Summary Elimination Reactions

Elimination reaction, 138. 383-393 biological examples of, 393 summary of, 393-394 Embden-Meyerhof pathway, 1143-1150 see also Glycolysis... 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

The observation of stable Pt(IV) alkyl hydrides upon protonation of Pt(II) alkyls has provided support for the idea that the methane which had been observed in earlier studies (89-92) of protonation of Pt(II) methyls could be produced via a reductive elimination reaction from Pt(IV). An extensive study of protonation of Pt(II) methyl complexes was carried out in 1996 (56) and an excellent summary of these results appeared in a recent review article (14). Strong evidence was presented to support the involvement of both Pt(IV) methyl hydrides and Pt(II) cr-methane complexes as intermediates in the rapid protonolysis reactions of Pt(II) methyls to generate methane. The principle of microscopic... 

Follow the steps listed in the preceding Visual Summary of Key Reactions section. Identify the leaving group, the electrophilic carbon, and the nucleophile (or base). Then determine which mechanism is favored (see Section 9.7). Watch out for stereochemistry where important, regiochemistry in elimination reactions, and carbocation rearrangements when the mechanism is SN1 or El. 

Introduction 392 9-2 Nomenclature of Alkynes 393 9-3 Physical Properties of Alkynes 394 9-4 Commercial Importance of Alkynes 395 9-5 Electronic Structure of Alkynes 396 9-6 Acidity of Alkynes Formation of Acetylide Ions 397 9-7 Synthesis of Alkynes from Acetylides 399 9-8 Synthesis of Alkynes by Elimination Reactions 403 Summary Syntheses of Alkynes 404 9-9 Addition Reactions of Alkynes 405... 

A summary of most of the available routes to cyclobutenes and cyclobutenones is given in equations (4H7). These tqiproaches can be divided into two major strategies, (a) Cycloaddition between an alkyne and an alkene to give directly a cyclobutene. In the case where the alkene partner is a ketene, cyclobutenones are obtained (see Section 6.1.5). (b) Introduction of a double bond into a preformed cyclobutane derivative, typically via an elimination reaction. 

Summary Nucleophilic substitution and p elimination reactions of alcohols... 

Summary Silicon atoms in solid argon react with amines (NR3, R = H, CH3) and phosphine (PH3) to form donor-acceptor complexes, which are stable under matrix conditions. Upon subsequent photochemical excitation, rearrangements take place leading to the corresponding aminosilylenes or to phosphinosilylene (formal insertion products). On further irradiation, additional isomerizations and elimination reactions occur. In matrices containing high concentrations of amines the final products are diaminosilanes. 

Summary Bulky monodentate ligands affect the structure and reactivity of siliconium ion complexes in several ways they enhance ionization, they promote a methyl halide elimination reaction, and they severely distort complex geometries. The latter effect enabled the assembly of a reaction coordinate model for the Berry pseudorotation, composed of crystal structures with varying NSiN and OSiO bond angles. In a competition between opposing effects of electron withdrawal by CF3 and steric bulk of a cyclohexyl ligand in the same molecule, a nonionic dissociation of the dative N->Si bond was observed. 

Table 11.3 Summary of the Reactivity of Alkyl Halides in Elimination Reactions ...

This section concludes the coverage of alcohol chemistry for now. A summary chart concerning the various conditions for substitution and elimination reactions follows. 

MMC surfaces. Some examples of properties that can be influenced are listed in Table 14.7. A number of these approaches require particles of a stoichiometric nature. The properties of these particles can degrade or change if they undergo chemical reaction with the matrix. The short thermal cycle and relatively low temperature during FSP can help to avoid or eliminate reaction products. Table 14.8 provides a summary of various efforts to date (Ref 124-133). The initial results are very encouraging and clearly demonstrate the viability of FSP. 

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