Chem 1307 Ch 18.6 Hydrolysis of Amides

Summary

This lesson explores the hydrolysis of amides, a reverse reaction to amidation, where water breaks down amide bonds. Using either acid or base catalysts and heat, amides can be hydrolyzed to form carboxylic acids and ammonium salts or carboxylate salts and amines, respectively. The process involves balancing chemical equations and understanding the role of water and catalysts in the reaction.

Takeaways

• 🧪 Hydrolysis of amides involves breaking the amide bond using water, which is a reverse reaction of the amidation process.
• 🔥 Hydrolysis reactions often require heat and a catalyst to proceed efficiently.
• 🔄 Base hydrolysis of amides results in the formation of a carboxylate salt and an amine, whereas acid hydrolysis yields a carboxylic acid and an ammonium salt.
• 🌐 The hydrolysis process involves the splitting of the amide bond between the carbonyl carbon and the nitrogen atom.
• 💧 In acid hydrolysis, water molecules combine with HCl to form the carboxylic acid and the ammonium salt.
• 🛠 Base hydrolysis uses a base like sodium hydroxide to facilitate the reaction, leading to the formation of a carboxylate salt and an amine.
• 📚 The goal of the lesson is to understand and write balanced chemical equations for the hydrolysis of amides.
• 📉 Amines are weak bases and are soluble in water up to six carbons in length, after which solubility decreases due to increased nonpolarity.
• 🔬 Amines can be classified as primary, secondary, or tertiary based on the number of alkyl groups attached to the nitrogen atom.
• 🧬 Amines can also be heterocyclic, with nitrogen atoms within a carbon ring, and can function as neurotransmitters.
• 🔀 Amines react with carboxylic acids to form amides, which can then be hydrolyzed to break them down.

Q & A

What is hydrolysis in the context of amides?

Hydrolysis in the context of amides refers to the process of breaking an amide bond by adding water. It is a reverse reaction of amidation, where water and an acid or a base split the amide, often requiring a catalyst and heat to proceed.

What are the products of acid hydrolysis of an amide?

In acid hydrolysis of an amide, the products are a carboxylic acid and an ammonium salt. The amide bond is broken, and water and acid interact with the nitrogen to form the ammonium salt.

What are the products of base hydrolysis of an amide?

In base hydrolysis of an amide, the products are a carboxylate salt and an amine. The amide bond is broken, and the base reacts with the carbonyl carbon to form the carboxylate salt, while the nitrogen forms an amine.

Why is heat necessary in the hydrolysis of amides?

Heat is necessary in the hydrolysis of amides to increase the rate of the reaction. It provides the energy needed for the molecules to overcome the activation energy barrier, making the reaction proceed faster.

What is the role of a catalyst in the hydrolysis of amides?

A catalyst in the hydrolysis of amides helps to lower the activation energy of the reaction, thereby increasing the rate at which the amide bond is broken and the reaction proceeds.

How does the structure of an amide affect its hydrolysis?

The structure of an amide, particularly the nature of the R groups and the length of the carbon chain, can affect the ease of hydrolysis. Longer chains and more complex structures may require more energy or different conditions for hydrolysis to occur.

What is the difference between the hydrolysis of an amide using an acid versus a base?

The hydrolysis of an amide using an acid results in the formation of a carboxylic acid and an ammonium salt, whereas hydrolysis using a base results in the formation of a carboxylate salt and an amine. The choice of acid or base determines the nature of the products formed.

What is the chemical equation for the acid hydrolysis of n-methylpentanamide?

The chemical equation for the acid hydrolysis of n-methylpentanamide involves the reaction of n-methylpentanamide with water and hydrochloric acid to produce ammonium chloride and pentanoic acid.

What is the chemical equation for the base hydrolysis of n-methylpentanamide?

The chemical equation for the base hydrolysis of n-methylpentanamide involves the reaction of n-methylpentanamide with sodium hydroxide and water to produce sodium pentanoate and methylamine.

How do amines react with carboxylic acids to form amides?

