Editing Butylated hydroxytoluene (section)

== Reactions ==
The species behaves as a synthetic [[structural analog|analog]] of [[vitamin E]], primarily acting as a terminating agent that suppresses [[autoxidation]], a process whereby unsaturated (usually) organic compounds are attacked by atmospheric oxygen.  BHT stops this [[autocatalytic]] reaction by converting peroxy radicals to hydroperoxides.  It effects this function by donating a hydrogen atom:
:RO<sub>2</sub>•  +  ArOH  →  ROOH  +  ArO•
:RO<sub>2</sub>•  +  ArO•  →  nonradical products
where R is [[alkyl]] or [[aryl]], and where ArOH is BHT or related phenolic antioxidants.  Each BHT consumes two peroxy radicals.<ref>{{cite journal | author = Burton G. W., Ingold K. U. | year = 1981 | title = Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro | journal = Journal of the American Chemical Society | volume = 103 | issue = 21| pages = 6472–6477 | doi = 10.1021/ja00411a035 | bibcode = 1981JAChS.103.6472B }}</ref><ref>{{Cite journal |last1=Fujisawa |first1=Seiichiro |last2=Kadoma |first2=Yoshinori |last3=Yokoe |first3=Ichiro |date=July 2004 |title=Radical-scavenging activity of butylated hydroxytoluene (BHT) and its metabolites |url=https://linkinghub.elsevier.com/retrieve/pii/S0009308404000349 |journal=Chemistry and Physics of Lipids |language=en |volume=130 |issue=2 |pages=189–195 |doi=10.1016/j.chemphyslip.2004.03.005|pmid=15172835 }}</ref> The electron-donating alkyl groups on the ''ortho'' and ''para'' positions of BHT increase the electron density of the phenolic hydroxyl moiety through the inductive effect and the hyperconjugation effect,<ref name=":1">{{Cite book |url=https://pubs.acs.org/doi/abs/10.1021/bk-1992-0507.ch015 |title=Phenolic Compounds in Food and Their Effects on Health II: Antioxidants and Cancer Prevention |chapter=Thermal Degradation of Phenolic Antioxidants |date=1992-10-01 |publisher=American Chemical Society |isbn=978-0-8412-2476-6 |editor-last=Huang |editor-first=Mou-Tuan |series=ACS Symposium Series |volume=507 |pages=200–218 |location=Washington, DC |language=en |doi=10.1021/bk-1992-0507.ch015 |editor-last2=Ho |editor-first2=Chi-Tang |editor-last3=Lee |editor-first3=Chang Y.}}</ref> reduce the bond dissociation energy of the phenolic hydroxyl group, and enhance its reactivity to lipid free radicals. Meanwhile, the phenoxy radical generated by BHT is stabilized due to the delocalization of unpaired electrons around the aromatic ring<ref name=":1" /><ref>{{Cite journal |last1=Shahidi |first1=Fereidoon |last2=Janitha |first2=P. K. |last3=Wanasundara |first3=P. D. |date=1992 |title=Phenolic antioxidants |url=https://www.tandfonline.com/doi/abs/10.1080/10408399209527581 |journal=Critical Reviews in Food Science and Nutrition |language=en |volume=32 |issue=1 |pages=67–103 |doi=10.1080/10408399209527581 |pmid=1290586 |issn=1040-8398}}</ref> and the steric hindrance effect of ortho ''tert''-butyl groups.<ref>{{Cite journal |last1=Breese |first1=K.D. |last2=Lamèthe |first2=J.-F. |last3=DeArmitt |first3=C. |date=2000 |title=Improving synthetic hindered phenol antioxidants: learning from vitamin E |url=https://linkinghub.elsevier.com/retrieve/pii/S014139100000094X |journal=Polymer Degradation and Stability |language=en |volume=70 |issue=1 |pages=89–96 |doi=10.1016/S0141-3910(00)00094-X}}</ref><ref>{{Cite journal |last1=Ariffin |first1=Azhar |last2=Rahman |first2=Noorsaadah Abdul |last3=Yehye |first3=Wageeh A. |last4=Alhadi |first4=Abeer A. |last5=Kadir |first5=Farkaad A. |date=2014 |title=PASS-assisted design, synthesis and antioxidant evaluation of new butylated hydroxytoluene derivatives |url=https://linkinghub.elsevier.com/retrieve/pii/S0223523414009271 |journal=European Journal of Medicinal Chemistry |language=en |volume=87 |pages=564–577 |doi=10.1016/j.ejmech.2014.10.001|pmid=25299680 }}</ref> Isobutene is one of the possible degradation products formed by BHT oxidation with computational studies suggesting that there are two possible mechanism that can lead to isobutene formation with the OH addition pathways at the C2 site of BHT more likely to result in isobutene formation than pathways of H abstracts from the ''t''-butyl group.<ref>{{Cite journal |last1=Zhou |first1=Junwei |last2=Chen |first2=Hongrui |last3=Chen |first3=Jianfa |last4=Wan |first4=Daihong |last5=Zhang |first5=Huikun |last6=Wang |first6=Rong |last7=Xie |first7=Daiqian |last8=Mao |first8=Chengli |date=2022-05-26 |title=Mechanisms and Kinetics Studies of Butylated Hydroxytoluene Degradation to Isobutene |url=https://pubs.acs.org/doi/10.1021/acs.jpca.2c01961 |journal=The Journal of Physical Chemistry A |language=en |volume=126 |issue=20 |pages=3210–3218 |doi=10.1021/acs.jpca.2c01961 |pmid=35549278 |bibcode=2022JPCA..126.3210Z |issn=1089-5639}}</ref>