Kharash

KHARASH - SOSNOVSKY AHyDcOxidation AllyBc orpropargylic oxidation with t-butyl peresters. 

The last decades have witnessed the emergence of new living Vcontrolled polymerizations based on radical chemistry [81, 82]. Two main approaches have been investigated the first involves mediation of the free radical process by stable nitroxyl radicals, such as TEMPO while the second relies upon a Kharash-type reaction mediated by metal complexes such as copper(I) bromide ligated with 2,2 -bipyridine. In the latter case, the polymerization is initiated by alkyl halides or arenesulfonyl halides. Nitroxide-based initiators are efficient for styrene and styrene derivatives, while the metal-mediated polymerization system, the so called ATRP (Atom Transfer Radical Polymerization) seems the most robust since it can be successfully applied to the living Vcontrolled polymerization of styrenes, acrylates, methacrylates, acrylonitrile, and isobutene. Significantly, both TEMPO and metal-mediated polymerization systems allow molec-... 

Sventoslavsky (Ref 2a) developed in 1908 a method of calculation of heats of combustion which later proved to be in agreement with the method developed by Kharash (Ref 4). Kassatkin Planovsky gave a good description of Sventoslavsky s method (Ref 7, p 31). Later, Thornton (Ref 2b) has shown that the molar heat of combustion at constant volume of any saturated hydrocarbon at room temperature is approximately 52.7 kcal for each atomic weight of oxygen required to burn it. For example, methane, which burns according to the equation ... 

Kharash (Ref 4) has developed a comprehensive method for estimating the heat of combustion of an organic compound from a knowledge of its molecular structure and the total number of electrons shifted in the formation of CO2 molecules. He assumed... 

Qc = [26.05 x N + c] kcal/mole where (N) is the number of electrons inter-displaced between C and O atoms and (c) correction factor, depending on the type of compound. These factors are given in Ref 4 and some additional data may be found in Ref 7. The value given earlier by Sventoslavsky was 26.12 kcal/mole, which is considered as being very close to that of Kharash (26.05)... 

As an example, let us calculate the heat of combustion of methane (which requires no correction) by the Kharash method H... 

Kharash, Preparation of Trinitroethylbenzene", OSRD Repts 285 295(1941) 4) ADL, Pure-... 

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