Draw all possible stereoisomers of 1,2-cyclobutanedicarboxylic acid, and indicate the interrelat

Draw all possible stereoisomers of...

Key Concepts

Stereoisomerism

Stereoisomerism refers to the phenomenon where molecules have the same molecular formula and bond connectivity but differ in the arrangement of atoms in three-dimensional space. This concept is central to understanding how compounds that share the same connectivity can exhibit different physical and chemical properties due to variations in their spatial orientations.

Geometric (cis/trans) Isomerism

Geometric isomerism, specifically cis/trans isomerism, occurs when substituents around a ring or a double bond adopt different relative positions. In cyclic compounds, such as cyclobutane derivatives, the rigidity of the ring system means that substituents can be located on the same side (cis) or opposite sides (trans) of the plane of the ring, leading to distinct stereoisomers with unique properties.

Chirality

Chirality is a property of a molecule that makes it non-superimposable on its mirror image, often due to the presence of one or more asymmetric (chiral) centers. A chiral molecule can rotate plane-polarized light, and its mirror image (an enantiomer) will have identical physical properties except for the direction in which it rotates light. The presence or absence of chirality determines whether a stereoisomer is optically active.

Meso Compounds

Meso compounds are a unique class of stereoisomers that contain multiple chiral centers but possess an internal plane of symmetry, rendering the overall molecule achiral. Despite having stereocenters, the internal symmetry cancels out optical activity, which means meso compounds do not rotate plane-polarized light and are not optically active.

Interrelationship of Stereoisomers

The interrelationship of stereoisomers involves understanding how different forms (enantiomers, diastereomers, and meso forms) relate to each other. Enantiomers are non-superimposable mirror images, diastereomers are stereoisomers that are not mirror images, and meso compounds, as noted, are achiral despite having stereogenic centers. Recognizing these relationships is crucial in predicting properties such as optical activity and reactivity patterns in organic molecules.

Transcript

00:01 So they first want us to draw all possible stereoisomers of 1 -2 and 1 -3 cyclo -butane di -carboxylacin.

00:11 And then they want us to explain if these are optically active and any kind of interrelationships between the molecules.

00:18 So let's go ahead and draw out first the stereoisomers for 1 -2.

00:23 Now when we look at this, we can tell what the parent structure is going to be because it says cyclobutane.

00:30 Butane.

00:33 I don't know why it's lagging behind like that.

00:35 That was weird.

00:36 Yeah, so it's going to be a cyclobutane.

00:41 So let's go ahead and draw that.

00:42 And i'm going to try to draw this in two dimensions.

00:45 Probably not going to do too good of a job of it, but yeah, i'm drawing my best.

00:49 And then we have di -carboxylic acid here.

00:53 So at positions one and two, we're going to have a carboxylic acid.

00:57 So remember, since this is planar, we would have the possibility of having these groups.

01:05 One pointing kind of up, one kind of point down, one kind of point up, one kind of point down, like that.

01:12 So the first possible stereo isomer, we can have where the carboxylacid acids are on.

01:18 I'll do the same side of this, and then so that means we'd have these hydrogens over here.

01:25 And so that's one possible stereo isomer.

01:28 And now notice we can't do like the enantamer where like, the mirror image of this, because notice if we were to just take this and rotate it 180 degrees, then both of these are going to become on the bottom.

01:45 So you can see how we can't really draw the other one for this.

01:50 So that's one of them.

01:53 And actually, since both of these are on the same side, we would say this is a cis.

01:58 And i believe we'll need to kind of list this out because later on we'll be list trans.

02:02 We want to kind of list what kind of sterilized these are.

02:06 So i guess it's kind of good to just say this is cysts since they're on the same side.

02:10 Now let's come over here.

02:12 And so now i'll keep this carboxylk acid up top.

02:19 So then that means we have a hydrogen here and then i'll put a carboxylk acid on the bottom and then one on top.

02:24 So you can see at least this for sure is different from what we have over here because now these are on opposite sides and these are trans of each other.

02:33 All right.

02:35 And notice that we could also do the other one where over here, the hydrogen is on top on the left, and then the carbocic acid is on the, let me draw it a little bit better, and the carbocilc acid is on the bottom.

02:57 And then over here, the carboxic acid is on top, and then the hydrogen is on bottom.

03:03 And notice, like, no matter how we try to rotate this, like we can try to do it 180 degrees, like flipping.

03:09 It will just keep giving us the same one here.

03:11 And same thing here as well.

03:14 And even if we were to try to maybe spin it around in the plane, it still isn't going to give us what we have over here.

03:22 So these are distinct molecules.

03:26 And so this one over here is also going to be trance.

03:31 Now one thing you might notice is, if i were to pick this up and move it like this, you can see how.

03:43 How these two are going to be mirror images of each other.

03:52 And so remember, mirror images are inantomers.

03:55 So these two are going to be, i never remember how to spell this word, so i have to always look it up.

04:03 So these are inantomers of each other.

04:13 And between these two and this one, the relationship is going to be, or maybe i should just do it like this.

04:20 So the relationship between this, and the relationship between this, well, these aren't mirror images, but these do give different confirmations of all we're really doing is flipping around one of the positions here.

04:37 So like one of the carbons.

04:39 So here, the carboxyl gas is pointing up, but over here it is pointing down.

04:43 And then over here, this carbacil gas is point up, but over here it's pointing down.

04:47 So in this case, when we just have like where one of our chiral centers is rearranged, those are diosteromers...

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