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Organic Synthesis Reactions: Worked Example 1

How to transform 1-chloropropane into ethyl propanoate

Organic Synthesis

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Lesson Transcript

1. It’s A Syn
2. Organic Synthesis: Year 12 Recap
3. Organic Synthesis: Year 13 Part 1
4. Organic Synthesis: Year 13 Part 2
5. Organic Synthesis: Aromatic Compounds
6. Multi-step Synthesis
7. Conversion of Primary Alcohols to Carboxylic Acids
8. Designing an Organic Synthesis: Worked Example 1
9. Designing an Organic Synthesis: Worked Example 2
10. Designing an Organic Synthesis: Worked Example 3
11. Designing an Organic Synthesis: Worked Example 4
12. Tips for Answering Synthesis Questions
13. Synthesis Questions
14. Choosing a Route: Limitations of Reaction Types
15. Choosing a Route: Waste
16. Choosing a Route: Solvent and Starting Materials

In a two-step synthesis, propyl ethanoate can be formed from 1-chloropropane

Draw the structure of compound A…

And suggest reagents and conditions for each step.

Now, to answer this question, we should first look at the functional groups of the compounds we’re given

This compound contains a chlorine atom, so it’s a…

This compound is a halogenoalkane…

And this compound is an ester.

Next, we look at the number of carbons in each compound

So, this compound contains…

Our halogenoalkane contains three carbons…

But our ester contains an additional two carbons here.

So, we know that to make this ester, we need to:

Remove the chlorine atom…

Add an ester functional group…

And add two carbons to the molecule.

Now, we’ve seen that we can make an ester by reacting…

We can make an ester by reacting an alcohol with either a carboxylic acid, acyl chloride or acid anhydride

So, we know that compound A is going to be one of these four types of compound

And of these, we know how to convert a halogenoalkane to a…

Of these options, we’ve only seen how to convert a halogenoalkane to an alcohol

So, compound A must be…

When we convert a halogenoalkane to an alcohol, the halogen is substituted for an alcohol group

So, compound A must be propan-1-ol!

Now that we’ve got the structure of compound A, we can focus on how to add this two carbon chain.

We’ve seen that to form an ester, we can either react our alcohol with a carboxylic acid, an acyl chloride or an acid anhydride

So, which of these compounds could we react with the alcohol?

Both of these compounds would react with the alcohol to form this ester.

However, as we only need to write down one, let’s go with the carboxylic acid!

So now we’ve got the structure of compound A…and a reagent in step 2.

All we need to do now is fill in the remaining conditions for step 2…

And give reagents and conditions for step 1!

So, for step 1, we need…

To convert a halogenoalkane to an alcohol, we need an aqueous hydroxide, like sodium hydroxide, and heat.

And for step 2, we need…

For step 2, we need to heat the alcohol and carboxylic acid together with an acid catalyst like sulfuric acid

And now, this is our complete synthesis!

Up Learn – A Level Chemistry (aqa) – Organic Synthesis

Organic Synthesis Reactions: Worked Example 1

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