The Formation of Coniferyl Alcohol During Alkaline Delignification with Anthraquinone

Mortimer, R. D.

doi:10.1080/02773818208085142

Cited by 32 publications

(18 citation statements)

References 13 publications

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“…[2] Another interesting observation from the prior research was that the products from AP+EG condensation and VG+EG condensation were identical (3-6 generated in both cases) and the belief is that AP and VG rearrange to the identical QM (shown in Figure 1). [1] It is conclusive that VG is generated in SAQ pulping of both softwoods [5,7] and hardwoods. [11] Therefore, if EG is added to SAQ pulping of wood chips, then 5 should be found in the pulping effluent.…”

Section: Introductionmentioning

confidence: 88%

“…[5][6][7] A fraction of the CA is transformed to vinylguaiacol (8) and isoeugenol (9). [5,7] Since all three of these monomers can rearrange to quinone methides, [5,8] one would expect a higher rate of lignin-lignin condensation in SAQ pulping as compared to kraft by the mechanism shown in Figure 1. The C-5 position of a guaiacyl unit would add to the QM from one of the three monomers above (CA, VG, or IE).…”

Section: Introductionmentioning

confidence: 99%

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Soda/AQ Pulping of a Hardwood with Trapping of the Generated Coniferyl Alcohol

Kanungo

Omori

Francis

et al. 2011

Journal of Wood Chemistry and Technology

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Coniferyl alcohol is generated from the cleavage of β-O-4 bonds during alkaline pulping of hardwoods and softwoods. Once formed, some of the coniferyl alcohol (CA) is transformed into vinylguaiacol (VG) and isoeugenol (IE). All three of these compounds (CA, VG, and IE) can rearrange to quinone methides (QMs) under alkaline conditions and become involved in condensation reactions with lignin and carbohydrate moieties. The aim of this investigation was to see if ethylguaiacol (EG) addition to soda-AQ (SAQ) pulping systems would lead to its reaction with the QMs from CA, VG, and IE to form dimers that are unreactive towards further condensation. Sugar maple wood meal was delignified by the SAQ process with EG added at 5.0 wt% on wood meal. Three dimers were detected in the pulping effluent and identified as a combination of EG with CA, VG, and IE. The total yield of the three dimers corresponded to ∼80% of the estimated CA that would have been generated. Conventional kraft, SAQ, and SAQ+EG pulping of the maple chips were then performed. The bleachability of the SAQ+EG pulp was significantly improved as compared to the SAQ pulp and it was estimated to be superior to the kraft pulp as well.

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Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Soda/AQ Pulping of a Hardwood with Trapping of the Generated Coniferyl Alcohol

Kanungo

Omori

Francis

et al. 2011

Journal of Wood Chemistry and Technology

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“…Although the identification of diphenylmethane-type structures in the isolated lignin samples was reported by a 31 P NMR method, [14] this may require further confirmation. [6] The modified side-chain units identified in kraft pulps included the formation of enol ether, [38] stilbene, [39] reduced, [6,13] and coniferyl alcohol [45,46] structures.…”

Section: Influence Of Kraft and O 2 -Delignification On The Phenolic mentioning

confidence: 99%

“…[13] It is anticipated that the structures of the enol ether, [38] stilbene, [39] and coniferyl alcohol [45,46] types generated in kraft cooks would be largely degraded in O 2 delignification based on their high reactivity observed in model compound reactions. [48] …”

Section: Influence Of Kraft and O 2 -Delignification On The Phenolic mentioning

confidence: 99%

Characterization of the Residual Kraft Pulp LigninIn Situby Sulfite Treatments

Yang

Lai

2009

Journal of Wood Chemistry and Technology

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The O 2 delignification of kraft pulps from Norway spruce was shown having a significant impact on the reactivity of the residual pulp lignin as revealed from their responses to sulfite treatments at pH 7.5. A substantial higher ratio of lignin sulfonation to the phenolic hydroxyl group content of residual pulp lignin was observed for the O 2 -delignified kraft pulps (∼0.8) as compared to a value of ∼0.3 for the unbleached samples and ∼1 for the spruce wood lignin. Under the prevailing sulfite treatment conditions, the sulfonation would be largely attributed to the phenolic lignin component and the etherified structures containing an α-carbonyl or -unsaturated group. The contribution from the latter units, evaluated by a borohydride pretreatment of pulps prior to the sulfite treatment, can only account for approximately 15% of the sulfonation observed for the O 2 -delignified sample. Thus, the nature of phenolic structures in the O 2 -delignified pulps was more similar to that of the wood lignin than that of the kraft pulps.

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“…CA is formed under several pulping conditions which include soda-, soda-anthraquinone and kraft-anthraquinone pulping. 15 Under these conditions, it is suggested that CA may react further through condensation reactions to form vinyl guaiacol. The use of flow through reactors has however more recently been shown to increase the CA concentrations.…”

Section: Introductionmentioning

confidence: 99%

A one-pot biomimetic synthesis of selectively functionalized lignins from monomers: a green functionalization platform

2018

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Lignin is the most abundant renewable source of phenolic compounds with great application potential in renewable materials, biofuels and platform chemicals. The current technology for producing celluloserich fibers co-produces heterogeneous lignin, which includes an untapped source of monomeric phenolics. One such monomer also happens to be the main monomer in soft wood lignin biosynthesis, namely coniferyl alcohol. Herein, we investigate the potential of coniferyl alcohol as a platform monomer for the biomimetic production of tailored functionalized oligolignols with desirable properties for material synthesis. Accordingly, a bifunctional molecule with at least one carboxyl-ended functionality is included with coniferyl alcohol in biomimetic lignin synthesis to, in one pot, produce a functionalized lignin. The functionalization mechanism is a nucleophilic addition reaction to the quinone methide intermediate of lignin polymerization. The solvent system applied was pure water or 50% aqueous acetone. Several bifunctional molecules differing in the second functionality were successfully inserted in the lignin demonstrating the platform component of this work. Detailed characterization was performed by a combination of NMR techniques which include 1 H NMR, COSY-90, 31 P NMR, 13 C NMR, 13 C APT, HSQC, HMBC and HSQC TOCSY. Excellent selectivity towards benzylic carbon and a high functionalization degree were noted. The structure of lignin was tailored through the solvent system choice, with 50% aqueous acetone producing a skeletal structure favorable for a high degree of functionalization. Finally, material concepts are demonstrated using classical thiol-ene-and Diels-Alder-chemistries to show the potential for the thermoset and thermoplastic concepts, respectively. The functionalization concept presents unprecedented opportunities for the green production of lignin-based recyclable biomaterials.

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The Formation of Coniferyl Alcohol During Alkaline Delignification with Anthraquinone

Cited by 32 publications

References 13 publications

Soda/AQ Pulping of a Hardwood with Trapping of the Generated Coniferyl Alcohol

Soda/AQ Pulping of a Hardwood with Trapping of the Generated Coniferyl Alcohol

Characterization of the Residual Kraft Pulp LigninIn Situby Sulfite Treatments

A one-pot biomimetic synthesis of selectively functionalized lignins from monomers: a green functionalization platform

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