Coniferyl alcohol structures, Raman

Raman Spectroscopic Evidence for Coniferyl Alcohol Structures in Bleached and Sulfonated Mechanical Pulps... 

AGARWAL AND ATALLA Raman Evidence for Coniferyl Alcohol Structures 27... 

Other Structures. From the results on the pulps studied here, it appears that coniferyl alcohol structures survive bleaching and sulfonation treatments. As alternative causes of residual intensity at 1654 cm-1, we have considered quinone and stilbene structures. Stilbene structures (samples 25 and 26) give a Raman band around 1635 cm-1 (Table I, Fig. 61,J). Such structures have not been... 

Implications to Photoyellowing. On the basis of the Raman spectral results, survival of coniferyl alcohol structures (this includes both phenolics and those etherified at the para-position) in bleached and sulfite pulps would seem to be a major reason why pulps yellow in daylight. Such groups are expected to participate in the primary photochemical events that lead to yellowing. Thus, in pulps, coniferyl alcohol structures would act as leucochromophores. Photoyellowing of coniferyl alcohol structures has been evaluated [34], and it has been reported that the free phenolic structure contributes much more to yellowing than does the para-etherified unit. 

UP Agarwal and RH Atalla. Raman Spectroscopic Evidence for Coniferyl Alcohol Structure in Bleached and Sulfonated Mechanical Pulps. In C Heitner and 1C Scaiano, eds. Photochemistry of Lignocellulosic Materials. ACS Symposium Series, 531. Washington, DC American Chemical Society, 1993, pp. 26-44. 

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