Carboxylic Acid Derivatives Overview and Reaction Map

Summary

This video offers a concise overview of carboxylic acid derivatives and their interconversion reactions. It covers common derivatives like acid halides, anhydrides, esters, and amides, and discusses their reactivity and synthesis methods. The importance of understanding the reactivity order and the conditions required for converting between these derivatives is highlighted.

Takeaways

• 🧪 Carboxylic Acids and Their Derivatives: The video provides an overview of carboxylic acid derivatives and the reactions to convert between them, starting with the basic structure of a carboxylic acid.
• 🔍 Carboxylic Acid Structure: A carboxylic acid is characterized by a carbon chain with a functional group featuring a carbon double-bonded to an oxygen, single-bonded to another oxygen, and hydrogen.
• 🔄 Derivative Formation: By replacing the OH group in a carboxylic acid with different groups, various carboxylic acid derivatives can be formed, leading to new sets of reactions for synthesis.
• 🌟 Common Derivatives: The video lists common carboxylic acid derivatives, including acid halides, acid anhydrides, esters, and amides, in order of reactivity from most to least reactive.
• 🧩 Derivative Reactivity: Acid halides are the most reactive, followed by acid anhydrides, esters, and amides being the least reactive, indicating the ease and speed of reactions they can undergo.
• 🔄 Conversion Reactions: The video explains how to convert between different carboxylic acid derivatives, emphasizing the use of acid halides as a common intermediate for such conversions.
• 📚 Carboxylic Acid Cheat Sheet: A reference cheat sheet is available for a comprehensive review of carboxylic acid derivatives and their reactions, accessible through the provided link.
• 🔬 Synthesis Application: The video highlights the importance of understanding the reactivity of different derivatives for their application in synthesis, especially in exam scenarios.
• 🔄 Reactivity and Stability: More reactive derivatives are less stable before the reaction but more stable after the departure of the leaving group, while less reactive derivatives are more stable overall.
• ⚗️ Conversion to Derivatives: The video demonstrates how to convert a carboxylic acid to its derivatives using specific reagents and conditions, such as using SOCl2 for acid halides and alcohols for esters.
• 🔙 Returning to Carboxylic Acid: It is shown how to revert derivatives back to the carboxylic acid form, using reactions with water, acid catalysts, or ammonia, depending on the derivative.

Q & A

What is a carboxylic acid?

A carboxylic acid is a molecule that has a carbon chain with a functional group featuring a carbon double bond to an oxygen and a single bond to another oxygen with a hydrogen. This functional group is a combination of a carbonyl and a hydroxyl group.

What happens when you remove the OH group from a carboxylic acid and replace it with different groups?

When the OH group is removed and replaced with different groups, you get a derivative of the carboxylic acid. These derivatives can lead to a whole new set of reactions that can be used in synthesis.

What is an acid halide and how is it formed?

An acid halide is a derivative of a carboxylic acid where the OH group is replaced with a halogen, such as chlorine. It can be formed by reacting a carboxylic acid with SOCl2, which converts the OH group into a good leaving group and introduces a chlorine atom.

How is an acid anhydride related to a carboxylic acid?

An acid anhydride is formed by replacing the OH group of a carboxylic acid with another carbonyl group, essentially linking two carboxylic acid moieties together. It can be thought of as half a molecule of a carboxylic acid without water.

What is an ester and how is it formed?

An ester is a carboxylic acid derivative where the OH group is replaced with an OR group. It is formed by replacing the entire OH group with an oxygen and an R-group, resulting in a new functional group.

What is an amide and how does it differ from other carboxylic acid derivatives?

An amide is a carboxylic acid derivative where the OH group is replaced with a nitrogen-containing group, such as NH2, NHR, or NR2. It is characterized by the presence of a nitrogen atom in the functional group, which distinguishes it from other derivatives.

What are the reactivity levels of common carboxylic acid derivatives?

The reactivity levels of common carboxylic acid derivatives, from most to least reactive, are: acid halide, acid anhydride, ester, and amide. The reactivity is determined by the stability of the leaving group and the conditions required for the reaction.

How can you convert a carboxylic acid to an acid anhydride?

To convert a carboxylic acid to an acid anhydride, first form an acid halide by reacting the carboxylic acid with SOCl2. Then, react the acid halide with a carboxylate ion, which will displace the chlorine and form the acid anhydride.

What is the relationship between a carboxylic acid and an ester in terms of reactivity?

A carboxylic acid and an ester are closely related in terms of reactivity. It is relatively easy to interconvert between the two depending on the reaction conditions, such as the presence of an acid catalyst.

How can you convert an ester to a carboxylic acid?

