Addition Of Lewis Bases Research Articles

The Effect of Lewis Base Chemisorption on the Luminscence of Porous Silicon

ABSTRACTWe report here studies on the effects of Lewis base addition on the observed luminescence of porous silicon generated non-anodically from a stain etch of <100> p-type wafers and whose surface morphology has been characterized by atomic force microscopy (AFM). Addition of dilute heptane solutions of alkyl amines such as n-butyl amine (C4H7NH2) results in dramatic quenching of the steady-state photoluminescence (PL) near 625 nm. The observed fractional changes in integrated PL intensity as a function of amine concentration have been fit to a simple equilibrium model demonstrating Langmuir-type behavior from which adduct formation constants have been calculated. These steady-state PL measurements are complemented by Fourier Transform Infrared (FT IR) spectroscopic measurements monitoring the effect of amine adsorption on the silicon hydride stretching modes [v(Si-Hx)] near 2100 cm-1. Based on these results, a physical model for the amine interactions with the porous silicon surface is presented.

Stereoselectivity of cyclization of substituted 5-hexen-1-yllithiums: regiospecific and highly stereoselective insertion of an unactivated alkene into a carbon-lithium bond

Substituted 5-hexen-1-yllithiums, which were prepared in solutions of n-C 5 H 12 -Et 2 O (3:2 by vol) by low-temperature lithium-iodine exchange between t-BuLi and the appropriate iodide, undergo clean, 5-exo-trig cyclization upon warming to give substituted (cyclopentyl)methyllithiums, in good yield and with a high degree of stereocontrol. In each case, the major product is the same isomer as that observed in studies of the isomerization of analogously substituted 5-hexen-1-yl radicals, but the organolithium cyclizations are invariably much more stereoselective than radical-mediated processes. Lewis base additives such as THF, TMEDA, and PMDTA serve to increase the rate of cyclization of the substituted 5-hexen-1-yllithiums, but such additives do not reduce the high stereoselectivity of the process. The observed regioselectivities and stereoselectivities of the intramolecular addition of a C-Li bond to an unactivated alkene suggest that the closure of the anion proceeds via a transition state that resembles a chair cyclohexane in which substituents preferentially occupy pseudoequatorial positions

Flash photolysis studies of Lewis base addition to cyclopentadienyliron complex CpFe(CO)(.eta.3-CH2C6H5)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFlash photolysis studies of Lewis base addition to cyclopentadienyliron complex CpFe(CO)(.eta.3-CH2C6H5)Richard S. Herrick, Aaron B. Frederick, and Ronald R. Duff Jr.Cite this: Organometallics 1989, 8, 4, 1120–1121Publication Date (Print):April 1, 1989Publication History Published online1 May 2002Published inissue 1 April 1989https://doi.org/10.1021/om00106a042RIGHTS & PERMISSIONSArticle Views34Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (297 KB) Get e-Alerts Get e-Alerts

Control of Product in the Reaction of Tributyltin ω-Haloalkoxide (n-Bu3SnO(CH2)nX) with Diphenylketene

Abstract The reaction of tributyltin ω-haloalkoxide with diphenylketene gave cyclic ketene acetals and/or lactones, and the ratio of these products were controled by the number of methylene groups and by the addition of Lewis base in the reaction system. Moreover, the direct cycloaddition of diphenylketene with cyclic ethers proceeded in high yields, catalyzed by organotin halide–Lewis base complexes.

Ligand Induced Spin Crossover in Penta-Coordinated Ferric Dithioearbamates

Abstract On addition of lewis bases to Fe(dtc)2X, ligand exchange takes place through a SN2 mechanism, with a parallel spin crossover in the ferric ion. The two species (S = 3/2 and S = 5/2) formed are in dynamic chemical equilibrium, and a slow decomposition is then initiated.

Nitration of p-dimethoxybenzene by dinitrogen tetroxide in carbon tetrachloride

Nitration by dinitrogen tetroxide in carbon tetrachloride appears to proceed by slow nitrosation of the p-dimethoxybenzene followed by rapid oxidation of the nitroso-intermediate. The increase in reaction rate on addition of Lewis acids and the decrease in rate on addition of Lewis bases indicate an ionic mechanism for the nitrosation reaction.

The Ionic Telomerization of Conjugated Diene Compounds. III. The Effects of the Addition of Lewis Bases on the Cationic Telomerization of Butadiene with Its Hydrochlorides

Abstract The effects of the addition of several oxygen- and nitrogen-containing compounds on the cationic telomerizations of butadiene with its hydrochloride were investigated. The addition of both acetonitrile and ethyl ether to an ethyl bromide solution of ferric chloride or a methylene chloride solution of titanium tetrachloride resulted in large decreases in the catalytic activities of the solutions at low temperatures. On the other hand, the addition of nitroethane to an ethyl bromide solution of aluminum chloride increased the activity of the catalyst, although the addition of nitrobenzene decreased it. The addition of ethyl ether to ferric chloride or titanium tetrachloride led to the formation of telomers with lower molecular weights and larger degrees of unsaturation, whereas a nitroethane - aluminum chloride catalyst gave telomers with higher molecular weights. The monomolecular addition complexes of several Lewis acids and Lewis bases were isolated, and the catalytic abilities of the complexes in halogenated hydrocarbons were investigated. The structures of the higher telomers were analyzed and will be discussed.