A study of the mechanism of action of aromatic thiols on carotenoid pigments

Aromatic thiols are used widely to bleach carotenoid plant pigments present in natural rubber latex in trace quantities, in the manufacture of white latex crepe rubber. If this is not done these pigments impart a yellow colour to the crepe, thereby lowering its grade. The bleaching reaction between...

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Bibliographic Details
Published in:Polymer degradation and stability 1987, Vol.19 (3), p.213-219
Main Authors: Tillekeratne, L.M.K., Tillekeratne, L.M.V., Vimalasiri, P.A.D.T.
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Natural polymers
Natural rubber
Physicochemistry of polymers
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Summary:Aromatic thiols are used widely to bleach carotenoid plant pigments present in natural rubber latex in trace quantities, in the manufacture of white latex crepe rubber. If this is not done these pigments impart a yellow colour to the crepe, thereby lowering its grade. The bleaching reaction between carotenoid pigments and aromatic thiols is known to occur in the presence of at least diffuse daylight. In this mechanistic study it was observed that the aromatic thiols have no action on unoxidised carotene. However, the peroxy radicals formed on the carotene molecule undergoing autoxidation under the influence of uv light initiate radical formation on the thiol, which is difficult to split by other means. These radicals then combine with the unsaturated chains of both carotene and cartenoids in the system, thereby disrupting the double bond conjugation and making the compounds colourless.
ISSN:0141-3910
1873-2321
DOI:10.1016/0141-3910(87)90056-5