Dipole moments ethers

Ethers like water and alcohols are polar molecules Diethyl ether for example has a dipole moment of 1 2 D Cyclic ethers have larger dipole moments ethylene oxide and tetrahydrofuran have dipole moments m the 1 7 to 1 8 D range—about the same as that of water (1 8D)... 

View molecular models of dimethyl ether and ethylene oxide on Learning By Modeling Which one has the greater dipole moment Do the calculated dipole moments bear any relation ship to the observed boiling points (ethylene oxide +10°C dimethyl ether —25°C) d... 

Oxadiazoles, 6, 365-391 aldol condensation, 6, 383 bond lengths, 6, 378 catalytic hydrogenation, 5, 75 chemotherapy, 6, 391 dipole moments, 6, 378 electron densities, 6, 378 electrophilic substitution, 6, 382 ethers... 

For non-hydrogen-bonding polar compounds such as carbonyls and ethers, Tsonopoulos recommends that Eq. (2-68) be expanded to a third term that is a function of the reduced dipole moment ( I ) as described by Eqs. (2-71) through (2-73) ... 

The rate enhancement of the Diels-Alder reaction in LP-NM has been attributed to the high dipole moment of nitromethane (3.40 D) in comparison with diethyl ether (1.33 D). 

Drawings using arrows help us see why acetone has a larger dipole moment than dimethyl ether. The arrows show the charge displacement for each polar bond. Experimental values for the dipole moments are butane, 0 D methyl ethyl ether, 1.12 D and acetone, 2.88 D. 

The measurement of change in the surface potentials of aqueous solutions of electrolytes caused hy adsorption of ionophore (e.g., crown ether) monolayers seems to he a convenient and promising method to ascertain selectivity and the effective dipole moments of the ionophore-ion complexes created at the water surface. 

Ethers are polar compounds. A molecule of ether possesess a dipole moment, /a (Debye) values of a few ethers are given below [6],... 

Substitution of methanol by another alcohol such as propanol would not be expected to radically change selectivity because in both cases a proton donor solvent is present. However, a greater change in selectivity can be expected by using ethyl ether (proton acceptor) or methylene chloride (large dipole moment). 

Models (Hi) and (iv). Strictly, the only way of finding out definitely whether there is any complexation between the growing cation and the monomer or the polymer, or both, is to investigate whether (and if so, how) the apparent kp+ depends on monomer concentration [16, 17]. We have such evidence only for ACN and styrene and for these the value of kp does not depend on m. This is in accord with the prediction [15,17] that in a highly polar solvent the complexation of Pn+ by a Jt-donor monomer or its polymer is likely to be negligible. The likely behaviour of the w-donor vinyl ethers and their polymers is less clear, but a consideration of the dipole moments and concentrations involved makes it extremely unlikely that these monomers or their polymers could compete successfully for a place in the solvation shell of the growing cations. 

The C-O bonds In ethers are polar and thus, ethers have a net dipole moment. The weak polarity of ethers do not appreciably affect their boiling points which are comparable to those of the alkanes of comparable molecular masses but are much lower than the boiling points of alcohols as shown in the following cases ... 

Colorless gas with faint sweet odor and taste heavier than air, density in air 1.53 (air=l) gas density 1.977 g/L at 0°C noncombustible gas supports combustion liquefies to a colorless liquid at -88.5°C liquid density 1.226 g/mL at -89°C freezes to a cubic crystalline solid at -90.8°C dipole moment 0.166 critical temperature 36.5°C critical pressure 71.7 atm solubdity in water 130 mL gas dissolves in lOOmL water at 0°C and 56.7 mL in 100 ml water at 25°C soluble in alcohol, ether and sulfuric acid. 

Yellowish red oily liquid pungent penetrating odor fumes in air refractive index 1.670 at 20°C density 1.69 g/mL dipole moment 1.60 dielectric constant 4.9 at 22°C freezes at -77°C boils at 137°C reacts with water soluble in ethanol, benzene, ether, chloroform, and carbon tetrachloride dissolves sulfur at ambient temperature (67 g/100 g sulfur chloride). 

The H NMR spectra of monosubstituted, acyclic nitronates show two resonances in the range of 5.5 and 7.2 ppm (Table 2.17) (39,40). The peaks are nonequilibrating and are assigned to the two possible nitronate diastereomers. This result is in contrast to the silyl nitronates, in which the two diastereomers were observed to be in rapid equilibrium. Based on the measurement of their respective dipole moments (39), and comparison to known nitrones and oxime ethers (72,73), the downfield signal is assigned to the trans isomer. 

Problem 14.2 Account for the following, (a) Ethers have significant dipole moments (=1.18 D). (b) Ethers have lower boiling points than isomeric alcohols, (c) The water solubilities of isomeric ethers and alcohols are comparable. d... 

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