Amines react with carboxylic acids through a condensation reaction where the amine donates a hydrogen and the carboxylic acid donates a hydroxyl group, forming an amide and releasing a molecule of water.

What is the significance of the hydrolysis of amides in biological systems?

In biological systems, the hydrolysis of amides is significant as it is involved in the breakdown of proteins and peptides. This process is crucial for the metabolism and recycling of amino acids in the body.

Outlines

00:00

🧪 Hydrolysis of Amides: Breaking Bonds with Water

This paragraph delves into the chemical process of hydrolysis as it pertains to amides. It explains that hydrolysis is essentially the reverse of amidation, where water is used to break down the amide bond. The process requires heat and possibly a catalyst to facilitate the reaction. The paragraph provides an example using n-methylpentanamide, illustrating how a base can cleave the amide bond to yield a carboxylate anion and an amine. It also contrasts this with acid hydrolysis, which results in a carboxylic acid and an ammonium salt. The goal is set to write balanced chemical equations for these hydrolysis reactions.

05:00

🔍 Base and Acid Hydrolysis of Amides: A Comparative Analysis

The second paragraph continues the discussion on amide hydrolysis, focusing on the differences between base and acid hydrolysis. It describes the process of acid hydrolysis, where an amide reacts with acid and heat to form a carboxylic acid and an ammonium salt. The paragraph uses a step-by-step approach to show the chemical changes, emphasizing the role of water molecules in the reaction. It then contrasts this with base hydrolysis, where the products are a carboxylate salt and an amine. The paragraph also includes a practical example, detailing the hydrolysis of n-methylpentanamide with sodium hydroxide, and explains how to write the IUPAC names for the resulting products.

10:02

📚 Chapter Summary: Amines and Amides

The final paragraph serves as a comprehensive summary of the chapter on amines and amides. It starts by defining amines and their properties, such as their solubility in water and their weak basic nature. It also touches on the concept of heterocyclic amines and their role as neurotransmitters. The paragraph then connects amines to amides, explaining how they can react with carboxylic acids to form amides, which can later be hydrolyzed under either acidic or basic conditions. The summary concludes with a concept map that encapsulates the key points and reactions discussed throughout the chapter.

Keywords

💡Hydrolysis

Hydrolysis is a chemical reaction in which a molecule is broken down with the addition of water. In the context of the video, hydrolysis is used to describe the process of breaking apart an amide bond using water. This is a reverse reaction of amidation, where water and either an acid or a base are used to cleave the bond, resulting in the formation of a carboxylic acid or carboxylate salt and an amine or ammonium salt.

💡Amides

Amides are organic compounds containing a carbonyl group bonded to a nitrogen atom. They are formed through a condensation reaction between a carboxylic acid and an amine. In the video, amides are the focus of hydrolysis reactions, where they are broken down into their constituent parts, such as carboxylic acids and amines, using water and either an acid or a base.

💡Acid Hydrolysis

Acid hydrolysis is a specific type of hydrolysis where an acid is used to break down a compound. In the video, acid hydrolysis of amides results in the formation of a carboxylic acid and an ammonium salt. This process involves the addition of water and an acid, such as hydrochloric acid (HCl), to the amide, leading to the cleavage of the amide bond and the formation of the respective products.

💡Base Hydrolysis

Base hydrolysis is another type of hydrolysis where a base is used to break down a compound. The video discusses base hydrolysis of amides, where a base like sodium hydroxide is used to cleave the amide bond, resulting in the formation of a carboxylate salt and an amine. This reaction is crucial in understanding how amides can be broken down in the presence of a base.

💡Carboxylic Acid

A carboxylic acid is an organic compound containing a carboxyl group (-COOH). In the video, carboxylic acids are formed as one of the products in the hydrolysis of amides, particularly in acid hydrolysis. For example, when an amide undergoes acid hydrolysis, the carbonyl carbon bonds with a hydroxyl group from water, forming a carboxylic acid.

