1.2- Difluoroethane, structure

Two wider ranging, more systematic investigations of conformational dependence have since been performed to establish whether the conformational sensitivity noted in the above PECD smdies may generally provide a means for identifying and distinguishing gas-phase structure of suitable chiral species. The B-spline method has been applied to the model system (l/f,2f )-l,2-dibromo-l,2-dichloro-l,2-difluoroethane [60]. Rotation around the C C bond creates three stable conformational possibilities for this molecule to adopt. The results for both core and valence shell ionizations reaffirm an earlier conclusion a and p are almost unaffected by the rotational conformation adopted, whereas the PECD varies significantly. Eor the C Ij ionization to show any sensitivity at aU to the relative disposition of the halogen atoms further reinforces the point made previously in connection with the core level PECD phenomenon. 

Disclosed is an ethylene polymer foam structure having enhanced processing and physical properties. The foam structure comprises an ethylenic polymer material and a blowing agent of isobutane and 1,1-difluoroethane. Further disclosed is a process for making the foam structure. 

Femholt, L. and Kveseth, K. (1980) Conformational analysis. The temperature effect on the structure and composition of the rotational conformers of 1,2-difluoroethane as studied by gas electron diffraction. Acta Chem. Scartd, A., 34, 163-170. 

Friesen, D. and Hedberg, K. (1980) Conformational analysis. 7. 1,2-Difluoroethane. An electron-diffraction investigation of the molecular structure, composition, trans-gauche energy and entropy differences, and potential hindering internal rotation. J. Am. Chem. Soc., 102, 3987-3994. 

In Table 7, the bond lengths of the C-C bonds adjacent to the C-F or C-0 bonds of some fluorohydrocarbons and ethanol are given. Since rg, rg or ro structures are available for 1,2-difluoroethane [46-49], 1-fluoropropane... 

The molecular structure of 1,2-difluoroethane in the gas phase has been redetermined by electron diffiraction at room temperature only the synclinal ( gauche or skew ) conformation was found, the torsion angle (F-C-C-F) being 74.5 and the C—C, C— F, and C—H bond lengths 153.5, 139.4, and 113 pm, respectively. Several groups have discussed the conformational behaviour of 1,2-difluoroethane and related systems. ... 

If a molecule has only an inversion centre present it has Q symmetry. Examples of this point group are less common, but substituted ethanes such as (15,2/ )-l,2-dichloro-1,2-difluoroethane (Figure 3.5a) can take on conformations with C, symmetry, and some bimetallic complexes, such as the general structure shown in Figure 3.5b, also fall into this classification. 

Figure 3.5 Molecular structures with C, symmetry (a) a particular conformation of(IS,2R)-1,2-dichloro-l,2-difluoroethane (b) a bridged transition metal complex shown with nonspecific metal centre M and ligand L,X labels.

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