TBR Gen Chem Ch. 10 - Ox/Red Agents

[fizzlin]

Concept I'm confused about--oxidation agents and reduction agents!! I've always just memorized it, but in the TBR book, it starts applying agents to organic chemistry/biochemistry, and then I start getting lost.


TBR GCHEM Ch. 10 Electrochemistry, pg. 255-256

Oxidation: Loss of e-, ox. state increases, > O-bonds & < H-bonds, catabolic
Reduction: Gain of e-, ox. state decreases, < O-bonds & > H-bonds, anabolic
Reducing Agent: gets oxidized, causes reduction
Oxidizing Agent: gets reduced, causes oxidation

In the biological oxidation-reduction section, it says that a 6-C carbonyl compound gets oxidized so it needs an oxidizing agent (compound poor in H) in order to be broken down into 2 3-carbon carbonyl compounds.

I can't wrap my mind around this. This may be because I don't understand the definition of reducing agent itself, it's the compound that gets oxidized but how does it cause reduction?! If oxidation is occurring, that means that it's the reducing agent. So, if the compound is getting oxidized, then isn't it the reducing agent? Though I guess the 6-carbon compound is getting oxidized so that would be the reducing agent, while the NAD+ is the oxidizing agent, butajfhdjashfkajdshfa. I feel as if I'm going in circles.

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[QrtrLifeCrisis]

Concept I'm confused about--oxidation agents and reduction agents!! I've always just memorized it, but in the TBR book, it starts applying agents to organic chemistry/biochemistry, and then I start getting lost.


TBR GCHEM Ch. 10 Electrochemistry, pg. 255-256

Oxidation: Loss of e-, ox. state increases, > O-bonds & < H-bonds, catabolic
Reduction: Gain of e-, ox. state decreases, < O-bonds & > H-bonds, anabolic
Reducing Agent: gets oxidized, causes reduction
Oxidizing Agent: gets reduced, causes oxidation

In the biological oxidation-reduction section, it says that a 6-C carbonyl compound gets oxidized so it needs an oxidizing agent (compound poor in H) in order to be broken down into 2 3-carbon carbonyl compounds.

I can't wrap my mind around this. This may be because I don't understand the definition of reducing agent itself, it's the compound that gets oxidized but how does it cause reduction?! If oxidation is occurring, that means that it's the reducing agent. So, if the compound is getting oxidized, then isn't it the reducing agent? Though I guess the 6-carbon compound is getting oxidized so that would be the reducing agent, while the NAD+ is the oxidizing agent, butajfhdjashfkajdshfa. I feel as if I'm going in circles.

Okay. Calm down. It's a matter of semantics.

The way I like to think of it is, the reducing agent is the "Agent that causes Reduction and Becomes Oxidized" and the oxidizing agent is the "Agent that causes Oxidation and becomes Reduced."

Alternatively, you can work in opposites:

Reducing Agent = Becomes Oxidized
Oxidizing Agent = Becomes Reduced

You know that oxidation-reductions are coupled right? You can't have one without the other. In order for something to be oxidized, something else has to be reduced.

NAD+ is the oxidizing agent. It causes something ELSE to become oxidized, but it itself is reduced to NADH.

 

[AureatEagle]

Concept I'm confused about--oxidation agents and reduction agents!! I've always just memorized it, but in the TBR book, it starts applying agents to organic chemistry/biochemistry, and then I start getting lost.


TBR GCHEM Ch. 10 Electrochemistry, pg. 255-256

Oxidation: Loss of e-, ox. state increases, > O-bonds & < H-bonds, catabolic
Reduction: Gain of e-, ox. state decreases, < O-bonds & > H-bonds, anabolic
Reducing Agent: gets oxidized, causes reduction
Oxidizing Agent: gets reduced, causes oxidation

In the biological oxidation-reduction section, it says that a 6-C carbonyl compound gets oxidized so it needs an oxidizing agent (compound poor in H) in order to be broken down into 2 3-carbon carbonyl compounds.

I can't wrap my mind around this. This may be because I don't understand the definition of reducing agent itself, it's the compound that gets oxidized but how does it cause reduction?! If oxidation is occurring, that means that it's the reducing agent. So, if the compound is getting oxidized, then isn't it the reducing agent? Though I guess the 6-carbon compound is getting oxidized so that would be the reducing agent, while the NAD+ is the oxidizing agent, butajfhdjashfkajdshfa. I feel as if I'm going in circles.

The terminology is confusing as hell because of the "agent" term. Think of the "agent" term as a verb-- as in, the molecule that is the oxidizing agent is DOING the oxidation, and the molecule that is the reducing agent is DOING the reducing. Lets break it down for your example:

6CC is oxidized by NAD+. In the process, electrons from 6CC are transferred to NAD+. Thus, 6CC is oxidized, and NAD+ is reduced.

In this scenario, we would call NAD+ the "oxidizing agent" because NAD+ was the species that took electrons away from 6CC. NAD+ oxidized 6CC, and is itself reduced in the process, since it is gaining electrons.

6CC would be called the "reducing agent" because upon losing its electrons, those very same electrons from 6CC are given away and used to reduce NAD+. Thus, 6CC reduces NAD+.

In summary: NAD+ oxidizes 6CC's (so we call NAD+ the oxidizing agent) and it is reduced in the process. And equivalently, 6CC reduces NAD+ with the electrons it lost (so we call 6CC the reducing agent), and is oxidized in the process.

 

[fizzlin]

The terminology is confusing as hell because of the "agent" term. Think of the "agent" term as a verb-- as in, the molecule that is the oxidizing agent is DOING the oxidation, and the molecule that is the reducing agent is DOING the reducing. Lets break it down for your example:

6CC is oxidized by NAD+. In the process, electrons from 6CC are transferred to NAD+. Thus, 6CC is oxidized, and NAD+ is reduced.

In this scenario, we would call NAD+ the "oxidizing agent" because NAD+ was the species that took electrons away from 6CC. NAD+ oxidized 6CC, and is itself reduced in the process, since it is gaining electrons.

6CC would be called the "reducing agent" because upon losing its electrons, those very same electrons from 6CC are given away and used to reduce NAD+. Thus, 6CC reduces NAD+.

In summary: NAD+ oxidizes 6CC's (so we call NAD+ the oxidizing agent) and it is reduced in the process. And equivalently, 6CC reduces NAD+ with the electrons it lost (so we call 6CC the reducing agent), and is oxidized in the process.

It all clicks!!

Super helpful, thanks Qrtr and Aureat! Aureat--the DOING concept really helps. I think I was semi-starting to get it, as I was asking the question, but with both of your explanations, I actually understand it. It's a whole lot of the same confusing terminology.



Almost done with Electrochemistry and then done with Gen. Chem. review!

 

[AureatEagle]

You're welcome, glad it makes sense 😉

Good luck with the rest of your review!