💡Carboxylate Salt

A carboxylate salt is a salt that contains a carboxylate anion, which is derived from a carboxylic acid. In the video, carboxylate salts are formed during base hydrolysis of amides. The reaction involves the formation of a carboxylate anion by the addition of a hydroxide ion from the base, which then forms a salt with a metal cation, such as sodium.

💡Amine

An amine is an organic compound that contains a nitrogen atom bonded to one or more carbon atoms. In the video, amines are formed as one of the products in the hydrolysis of amides. For instance, when an amide is hydrolyzed in the presence of a base, the nitrogen atom bonds with a hydrogen atom from the base, resulting in the formation of an amine.

💡Ammonium Salt

An ammonium salt is a salt that contains the ammonium cation (NH4+). In the video, ammonium salts are formed during acid hydrolysis of amides. The reaction involves the addition of a proton from the acid and a hydrogen from water to the nitrogen atom of the amide, resulting in the formation of an ammonium ion that forms a salt with an anion, such as chloride.

💡Condensation Reaction

A condensation reaction is a type of chemical reaction where two molecules combine to form a larger molecule, often with the release of a small molecule like water. In the video, condensation reactions are mentioned in the context of forming amides from carboxylic acids and amines, which is the reverse process of the hydrolysis reactions being discussed.

💡Catalyst

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. In the video, catalysts are mentioned as being potentially necessary to help the hydrolysis reaction of amides proceed more quickly. This is important in understanding how the reaction can be facilitated under certain conditions.

💡Heat

Heat is a form of energy that can be transferred between substances or systems. In the video, heat is mentioned as a factor that can help the hydrolysis reaction of amides proceed faster. This is a common practice in chemical reactions to increase the kinetic energy of the molecules, thereby increasing the rate of reaction.

Highlights

Hydrolysis of amides is a reverse reaction of amidation, involving the use of water to break the amide bond.

A catalyst and heat may be required for hydrolysis to proceed efficiently.

Base hydrolysis of an amide results in the formation of a carboxylate anion salt and an amine.

Acid hydrolysis of an amide leads to the production of a carboxylic acid and an ammonium salt.

The process of hydrolysis involves the splitting of the amide bond between the carbonyl carbon and the nitrogen.

In acid hydrolysis, water and hydrochloric acid are used to facilitate the reaction.

Ammonium salts are formed when hydrogens from water and hydrochloric acid bond with the nitrogen of the amide.

Base hydrolysis involves the reaction of the amide with a base like sodium hydroxide, resulting in a carboxylate salt and an amine.

The carboxylate salt and amine are the products of base hydrolysis, differing from the products of acid hydrolysis.

Sodium oxide from sodium hydroxide bonds with the carbonyl carbon to form a carboxylate salt in base hydrolysis.

Methylamine is an example of an amine product from the base hydrolysis of an amide.

Ammonium chloride is an example of an ammonium salt produced during acid hydrolysis.

The hydrolysis of amides can be represented by balanced chemical equations.

Hydrolysis reactions are more complex than initially described, involving the participation of water molecules.

Amine classification includes primary, secondary, and tertiary amines based on the number of alkyl chains bonded to nitrogen.

Amines are soluble in water up to six carbons in length, with solubility decreasing as the molecule becomes more nonpolar.

Amines react as weak bases in water with low Kb values, participating in neutralization reactions with acids.

Heterocyclic amines have a nitrogen atom within the carbon ring and can act as neurotransmitters.

Amines can react with carboxylic acids to form amides, which can later be hydrolyzed.

The chapter concludes with a concept map summarizing the topics of amines and amides, including their properties and reactions.

