Diethyl ether, molecular model

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. 

The cord factor from Mycobacterium tuberculosum could be permethylated with methyl iodide and sodium hydride in a diethyl ether-dimethylformamide mixture in the presence of a molecular sieve.It was confirmed that the mycolic acids were esterified at the 6,6 positions of the aa-trehalose molecule. Using 4-palmitoyl-D-glucose as a model compound, it was verified that acyl migration did not occur in this system. 

The water models used were TIP3P and TIP4P [15]. The molecular volume, mass density of the pure liquid, enthalpy of vaporization and enthalpy of solvation of diethyl ether were calculated to validate the force field parameter set. The trajectory was sampled by extracting frames every 200 fs for statistical analysis. The mean value variations were quantified by means of standard deviations. 

This study comprises a theoretical investigation of all possible stable conformers of two monomers and a dimer containing alkyl-bound ether fragments simulated with two quantum chemical methods. Basic structural parameters, characteristic vibrational frequencies and atomic electron density distribution are evaluated. Rotation barriers about the ether bond are estimated. The mean values of these quantities averaged over the entire conformer ensemble are supplemented to the parameters of the molecular mechanics force field AMBER and tested by several molecular dynamics simulations of one of the model systems - diethyl ether. 

Maleate/vinyl ether formulations based on a model unsaturated polyester prepared from maleic anhydride and 1,5-pentane diol and triethylene glycol divinyl ether were studied. At molecular weights of less than about 10,000 the cured films were extremely brittle. When the equivalent weight of the unsaturated polyester was increased by replacing some of the maleic anhydride with succinic anhydride, measurable values for film elongation could be obtained but the cure speed was definitely slower. When either diethyl maleate or isobutyl vinyl ether were added as monofunctional diluents the cure dose needed to obtain 200 MEKDR was increased and the flexibility measured by pencil hardness increased as the amount of diluent was increased. A urethane vinyl ether was synthesized and used to replace DVE-3 and films with increased elongation were obtained at equivalent at dosages as low as 1 J/cm2. 

---