Please use this identifier to cite or link to this item:
|Title:||Investigation of the influence of hydroxy groups on the radical scavenging ability of polyphenols|
|Authors:||Thavasi, V. |
|Source:||Thavasi, V., Leong, L.P., Bettens, R.P.A. (2006-04-13). Investigation of the influence of hydroxy groups on the radical scavenging ability of polyphenols. Journal of Physical Chemistry A 110 (14) : 4918-4923. ScholarBank@NUS Repository. https://doi.org/10.1021/jp057315r|
|Abstract:||Recently, O-H bond dissociation enthalpies (BDEs) have been successfully used to express the free radical scavenging ability of polyphenolic antioxidants. In this work, the BDEs of phenol, catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, 1,2,4-benzenetriol, and 5-hydroxypyrogallol have been calculated at B3LYP/6-311G++(3df, 3pd) and used to elucidate the effect of OH groups. Increasing the number of OH groups in the adjacent (vicinal) position decreases the BDE of phenols. Increasing the number of O - H groups in the alternative position C(1,3) as in resorcinol and C(1,3,5) as in phloroglucinol does not show any notable change in the BDEs when compared to that of OH in C(1) as in phenol. 5-Hydroxypyrogallol has the smallest BDE (250.3 kJ mol-1) followed by pyrogallol (289.4 kJ mol-1), then 1,2,4-benzenetriol (294.8 kJ mol-1), and then catechol (312.8 kJ mol-1). Overall, our results indicated that the presence of ortho and para hydroxy groups reduces the BDEs. An intramolecular hydrogen bond (IHB) develops due to the ortho arrangement of OH's and plays a dominant role in decreasing the BDEs. This key study on phenols showed that the reactive order of OH position in the benzene ring is the following: 5-hydroxypyrogallol > pyrogallol > 1,2,4-benzenetriol > catechol > hydroquinone ≫ phenol ∼ resorcinol ∼ phloroglucinol. © 2006 American Chemical Society.|
|Source Title:||Journal of Physical Chemistry A|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Feb 15, 2018
WEB OF SCIENCETM
checked on Jan 30, 2018
checked on Feb 19, 2018
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.