Transcripts

the next lesson will be 18.6 and it

describes the hydrolysis of amides so

just like we did a dehydration or a

condensation reaction to create the

amide we can also break them apart by

adding water hydrolysis means that we

are breaking a molecule apart with the

use of water

so this is a reverse reaction of the

amidation

and hydrolysis occurs when water and an

acid or a base split the amide so you

may need a catalyst to help this

reaction proceed you will also need heat

so that this reaction can go a little

faster

so here we have an example of an amide

you have n

methyl

pentanamide one two three four five

carbons in the chain with our amide here

and what we're gonna do is we're gonna

use the base to kind of get in between

this amide so we're going to break the

amide bond so what you're going to get

is the salt of the carboxylate anion if

you use a base

if you use an acid you're going to get

the carboxylic acid and of course on the

other end you're going to get the amine

or ammonia depending on what you have as

your side chains do we have hydrogens or

r groups

the goal of this section will be to

write balanced chemical equations for

the hydrolysis of amides

so we took a look at the base hydrolysis

we'll describe that in detail in just a

second but let's start with the amides

that undergo acid hydrolysis

so we're going to add acid and heat to

produce a carboxylic acid and an

ammonium salt

so earlier we said that this type of

reaction is going to break the amide

bond between the carbon of the carbonyl

and the nitrogen of the amide

so we're going to add water to help us

break that apart so part of the water is

going to go here to create the

carboxylic acid so oh and then the other

part of the water the hydrogen is going

to come with the chloride

and interact with the amine part right

with the nitrogen section to create a

quaternary ammonium salt so we're going

to add the two hydrogens one from the

water one from the hcl and that creates

nh4 plus and of course the counter ion

is the chloride from here so we had a

positive one

for our

hydrogen and a negative one for the

chloride so adding four hydrogens to the

nitrogen gives it a positive charge we

have the ammonium salt and of course the

counter ion is the chloride our product

is ammonium chloride and ethanoic acid

which is also known as acetic acid

so we did acid hydrolysis again you want

to see where that water is kind of going

to go on to this molecule you have a

portion of the water molecule

that's going to come onto the carbonyl

split this in half and then the hydrogen

along with this proton from the acid

are going to come on the nitrogen side

to create the ammonium salt because now

there's four hydrogens it's a positive

charge and the chloride is going to want

to interact with that ammonium because

we have a counter ion right opposites

attract

so this is the acid hydrolysis of a

mites

now let's take a look at the base

hydrolysis of a mite the reaction is

pretty similar in that you're going to

split

the amide between the carbon of the

carbonyl and the nitrogen of the amide

so you're going to break the amide bond

however what you get as a product is a

little bit different in this case you're

going to get the carboxylate salt and an

amine in our previous example the acid

hydrolysis gave us on a quaternary

ammonium salt and the carboxylic acid

where now we have the carboxylate salt

and the amine so what's going to happen

is you're going to have this sodium

and oxygen

come here

and the hydrogen come there

so this hydrogen is here now

and of course you have your carboxylate

now this is the simplest way to describe

this reaction and from this chemical

reaction it seems like the water itself

is not really being used but it is this

is a hydrolysis reaction this reaction

is a little bit more complicated than

what you're seeing but what i do want

you to know is that the sodium oxide is

going to come to make the carboxylate

salt and the hydrogen is going to come

to make the

amine so we're going to kind of simplify

it just a little bit in this reaction we

had n n-methylpropanamide

so there's my n-methyl one two three

propane amide reacting with sodium

hydroxide in the presence of heat to

create

sodium propanoate the propanoate is the

salt the sodium is the counter ion and

the amine is methylamine so let's try a

base hydrolysis of anamide this problem

asks us to draw the condensed structural

formulas and write the iupac names for

the products from the hydrolysis of

n-methylpentanamide with sodium

hydroxide so what is our given we have

our amide and methylpentanoid and we

have our base sodium hydroxide because

we have a base present then we know that

this is the base hydrolysis of an amide

and because we have a base hydrolysis

we know that we need to form a

carboxylate salt and an amine

let's try it

so here i've gone ahead and drawn the

amide we have n methylpentanomide

here's my n methyl one two three four

five carbons

in my amide so end methylpentanomide

