{"id":{"repo_id":"aston","oai_identifier":"oai:publications.aston.ac.uk:11626"},"canonical_url":"https://search.dev.ndltd.org/etd/aston/oai:publications.aston.ac.uk:11626","repository":{"repo_id":"aston","name":"Aston University","base_url":"https://publications.aston.ac.uk/cgi/oai2"},"display":{"title":"Spectroscopic Studies of Some Semiquinone Radical Ions","abstract":"Previous ESR and UV spectroscopic studies of semiquinone cations are reviewed. Cations of 4,4'-bipheno-semiquinones prepared by chemical oxidation of the corresponding diols and reduction of the quinones in sulphuric acid, were studied using ESR and UV spectroscopy. Oxidation of biphenyl-4,4'-diol in sulphuric acid leads to either the 4,4'-biphenosemiquinone cation or it's 3,3'-disulphonated derivative, whereas, oxidation in aluminium chloride-nitromethane yields only the parent cation. Reduction of 4,4'-biphenoquinone in dideutero-sulphuric acid initially gives the 4,4'-biphenos emiquinone cation which subsequently undergoes a stepwise exchange of the protons in the 3,3',5 and 5' positions for deuterons. A variable temperature study of this process is reported and discussed. Similar patterns of behaviour are observed in the 1,4-dihydroxybenzene-1,4-benzogquinone system, The 3,3',5,5'—te tra-t—bu ty 1-4, 4'-biphenosemiquinone cation under certain conditions undergoes dealkylation to give secondary radicals. Anions of some alkylated 4,4'-biphenosemiquinones were prepared by the air oxidation of the diols in a variety of solvent mixtures and studied by ESR. The solvent dependance of the hyperfine coupling constants for the 3,3',5,5'-tetramethyl- derivative are reported and discussed in terms of an equilibrium between semi-quinone anions and hydrogen-bonded complexes of such anions with the hydroxylic solvent. The theory of Gendell, Freed and Fraenkel is shown to be quantitatively in agreement with the results. A correlation between the electron-donating power of the solvent and the equilibrium constant for the dissocation of the hydrogen-bonded complexes is also discussed. Molecular orbital calculations were performed for the 4,4'-biphenosemiquinone system and it's 3,3',5,5'- tetramethyl-derivative. Changes in the hyperfine coupling constants between the anion and the cation of 4,4'-biphenosemiquinone are consistent with these qualitative predictions. Several electron donor compounds were treated with 3,3',5,5'-tetrachloro- and 3,3',5,5'-tetrabromo—4,4'— biphenoquinones. Paramagnetic products were only detected in the case of phenothiazine.","abstract_html":"Previous ESR and UV spectroscopic studies of semiquinone cations are reviewed. Cations of 4,4'-bipheno-semiquinones prepared by chemical oxidation of the corresponding diols and reduction of the quinones in sulphuric acid, were studied using ESR and UV spectroscopy. Oxidation of biphenyl-4,4'-diol in sulphuric acid leads to either the 4,4'-biphenosemiquinone cation or it's 3,3'-disulphonated derivative, whereas, oxidation in aluminium chloride-nitromethane yields only the parent cation. Reduction of 4,4'-biphenoquinone in dideutero-sulphuric acid initially gives the 4,4'-biphenos emiquinone cation which subsequently undergoes a stepwise exchange of the protons in the 3,3',5 and 5' positions for deuterons. A variable temperature study of this process is reported and discussed. Similar patterns of behaviour are observed in the 1,4-dihydroxybenzene-1,4-benzogquinone system, The 3,3',5,5'—te tra-t—bu ty 1-4, 4'-biphenosemiquinone cation under certain conditions undergoes dealkylation to give secondary radicals. Anions of some alkylated 4,4'-biphenosemiquinones were prepared by the air oxidation of the diols in a variety of solvent mixtures and studied by ESR. The solvent dependance of the hyperfine coupling constants for the 3,3',5,5'-tetramethyl- derivative are reported and discussed in terms of an equilibrium between semi-quinone anions and hydrogen-bonded complexes of such anions with the hydroxylic solvent. The theory of Gendell, Freed and Fraenkel is shown to be quantitatively in agreement with the results. A correlation between the electron-donating power of the solvent and the equilibrium constant for the dissocation of the hydrogen-bonded complexes is also discussed. Molecular orbital calculations were performed for the 4,4'-biphenosemiquinone system and it's 3,3',5,5'- tetramethyl-derivative. Changes in the hyperfine coupling constants between the anion and the cation of 4,4'-biphenosemiquinone are consistent with these qualitative predictions. Several electron donor compounds were treated with 3,3',5,5'-tetrachloro- and 3,3',5,5'-tetrabromo—4,4'— biphenoquinones. Paramagnetic products were only detected in the case of phenothiazine.","abstract_has_math":false,"creators":["Wheway, Ashley G."],"institution":"Aston University","degree_name":"Ph.D.","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1974,"date_issued":"1974-03","date_published":"1974-03","updated_at":"2026-07-24T01:01:33Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Wheway, Ashley G."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1974-03"]},{"key":"dc:date.issued","label":"Date","values":["1974-03"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Chemical Engineering & Applied Chemistry"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["Aston University"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://publications.aston.ac.uk/id/eprint/11626/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Ph.D."