To convert an ester to a carboxylic acid, you need a large amount of water, which acts as the conjugate acid of the OH group. The reaction is facilitated by an acid catalyst.

What is the general strategy for converting carboxylic acid derivatives to other derivatives?

A general strategy for converting carboxylic acid derivatives to other derivatives is to first form an acid halide, which is highly reactive. Then, react the acid halide with the appropriate reagent (e.g., a carboxylate ion for anhydrides, an alcohol for esters, or ammonia for amides) to form the desired derivative.

How can you revert back to a carboxylic acid from its derivatives?

To revert back to a carboxylic acid from its derivatives, you can react the derivative with water (for acid halides and esters) or use an acid catalyst (for amides). This process involves the removal of the functional group and the restoration of the original carboxylic acid structure.

Outlines

00:00

🧪 Carboxylic Acid Derivatives Overview

In this segment, Leah introduces carboxylic acid derivatives and their reactions, providing a quick overview. Carboxylic acids have a carbon chain with a functional group that includes a carbonyl (C=O) and a hydroxyl (OH). By replacing the OH group with different groups, various derivatives are formed, such as acid halides, acid anhydrides, esters, and amides. These derivatives are crucial in synthesis reactions. Leah also discusses less common derivatives like nitriles, cyclic derivatives (lactones and lactams), and cyclic anhydrides. The video is accompanied by a carboxylic acid cheat sheet available on Leah's website.

05:03

🔬 Reactions of Carboxylic Acid Derivatives

This paragraph delves into the reactivity and reactions of carboxylic acid derivatives. Leah explains that acid halides are the most reactive, followed by acid anhydrides, esters, and amides, which are the least reactive. The reactivity is crucial in determining how easily a derivative can be converted into another. Leah outlines the steps to convert a carboxylic acid to its derivatives, such as using SOCl2 to form an acid halide and then reacting it with a carboxylate to form an acid anhydride. She also discusses the interconversion between carboxylic acids and esters, and the process of forming amides from carboxylic acids. The summary emphasizes the importance of understanding the reactivity order and the conditions required for these conversions, which is essential for synthesis in chemistry.

Keywords

💡Carboxylic Acid

A carboxylic acid is an organic compound that contains a carboxyl functional group, which is a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group. In the script, it is described as the starting molecule for the formation of carboxylic acid derivatives, highlighting its importance as the parent compound in organic chemistry.

💡Derivatives

In the context of this video, derivatives refer to the functional groups that result from the substitution of the hydroxyl group (OH) in a carboxylic acid with different atoms or groups. The script explains how these derivatives, such as acid halides, anhydrides, esters, and amides, are formed and their reactivity, which is central to the theme of the video.

💡Acid Halide

An acid halide, also known as an acyl halide, is a carboxylic acid derivative where the hydroxyl group is replaced by a halogen. The script mentions that acid halides are highly reactive and can be formed by reacting a carboxylic acid with thionyl chloride (SOCl2), making them a key intermediate in organic synthesis.

💡Acid Anhydride

An acid anhydride is a derivative of a carboxylic acid where two carboxylic acid molecules are linked by an oxygen atom, effectively removing a water molecule. The script describes the formation of an acid anhydride from an acid halide and a carboxylate, emphasizing its role in the synthesis of other derivatives.

💡Ester

An ester is formed when the hydroxyl group of a carboxylic acid is replaced by an alkoxy group (OR). The script explains that esters are less reactive than acid halides and anhydrides but more reactive than amides, and they can be formed by the reaction of a carboxylic acid with an alcohol in the presence of an acid catalyst.

💡Amide

An amide is a carboxylic acid derivative where the hydroxyl group is replaced by an amine group (NH2, NHR, or NR2). The script points out that amides are the least reactive of the common carboxylic acid derivatives, which is important for understanding the directionality of reactions in organic synthesis.

💡Cyclic Derivatives

Cyclic derivatives are carboxylic acid derivatives that form a ring structure. The script introduces cyclic esters (lactones) and cyclic amides (lactams), explaining that they are derived from their linear counterparts but with a ring structure that can be intimidating to students, though they follow similar reactivity principles.

💡Reactivity

Reactivity in the context of this video refers to the tendency of a chemical compound to undergo a chemical reaction. The script outlines the reactivity order of carboxylic acid derivatives, from most reactive (acid halide) to least reactive (amide), which is crucial for understanding the conditions required for interconversion between these compounds.

💡Thionyl Chloride (SOCl2)

Thionyl chloride is a reagent used in organic chemistry to convert carboxylic acids into acid halides. The script describes its role in making the hydroxyl group a good leaving group, thus facilitating the formation of acid halides, which is a critical step in the synthesis of various carboxylic acid derivatives.

