Show how you could prepare each of the following carboxylic...

Key Concepts

Grignard Reagents

Grignard reagents are organometallic compounds typically represented as RMgX (where R is an organic group and X is a halogen). They act as strong nucleophiles and bases and are commonly used in organic synthesis to form carbon–carbon bonds. Their reactivity toward electrophilic centers under anhydrous conditions makes them particularly useful in reactions that build up more complex molecules, including the synthesis of carboxylic acids.

Carboxylation Reaction

The carboxylation reaction involves the nucleophilic addition of a Grignard reagent to carbon dioxide. In this process, the negatively polarized carbon of the Grignard reagent attacks the electrophilic carbon in CO2, leading to the formation of a magnesium carboxylate intermediate. This reaction is a fundamental method for introducing a carboxyl group (-COOH) into an organic molecule, allowing for the conversion of simple organomagnesium compounds into more complex carboxylic acids.

Acidic Workup

After forming the magnesium carboxylate intermediate through the carboxylation of CO2, an acidic workup is typically performed. This step involves the addition of a proton source, usually aqueous acid, which protonates the carboxylate to yield the corresponding carboxylic acid. The acidification step is essential to complete the synthesis, converting the intermediate into the desired carboxylic acid product and removing any residual metal salts.

Transcript

00:03 Suppose we want to synthesize this carboxylic acid from greener synthesis or a greenered reagent.

00:12 So a key thing to note about using greenerd reagents is that when you use greenerd reagent, what you're doing is you're first adding magnesium in ether.

00:27 You can use any kind of ether.

00:30 Typically, we use diethyl ether, also denoted as.

00:34 This or tetrahidrophuren, which, oops, like that, also known as thf.

00:48 We can use either one of these as our solvent, as long as we use an ether that is pretty unreactive, like most ethers.

00:58 And then we follow it up with co2, and finally an acid workup.

01:06 A key thing to note here is this co2 adds a carbon.

01:14 So if you were to synthesize a carboxylic acid, say from a haloalkane or a halo alkan with like bromine, your molecule with bromine or chlorine, if you choose to use that, should have a, should have one less carbon than what you desire to end with.

01:36 Because that last carbon is right there and you're adding it to the reaction.

01:46 And also another key thing to note is greenyard can be done with most reagents.

01:55 And this becomes an issue when we're talking about nitrils to synthesize carboxylic acids because nitrils can only be done on s &2 conditions, like sp3, hybridized carbons and et cetera, whereas grinjord reagent can be done on basically any and every molecule.

02:29 So if we were to synthesize this molecule using grinjord, our starting material, let's take bromine, but you can use chlorine instead, would have one less carbon.

02:42 We're adding that carbon because that is part of the carboxylic acid, which means that that carbon gets replaced by bromine.

02:54 And we'd use our greenyard reagent.

03:03 Let's actually do it step by step.

03:09 And we'd get this molecule, gbr.

03:18 Then we'd react it with first co2, followed by our acid.

03:24 Workup to get our desired product, which would add that carbon right there.

03:40 Let's try another example.

03:45 Well, if we were to add with grinjord, all this time i'll use chlorine, but it can be either bromine or chlorine for any of these examples.

03:56 And what we can do is, well, we take one less carbon out and replace it with our halogen.

04:09 And we'd react it with magnesium and diethyl ether.

04:22 And finally, we will add carbon dioxide with h2o and h+.

04:32 To get our desired product...

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