Functional group formation/elimination in residual kraft lignin

Article Abstract:

Functional group formation and elimination have been studied in residual kraft lignin using 31P NMR. An unseen set of alkali-induced fragmentation and condensation reactions was seen. Residual kraft lignin was oxidized as a function of time and as a function of temperature with elevated temperatures, pressures and pHs. Oxidative demethoxylation reactions brought formation of catechols, likely reactive intermediates of the oxidation. Rate of carboxylic acid formation and guaiacyl phenol elimination was in two distinct phases, the first fast, the second slower.

Canada, Observations, Oxygen, Materials science, Bleaching, Chemical reaction, Rate of, Chemical kinetics, Carboxylic acids, Phosphorus, Phosphorus (Chemical element)

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Coupling P-31 NMR with the Mannich reaction for the quantitative analysis of lignin

Article Abstract:

Reactivity of lignin model compounds has been studied under Mannich conditions with formaldehyde and piperidine. The piperidinomethyl group was introduced quantitatively at sterically unhindered positions ortho to a phenolic hydroxyl when substrate could react under ambient conditions. Reliability of the technique was studied with a series of dissolved kraft lignins at different stages in delignification. Data were similar to those from permanganate oxidation.

Analysis

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On the formation of diphenylmethane structures in lignin under kraft, EMCC, and soda pulping conditions

Article Abstract:

Efforts have been made to establish the nature of formation of diphenylmethane moieties in lignin during conventional soda and kraft pulping conditions. Using 31P NMR spectroscopy, formation of phenolic hydroxyl groups of the diphenylmethane units can be followed. They can be identified and quantified. Experimentation has indicated that diphenylmethanes form in greater amounts in conventional pulping than in EMCC pulping, when the kappa number is the same.

Methods, Production processes, Spectrum analysis, Spectroscopy, Kraft paper, Kraft papers, Soda pulping process, Soda pulping

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