💡Conjugate Acid

A conjugate acid is a substance that can donate a proton (H+). In the script, the term is used to describe the role of water (H3O+) in converting esters back to carboxylic acids through an acid-catalyzed hydrolysis reaction, illustrating the concept of acid-base chemistry in the context of derivative interconversion.

💡Imide

An imide is a compound with a carbonyl group on either side of a nitrogen atom. The script briefly mentions cyclic imides, which are cyclic versions of imides, to illustrate the diversity of carboxylic acid derivatives and the structural variations that can occur.

Highlights

Carboxylic acid derivatives and their reactions are discussed in the video.

The carboxylic acid cheat sheet is available on Leah4Sci's website.

A carboxylic acid has a carbon chain with a functional group featuring a carbon double bond to an oxygen and a single bond to another oxygen with a hydrogen.

Derivatives of carboxylic acids are formed by replacing the OH group with different groups.

Professors may refer to derivatives as the carboxylic acid parent with a Y or Z representing the new group.

Acid halides are formed by replacing the OH with a halogen, such as chlorine.

Acid anhydrides are created by replacing the OH with another carboxylic acid without the hydrogen.

Esters are formed by replacing the OH with an OR group.

Amides are produced by replacing the OH with a nitrogen group.

Less common carboxylic acid derivatives include nitriles and cyclic derivatives.

Cyclic derivatives can be ester-like (lactones) or amide-like (lactams).

The reactivity of carboxylic acid derivatives ranges from acid halides being the most reactive to amides being the least.

Carboxylic acids can be converted to acid halides using SOCl2.

Acid anhydrides are formed by reacting acid halides with carboxylates.

Esters can be formed from carboxylic acids and alcohols in the presence of an acid catalyst.

Amides can be synthesized from carboxylic acids and ammonia or amines.

Converting carboxylic acids to derivatives involves understanding the reactivity and leaving groups.

Acid halides can be converted to acid anhydrides, esters, or amides depending on the reaction conditions.

Carboxylic acids can be regenerated from derivatives like acid halides, esters, and amides.

The carboxylic acid cheat sheet is a valuable resource for understanding the relationships and reactions of carboxylic acid derivatives.

Transcripts

Leah here from leah4sci.com and in this video we're going to look at a quick overview of

the carboxylic acid derivatives and the reactions to convert between them.

This video follows along with the carboxylic acid cheat sheet which you can find on my

website linked below or visiting leah4sci.com/carboxylic-acid.

A carboxylic acid is a molecule that has a carbon chain with a functional group featuring

a carbon double bound to an oxygen single bound to another oxygen with a hydrogen.

This portion is a carbonyl, this portion is hydroxy but it's not an alcohol because together

they form one functional group called the carboxylic acid if we remove that OH and replace

it with different groups, we get a derivative of carboxylic acid because we're deriving

it from the carboxylic acid molecule and this leads to a whole new set of reactions that

you can use in synthesis.Some professors will refer to the derivatives as the carboxylic

acid parent with either a Y or a Z here with that Y or Z represents the new group which

gives you the specific type of derivative.

Let's look at some common derivatives from most to least reactive.

If i replace the OH with a Halogen for example Chlorine, that will give me an acid halide

as a general class or an acid chloride for the specific molecule.

This is also called an Acyl Chloride or an Acyl Halide.

If I replace the OH with what looks like another carboxylic acid without the hydrogen so we'll

just have this portion here giving us an oxygen, a carbon double bound to an Oxygen and then

a second R-group.

This is called and Acid anhydride or simply anhydride.

If you think about it, if we split the molecule in half and add in a water OH and another

H for H2O, that would give me 2 carboxylic acids to we have the acid without water and

hydride without water, that's how we get the acid anhydride derivative.

If we replace the OH with an OR group and it's not just the H that we're replacing with

an R, the entire group got swapped for a brand new oxygen and R-group, then I get what's

called an Ester.

And if I replace the OH with a Nitrogen for example NH2 or we can have NHR or NR2, these

are just different substitute in Nitrogen.

We get what's called an Amide or amide.

Let's face it, your professor is not just taking to the common derivatives, you might

also see some of these less common molecules.

As a reminder, a carboxylic acid starts out with a carbon double bound to an oxygen.

So if we replace the Y, we get a derivative.

But recognize that what we have here is a carbon bound 1,2,3 times.

So if we have carbon bound three times to something else, that would still qualify as

a carboxylic acid derivative for example, if I remove that oxygen, and instead have

3 bonds to a Nitrogen, that gives me the Nitrile derivative.

