Answer 1:
Butylated hydroxytoluene (IUPAC
name2,6-bis(1,1-dimethylethyl)-4-methylphenol) is
used as an antioxidantand preservative in food. It
is similar in structure to vitamin E,which is a
naturally occurring antioxidant (also called a
reducingagent) in cells that protects lipids from
oxidation. Butylated hydroxytoluene (BHT)
protects against radicals and the propagation of
destructive reactions caused by radicals. A
radical is a chemical species with an unpaired
electron. Since species withunpaired electrons are
unstable, they also tend to be very reactive.This
reactivity can be dangerous to biological systems
as well as food. When a radical attacks a
lipid (or other molecules), it transfers the lone
electron. The lipid then becomes a radical that
can react with itself or other molecules in a
destructive chain reaction. BHT is able to inhibit
the propagation of the radical
reaction. When the hydrogen is removed from
the phenol in the BHT, the remaining phenoxide ion
becomes a good electron donor. The phenoxide can
donate an electron to a radical species, which
ends the propagation of radical reactions. The BHT
is then itself a radical, but it is much less
reactive than most radical species because the
lone electron is stabilized by the conjugation in
the phenyl ring and the sterichindrance from the
two butyl groups further impedes the possibility
of a reaction. I have attached structures of
BHT showing how the name corresponds to different
parts of the structure for both the common name
and theIUPAC name. BHT1
BHT2
References:Structures
from
Butylated-H
Vollhardt,
K. Peter C., and Neil Eric Schore. "Chapter 22:
Chemistryof Benzene Substituents." Organic
Chemistry: Structure and Function.New York: W.H.
Freeman and, 2003. 134-37. Print.
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