Name: Sn2反應 (Sn2 Reactions)
Uploaded: 2021-01-14T05:31:49.000Z
Duration: 11 min 31 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

And you're going to see a lot of these in organic chemistry.

But it really just stands for-- the S stands for

And then the 2, and this is probably maybe the least

obvious part of Sn2, the 2 comes from the fact that the

And it'll actually be probably more clear when we compare it

And then you have another hydrogen in the back.

And then you have a hydrogen that comes up just like that.

And here, the three dimensions won't matter that much.

But in the future, we'll think about chiral carbons and what

might happen to them as they undergo Sn2 reactions.

And let's say we also have some hydroxide in

You could imagine that the way that you get a hydroxide is if

you start off with water, that looks like this.

And maybe there's another water someplace else that

And maybe in one step, this water right here takes this

Remember, there's a partially positive charge on the

hydrogen, partially negative charge on the oxygen.

So maybe he gives one of his electrons to the hydrogen,

which will end up with a positive charge.

And then this electron takes back that extra electron from

And so now, he's going to have seven valence electrons.

That was at this end of the bond of the one that he's

And then that's two, three, four, five, six, and then this

So he's going to have one, two, three, four, five, six,

And he's going to have a negative charge.

When he takes an extra electron, it's going to have a

And you could imagine this is in a solution with water, that

So let me put a negative charge right here.

And in this reaction, just so we know what's what, this

hydroxide molecule, or this hydroxide anion, is our

And the best way to think about a nucleophile is it

It likes them because nucleuses are positive.

In this case, it has a negative charge, so it is

Nucleuses of atoms are positive, so it is attracted

Phile, I'm not a Greek scholar, but it means to be

And if you want to compare it to acids or bases, you'd

classify this actually as a Lewis base, something that

But we're not going to go into that right now.

It is attracted to nucleuses, to positive things.

Now, what's going to happen is that this is going to give an

This carbon's going to say, oh, I got an electron.

Let me give away an electron to somebody who probably wants

And in this case, it's going to be the bromine because

we've seen multiple times that the bromine is very

It already is starting to hog the electrons, and it would

Or it's actually going to happen very quickly the way I

drew it, because it's really a one-step reaction.

So you're going to have one of these electrons right here

字幕列表影片播放

Sn2反應 (Sn2 Reactions)

state

negative

positive

determine