Characteristic Bond Lengths in Free

CFC s, global warming potential, 14-34 to 35 CFC s, various properties, 6-133 to 135 Characteristic Bond Lengths in Free Molecules, 9-48... 

The conformation parameter a (=A/Af, where Af is A of a hypothetical chain with free internal rotation) for cellulose and its derivatives lies between 2.8-7.5 2 119,120) and the characteristic ratio ( = A2Mb//2, where Ax is the asymptotic value of A at infinite molecular weight, Mb is the mean molecular weight per skeletal bond, and / the mean bond length) is in the range 19-115. These unexpectedly large values of a and Cffi suggest that the molecules of cellulose and its derivatives behave as semi-flexible or even inflexible chains. For inflexible polymers, analysis of dilute solution properties by the pearl necklace model becomes theoretically inadequate. Thus, the applicability of this model to cellulose and its derivatives in solution should be carefully examined. 

To sum up what we have said so far, clearly, the best experimental path to a knowledge of what aromaticity is, is the study of the molecular characteristics in the ground state of the resting compound, i.e. the compound as free as possible of any external perturbation. Measuring the bond lengths, for example, will give us the opportunity to analyse the famous bond alternation aromaticity criterion. 

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