20.2 Synthetic Routes

In order to change one substance into another you need to be able to alter functional groups.

These are the interconversions needed for non-aromatic compounds.

QUESTION: Under what conditions could you convert Methane (CH₄) to Chloromethane (CH₃Cl). Write an equation. What class of reaction is this?

QUESTION: Under what conditions could you convert Ethene (C₂H₄) to Chloroethane (C₂H₅Cl). Write an equation. What class of reaction is this?

QUESTION: Under what conditions could you convert Chloroethane (C₂H₅Cl) to Ethanol (C₂H₅OH). Write an equation. What class of reaction is this?

QUESTION: Under what conditions could you convert Ethanol (C₂H₅OH) to Ethanoic Acid (CH₃COOH). Write an equation. Write an equation using [O] to represent the oxidising agent.

QUESTION: Under what conditions could you convert Ethanol (C₂H₅OH) to Ethanal (CH₃CHO). Write an equation using [O] to represent the oxidising agent.

QUESTION: Under what conditions could you convert Ethanoic Acid (CH₃COOH) to Ethanol (C₂H₅OH). Write an equation. Write an equation using [H] to represent the reducing agent.

QUESTION: Under what conditions could you convert Ethanal (CH₃CHO) to Ethanol (C₂H₅OH). Write an equation. Write an equation using [H] to represent the reducing agent.

QUESTION: Under what conditions could you convert Ethanol (C₂H₅OH) to Ethyl MEthanoate (HCOOC₂H₅). Write an equation.

QUESTION: Under what conditions could you convert Benzene (C₆H₆) to Nitrobenzene (C₆H₆NO₂). Write an equation.

Chemists are usually trying to find ways of making a known substance that is not easily available from another substance that is cheap and readily available.

If the starting material is known then we can think about what we can do to its functional groups.

And we can think about what we can turn into the functional groups on the desired products.

Hopefully, we’ll be able to meet in the middle.

Eg. How could we convert Ethene into Ethyl Ethanoate.

STEP 1. How do we make Esters? Which two reactants are needed?

STEP 2. Which reactant can be made directly from the starting reagent? How?

STEP 3. Can we make the other reactant from the first reactant? How?

QUESTION: How could we convert Propene into Propanone.

STEP 1. How do we make ketones?

STEP 2. Which alcohol is needed? Can we make it directly from Propene? How?

Note. We could do this as a three step synthesis. Or a four step synthesis. Suggest how?

Why would we usually prefer a 2-step synthesis to a 3 or 4 step one?

QUESTION: How could we convert Benzene into Phenylamine.

STEP 1. What can we make Phenylamine from?

STEP 2. Can we make this substance from Benzene? How?