Antoine-​Laurent Lavoisier

For a millenium, till the time of Lavoisier, Alchemy was practised. Alchemy was unscientific, but its practitioners developed useful exptl. methodologies, materials and medicines. In the seventeenth century phlogiston' theory was introduced to explain the results of combustion. Lavoisier, through his extraordinary logical capabilities developed systematic exptl. procedures by adopting proper weighing and measuring methods. This brought about radical change in scientific thoughts and ushered in the era of modern chem. Lavoisier was not only a great scientist, but a revolutionary thinker, a social reformer, a good administrator, a helpful and sociable person and an institution builder. Despite these uncommon qualities, the frenzy of the French Revolution consumed his life in a very tragic way

An appreciation of free radical chemistry 3. Free radicals in diseases and health

In the last 20-25 years, considerable insight has been gained regarding the pivotal role played by free radicals in controlling and directing biological processes that cause diseases, as well as defend against them to maintain health. The manifestation of several hereditary diseases has been traced to the eventual tissue injury/DNA damage through free radical reactions taking place at various levels in the biological system. A large body of experimental evidence indicates that the chemical transformations that induce cancer, stimulate atherosclerosis, lead to Parkinson's and Alzheimer's diseases, cause ischemia, and impel ageing process are basically free radical in nature. Ironically, free radicals are also part of the body's defence mechanism. If genetic predisposition and the life style favour the former, then health becomes the casualty

ChemInform Abstract: 3‐Trimethylsilylbicyclo[3.2.1]oct‐2‐ene in the Synthesis of Functionalized Bicyclo[3.2.1]octane Systems

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

Effect of a trimethylsilyl moiety on the nucleophilic character of the CC bond: a comparative kinetic investigation of the epoxidation of substituted and unsubstituted cycloalkenes

The rates of epoxidation of twelve cycloalkenes (6–17) with MCPBA were determined at four temperatures (298, 303, 308 and 313 K). All of them were found to follow second-order kinetics. The silylated cycloalkenes (10–13) react faster than the corresponding unsubstituted cycloalkenes (6–9), but slower than the corresponding methyl cycloalkenes (14–17). Thus, for epoxidation, the silyl moiety is a deactivating group relative to an alkyl group, while it is activating in comparison with hydrogen. When the homologous series 6–9, 10–13 and 14–17 are considered, the order of the rates of epoxidation in each series seems to follow the order of strain energy of its members, i.e., the rate decreases in the sequence: 5-membered > 8-membered > 7-membered > 6-membered. The rate data obtained at four temperatures were employed to calculate ΔH‡, ΔS‡ and ΔG‡, based on which a common reaction mechanism is proposed

The 2010 Chemistry Nobel Prize: Pd(0)​-​catalyzed organic synthesis

The 2010 Nobel Prize in Chem. was awarded to three scientists, R F Heck, E-​I Negishi and A Suzuki, for their work on "Palladium-​Catalyzed Cross Couplings in Org. Synthesis". It pertains to research done over a period of four decades. The synthetic procedures embodied in their work enable construction of C-​C bond selectively between complex mols. as in simple ones at desired positions without disturbing any functional groups at other parts of the reacting mols. The work finds wide applications in the synthesis of pharmaceuticals, agricultural chems., and mols. for electronics and other applications. It would not have been possible to synthesize some of the complex natural products or synthetic compds. without using these coupling reactions in one or more steps

Trimethylsilylcyclooctadiene-​transition metal complexes: metal-​catalyzed protodesilylation of cyclic vinylsilanes, and transfer hydrogenation promoted by the displaced silyl group

Complexes of 1-​trimethylsilyl-​1,​5-​cyclooctadiene (TMS-​COD) with AgI, RhI, PdII and PtII have been prepd. and characterized. The distortion in their structures in comparison with the near sym. structures of the corresponding, 1,​5-​cyclooctadiene (COD) complexes, which is obviously attributable to the presence of vinylic SiMe3 group, is clearly indicated by their 1H and 13C NMR spectral characteristics. The silver complex is somewhat unstable, but the other complexes are quite stable. An unstable CuI complex that could not be satisfactorily characterized was also obtained. If appropriate conditions for the prepn. of Rh and Pd complexes are not maintained, desilylation occurs, accompanied by redn. of COD to cyclooctene by transfer of hydrogen from the solvent alc. The displaced silicon-​contg. moiety seems to enhance the transfer hydrogenation. Attempts to prep. a RuII complex resulted in the formation of a complex of desilylated diene (RuII-​COD)​

gem-​Chloronitrosocyclododecane, (CH22)​n-​1CNOCl, with n = 12

The title compd., C12H22ClNO, adopts the square conformation [3333] obsd. in other known satd. twelve-​membered rings. Disorder is obsd., resulting from exchange of the chloro and nitroso substituents. Crystallog. data are given

Vinylsilanes in synthesis: 2-Halo-lcyclopentenyl alkyl/aryl ketones from 2-halo-1-trimethylsilylcyclopentenes

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