Hydrocarbons substitution

Aromatic hydrocarbons substituted by alkyl groups other than methyl are notorious for their tendency to disproportionate in Friedel-Crafts reactions. This tendency has previously limited the application of the isomerization of para- or ortho-) m ky -benzenes to the corresponding meta compounds. At the lower temperature of the present modification, disproportionation can be minimized. 

Development of the chemistry of metal carbenes commenced with the characterization of complexes such as (CO)sW=C(OMe)Ph by Fischer and his co-workers (e.g., Ref. 14 and references therein). The series of hydrocarbon-substituted carbene compounds discovered later by the Schrock group (e.g., Ref. 15 and references therein) appeared to be so different from the other known carbene complexes that they were placed in a different class altogether. Overemphasis of this distinction has persisted in the literature of carbene complexes, even to the present day. 

The symmetrical diphenyl-substituted porphyrazines M[pzPh8], where Ph = phenyl, were the first type of hydrocarbon-substituted pz to be reported. These macrocycles were prepared in 1937 by Linstead and co-worker (19) via melts of various metal salts with diphenylmaleonitrile and purified by chromatography. No... 

TABLE 1. Enthalpies of formation of hydrocarbon-substituted hydroperoxides and peroxides (kJ mol )... 

CHLP protocol, 147, 149, 150, 161, 165 hydrocarbon-substituted peroxides, 147, 149-50, 153-4 aromatic substituents, 150 peroxycarboxylic acids and derivatives, 160, 161... 

T. Urbanski and Rabek-Gawronska [11] found that cyclonite dissolves in molten, highly-nitrated aromatic hydrocarbons, substituted urea derivatives, and camphor to form eutectics of the composition given in Table 18. It is almost insoluble in molten diphenylamine. 

The intensity of undesirable sensory notes has been positively correlated with the content of carbonyl compounds formed through lipid autoxidation reactions. In general, the carbonyl compounds present have the greatest impact on flavor owing to their low flavor thresholds in comparison with hydrocarbons, substituted furans, and alcohols. Aldehydes are major contributors to the loss of desirable flavor in meats because of their rate of formation during lipid oxidation and low flavor threshold. Thus, an alternative approach for monitoring the extent of lipid oxidation in fats and oils is to measure... 

Bis(tj6-arene) complexes, with chromium hydrocarbon-substituted arenes, 5, 338 with peripheral heteroatoms, 5, 340 with ring integral heteroatoms, 5, 339 theoretical considerations, 5, 338 Bis(l,2-arenedithiolato) compounds, in mono-Cp Ti(IV) complexes, 4, 503-504... 

The positron-trap technique has been used to measure the annihilation rate of positrons interacting with a wide variety of molecules. The species investigated by Iwata et al. (1995) include many hydrocarbons, substituted (e.g. fluorinated and chlorinated) hydrocarbons and aromatics as mentioned in section 6.1, large values of (Zeff) (in excess of 106) were found for some molecules. Several distinct trends are exhibited in the data of Iwata et al. (1995). Though much of the detailed physics involved in the annihilation process on these large molecules is still unclear, the model of Laricchia and Wilkin (1997), described in section 6.1, may offer a qualitative explanation of the observations. 

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