Don’t let your organic chemistry textbook intimidate you!
And to add…don’t let your organic chemistry class intimidate you. There is no need to stress about this class. Just find a way to simplify.
Here is one way to help you do just that!
If you are familiar with my blog, then you know I like mentioning nucleophiles and electrophiles.
They are so important in OChem…
…Because they are in every reaction!
Yes…every single one!
If you remember, Mechanisms Made Easy Part 1 went over how to identify the characteristics of nucleophiles. Check it out if you need a quick refresher.
Well, rather than me just babbling on about it, let’s get to some examples!
OK – We’ll start by picking a chapter – Alkynes in Organic Chemistry.
And let’s jump ahead to the following reaction:
This first reaction has a terminal alkyne and NaNH2 (sodium amide). This is simply the interaction between a nucleophile and an electrophile.
Yes, I hear you. And you heard me correctly.
Nucleophile and Electrophile.
You may be thinking that you learned this as an acid/base reaction. And you are right…you did.
However, how do you think the hydrogen is being removed? By a nucleophilic attack on the “backside” of the proton. And the rest of the structure is the “leaving group.”
Ahhh – I just saw many “light bulbs” go off. You see…I told you…they are everywhere.
So, now it’s simple, right?
All you need to do is look for your nucleophile and electrophile in every reaction.
When you find this pair, you are golden. And it even works if you are stuck in the middle of working on a mechanism.
Here, I’ll show you…
Since your exams will skip all over the place, we’ll do the same. Let’s move away from alkynes and now look at the following reaction:
Let’s start by labeling things with different colors. This will make it easier to keep track.
Now, let’s look at a particular point in the mechanism.
And let’s say we are here in the mechanism and trying to move forward.
If we look at the overall reaction and compare, we can see that we want the oxygens and the carbons from the ethylene glycol (HOCH2CH2OH) to be attached. But here, we have an “extra” OH.
So, what should we do?
Find our nucleophile and electrophile…of course!
OK – we have an “extra” hydrogen on our ethylene glycol and an “extra” OH. Under acidic conditions, if you want to get rid of something (have it leave), you need to protonate it.
So, we want to keep our protonated oxygen and lose the OH group.
Well….we can simply use our OH as the nucleophile (the lone pairs) and our protonated OH as our electrophile.
I’ve “greyed out” our carbon chain to make it easier to see. And see how this is just an intramolecular substitution reaction?
Now, you are ready to crush your OChem exams!