The Constitution of the Grignard Reagent

Dessy, Raymond E.; Handler, George S.; Wotiz, John H.; Hollingsworth, C. A.

doi:10.1021/ja01570a045

Cited by 47 publications

(17 citation statements)

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“…[4][5][6] However, the negative sign of the constant indicates a smaller polarity of the transition state in comparison with the reactants. This seems to be consistent with the fourcentre mechanism postulated by Dessy et al 13 for this reaction and subsequently supported by evidence of nucleophilic assistance in the reaction (see, e.g., Refs 1,14 and 15). In contrast, the preponderant solvent polarizability term, suggesting a charge separation during the activation process, is less readily understood in this context.…”

Section: Resultssupporting

confidence: 90%

Solvent effects in the Grignard reaction with alkynes

Tuulmets

Pällin

Tammiku-Taul

et al. 2002

J of Physical Organic Chem

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Kinetic studies were carried out on the reaction of phenylmagnesium bromide with hex-1-yne in diethyl ether, and in binary mixtures of diethyl ether with toluene, chlorobenzene and dichloromethane. The reaction was accelerated by addition of non-donating solvents. The replacement of a coordinated solvent molecule by the alkyne is necessary for the reaction to proceed, according to density functional theory (DFT) calculations with B3LYP/6-31 G* method. The non-donating solvents accelerate the reaction by shifting the replacement equilibrium in favour of the complex formation. An analysis in terms of the Koppel-Palm equation revealed a rate decrease with increase in solvent polarity and polarizability.

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Section: Resultssupporting

confidence: 90%

Solvent effects in the Grignard reaction with alkynes

Tuulmets

Pällin

Tammiku-Taul

et al. 2002

J of Physical Organic Chem

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“…Based on previous work, the general structure of the initiating complex should be R2Mg MgX2. 21,22 The reaction has been studied by previous investigatorsB*" and classified as an anionic polymerizationB in which stereoregular propagation proceeds through coordination between incoming monomer and the active chain end. Our reaction flasks contained a mechanical stirrer, a graduated addition funnel with a rubber septum bottle cap, a thermometer, as well as an inlet and outlet for dry, oxygen-free nitrogen.…”

Section: Chemical Synthesismentioning

confidence: 99%

Solid matrix polymerization and stereoisomeric complexes of poly(methyl methacrylate)

Yau

Stupp

1985

J. Polym. Sci. Polym. Chem. Ed.

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The polymerization of methyl methacrylate within solid matrices of stereoregular poly(methyl methacrylate) has been studied by proton NMR and wide angle X‐ray diffraction. The semi‐crystalline isotactic (i‐) PMMA matrix was synthesized in the laboratory by anionic polymerization initiated by phenylmagnesium bromide, and the syndiotactic (s‐) PMMA matrix was synthesized through a Ziegler–Natta reaction. Matrix polymerization of the monomer was initiated through the redox activation of benzoyl peroxide with N,N‐dimethyl‐p‐toluidine. NMR measurements of triad distributions in matrix‐polymerized chains suggest that the well‐known stereospecific replica polymerization in PMMA (syndiotactic sequences promote isotactic sequences and vice versa) plays only a limited role in the systems studied. Experimental results indicate that chains grown within the i‐PMMA or s‐PMMA solid matrices have greater degrees of configurational disorder. The greater concentration of atactic triads in these chains could be the result of limited free volume or steric effects during polymerization in a highly condensed environment. X‐ray diffraction studies of solution cast blends of isotactic PMMA and PMMA with conventional tacticity reveal some crystallinity with a structure characteristic of the stereocomplex formed by isotactic and syndiotactic PMMA from suitable solvents. Evidence was obtained for the presence of this complex in solidified mixtures of the i‐PMMA solid matrix and liquid monomer. This observation is an example of special intermolecular structures that can form under conditions of in situ growth of chains within a pre‐polymerized matrix.

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“…equilibrium [2,3,5] where X = CI, Br, or I and R = alkyl or aryl, adequately describes the composition of a wide range of Grignard solutions, although other structures, such as R--Mg(/XC1E)Mg--C1 may also be involved [3,7,24,25]. In general, all the Grignard reagents, RMgX, are very reactive, with iodides being the most reactive, and chlorides the least reactive; alkyl Grignards are more reactive than aryl Grignards [29].…”

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confidence: 99%

An ab initio molecular orbital study of the grignard reagents CH3MgCl and [CH3MgCl]2: The Schlenk equilibrium

et al. 1994

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Ab initio molecular orbital calculations are used to study the modified Schlenk equilibrium: 2RMgCI ,-~ (RMgCI) 2 ~ MgR2 + MgCI2 "-' Mg(CI2)MgR2 with R = H and CH 3. In the absence of any solvents, calculations indicate that the formation of the various possible bridged dimers (RMgC1)2 is substantially exothermic. However, using dimethylether as a model solvent, we show that the formation of the dimer (Me20)(CH3)Mg(~CI2)Mg(CH3)(OMe2) is exothermic only when entropic effects are included.

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The Constitution of the Grignard Reagent

Cited by 47 publications

References 0 publications

Solvent effects in the Grignard reaction with alkynes

Solvent effects in the Grignard reaction with alkynes

Solid matrix polymerization and stereoisomeric complexes of poly(methyl methacrylate)

An ab initio molecular orbital study of the grignard reagents CH3MgCl and [CH3MgCl]2: The Schlenk equilibrium

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