Download Chemistry activity 10 organic structures

Organic Structures
Target Audience
Students studying A2 Chemistry who are interested in organic chemistry, chemical structures, synthesis.
Key Concepts
Organic chemistry, functional groups, chemical structures.
The Activity
How organic molecules react depends on the functional groups they contain. Very often during a
reaction the carbon backbone of a molecule remains unchanged and the action takes place at the
heteroatoms – that is, the atoms other than carbon and hydrogen. The most common heteroatoms in
organic molecules are oxygen, nitrogen, then perhaps sulfur and phosphorus and the halogens.
One useful strategy for making sense of the multitude of functional groups is to identify the functional
group level for a carbon atom in a particular group. This is simply the number of bonds that carbon
atom has to heteroatoms. For example, alcohols, or amines or halides are Level 1 functional groups
since the carbon atom has just one bond to the heteroatom. Aldehydes and ketones are Level 2 since
the carbon has two bonds to oxygen. Carboxylic acids, esters, amides, acyl chlorides are all examples
of Level 3 functional groups.
Changing from one functional group to another with the same level simply involves changing one
heteroatom for another, whereas going up a level generally requires an oxidising agent. To go down a
level requires either a reducing agent to put in a hydrogen, or some sort of carbon nucleophile to
create a new C—C bond.
Two limitations of this classification are that it cannot easily be applied to carbon atoms doubly or triply
bonded to other carbon atoms and that the heteroatoms should not be electropositive, i.e. not metals.
In this activity you will investigate a wide range of organic molecules and use this system of
classification to make sense of the functional groups they contain. Start with valium, ecstacy
and narcotine. Look up the structures of these molecules then identify, name and classify the
functional groups they contain. Once you have done this, move onto your own choice of
molecules. Aim to work on at least 12 different molecules.
Background Knowledge
The use of skeletal formulae for organic structures is useful, and some basic knowledge of organic
chemistry is helpful.
Resources
Any source to find organic structures! You could use IUPAC Nomenclature of Organic Chemistry http://www.acdlabs.com/iupac/nomenclature/.
Outcomes
This activity has many possible outcomes, for example, a report, display, or presentation.
Helpful hints
• You might like to see how many different functional groups you can find within one molecule.
Going further
Look back at the organic reactions you have studied during your course and see how the functional group
level changes during the course of each reaction. Does thinking about the functional group level help you
remember, or work out, if the reaction is an oxidation, reduction, hydrolysis or substitution?