Hydrochloric acid spruce lignins

To eliminate interfering side reactions caused by units having carbonyl and hydroxyl groups at the a-position, the lignin is reduced with borohydride and alkylated with methanolic hydrochloric acid prior to oxidation to convert these groups to o-quinones. Following a procedure based on the above reaction, spruce milled-wood lignin was found to contain 15-18% of uncondensed phenolic units (Adler and Lundquist 1961). 

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