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Full-Text Articles in Physical Sciences and Mathematics
Ring Strain In Cyclopropane, Cyclopropene, Silacyclopropane, And Silacyclopropene, Mark S. Gordon
Ring Strain In Cyclopropane, Cyclopropene, Silacyclopropane, And Silacyclopropene, Mark S. Gordon
Mark S. Gordon
The strain energy in four three-membered rings is calculated by using the appropriate isodesmic reactions. Calculations with and without d functions on the heavy atoms indicate that while these polarization functions tend to reduce ring strain, the addition of d orbitals has little effect on the predicted trends. While introduciton of unsaturation drastically increases the strain in the carbon system (cyclopropane---. cyclopropene), this is not the case for silicon (silacyclopropane--+ silacyclopropene). As a result cyclopropane and cyclopropene are predicted to be the least and most strained rings, respectively.
Synthesis Of Peroxyacetyl And Peroxyaroyl Nitrates. Complexation Of Perqxyacetyl Nitrate With Benzene, Tina M. Kravetz, Steve W. Martin, G. David Mendenhall
Synthesis Of Peroxyacetyl And Peroxyaroyl Nitrates. Complexation Of Perqxyacetyl Nitrate With Benzene, Tina M. Kravetz, Steve W. Martin, G. David Mendenhall
Steve W. Martin
Convenient procedures are given for the condensed-phase synthesis Of peroxyacetyl nitrate (PAN), peroxybenzoyl ni- sponding peracid% sulfuric acid, and sodium nitrate- The compounds of considerable interest because of their physio- logical and action in polluted atmospheres (1-4). Samples of such compounds are routinely needed for cali- several syntheses have been published (I, 5-8). The procedure of Louw et al. (5) is particularly convenient because the re- corrosive reagents are required. trate, and m-chloroperoxybenzoyl nitrate from the corre- position of the ‘H NMR signal from peroxyacetyl nitrate in CC14-benzene mixtures depended on the solvent composition benzene, with K,, = 0.095 at …
Ozonation At The Stander Water Reclamation Plant, Johannes Van Leeuwen, J. Prinsloo
Ozonation At The Stander Water Reclamation Plant, Johannes Van Leeuwen, J. Prinsloo
Johannes van Leeuwen
The results achieved by ozonation at the Stander Water Reclamation Plant, Pretoria, are discussed. A packed column together with an injector mixing device gave ozone· utilization levels higher than 95 % at dosages of about 10 mg/ dm3. Redistribution plates in the packing proved necessary to prevent poor adsorption due to backmixing in the gas phase. Disinfection is satisfactory if total oxidant residuals can be maintained at more than 0,2 mg/dm3 for 15 min. The results indicated that ozonation also lowered the chemical oxygen demand and total organic carbon concentration in the water. In spite of the fact that it …
The Effects On Grain-Boundary Processes Of The Steps In The Boundary Plane Associated With The Cores Of Grain-Boundary Dislocations, Alexander H. King, D. A. Smith
The Effects On Grain-Boundary Processes Of The Steps In The Boundary Plane Associated With The Cores Of Grain-Boundary Dislocations, Alexander H. King, D. A. Smith
Alexander H. King
The contribution of the associated steps to the properties of grain-boundary dislocations are investigated. Two methods of step-height determination are given and it is shown that the step height, like the Burgers vector, must be conserved during the reactions of grain-boundary dislocations: this is not always automatic and additional coherent steps must take part in some reactions. The energies associated with steps have been estimated and compared with the elastic energies of grain-boundary dislocations; these comparisons suggest that (a) the reduction of elastic energy alone may not be a sufficient criterion for the progress of a reaction and (b) that …