Relationship between the Chemical Shifts of Aromatic Carbons of Phenolic Compounds and Reactivity in Aqueous Alkaline Solution

摘要

Chemical shifts of aromatic carbons of phenolic compounds used in novolac synthesis commonly were recorded in aqueous alkaline solution and the results indicated that chemical shifts of para- position carbon was lower than that of ortho- position carbon, both of which were lower than that of meta- position carbons. Hydroxymethylation of some phenolic compounds with formaldehyde catalyzed by sodium hydroxide were investigated also. The research showed that hydroxymethylation could both occur at ortho- and para- positions, and occur at para- position more easily. Moreover, hydroxymethylated produts were stable in basic conditions compared with in acidic conditions. In summary, in basic conditions the lower the chemical shift of reactive site of phenolic compounds, the more easily the hydroxymethylation of the reactive site. Therefore, electrophilic substitution reaction of phenolic compounds in basic conditions can be predicted by chemical shift of reactive site. According to the regulation, a stepwise base-acid catalyzed reaction was used to synthesize various series of novolac with high Mw and low Mw/Mn, all of which have good application prospects in the field of direct digital plate-making and resists for LCD and IC.