Å·ÃÀAV

He played an important role in the BA Degree Course "Chemistry, Management, and Industry", and then "Chemistry, Resources, and the Environment"- for example, in setting up visits to power stations and sites of geological or geographical interest, including water sources.

Dr Thomas helped build up good working relationships with local companies, with subsequent opportunities for student scholarships, work experience and prizes - and was also very supportive of the pilot Exchange Scheme offering work experience with BP Chemicals (first in Hull, then Marseilles and Aachen).

He was closely involved with the development of the Department’s four-year Integrated Master’s courses (MChem), especially the version in which the extra year’s research study was spent at a university abroad (taught and assessed in the foreign language).

Its success owed much to Barry’s commitment and detailed knowledge (and love of travel). This involved careful liaison between the Department and the foreign universities, with regular checks on the progress and welfare of the students. For Barry that meant negotiation at partners in France (Caen, Grenoble, Marseille, Strasbourg), Germany (Aachen, Munster), Italy, (Milan), Spain (Seville) and Finland (Helsinki). The list is now longer, but his dedication and wisdom underpinned this substantial addition to the Department’s profile.

Barry’s wide experience of teaching and student support was also seen through his work for the University Teaching Committee, particularly in the areas of scrutiny of proposals for new courses, consideration of Examiners’ Reports, and visits to other departments to share good practice, as well as external Colleges seeking University validation.

Barry had many other important roles in the Department and University, including his substantial work in the department’s admissions team-for example helping mastermind the growth of a portfolio of Bachelors’ and Masters’ degrees (with choices involving Industrial, Environmental, and Biochemical variants, and year-out options), which increased the annual intake of chemistry students to nearly 200, without compromise in quality.

He was closely involved with enhancing opportunities for students (and schools) to visit the Department and University campus, including via Sixth-form (and Teachers’) Conferences.  He also worked for many years as an Editor of Chemistry Review, a magazine for sixth-formers run in the Department. And he helped over two hundred new University colleagues navigate the stresses of relocation, through the work of the Welcome Service, with advice about accommodation, school admissions, bank accounts, etc.

After formal retirement, he became Principal of Vanbrugh College, bringing to bear his wide experience of student support roles. And he continued to play an active part in promoting the biodiversity of the campus, especially with his love and knowledge of bird-life on the lake(s)-in his first year as a student he had persuaded Lord James (the first Vice-Chancellor) to provide £1000 to attract native wild birds to the lake in Heslington, and subsequently helped manage the evolution of the habitat during his long career at York.

Barry’s research was based on the investigation of electron-transfer reaction mechanisms, and the identification of short-lived intermediates in the oxidation of organic compounds, largely involving transition metals: and, often, collaboration with colleagues in the Department and in industry.

In his earlier work with Professor Norman he employed product-confirmation studies, with mass spectrometry and gas chromatography, in a detailed investigation of the reactions of lead tetra-acetate (LTA). For example, with a range of styrene derivatives with alkyl and triaryl-alkyl substituents. Aryl-substituted derivatives were found to react via carbonium-ion formation, and, for alkylated styrenes the reaction pathways are dominated by radical-chain and heterolytic pathways, with some carbonium-ion formation and evidence for acetoxonium ions (cf. the Prévost reaction).

For dialkoxybenzenes, one-electron and two-electron oxidations, and electrophilic plumbylation, could be distinguished. Oxidative rearrangement of styrene derivatives to aldehydes and ketones were demonstrated, following reaction in trifluoroacetic acid.

In subsequent studies, Barry and his co-workers explored a range of oxidation reactions with palladium(ll), including the conversion of styrene derivatives into indenes via oxidative cyclisation, probably via slow intramolecular electrophilic aromatic substitution within a π-alkene palladium(II) complex.  Replacement of acetic acid by trifluoroacetic acid led to a system showing ready oxidations of arenes to biaryls, with diarylmethanes formed from alkylated benzenes. Other studies involved styrenes and aromatic iodides, mainly to give biaryls.

