2. A Level Chemistry A Topic Exploration Pack – Organic Synthesis Identifying functional groups

3. At A Level there are many functional groups to recognise and memorise
At A Level there are many functional groups to recognise and memorise. One way to deal with this large amount of information is to break it into chunks.
On the following slides, the functional groups have been grouped with other similar groups.
The names of the groups (like ‘simple functional groups’) are not official titles. They are just a reference for this activity, and you don’t need to learn them.

4. Simple functional groups
Type of compound
Functional group
Alkene
C=C
Amine
–NH2
Alcohol
–OH
Nitro compound
–NO2
Haloalkane
–Cl; –Br; –I
Nitrile
–CN
Alkenes include a double bond. The other groups are attached to the carbon chain or a benzene ring.

5. Simple carbonyls
Type of compound
Functional group
Aldehyde
Ketone
These have an oxygen atom double bonded to a carbon, which itself is bonded to only carbon and/or hydrogen.

6. Compound carbonyls
Type of compound
Functional group
Carboxylic acid
Acyl chloride
1° amide Cl
These have an oxygen atom double bonded to a carbon, which is bonded to another atom other than carbon or oxygen.

7. Bridging groups
Type of compound
Functional group
Ester
2° amide (peptide)
Acid anhydride
Here, a carbon is double bonded to an oxygen and bonded to another atom other than carbon or hydrogen. This atom in turn is bonded to another carbon chain.

8. Organic salts
Functional group
Diagram
Carboxylate salt
Phenoxide salt
These have a metal ion bonded to an oxygen ion. The metal is most commonly sodium.

9. Aromatics / arenes
These contain a benzene ring, often with alkyl groups or other functional groups attached.

10. Phenols
These contain a benzene ring with a –OH group directly attached, often with other alkyl groups or functional groups attached.

11. Identifying the groups
When given a complex unknown molecule it is important to be able to rule out certain groups to make identifying it easier.
The following flow chart should help you to reduce the number of options down quickly.
The blue boxes are key questions to help you rule certain options in or out.

12. Does the main chain contain anything but carbon?
Is there a benzene ring?
Does the main chain contain anything but carbon?
Is there a –OH directly attached?
Does it have a C=O bond No
Phenols
Aromatics
Bridging
groups
Compound
carbonyls
Does the carbon have any other groups attached?
Simple
functional groups
Yes

13. Tasks
The worksheet contains pictures of molecules. For each molecule you need to identify all of the functional groups.
For an extra challenge, have a go at naming the basic compounds.
The advanced molecules are intended to have some discussion points for the group.

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