Following are stereorepresentations for the four stereoisomers of 3 -chloro-2-butanol. (a) Assig

Following are stereorepresentations for the four...

Key Concepts

Diastereomers

Diastereomers are stereoisomers that are not mirror images of each other. They differ in configuration at one or more of the chiral centers and often have different physical and chemical properties. This concept is important for distinguishing between various types of stereochemical relationships in molecules that have multiple chiral centers.

Enantiomers

Enantiomers are pairs of stereoisomers that are non-superimposable mirror images of each other. They possess identical physical properties except for the direction in which they rotate plane-polarized light and their interactions with other chiral environments. Understanding enantiomeric relationships is fundamental in stereochemistry and in fields such as pharmaceuticals.

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog priority rules are a set of guidelines used to assign priorities to the substituents attached to a chiral center. By ranking these substituents and orienting the molecule appropriately, one can assign an R (rectus) or S (sinister) configuration, thereby providing a systematic way to describe the three-dimensional configuration of a stereocenter.

Chirality

Chirality refers to the geometric property wherein a molecule cannot be superimposed on its mirror image, typically due to the presence of at least one carbon atom bonded to four distinct substituents. This feature is crucial because it leads to stereoisomerism, where molecules can exist as non-superimposable mirror images with different spatial arrangements.

Transcript

00:01 So in this question, we're determining stereoisomers from hydroporacin oxidation of certain alkenes, and also giving rs configurations for the chiral centers.

00:11 So we're starting with a, we've got cyclohexene, which nice and easy looks something like that.

00:21 If i react that, i'm just going to make cyclohexanol, which was where i just add an oh off here.

00:27 This doesn't have any carol centers, so we don't have to worry about stereoisomerism.

00:31 All right, so moving on to b.

00:34 Now we're giving one ethyl cyclohexene.

00:38 So i'm going to start with my cyclohexene here.

00:43 And one ethyl, i'm just going to write e .t for ethel instead of writing out the whole carbon chain.

00:52 So from here, if i react this, obviously i'm going to form two products.

00:58 The first is going to be, i can just have this ethel here, which is you can.

01:05 Means the stereochemistry of the oxygen has to be opposite.

01:10 I can also get kind of the mirror image where i have this and this.

01:22 All right, so these are in the interest of one another.

01:26 So now i'm going through and doing chirality, starting with the first product.

01:32 Notice, obviously, starting with this carbon here, i can kind of label this as one, two, three.

01:40 So that goes in a counterclockwise direction making this one r.

01:47 And i'm like kind of erase some of these numbers here.

01:51 And that's because i've also, i have an applied hydrogen kind of in the backwards plane of the image.

01:57 So i don't have to worry about flipping stereochemistry.

02:01 All right.

02:01 So now we have an oxygen going to this carl center right here.

02:07 Obviously oxygen is going to be the first priority followed by this is going to be second.

02:15 Priority and this is going to be third priority.

02:17 Now this looks like it's s, right? because if you go one, two, three, that goes into a counterclockwise direction.

02:23 But notice that the hydrogen that we have to draw here is actually going to be on a wedge.

02:29 And that's since the lowest priority is on a wedge, you can think of kind of just flipping the orientation, making this r.

02:37 All right.

02:37 So now, kind of using a shortcut, we know that the second product is going to be a nanshemer, which means it's just the complete mirror image.

02:46 So what we would expect anyways is for both of these chirocenters to be s.

02:51 And if you go through, you can double check and that is in fact the case.

02:55 So moving on to c.

02:57 Let's do this.

02:58 Stay consistent here.

03:00 We're given cis 2 butine.

03:06 So we have something that looks like this.

03:11 So if i react to this, what i'm going to get is, i'm going to get two products, right? and i'm just going to draw them in their perspective form, right? so i'm going to have one of the methyl forcing up, and i'm just going to draw this.

03:37 I'm going to force hydrogen back into the back, and then i'm going to have an alcohol up front.

03:44 And you'll notice that all three of our, i'm sorry, all four of our carbons are still accounted for.

03:50 So we're good on that front.

03:52 Now the other thing i can do is draw the inaneum mirror, right? so i can draw something that looks like this.

04:04 Making sure this is actually carbon.

04:23 So now if i'm going to look at the product on the left, i'm going to figure out, you know, priorities.

04:28 So starting with the oxygen, we're going to have one...

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