Acid Degradation of Lignin. III. Formation of Formaldehyde.

13C-NMR Spectra of Kraft Lignins

“…However, alkalistable aryl-vinyl ether structures are formed, to some degree, äs a result of alkali-promoted elimination of the -hydroxymethyl groups (Adler et al 1964a, Gierer et al 1964, Gierer and Ljunggren 1979. These vinyl ethers are unstable under acidic conditions (Gierer and Noren 1962, Lundquist and Ericsson 1970, Lundquist 1973) and therefore may decompose during the lignin Isolation procedure used in the present investigation. However, the 13 C-NMR spectra in Fig.…”

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

“…Another competing route (route B), which also leads to β-O-4 bond cleavage, has been previously described in the literature (Lundquist and Ericsson 1970). Formaldehyde is released from the γ-position of II and another enol ether type substructure VI forms.…”

Structural changes of lignin in biorefinery pretreatments and consequences to enzyme-lignin interactions - OPEN ACCESS

“…These species are not stable under acidic conditions and undergo hydrolysis to Hibbert ketones and phenyl acetic aldehydes (Fig 4 Routes B−C). Released formaldehyde (Lundquist, Ericsson, 1970) can, in turn, undergo condensation reactions via hydroxymethylation of the aromatic ring to generate diphenylmethane motifs, or alternatively form cyclic acetal structures with unmodified side chains (Shuai et al 2016a). The main reaction pathway for the benzylic cation under acidic pathway is the nucleophilic addition to the C-α of the lignin side chain .…”