P1254325742BuYin

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2. Oxidation and reduction reactions involve
loss or gain of electrons.
Oxidised carbon atoms have more bonds to
oxygen (which is electron-withdrawing). Reduced
carbon atoms have fewer bonds to oxygen and more
bonds to hydrogen (which is not
electron-withdrawing).
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More oxidised More bonds to O
Carboxylic acid
Aldehyde (or ketone)
Imine
Amine
Alcohol
Less oxidised Fewer bonds to O
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During conversion of an aldehyde to an acyl
phosphate, the carbon atom is oxidised.
The reaction also yields a proton (H) and a
hydride ion (H- , a proton plus 2 electrons).
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During conversion of a primary alcohol to an
aldehyde, the carbon atom is oxidised.
The reaction also yields a proton (H) and a
hydride ion (H- , a proton plus 2 electrons).
Oxidation of a secondary alcohol gives a ketone.
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Many oxidations involve C-H bond cleavage with
transfer of the two bonding electrons to an
acceptor like NAD
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NAD
NADP has a phosphate at this position.
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The nicotinamide ring functions in hydride ion
transfer.
NADH has an aliphatic ring. Hydride ion transfer
is energetically favourable.
Oxidised form NAD has a stable aromatic ring
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(No Transcript)
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Reduction of NAD to NADH requires energy.
The energy can come from oxidation of a substrate.
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Active site of a lactate dehydrogenase.
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3. Eliminations, isomerisations and rearrangements
Eliminations generate double bonds e. g.
dehydration of an alcohol.
Isomerisations change the structure without
changing the molecular formula e. g. aldose -
ketose isomerisation, keto-enol tautomerism.
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Aldose-ketose interconversion
O
H
C
C
H
O
H
Aldose