reacting with sodium hydroxide now i

colored in the sodium oxide part of

sodium hydroxide blue so you could see

where that's going to go and the

hydrogen red so also we can pinpoint

where that's going to go

so let's go ahead and split up our

molecule in half here at the amide bond

right and we said that this portion the

sodium oxide is going to go with the

carbon of the carbonyl

and the hydrogen is going to go with the

nitrogen

to create the amine

the sodium oxide creates the carboxylate

salt so let's go ahead and draw our

products

so what we're going to get is

ch

ch2 ch2

ch2 that's 4

c double bond o

and then

we have our

o minus

n a

plus

this is our

carboxylate

salt

okay

so the sodium hydro sodium oxide bonded

to the carbon of the carbonyl now what's

my other product so my other product is

the amine

so i had n

ch3

h and now we have that hydrogen from the

base

so this gives me my amine

this compound here the carboxylate salt

is called sodium we have sodium

pentanoate

is the carboxylate salt and the amine is

methyl amine if you use the common name

which is

often used

or

methanoid

excuse me methanamine

if you're using iupacne

so these are our products

so let's check our solution we did get

sodium pentanoate as our carboxylate

salt and methanamine as our amine

so let's try this learning check

draw the condensed structural formulas

for the products from the hydrolysis of

the following amide with hcl so this

particular one is an acid hydrolysis

we're going to use water and acid

all right so this is an acid hydrolysis

we have n methylpropanamide

so n methyl one two three propane amide

reacting with water and hydrochloric

acid to produce

we know we need to get the carboxylic

acid right so we're gonna get a

carboxylic acid

plus an ammonium

salt okay so let's create

those two compounds

first we want to show where we're going

to break the molecule we're going to

break the amide bond that's the bond

between the carbon of the carbonyl and

the nitrogen of the amide i've colored

the different

atoms and the molecules that are

reacting with the amide um

sort of color coordinated so we can see

where those

different portions of the molecule are

going

um so for one we're going to create our

carboxylic acid right so

this particular region of the water

is going to

[Music]

bond

to

the carbonyl right the carbon of the

carbonyl that's going to create our

carboxylic acid then we're going to have

these hydrogens

interacting or bonding to the nitrogen

to create the ammonium ion and the

counter ion the chloride will bond

electrostatically to that ammonium ion

to create the ammonium salt so let's do

the first part we have our carboxylic

acid so let's draw it ch3

ch2

carbonyl oh this is one two three this

is

propanoic

acid

right and of course we probably want to

highlight this blue so we can show that

that came from the water

then we have our

ammonium ion

so n we had an r group which was a ch3

we had an a hydrogen

and now from the water comes one

hydrogen from the hcl comes another

hydrogen creating a positively charged

ammonium ion

and that is attracted to the counter ion

the chloride so what we have as our

product here is n

methyl

ammonium

chloride

and those are our two products for the

acid hydrolysis of this amide

so let's check our answer

we did get propanoic acid right and then

we got the

n methyl ammonium chloride they didn't

add in the counter ion here but i'm

going to go ahead and add in that

chloride because remember we said this

is an ammonium

salt in order to have the salt you need

both the plus and the minus

so this concludes our lesson on the

hydrolysis of amides this also concludes

the chapter 18 topics amines and amides

so here we have the concept map that

kind of summarizes what we learned in

this chapter

make sure that you do include this in

your notes because it is really helpful

so we have a means and a minds let's

start with the amines amines have a

nitrogen atom they are bonded to an

alkyl chain or an aromatic group and of

course it can be bonded to more than one

alkyl chain we did our classification of

primary secondary and tertiary amines

they are soluble in water up to six

carbons long right after five carbons

they start to struggle because the

molecule becomes more nonpolar

these react in water as a weak bases and

they're very weakly basic so they have

low kbs

and they're going to react with acids in

a neutralization reaction

amines can also be heterocyclic which

means that there's a nitrogen within the

carbon chain right within the carbon

ring

these amines can also act as

neurotransmitters neurotransmitters are

substances that create the nerve

impulses amines can react with

carboxylic acids to form amides

then amides can be broken down in a

hydrolysis reaction

to form either carboxylic acids and

ammonium salts or carboxylate salts and

amines depending on whether you use acid

hydrolysis or base hydrolysis

so this kind of summarizes what we

learned in this chapter