{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T04:48:35Z","timestamp":1792212515709,"version":"4.4.0"},"reference-count":50,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T00:00:00Z","timestamp":1754870400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MCIN\/AEI\/10.13039\/501100011033 and European Union \u201cNextGenerationEU\/PRTR\u201d","award":["TED2021-132224B-I00"],"award-info":[{"award-number":["TED2021-132224B-I00"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The role of p-benzoquinone (BQ) as a photocatalyst in the synthesis of solketal under UV irradiation has been studied, along with the combined use of BQ\/TiO2 P25 as a photocatalytic system for the process. The presence of the O2\/O2\u2212\u2022 redox couple is essential for the reaction to take place. However, experiments with p-benzoquinone as a superoxide radical scavenger failed, with the opposite effect of enhancing the reaction being observed. It was found that p-benzoquinone and oxygen compete for photogenerated electrons in the conduction band of titania. A redox equilibrium between p-benzoquinone and hydroquinone (H2Q), mediated by the O2\/O2\u2212\u2022 system, was identified as a key factor in enabling the reaction. Furthermore, EPR spin-trapping experiments confirmed the presence of the carbon-centered radical 2-hydroxypropan-2-yl, which was determined to be the main radical species involved in the process. Either acetone or 2-propanol can generate this radical, with the BQ\/H2Q redox system being pivotal in the formation of the hemiacetal intermediate. This intermediate is subsequently converted into the final acetal (solketal), with H2Q acting as a photoacid through an excited-state proton transfer (ESPT) mechanism. The photoacid behavior of hydroquinone was confirmed using pyridine as a basic probe, as the formation of hydroquinone\u2013pyridine adducts was detected by Raman spectroscopy.<\/jats:p>","DOI":"10.3390\/molecules30163339","type":"journal-article","created":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T14:32:36Z","timestamp":1754922756000},"page":"3339","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Role of p-Benzoquinone in the Photocatalytic Production of Solketal"],"prefix":"10.3390","volume":"30","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-3265-522X","authenticated-orcid":false,"given":"Alejandro","family":"Ariza-P\u00e9rez","sequence":"first","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0791-7490","authenticated-orcid":false,"given":"Juan","family":"Mart\u00edn-G\u00f3mez","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6707-9804","authenticated-orcid":false,"given":"M. Carmen","family":"Herrera-Beurnio","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1807-7829","authenticated-orcid":false,"given":"Francisco J.","family":"L\u00f3pez-Tenllado","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6403-4734","authenticated-orcid":false,"given":"Jes\u00fas","family":"Hidalgo-Carrillo","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2693-0711","authenticated-orcid":false,"given":"Alberto","family":"Marinas","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3489-1601","authenticated-orcid":false,"given":"Francisco J.","family":"Urbano","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica Org\u00e1nica, Instituto Qu\u00edmico para la Energ\u00eda y el Medioambiente (IQUEMA), Universidad de C\u00f3rdoba, E-14071 C\u00f3rdoba, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2400160","DOI":"10.1002\/adsu.202400160","article-title":"Advancing Sustainable Energy: Exploring New Frontiers and Opportunities in the Green Transition","volume":"8","author":"Soni","year":"2024","journal-title":"Adv. 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