrimethylsilane (II) with NBS were examined. The former reaction gave 3-nortricyclyl bromide (IV) as the only detectable product, arising from the carbon—silicon bond cleavage. The latter reaction, however, gave 3-bromo-1-nortricyclyltrimethylsilane (V) as the major product, resulting from cleavage of the carbon—hydrogen bond α to silicon, together with IV and an unidentified product. GLC-monitoring of the reactions showed the higher reactivity of the norbornenyl derivative having the leaving group in theendo position irrespective of whether the leaving group is SiF₅ or H. Since no inhibition was observed by the addition of hydroquinone in the dark, the reactions have been regarded as homoallylic electrophilic substitutions. A concerted mechanism seems to be consistent with the experimental data. Cleavage of 1-nortricyclyltrimethylsilane by iodine monochloride to give 1-iodonortricyclene has also been studied.     

On the light-cone formulation of classical non-abelian gauge theory

For a classical Yang-Mills field which is periodic in the longitudinal light-cone coordinate: (a) a gauge condition is formulated, (b) the presence of field singularities in this gauge is shown, and (c) the relevance of these singularities to the topological charge is demonstrated.Also of the Science Sector, UNESCO