Diethyl ether conformation

Typical carbon-oxygen bond distances m ethers are similar to those of alcohols (—142 pm) and are shorter than carbon-carbon bond distances m alkanes (—153 pm) An ether oxygen affects the conformation of a molecule m much the same way that a CH2 unit does The most stable conformation of diethyl ether is the all staggered anti conformation Tetrahydropyran is most stable m the chair conformation—a fact that has an important bearing on the structures of many carbohydrates... 

As well as the disubstituted C2-symmelrie pyrrolidines E and F, the monosubstituted (f> )-2-(mcthoxymethyl)pyrrolidine G can be used as chiral auxiliary for the diastereoselecti ve addition of organomctallic reagents to a-oxo amides16. As with the phenylglyoxylic acid derivatives derived from amines E and F. methyllithium or methylmagnesium bromide in diethyl ether preferentially attack the (,S)-mms-conformer 11 (R = ( 6H5), leading to predominant formation of the (2 S)-diastercomer by Re-side attack. 

Acid catalyzed intramolecular Diels-Alder reactions in lithium perchlorate-diethyl ether acid promoted migration of terminal dienes prior to [4 + 2] cycioaddition in conformationally restricted substrates [101]... 

On the basis of a variety of physical and spectroscopic measurements, Nelson and Heal concluded that S Nj is a 6-membered ring with nitrogen atoms in the 1,3-positionsHowever, because of its low melting point (23 °C) and thermal instability, the conformation of the ring has been difficult to ascertain. The discovery that S4N2 can be recrystallized from diethyl ether at —20 °C has enabled the low temperature (—100 °C) X-ray crystal structure to be determined. As indicated... 

Material. Diethyl ether shall be made from ethyl alcohol conforming to the requirements... 

Chemical and Physical Properties. The diethyl ether shall conform to the requirements specified in Table Et 3... 

Cyclic oligomers with x - 2-9 are found to be present in poly(1,3-dioxolane) samples prepared by monomer-polymer-equilibrations using boron trifluoride diethyl etherate as catalyst. The molecular cyclization equilibrium constants 7fx are measured and the values are in agreement with those calculated by the Jacobson-Stockmayer theory, using an RIS model to describe the statistical conformations of the corresponding chains and assuming that the chains obey Gaussian statistics. 

Material. Diethyl ether shall be made from ethyl alcohol conforming to the requirements for grade 1 or grade 2 of Specification MIL-A-463 (See in this Vol under Ethanol), or ether shall be made as a co-product in the manuf of Ethanol from ethylene... 

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