Which of the following compounds would you expect to undergo aldol selfcondensation? Show the pr

Which of the following compounds would you expect to undergo...

Key Concepts

Self-Condensation Reactions

Self-condensation refers to an aldol reaction where identical carbonyl compounds react with each other. This process depends on the molecule having both enolizable alpha hydrogens and an electrophilic carbonyl carbon, and it is distinguished from cross-condensation where two different carbonyl compounds are involved.

Alpha Hydrogen Acidity

The presence and acidity of alpha hydrogens adjacent to the carbonyl group are crucial for the reaction. Only compounds with sufficiently acidic alpha hydrogens can form enolates, making this a key factor in determining whether a molecule is able to undergo aldol condensation.

Steric Effects

Steric hindrance can affect both the formation of the enolate and its ability to attack the carbonyl carbon. Bulky substituents near the carbonyl or alpha positions can impede these processes, thereby influencing the reactivity and overall outcome of the aldol reaction.

Aldol Condensation

Aldol condensation is a reaction in which carbonyl compounds (aldehydes and ketones) possessing alpha hydrogen atoms react (usually under basic or acidic conditions) to form ?-hydroxy carbonyl compounds, which can often dehydrate to produce ?,?-unsaturated carbonyl compounds. This reaction is foundational in carbon–carbon bond formation in organic synthesis.

Enolate Formation

Central to the aldol process is the formation of an enolate ion, where a base deprotonates an accessible alpha hydrogen adjacent to the carbonyl group. The resulting enolate is a nucleophile that attacks another molecule’s electrophilic carbonyl carbon, initiating the aldol addition.

Transcript

00:01 Okay, this problem is asking us which of these compounds would undergo an aldo condensation with itself.

00:06 So let's figure this one out.

00:07 First up, we're given the molecule trimethyl methyl acetylth.

00:11 So i'll just try that out.

00:15 Trimethylmethylacid aldehyde.

00:18 Okay, so because we're not given the structure of the molecule, we have to figure it out for ourselves.

00:23 So the very first thing i'll do is work backwards.

00:26 So i start with the very end and work my way this way.

00:29 So i see that i have aldehyde.

00:31 Aldehyde so i know i'm going to have something that looks like this in which i have my aldehyde and then my r group okay next up i have acetyt acetyl ald so acetylde alth is corresponding to just my one carbon attached to my carbonyne okay so we've seen that in like acetone acetic acid in which you just have a c .h3 or at least one carbon attached to this central carbon okay and then the trimethyl is associated with three methyl groups coming off of that other carbon okay so trimethyl acet alohide.

01:02 Okay, would this undergo an aldo condensation with itself? the answer is no, because for aldo -condentations, the very first step is a base.

01:12 We use sodium hydroxide, for example, to deprotonate an acidic hydrogen so that we can eventually do my alve condensation.

01:19 And in this case, we do not that, we do not have that hydrogen associated with the alpha carbon, so it would not perform an alvealconcentation.

01:28 Okay, next step.

01:29 We have cyclobutan.

01:32 So cyclobutanone, same thing, i'll write it out, cyclobutanone, and let's think about the structure.

01:39 So first thing i would do, work backwards.

01:41 Own, i recognize that as a ketone.

01:44 So i know i'm going to have something that looks like this with r groups.

01:47 Okay, we don't know what those r groups are yet, but we know it's going to be a ketone.

01:50 Next step, i have butte.

01:52 So butan, that corresponds to my four carbons.

01:57 So i know i'm going to have four carbons.

01:59 And the question is, are those carbons going to be associated with this? way, that way, we don't know yet.

02:03 So cyclo.

02:04 Cyclo, we know, is associated with a cyclic compound.

02:07 So all i have to do is make my square or my diamond.

02:11 That is one, two, three, four carbons.

02:13 So we're done.

02:14 Cyclobutanone.

02:15 Is this going to undergo an olive -boughtonation with itself? all we have to do for these types of problems is identify.

02:22 Do we have an acidic hydrogen? if we do, then we can proceed.

02:25 And luckily, we have two acidic hydrogens.

02:27 We can proceed with the reaction, and it would follow like this, in which we have, sorry, in which we have the connection of another cyclobutane.

02:40 Okay, so this is a trick, actually.

02:42 Essentially, all we have to do is identify my nucleophilic position.

02:46 So i'll redraw it.

02:48 Identify my nucleophilic position, and then draw out another molecule of what we started with, and then erase this oxygen, and then connect this to my nucleophilic position like that.

03:00 Okay, and then that would be my answer.

03:02 So yes, this will undergo an alkyphalconcentation with itself.

03:08 Okay, next up is we have benzophenone.

03:15 So benzofinone looks like this.

03:19 I believe they gave us another word that might be a little bit more understandable in the textbook, but benzofinone just looks like this.

03:27 Okay, and that is a ketone with two phenyl groups coming off of it.

03:31 Okay, so will this undergo an aldo connoacconcentation with itself? the answer? no.

03:36 Simply because there are no hydrogens associated with the alpha carbons.

03:39 So no.

03:41 Okay, next up, we have, let's see, three pentanone.

03:46 So writing it out, three pentanone.

03:51 Okay, same thing as before...