1. I. Introduction into Redox Reactions
Rx of Sugars
I. Introduction into Redox Reactions

2. Redox Reactions All reactions exchange electrons
The substrate that gains e- is reduced
The substrate that loses e- is oxidized
Indicated by brackets

3. Another helpful acronym
"OIL RIG" O
Oxidation I Is L
Loss of electrons R
Reduction G
Gain of electrons

4. Oxidation Numbers
Oxidation numbers, ON, are a measure how oxidized (or reduced) an element is
The more negative the ON, the more reduced an element is
Comparing ON before and after a Rx shows if an element was oxidized or reduced
Ex: → symbolizes Oxidation
O → symbolizes Reduction

5. Example

6. Assigning Oxidation numbers
1. Ions/Ionic compds: ionic charge = ON O2- : -2 CaO : Ca2+ O2- so Ca: +2 O: -2 Pb(SO4)2 Pb: ____ SO4: ____ 2. Diatomic molecular compounds: neutral H2, O2 : 0 3. Monoatomic Metals: neutral Mg: 0

7. 4. ON in Molecular compounds
Finding ON from elements in molecules Add up ON from ligands: a) Oxygen: (High EN 3.5) is always -2 b) Hydrogen: ( low EN is 2.1) is always +1 Carbon: will assume ON so overall neutral CH4: H: +4 H3COH H: +4 C: -4 O: C: -2 0

8. Oxidation number of elements in molecules

9. Problem: e- are invisible! Use transfer of O and H
Reduction: gain of H or loss of O
Oxidation: gain of O or loss of H
Example:
Carbon: oxidized lost H
Oxygen: reduced gained H

10. Example

11. Reducing and Oxidizing Agents
XH + Y → X + YH Reducing Agent is a substance (X) that reduces another substance and becomes oxidized in the process Oxidizing Agent is a substance that…..opposite

12. Oxidation of Monosaccharides Testing for reducting sugars: Benedict’s Test
Glucose is __________ and is a(n)________agent
Copper is ___________ and is a(n) ________agent
Cu2+ copper is (___) →Cu2O copper (___)
Cu+SO3
+ Cu2O red
+Cu2+ blue
+O2

13. Oxidation of Disaccharides
All disaccharides that have an accessible α/β in the 2nd monosacch. can open and oxidize
Which of our 3 disaccharides can oxidize?

14. Oxidation of Polysaccharides
do not oxidize
are not reducing carbs