Refraction of bonds

Table LXIX. Refraction of Bonds Containing Hydrogen...

H in H3O+ (Table LXVIII) is I 01 cc whilst that of N+—H in +NH4 (Table LXVIII) is i 02 cc. Both these values are considerably less than the corresponding values for O—H and N—H (Table LXIX). As expected, the refractions of bonds in anions are greater than in the corresponding neutral molecules. Thus in... 

For terminal groupings the data are somewhat below the 1952 estimates. Other workers who have demonstrated the sensitivity of i c==c to the position of C=C in a carbon chain are von Auwers (1935), Campbell and Eveslage (1945), and Hennion and Banigan (1946). West and Rochow (1952) quote three refractions for C—Si respectively as the carbon atom is primary, secondary, or tertiary. Tolkmith (1959) has emphasized the structure-dependent nature of the refractivities of bonds between phosphorus and other elements. 

The foregoing conclusions are further supported by a refined X-ray analysis of pyrid-2-one, which indicated that the mobile hydrogen atom is attached to the nitrogen atom in the solid state and that individual molecules are bound into helices by N—H- -0 hydrogen bonds. An oxo structure is also indicated by the molar refractivity of pyrid-2-one. The dipole moment of 4-methoxypyridine is ca. 3.0 debyes in dioxane, whereas the values for pyrid-4-one and its 1-methyl derivative are much higher, ca. 6.0 debyes indicating the... 

The transition between crystalline and amorphous polymers is characterized by the so-called glass transition temperature, Tg. This important quantity is defined as the temperature above which the polymer chains have acquired sufficient thermal energy for rotational or torsional oscillations to occur about the majority of bonds in the chain. Below 7"g, the polymer chain has a more or less fixed conformation. On heating through the temperature Tg, there is an abrupt change of the coefficient of thermal expansion (or), compressibility, specific heat, diffusion coefficient, solubility of gases, refractive index, and many other properties including the chemical reactivity. 

An understanding of the limitations of the Kirkwood-Vinti approximation should therefore lead to considerable advances in the theory of bonding. In its absence, we shall here use diamagnetic susceptibility as the principal method of measuring yms and use refractive index only as a secondary method. 

Exaltation. The amt by which the molecular refractivity of a compd exceeds the sum of the refractivities of its atoms it is an indication of constitution (presence of double bonds, etc)... 

Some values of polarizabilities for the more common types of bonds are given in Table IX. It is found that the refractive indices of strongly... 

If, instead, we assume that only one bond is perturbed at any one time then it would be the average polarizability that is important. This would lead to the use of the average bond refraction (Rx) rather than the sum of bond refractions in Eq. (1). 

It is surprising that the mole refraction of the latter two compounds is not in agreement with the rules of Eisenlohr and Lorenz-Lorentz. No explanation has so far been given for the difference between experimental data and the theory. The Si—Si bond has not been found to have an abnormal increment. 

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