Reversible lignin stabilization in traditional aqueous pulping conditions using boric acid

Reversible lignin stabilization in traditional aqueous pulping conditions using boric acid | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Physical Sciences - Article Reversible lignin stabilization in traditional aqueous pulping conditions using boric acid Jeremy Luterbacher, Zezhong Li, Ran Bi, Songlan Sun, Claire Bourmaud, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8286892/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Lignin’s uncontrolled condensation during wood pulping in aqueous alkaline conditions has long limited the valorization of technical lignin’s aromatic functionality for chemical production. Several “lignin-first” processes have been proposed to chemically stabilize lignin during biomass fractionation, allowing its valorization to mono- or bisphenols or as high-performance adhesives.1–3 However, all these methods are orthogonal to traditional pulping, starting with their systematic use of organic solvents to solubilize lignin and facilitate stabilization. Here, we used boric and boronic acid chemistry to stabilize lignin in traditional aqueous alkaline pulping conditions (130-180°C, pH 13-14). Notably, boric acid (BA) reversibly formed cyclic esters with lignin’s β–O–4 hydroxyl groups in water, enhancing lignin solubility beyond Kraft lignin suggesting that BA could partially replace Na2S used in the Kraft process. Simple acidification led to near-complete (>99.7%) recovery of BA and produced uncondensed lignin that could be used directly as a wood adhesive, or hydrogenolyzed to monophenolics at yields ~3-fold those of lignin extracted without BA. The process recovered 95% glucan as cellulosic fibers with comparable properties to Kraft pulp, and 80-90% xylan with >96% purity. BA use thus offers a practical route to directly integrate lignin-first chemistry and xylan recovery into existing pulp mills. Physical sciences/Chemistry/Green chemistry Physical sciences/Engineering/Chemical engineering Full Text Additional Declarations Yes there is potential Competing Interest. Z. J. L. and J.S.L. are co-inventors on the European patent application EP2024/211663.0 on methods to preserve lignin using boric and boronic acids in alkaline pulping conditions. J.S.L. is an inventor on European patent applications (EP19203000.5 and EP19202957.7, and EP16165180.7) on methods for producing the renewable monomer and polymer through aldehyde-assisted fractionation, methods for producing fragments of lignin with functional groups, and methods for producing lignin monomers from lignocellulosic biomass during biomass depolymerization. J.S.L. is a co-founder of Bloom Biorenewables Ltd, which explores commercial opportunities for aldehyde-stabilized lignin and aldehyde-protected xyloses. The remaining authors declare no competing interests. Supplementary Files BAFSIv14.pdf Supplemental information Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8286892","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":588935752,"identity":"4f3ea05a-08b3-4419-99ad-cd8bca594486","order_by":0,"name":"Jeremy 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J. L. and J.S.L. are co-inventors on the European patent application EP2024/211663.0 on methods to preserve lignin using boric and boronic acids in alkaline pulping conditions. J.S.L. is an inventor on European patent applications (EP19203000.5 and EP19202957.7, and EP16165180.7) on methods for producing the renewable monomer and polymer through aldehyde-assisted fractionation, methods for producing fragments of lignin with functional groups, and methods for producing lignin monomers from lignocellulosic biomass during biomass depolymerization. J.S.L. is a co-founder of Bloom Biorenewables Ltd, which explores commercial opportunities for aldehyde-stabilized lignin and aldehyde-protected xyloses. The remaining authors declare no competing interests.","formattedTitle":"Reversible lignin stabilization in traditional aqueous pulping conditions using boric acid","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8286892/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8286892/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Lignin’s uncontrolled condensation during wood pulping in aqueous alkaline conditions has long limited the valorization of technical lignin’s aromatic functionality for chemical production. Several “lignin-first” processes have been proposed to chemically stabilize lignin during biomass fractionation, allowing its valorization to mono- or bisphenols or as high-performance adhesives.1–3 However, all these methods are orthogonal to traditional pulping, starting with their systematic use of organic solvents to solubilize lignin and facilitate stabilization. Here, we used boric and boronic acid chemistry to stabilize lignin in traditional aqueous alkaline pulping conditions (130-180°C, pH 13-14). Notably, boric acid (BA) reversibly formed cyclic esters with lignin’s β–O–4 hydroxyl groups in water, enhancing lignin solubility beyond Kraft lignin suggesting that BA could partially replace Na2S used in the Kraft process. Simple acidification led to near-complete (\u003e99.7%) recovery of BA and produced uncondensed lignin that could be used directly as a wood adhesive, or hydrogenolyzed to monophenolics at yields ~3-fold those of lignin extracted without BA. The process recovered 95% glucan as cellulosic fibers with comparable properties to Kraft pulp, and 80-90% xylan with \u003e96% purity. BA use thus offers a practical route to directly integrate lignin-first chemistry and xylan recovery into existing pulp mills.","manuscriptTitle":"Reversible lignin stabilization in traditional aqueous pulping conditions using boric acid","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-11 03:26:35","doi":"10.21203/rs.3.rs-8286892/v1","editorialEvents":[],"status":"published","journal":{"display":false,"email":"[email protected]","identity":"nature","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"nature","sideBox":"Learn more about [Nature](http://www.nature.com/nature/)","snPcode":"","submissionUrl":"","title":"Nature","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"153a17d9-711e-46e5-90fb-f749451797e3","owner":[],"postedDate":"February 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":62659244,"name":"Physical sciences/Chemistry/Green chemistry"},{"id":62659245,"name":"Physical sciences/Engineering/Chemical engineering"}],"tags":[],"updatedAt":"2026-02-11T03:26:36+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-11 03:26:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8286892","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8286892","identity":"rs-8286892","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}