Dipole moment compounds

Method of dipole moments. Many cis-trans isomers show characteristic differences in the magnitude of their dipole moments. Compounds of the type XCH=CHX where X is a single atom or a simple group with cylindrical symmetry, the dipole moment of the trans form is zero ... 

There are two mechanisms by which microwaves interact with reaction mixtures [7]. Polarization of dielectric material arises when the distribution of an electron cloud is distorted or physical rotation of molecular dipoles occurs. For generation of heat on irradiation with microwaves, at least one component of a reaction mixture must have a dipole moment. Compounds with high dipole moments also have large dielectric constants, e. The selectivity of microwave irradiation is clear when comparing the heating of water and hexane. Water, a polar solvent, has a high dielectric constant and therefore heats rapidly on microwave irradiation whereas hexane, a nonpolar solvent, heats very slowly. 

FIGURE 1.47 COMPOUND STRUCTURE DIPOLE MOMENT COMPOUND STRUCnjRE DIPOLE MOMENT... 

PM3/TM is an extension of the PM3 method to transition metals. Unlike the parameterization of PM3 for organics, PM3/TM has been parameterized only to reproduce geometries. This does, of course, require a reasonable description of energies, but the other criteria used for PM3 parameterization, such as dipole moments, are not included in the PM3/TM parameterization. PM3/TM tends to exhibit a dichotomy. It will compute reasonable geometries for some compounds and completely unreasonable geometries for other compounds. It seems to favor one coordination number or hybridization for some metals. 

The compounds FCl and ICl have dipole moments p, that are similar in magnitude (0 9 and... 

D respectively) but opposite in direction In one compound chlonne is the positive end of the dipole in the other it is the negative end Specify the direction of the dipole moment in each com pound and explain your reasoning... 

Which compound in each of the following pairs would you expect to have the greater dipole moment Why" ... 

Examine the molecular models of H2 HE CH4 CH3F and CF4 Find the calculated dipole moment of each compound and examine their electrostatic potential maps... 

The carbonyl group withdraws rr electron density from the double bond and both the carbonyl carbon and the p carbon are positively polarized Their greater degree of charge separation makes the dipole moments of a p unsaturated carbonyl compounds signifi cantly larger than those of comparable aldehydes and ketones... 

The carbon-bromine bond is longer than the carbon-chlorine bond therefore although the charge e in the dipole moment expression p, = e d k smaller for the bromine than for the chlo nne compound the distance d is greater... 

Tables 5.17 and 5.18 contain a selected group of compounds for which the dipole moment is given. An extensive collection of dipole moments (approximately 7000 entries) is contained in A. L. McClellan, Tables of Experimental Dipole Moments, W. H. Freeman, San Francisco, 1963. A critical survey of 500 compounds in the gas phase is given by Nelson, Tide, and Maryott, NSRDS-NBS 10, Washington, D.C., 1967.

Revised material for Section 5 includes the material on surface tension, viscosity, dielectric constant, and dipole moment for organic compounds. In order to include more data at several temperatures, the material has been divided into two separate tables. Material on surface tension and viscosity constitute the first table with 715 entries included is the temperature range of the liquid phase. Material on dielectric constant and dipole... 

Revised material in Section 5 includes an extensive tabulation of binary and ternary azeotropes comprising approximately 850 entries. Over 975 compounds have values listed for viscosity, dielectric constant, dipole moment, and surface tension. Whenever possible, data for viscosity and dielectric constant are provided at two temperatures to permit interpolation for intermediate temperatures and also to permit limited extrapolation of the data. The dipole moments are often listed for different physical states. Values for surface tension can be calculated over a range of temperatures from two constants that can be fitted into a linear equation. Also extensively revised and expanded are the properties of combustible mixtures in air. A table of triple points has been added. 

Chiral Smectic. In much the same way as a chiral compound forms the chiral nematic phase instead of the nematic phase, a compound with a chiral center forms a chiral smectic C phase rather than a smectic C phase. In a chiral smectic CHquid crystal, the angle the director is tilted away from the normal to the layers is constant, but the direction of the tilt rotates around the layer normal in going from one layer to the next. This is shown in Figure 10. The distance over which the director rotates completely around the layer normal is called the pitch, and can be as small as 250 nm and as large as desired. If the molecule contains a permanent dipole moment transverse to the long molecular axis, then the chiral smectic phase is ferroelectric. Therefore a device utilizing this phase can be intrinsically bistable, paving the way for important appHcations. 

Compound CAS Registry Number Boiling point, °C Density at 20°C, g/cm Dipole moment, 10-"° Cm Index of refraction, < PR nmr Parameters chemical t shift, ppm ... 

This particularly valuable technique for studying molecules which possess permanent dipole moments in the vapour phase has been reviewed on many occasions. For its application to heterocyclic compounds the excellent account by Sheridan <74PMH(6)53) should be consulted. 

Oxirane (1) and methyloxirane (3) are miscible with water, ethyloxirane is very soluble in water, while compounds such as cyclopentene oxide and higher oxiranes are essentially insoluble (B-73MI50501) (for a discussion of the solubilities of heterocycles, see (63PMH(l)l77)). Other physical properties of heterocycles, such as dipole moments and electrochemical properties, are discussed in various chapters of pmh. The optical activity of chiral oxiranes has been investigated by ab initio molecular orbital methods (8UA1023). 

There were also several calculations of geometrical parameters, dipole moment and energy of oxaziridine 71MI50800). Since the parent compound of oxaziridines is unknown, comparison of calculated and experimental values is still lacking. 

Furazano[3,4-/]quinoxaline, 7,8-diphenyl-synthesis, 6, 412 Furazanothiophene synthesis, 6, 417 Furazans, 6, 393-426 biological activity, 6, 425 bond angles, 6, 396 bond lengths, 6, 396 coordination compounds, 6, 403 diamagnetic susceptibilities, 6, 395 dipole moments, 6, 395, 400 heats of combustion, 6, 400 heterocyclic ring reactions, 6, 400-403 IR spectra, 6, 398 isoxazoles from, 6, 81 mass spectra, 6, 399 microwave spectroscopy, 6, 395, 396 MO calculations, 6, 395 monosubstituted... 

Tetrazole, l-(p-substituted phenyl)-antimicrobial activity, 5, 835 Tetrazole, 5-thio-rearrangements, 5, 823 Tetrazole, 2-thioacyl-reactions, 5, 109 Tetrazole, 5-(o-tolyl)-tautomerism, 5, 804 Tetrazole, 5-(p-tolyl)-dipole moments, 5, 795 tautomerism, 5, 804 Tetrazole, 5-(trimethylsilylamino)-synthesis, 5, 832 Tefrazolecarbaldehydes reactions, 5, 820 Tetrazole-5-carbaldehydes reactions, 5, 820 Tetrazolecarbonitriles reactions, 5, 820 Tetrazole carbonyl compounds reactions, 5, 820 Tetrazolecarboxylic acid, 5-aryl-acidity, 5, 816... 

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 physical data index summarizes the quantitative data given for specific compounds in the text, tables and figures in Volumes 1-7. It does not give any actual data but includes references both to the appropriate text page and to the original literature. The structural and spectroscopic methods covered include UV, IR, Raman, microwave, MS, PES, NMR, ORD, CD, X-ray, neutron and electron diffraction, together with such quantities as dipole moment, pX a, rate constant and activation energy, and equilibrium constant. 

Scheme 1.1. Dipole Moments for Some Organic Compounds "...

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