Particularly notable was the study of the nitration of benzenoid compounds by palladium nitrate and by palladium acetate/sodium nitrite. The latter system yields nitrobenzene semi-catalytically in chloroacetic acid in an oxygen environment. And, the use of nitrogen dioxide in place of sodium nitrite resulted in a catalytic system.

The mechanism proposed involves π-complexation of the aromatic ring (benzene) with palladium(II), followed by attack of nitrite ion to give a stabilised complex, and loss of Pd(0) and a proton to give nitrobenzene - the oxidant regenerates palladium(II) to complete the catalytic cycle. Some of this work inspired the writing of a critical review, dedicated to Barry, by his colleague, Ian Fairlamb (Angew.Chemie Int. Ed.,2015, 54, 10415-10427); this review highlights, in a broader context, the redox and non-innocent roles of nitrate and nitrite ions, as well as NO and NO2, in palladium-mediated processes.

Other related studies involved the nitration of aromatic compounds with nitrogen dioxide in trifluoroacetic acid, almost certainly via the nitronium ion, and the use of cerium (IV) trifluoroacetate in TFA to bring about dimerization of benzenoid hydrocarbons to give biaryls and diarylmethanes via one-electron transfer to give radical-cations; and reaction of electron-rich species with thallium, mercury, and gold salts were contrasted.  Conversion of aromatic ketones into α-aryl alkanoic acids with thallium(III) nitrate (cf. the Willgerodt reaction) was shown to involve a phenacylthallium species (though the reaction can be more effectively carried out with iodine-silver nitrate).

Barry also carried out a systematic investigation into the oxidation of oct-1-ene with manganese(III) acetate in acetic acid and acetic anhydride, which largely involve the radical ·CH2COOH, the most important factor being the solvent composition.   And, with Andrew Parsons, he reported a new and mild practical method for Mn(III)-mediated radical reactions leading to C-C bonds using an ionic liquid([bmim][BF4]).

Cation-radicals were shown to be generated in the reactions of lead(IV), cobalt(III) and manganese(III) with aryl-substituted alkenes in acetic acid, giving hydroxy-acetates (with an inverse relationship between the product yield and the ionisation potential of the substrate). And, in a collaboration with the ESR group at York, a series of radical-cations were generated by reactions of aryl-substituted alkanoic acids with the hydroxyl radical (in acid solution) and the sulfate radical-anion; deprotonation (to give benzylic radicals) and fragmentation mechanisms were established.

With Athel Beckwith, Barry utilised product confirmatory studies, in a seminal paper to establish that in some β-acyloxyl radicals, 1,2-acyloxy transfer proceeds via a concerted reaction mechanism involving a five-membered cyclic transition state; and 1,2 aryl migrations were also studied.

He was also closely involved with an ESR (flow system) study of the reaction of the hydroxyl radical with a variety of sugars. Whilst it was found that attack is largely unselective (all six radicals from each glucose anomer were directly detected), subsequent acid-catalysed fragmentation is governed by stereoelectronic effects (for example, an axial β-hydroxyl group is most readily lost). Potential routes for carbohydrate degradation, via glycosidic cleavage of initial radicals, were explored. And the enhanced reactivity of C5-H in the furanose ring of sucrose, again due to stereoelectronic effects, was suggested to have particular relevance to the mechanism of radiation damage in DNA

Barry had a remarkable range of interests and general knowledge - including trains, ships, planes, military history, Yorkshire, sport (rugby, squash), and natural history (especially ornithology). At a specific level, he was in particularly in demand as a member in the annual Å·ÃÀAV "Top of the Form" Quiz night at the York Brewery, helping secure victory on many occasions.

More generally, and over many years, he contributed substantially to numerous activities in the community - including that via his membership of the British Ornithological Trust (and as Chair of the York Ornithological Group), his role as Governor and Chair of a local school (for nearly thirty years), his on-going work with York Council and North Yorkshire County Council on School Appeals Panels, and a Child Safeguarding Panel, as well as several  focus groups for local users of buses and surgeries

Barry passed away at home on 25 April 2023, aged 80, leaving his children, Beth and Edward, and his six much-loved grandchildren, as well as his brothers Nigel and Neil.

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