Follow the flow of electrons indicated by the curved arrows in each of the following polar react

Follow the flow of electrons indicated by the curved arrows...

Key Concepts

Reaction Mechanism

This concept refers to the step-by-step description of how a chemical reaction occurs, including the breaking and forming of bonds. It outlines the sequence of elementary steps that lead to the overall transformation from reactants to products, providing insight into intermediate species and transition states.

Curved Arrow Notation

Curved arrows are used in organic chemistry to represent the movement of electrons during a chemical reaction. This notation helps visualize the flow of electron density from electron-rich centers to electron-poor centers, indicating which bonds are breaking or forming in each step of the reaction.

Nucleophiles and Electrophiles

In polar reactions, nucleophiles are species that donate a pair of electrons due to their electron-rich nature, while electrophiles are electron-deficient species that accept electron pairs. Understanding these roles is crucial for predicting how species interact in a reaction mechanism and for determining the site of attack during bond formation.

Leaving Groups

Leaving groups are atoms or groups that depart from a molecule during a reaction, taking with them the electrons from the bond they were involved in. Their ability to stabilize extra electron density after departure is a key factor in facilitating many polar reactions, influencing both the rate and the outcome of the reaction.

Intermediate Formation

Many reaction mechanisms involve the formation of transient species known as intermediates. These intermediates, which may include carbocations, carbanions, or free radicals, are crucial in understanding how the reaction progresses from reactants to products, as they often dictate the final product distribution.

Transcript

00:01 This problem is a very, very important problem in organic chemistry.

00:06 And what we're doing here is we're learning how to draw arrow pushing.

00:10 Now, what is arrow pushing? arrow pushing is how we denote the movement or transfer of electrons in a reaction.

00:20 And this is really the bulk of organic chemistry.

00:23 You're going to learn how to do mechanisms and arrow pushing is at the center of it.

00:28 So it's very, very important that we start understanding how these arrow pushings are working before we get into harder chemistry.

00:38 So for part a, this is our overall reaction.

00:42 So now what's happening? we want to show how these electrons move in our reactants to form our products.

00:51 Notice here that ignore the green arrows for a second.

00:54 We have this carbon with two methyl groups, an oh3 group, and an alcohol group.

00:59 And we're forming this carbon with a ketone and two methyl groups, and then also water and our leftover och3.

01:09 Now, how are we doing that? well, so we're reacting this with hydroxide, and hydroxide is a strong base.

01:16 So what does that mean? that means it can pick up this proton here, this hydrogen that's bound to the alcohol group.

01:23 So it's going to do that.

01:25 But now that's a problem, right? because we can't just leave this bond floating, we have to move those electrons somewhere.

01:33 So we're going to move it to this bond that attaches the carbon to the oxygen.

01:39 And then that disobeys the octet rule, right? because that means that carbon would have too many bonds.

01:48 So then we'd have to move the electrons from this bond to the carbon onto the oxygen of our och3 group.

01:55 And what does that do? that gives us our products here.

01:58 We'll have the double bond, water left over because our hydroxide picked up another hydrogen, and our och3 that's left over.

02:07 And so we're just going to repeat this process for each of the reactions.

02:11 On our second one here, we have this carbon -carbon bond, where we have three hydrogens coming off of one carbon, a methyl on the other, and a ketone group.

02:21 And then we're going to form this carbon that has a double bond to another carbon, that's an alkene, and a methyl group, and an oxygen, and then we'll also produce water.

02:31 So how would this happen? we are reacting this reactant with hydroxide again.

02:37 So hydroxide is a strong base.

02:39 It can easily pick up proton.

02:42 Hydroxide is going to pick up the proton here on carbon...

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