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Probing the antioxidative properties of combinations of an organotellurium compound, BHT and thiol in oil
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för biokemi och organisk kemi, Organisk kemi I.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för biokemi och organisk kemi, Organisk kemi I.
2006 (engelsk)Inngår i: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 18, nr 2, s. 87-94Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Differential scanning calorimetry experiments with an unsaturated polyolester oil at 190˚C showed that an organotellurium compound in combination with a thiol or a sterically hindered phenol (BHT) could act in a synergistic fashion to protect the material form oxidation. Under more realistic conditions for an oil antioxidant (elevated temperature in the presence of oxygen, water and a copper coil; rotating pressure vessel oxidation test) the antioxidant protection offered by BHT itself at similar concentrations. In order for the novel antioxidant systems to become useful for protection of oils and fluids, more robust organotellurium compounds must be prepared.

sted, utgiver, år, opplag, sider
2006. Vol. 18, nr 2, s. 87-94
Emneord [en]
antioxidants, oil, organotellurium compound, thiol, BHT, oxidative induction time, rotating pressure vessel oxidation test
HSV kategori
Identifikatorer
URN: urn:nbn:se:uu:diva-80549DOI: 10.1002/ls.8OAI: oai:DiVA.org:uu-80549DiVA, id: diva2:108463
Tilgjengelig fra: 2006-05-17 Laget: 2006-05-17 Sist oppdatert: 2017-12-14bibliografisk kontrollert
Inngår i avhandling
1. Design, Synthesis and Evaluation of Catalytic Chalcogenide Antioxidants
Åpne denne publikasjonen i ny fane eller vindu >>Design, Synthesis and Evaluation of Catalytic Chalcogenide Antioxidants
2005 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis describes the design, synthesis and evaluation of novel chalcogenide antioxidants.

A computational model for the prediction of antioxidant properties of chalcogen-containing antioxidants has been developed. The model has been used to probe the relationship between geometry, chalcogen substitution and activity for a series of α-tocopherol analogues of varying ring size and chalcogen substitution.

A series of simple diaryltellurides and aryl-alkyl tellurides have been synthesised. The selenium analogue of α-tocopherol has been synthesised in eleven steps and 6.5% total yield, with formation of the selenacycle by homolytic substitution at selenium as the key step. Tentative steps have been taken towards the construction of the tellurotocopherol structure by microwave-assisted radical cyclisation methodologies.

A combination of EPR and kinetic studies has been used to assess the antioxidant characteristics of selenotocopherol. A two-phase lipid peroxidation model revealed that the selenotocopherol is not catalytically regenerable. The same model has been used to assess the cooperativity of mixtures of tellurides with α-tocopherol and an aqueous thiol. It was seen that combinations of α-tocopherol with tellurides incorporating phenols displayed synergistic properties, and the mechanistic implications of this are discussed.

DSC measurements have been used to assess the antioxidant activity of tellurides together with coantioxidants in melts of polypropylene. The tellurides display excellent activity together with thiol or a sterically hindered phenol antioxidant. In chemiluminescence studies performed at lower temperatures, the telluride mixtures still outperform commercial blends, but to a lesser extent. In a synthetic oil a telluride has demonstrated promising antioxidant properties together with a thiol or phenolic antioxidant. However, under more realistic test conditions the telluride acts instead as a prooxidant. Some tellurides have been evaluated as antioxidants in paper. Water-soluble tellurides appear to function better than lipophilic tellurides, but neither is comparable in activity to α-tocopherol.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2005. s. 75
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 123
Emneord
Organic chemistry, antioxidant, tellurium, selenium, computational design, homolytic substitution, radical cyclisation, microwave-assisted synthesis, antioxidant regeneration, Organisk kemi
HSV kategori
Identifikatorer
urn:nbn:se:uu:diva-6164 (URN)91-554-6410-6 (ISBN)
Disputas
2005-12-16, Room B42, BMC, Husargatan 3, Uppsala, 09:15
Opponent
Veileder
Tilgjengelig fra: 2005-11-25 Laget: 2005-11-25 Sist oppdatert: 2013-07-31bibliografisk kontrollert

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