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://publications.aston.ac.uk/id/eprint/11626/1/176137_AG_Wheway_1974_reduced.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Previous ESR and UV spectroscopic studies of semiquinone cations are reviewed. Cations of 4,4'-bipheno-semiquinones prepared by chemical oxidation of the corresponding diols and reduction of the quinones in sulphuric acid, were studied using ESR and UV spectroscopy. Oxidation of biphenyl-4,4'-diol in sulphuric acid leads to either the 4,4'-biphenosemiquinone cation or it's 3,3'-disulphonated derivative, whereas, oxidation in aluminium chloride-nitromethane yields only the parent cation. Reduction of 4,4'-biphenoquinone in dideutero-sulphuric acid initially gives the 4,4'-biphenos emiquinone cation which subsequently undergoes a stepwise exchange of the protons in the 3,3',5 and 5' positions for deuterons. A variable temperature study of this process is reported and discussed. Similar patterns of behaviour are observed in the 1,4-dihydroxybenzene-1,4-benzogquinone system, The 3,3',5,5'—te tra-t—bu ty 1-4, 4'-biphenosemiquinone cation under certain conditions undergoes dealkylation to give secondary radicals. Anions of some alkylated 4,4'-biphenosemiquinones were prepared by the air oxidation of the diols in a variety of solvent mixtures and studied by ESR. The solvent dependance of the hyperfine coupling constants for the 3,3',5,5'-tetramethyl- derivative are reported and discussed in terms of an equilibrium between semi-quinone anions and hydrogen-bonded complexes of such anions with the hydroxylic solvent. The theory of Gendell, Freed and Fraenkel is shown to be quantitatively in agreement with the results. A correlation between the electron-donating power of the solvent and the equilibrium constant for the dissocation of the hydrogen-bonded complexes is also discussed. Molecular orbital calculations were performed for the 4,4'-biphenosemiquinone system and it's 3,3',5,5'- tetramethyl-derivative. Changes in the hyperfine coupling constants between the anion and the cation of 4,4'-biphenosemiquinone are consistent with these qualitative predictions. Several electron donor compounds were treated with 3,3',5,5'-tetrachloro- and 3,3',5,5'-tetrabromo—4,4'— biphenoquinones. Paramagnetic products were only detected in the case of phenothiazine."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Spectroscopic Studies of Some Semiquinone Radical Ions"]}]}],"canonical_facts":{"dc:creator":["Wheway, Ashley G."],"dc:date":["1974-03"],"dc:date.issued":["1974-03"],"dc:description.abstract":["Previous ESR and UV spectroscopic studies of semiquinone cations are reviewed. Cations of 4,4'-bipheno-semiquinones prepared by chemical oxidation of the corresponding diols and reduction of the quinones in sulphuric acid, were studied using ESR and UV spectroscopy. Oxidation of biphenyl-4,4'-diol in sulphuric acid leads to either the 4,4'-biphenosemiquinone cation or it's 3,3'-disulphonated derivative, whereas, oxidation in aluminium chloride-nitromethane yields only the parent cation. Reduction of 4,4'-biphenoquinone in dideutero-sulphuric acid initially gives the 4,4'-biphenos emiquinone cation which subsequently undergoes a stepwise exchange of the protons in the 3,3',5 and 5' positions for deuterons. A variable temperature study of this process is reported and discussed. Similar patterns of behaviour are observed in the 1,4-dihydroxybenzene-1,4-benzogquinone system, The 3,3',5,5'—te tra-t—bu ty 1-4, 4'-biphenosemiquinone cation under certain conditions undergoes dealkylation to give secondary radicals. Anions of some alkylated 4,4'-biphenosemiquinones were prepared by the air oxidation of the diols in a variety of solvent mixtures and studied by ESR. The solvent dependance of the hyperfine coupling constants for the 3,3',5,5'-tetramethyl- derivative are reported and discussed in terms of an equilibrium between semi-quinone anions and hydrogen-bonded complexes of such anions with the hydroxylic solvent. The theory of Gendell, Freed and Fraenkel is shown to be quantitatively in agreement with the results. A correlation between the electron-donating power of the solvent and the equilibrium constant for the dissocation of the hydrogen-bonded complexes is also discussed. Molecular orbital calculations were performed for the 4,4'-biphenosemiquinone system and it's 3,3',5,5'- tetramethyl-derivative. Changes in the hyperfine coupling constants between the anion and the cation of 4,4'-biphenosemiquinone are consistent with these qualitative predictions. Several electron donor compounds were treated with 3,3',5,5'-tetrachloro- and 3,3',5,5'-tetrabromo—4,4'— biphenoquinones. Paramagnetic products were only detected in the case of phenothiazine."],"dc:format":["text"],"dc:identifier.uri":["https://publications.aston.ac.uk/id/eprint/11626/1/176137_AG_Wheway_1974_reduced.pdf"],"dc:publisher.department":["Chemical Engineering & Applied Chemistry"],"dc:publisher.institution":["Aston University"],"dc:relation.isreferencedby":["https://publications.aston.ac.uk/id/eprint/11626/"],"dc:title":["Spectroscopic Studies of Some Semiquinone Radical Ions"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["Ph.D."]},"updated_at":"2026-07-24T01:01:33Z"}