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Hey guys, whats more acidic, pyruvic acid or lactic acid. im thinking lactic acid because both OH and the carbonyl contribute to acidity. I dont get why pyruvate is more acidic according to gay EK
Hey guys, whats more acidic, pyruvic acid or lactic acid. im thinking lactic acid because both OH and the carbonyl contribute to acidity. I dont get why pyruvate is more acidic according to gay EK
Wow...That's a great trick that I never bothered to learn. I guess I could kinda just tell when looking at two molecules based on those factors...Well lets take a proton (hydrogen) off each and compare stability shall we? There are 4 factors to look at in this easy approach: ARIO, which stands for Atom, Resonance, Induction, Orbital. That is the order from left to right from most important to least important.
First, lets see what Atom the charge is on. We see that the negative charge in both is on an Oxygen, so that didn't do us any good.
Second, we look at Resonance. Pyruvic acid and Lactic acid both have resonance, BUT pyruvic acid has even more resonance because of the extra carbonyl group that contributes to it. That's it, we're done, pyruvic acid wins.
Well lets take a proton (hydrogen) off each and compare stability shall we? There are 4 factors to look at in this easy approach: ARIO, which stands for Atom, Resonance, Induction, Orbital. That is the order from left to right from most important to least important.
First, lets see what Atom the charge is on. We see that the negative charge in both is on an Oxygen, so that didn't do us any good.
Second, we look at Resonance. Pyruvic acid and Lactic acid both have resonance, BUT pyruvic acid has even more resonance because of the extra carbonyl group that contributes to it. That's it, we're done, pyruvic acid wins.
I understand the resonance and induction parts of your system to determine which one is more acidic but could somebody explain with an example how the type of atom or orbital could effect this. Thank You.Well lets take a proton (hydrogen) off each and compare stability shall we? There are 4 factors to look at in this easy approach: ARIO, which stands for Atom, Resonance, Induction, Orbital. That is the order from left to right from most important to least important.
First, lets see what Atom the charge is on. We see that the negative charge in both is on an Oxygen, so that didn't do us any good.
Second, we look at Resonance. Pyruvic acid and Lactic acid both have resonance, BUT pyruvic acid has even more resonance because of the extra carbonyl group that contributes to it. That's it, we're done, pyruvic acid wins.
the only problem with this is that the presence of the carbonyl in pyruvate does NOT increase resonance. The carbonyl is not in a position where it can participate in resonance. Try drawing a valid resonance structure that involves the carbonyl and you'll see that it's not involved. If you go to the next thing, which is induction, that's where the actual effect is. You have a large delta + on the carbonyl which is adjacent to the carboxyl group. This decreases electron density in the carboxyl group which makes it better able to stabilize the negative charge that develops as the proton is lost. but it's not a resonance effect, it's an inductive effect.
These are just guidelines because there are exceptions ofcourse and things like the type of solvent can affect it (protic vs aprotic), but generally speaking this works most the time:I understand the resonance and induction parts of your system to determine which one is more acidic but could somebody explain with an example how the type of atom or orbital could effect this. Thank You.
Why does it not have a valid resonance structure? I drawed it out and it seems to work fine, the only problem I see is that it doesn't fill the octet on one of the oxygens which I admit is ugly but it technically is still an acceptable resonance contributor. Correct me if I'm wrong here.
What? That defies how acidity/basicity works for substituted alkanes. They are significant. It's just...relative.this brings up an important point: just because you can draw a resonance structure for something doesn't mean that it is a significant resonance contributor.
What? That defies how acidity/basicity works for substituted alkanes. They are significant. It's just...relative.