Solvation dimethyl ether

FIGURE 1. Transition state for the addition of (M)-l,2-butadienylzinc fluoride, as a dimethyl ether solvate, to acetaldehyde calculated at the B3LPY/6-31G level of theory... 

Abbotto, Streitwieser and Schleyer performed an exhaustive study, using the B3LYP /6-31-bG //PM3 calculation level, on the effect of dimethyl ether solvation on aggregated forms of the lithium enolate of acetaldehyde (CH2=CH0Li) (Me20) c. 

The n -coordination of lithium in 13a is retained in the most stable structure when the lithium is further coordinated with one or two molecules of dimethyl ether. Solvation with a third ether now completes the tetracoordination of lithium with four oxygens and the n -interaction is no longer necessary the C-O-Li bond in this fully solvated structure is almost linear. ... 

The main conseqnences of the solvation are fonnd to be the increment in bond lengths between the enolate oxygen atom and the lithinm in the mono and the disolvated a) enolates, together with the increment in the Li-Osolvent bond. However, the trend con-tinnes np to trisolvated species 3b (Fignre 4), where the Li-O distance is fonnd to be less than that in isolated species. These characteristics of larger Li-dimethyl ether distance (dne to the steric hindrance) and the absence of coordination to the double bonds snggest an ionic interaction of Li with enolate oxygen. 

Sodium reacts with naphthalene in dimethyl ether to form a dark green reactive complex. This addition product, naphtalenesodium, CioHsNa, is stabilized by solvation with ether. Anthracene, phenanthrene, biphenyl, and many other aromatics form similar complexes with sodium in the presence of methylethyl ether, tetrahyrofuran, dioxane, and other ethers. 

The kinetic and activation parameters for the decomposition of dimethylphenylsilyl hydrotrioxide involve large negative activation entropies, a significant substituent effect on the decomposition in ethyl acetate, dependence of the decomposition rate on the solvent polarity (acetone-rfe > methyl acetate > dimethyl ether) and no measurable effect of the radical inhibitor on the rate of decomposition. These features indicate the importance of polar decomposition pathways. Some of the mechanistic possibilities involving solvated dimeric 71 and/or polymeric hydrogen-bonded forms of the hydrotrioxide are shown in Scheme 18. 

Copper, silver, and gold colloids have been prepared by Chemical Liquid Deposition (CLD) with dimethoxymethane, 2-methoxyethyl ether, and ethylene glycol dimethyl ether. The metals are evaporated to yield atoms which are solvated at low temperatures and during the warm-up process colloidal sols with metal clusters are obtained. Evaporation of the solvent was carried out under vacuum-generating metal films. These films are showing very low carbon/hydrogen content and were characterized by elemental analyses and infrared spectroscopy (Cardenas et al., 1994). 

Comparable figures have been obtained from an extensive investigation on Vinoli in which several computational methods were compared207. Beyond the simple monomer, the solvation (by discrete addition of dimethyl ether) and aggregation phenomena were taken into account (Scheme 53). It was concluded from this very complete approach that ... 

With diethyl ether as solvent, the reaction proceeds with the selective reduction of the tosyl group to give 1-bromo-n-undecane, whereas in diethylene glycol dimethyl ether ( digl5Tne ), the bromo substituent is selectively reduced to yield n-undecyl tosylate. In diethyl ether, the lithium cation is poorly solvated and LiAlIEt reacts as an ion pair. In... 

Solvation of lithium enolates in ether solvents was modeled by a combination of specific coordination of dimethyl ether ligands on each lithium and dielectric solvation ... 

Ethers, such as tetrahydrofuran and 1,2-dimethoxyethane, have low dielectric constants (7.4 and 7.2, respectively), and the choice of supporting electrolyte is very limited. The ethers are difficult to reduce and are inert toward many metalorganic reagents [243] that are soluble in the ethers. Ethers are thus suitable as medium for the anodic addition of Grignard reagents to olefins [420]. Dimethoxyethane and polyethylene glycol dimethyl ethers have the ability to solvate electrons [421]. Dissociation constants for some acids and the relative strength of some bases in THE has been determined [422]. 

To obtain Binor-S the reaction must be conducted in nonpolar solvents such as heptane or toluene. In coordinating solvents such as tetrahydrofuran, dioxane, f-butyl alcohol, ethylene glycol or glycol dimethyl ether dimer mixtures are formed. The effect of these solvents is similar to that of bases (see below). Alcohols cause solvolysis in addition to forming solvates with the zinc atom (52). 

The reduction of Mn2(CO)io proceeds smoothly under an inert atmosphere, usually in tetrahydrofuran as solvent, yielding only the corresponding pentacarbonylmanga-nate( -1) anion . Synthesis of the [Re(CO)5] anion is more critical and the product is frequently contaminated by other carbonylrhenates. Reduction of Re2(CO)io by Na/Hg in dimethyl ether yields pure Na[Re(CO)5], whereas in tetrahydrofuran the solvated species Na[Re(CO)5] n(thf), is obtained. 

The effectiveness of tetrahydrofuran and the dimethyl ethers of ethylene and diethylene glycols ( glyme and diglyme, respectively) as media for reactions involving sodium may be due in part to the slight solubility of the metal, but the solvation of ions by ether molecules undoubtedly provides the most important contribution. Indeed there are numerous very stable and... 

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