And finally Cyclic Derivatives which are just cyclic versions of their linear counterparts

but for some reason seeing that ring scare students.

Don't let this scare you.

If I have a ring with a carbonyl, bound to an oxygen and then a ring happens to close

in on itself.

Doesn't this look like an Ester where we have an R-group here, and here, as two separate

chains?

This gives us a cyclic ester which is also called a lactone.

If I have the same structure with a Nitrogen instead of an Oxygen alongwith the Hydrogen

because Nitrogen needs 3 bonds where oxygen needs 2.

You should recognize this as a cyclic amide.

If we take off the bottom, this is simply carbon chain number 1 for the carboxylic acid

and this would be our second carbon chain for a substituted amide but the two chains

happen to be connected.

The cyclic amide is also called a lactam, and this is where students get confused.

The way I remember the difference is the lactone has the extra O for the cyclic ester, and

the lactam is the cyclic amide which tells me it has a nitrogen.

You may also come across something that look like this.

It's a cyclic structure with the oxygen in the middle but another carbonyl.

You should recognize this as a sideways acid anhydride.

And in fact, it's just a cyclic anhydride.

And if I take that same cyclic anhydride but replace the oxygen with a nitrogen, I don't

get a cyclic amide because the linear version would be called an Imide . Remember an imide

is when you have a carbonyl on either side of a nitrogen so this would simply be a cyclic

Imide.

When looking at reactions of carboxylic acid derivatives, it's important to remember that

the acid halide is most reactive then the acid anhydride then the the ester and least

reactive is the amide.

As a reminder all of these are listed out on the carboxylic acid derivative cheat sheet

which is linked below.

When you hear most reactive, recognize that it's going to react the fastest, has the best

leaving group, and therefore is least stable as is, but most stable when the leaving group

departs.

The amide being the least reactive tells us that it reacts slower.

It has a bad leaving group and therefore is least stable when you kick it out.

This is important to recognize because it's very easy to make a less reactive derivative

from a more reactive derivative but it's going to take more extreme condition to go from

something less reactive to something more reactive because it wants to go in that direction.

This video is just an overview of the reactions so let's see how you go from one to the next.

In doing so, we can forget the carboxylic acid because as a derivative we also need

to know how to go from a carboxy to any of the derivatives.

A carboxylic acid will form an acid halide when reacted with something like SOCl2 which

makes the OH a good leaving group and brings us a source of chlorine.

To go from a carboxylic acid to an acid anhydride, you need to detour.

First, you make your acid halide which is very reactive, then you simply react the acid

halide with a carboxylate or a negative deprotonated carboxylic acid which will kick out the chlorine

and give us the acid anhydride.

The carboxylic acid is very close to the reactivity of an ester.

That means it's very easy to go back and forth between the two depending on the reaction

conditions.

For example, putting this in an acid catalyst, the more of that derivative component that

you have in solution, the more of the reaction favors that direction.

To go from an ester to a carboxylic acid we just need a whole lot of water which is the

conjugate acid of the OH group.

So we'll show H3O+ or water and an acid catalyst.

To go from the carboxylic acid to ester, we just need a lot of OR so we put an alcohol

solution with an acid catalyst.

To go from the carboxylic acid to the amide, we react this in ammonia, but it doesn't stop

there.

Another way to make any of the derivatives especially if you're stuck on an exam synthesis

question and you don't remember the exact conditions, best way to do it, go from the

carboxylic acid to the acid halide.

Make sure you know the SOCl2 and then just take that red portion, the derivative portion,

react it with the acid halide and you're good to go.

We've already shown an acid halide to an acid anhydride using a carboxylate which is the

red portion of the anhydride.

If I react the acid halide with an alcohol which gives us the OR portion, I'll get an

ester, and if I react the acid halide with ammonia or an amine, I will get an amide.

Ammonia would give us just the NH2 amide but an amine will give us a substituted amide

which would be NRH or NR2.

But it doesn't stop there.

Anytime you want to make something more reactive, the less reactive group will get you there.

This means the anhydride will react with something like ammonia to give me the amide and so will

the ester.

Finally the last thing you should look at is how to go back to the carboxylic acid from

the derivative.

The acid halide is so reactive it reacts with water to give you a carboxylic acid and so

does the N hydride.

We've already shown that the ester will form a carboxylic acid using a water and an acid

catalyst.

And finally, the amide is a little tricky.

The NH2 is a bad leaving group, but if we react it in an acid catalyst now it's not

NH2, it's a protonated better leaving group and once again that'll bring us back to the

carboxylic acid.

For a complete review of everything we discussed, make sure you study the carboxylic acid cheat

sheet linked below or visit my website leah4sci.com/carboxylic-acid.