(a) Which of the carboxylic acids in Practice Problem 17.5...

Key Concepts

Carboxylic Acid Synthesis

This concept covers the methods that convert precursors such as nitriles or organometallic compounds into carboxylic acids through transformations like hydrolysis or carboxylation. It is fundamental in organic synthesis for preparing a wide range of carboxylic acid derivatives from various starting materials.

Nitrile Synthesis

Nitrile synthesis refers to the preparation of carboxylic acids through the hydrolysis of nitriles. In this route, a nitrile group is converted into a carboxylic acid under acidic or basic conditions, making it a valuable method when the target molecule can tolerate the conditions required for the nitrile intermediate and its subsequent hydrolysis.

Grignard Reaction

The Grignard reaction involves the formation of carbon–carbon bonds by reacting organomagnesium reagents with electrophiles, such as carbon dioxide, to yield carboxylic acids after an acidic workup. This method is widely used for synthesizing carboxylic acids, particularly when the introduction of a new carbon chain is required.

Functional Group Compatibility

This concept emphasizes the importance of the compatibility of different functional groups present in the substrate with the chosen synthesis method. Functional group tolerance can dictate whether a nitrile or Grignard route is more suitable, as some sensitive groups may react undesirably under the conditions required for one method over the other.

Transcript

00:04 Suppose in the previous example or in the previous problem when we used grinjord reagents to prepare these carboxylic acids.

00:15 What if we tried using a nitral synthesis? well, we'd start off with the same halalcane.

00:24 So suppose instead of grinjord, we had this halalcane and we wanted to use nitral synthesis.

00:34 Well, nitral synthesis, if you remember from.

00:38 Hala -kane reactions follows a s -n -2 mechanism.

00:49 It follows an s -n -t mechanism.

00:52 So the rules for s -n -2 stay the same.

00:55 And that would be an sp3 hybridized carbon, sp3 carbon, that is primary, secondary, or is simply just a methyl group.

01:13 And if we look, our reacting carbon would be this one, which is sp3 hybridized because it would form four bonds and it would, the other two bonds are with hydrogens.

01:28 So it is sp3 hybridized.

01:31 And it is primary.

01:33 So this does work.

01:36 And we can make our nitral group and then hydrolyize it.

01:44 H2oh plus with heat to make this molecule.

01:57 So that does work.

02:01 What about the next example? well, we do the same thing.

02:06 We'd start with our halalcane.

02:10 But notice how this is a tertiary carbon.

02:14 It is sp3, but it is tertiary.

02:18 And s &2 does not work in tertiary.

02:22 So this reaction would not make our desired product, which is a nitral, does not make nitral.

02:38 In fact, what it makes instead is this molecule, which is an alkene, and that is because of elimination, because of tertiary.

02:55 So that one would not.

02:57 What about this one? it's an sb3 hybridized carbon that is only bonded to one other carbon, making it primary.

03:13 This one would work.

03:20 And then we'd hydrolyze it.

03:28 To make our carboxylic acid.

03:35 How about methylbenzoic acid, or four methylbenzoic acid? well, our acid looks like this, and our halo al -cane was this molecule.

03:56 Is that carbon an sp2 hybridized carbon, or sp3 hybridized carbon? i kind of just gave it away there, but it is an sp2 hybridized carbon, not an sp3...

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