How to Synthesise Organic Compounds

Step-by-Step Guide

1. 1

   Step 1: Check if the starting chemical is a mixture.

   If your starting chemical is something like crude oil, you'll need to use distillation or fractional distillation to separate it into parts. , For example, they may contain an amine group or a carboxyl group, etc., You may need to crack the starting chemical into smaller parts.
   
   In our example, we need to crack the crude oil to obtain benzene and ethene., For the starting chemical, put the chemical in the middle, then draw arrows coming out of it showing all of the reactions it can be used in.
   
   For the target chemical, draw arrows going inwards, showing all of the reactions that can make it., More often than not, you'll have to change one functional group into another.
   
   For this, there is no shortcut: you have to learn how the different functional groups react., In our example, we need to change the ethene into ethanoyl chloride.
   
   How to do this? React it with water to change it into ethanol, then oxidise it to ethanoic acid.
   
   Then, react it with thionyl chloride to turn it into ethanoyl chloride.
   
   No shortcuts; just learn the reactions., Some functional groups are unnecessary.
   
   They need to be removed.
   
   Probably the easiest way to do this is to convert them into an alkene group, then react it with hydrogen to get rid of the double bond.
   
   If you need to remove carbon chains, crack it.
   
   Cracking can be accomplished with a zeolite catalyst and a slight pressure. , For carbon chains, one way is to use free radical substitution to add a halogen (chlorine, bromine etc.), then use other reactions to replace it with the group that you need.
   
   For aromatic compounds (e.g. benzene) there are specialised reactions (nitration, friedel-crafts acylation etc.) to add groups to the aromatic ring.
   
   In our example, we need to add an OH group and an NH2 group to the benzene ring.
   
   If we were starting with cumene, we could oxidise it to phenol and acetone.
   
   This is the most common way to add an OH group to a benzene ring.
   
   However, we are starting with benzene, not cumene.
   
   Fortunately, there's another way: oxidise the benzene directly using nitrous oxide, N2O.
   
   After that, simply react the phenol with nitric and sulphuric acid, then reduce it to get the NH2 group on to the compound. , After you've made the parts of your molecule, you'll need to stick them together.
   
   Acyl chlorides will react with a variety of groups: alcohols, water, ammonia and amines, mainly.
   
   This allows you to join two groups via an oxygen or nitrogen atom.
   
   In our example, the amine on the aromatic compound reacts with the chlorine in the ethanoyl chloride to give paracetamol and hydrochloric acid. , A grignard reagent consists of an organic chain, R, bonded to a magnesium atom, bonded to a bromine atom, like this:
   R
   - Mg
   - Br.
   
   The will react with a carbonyl, R
   - C(=O)
   - R, to form an alcohol, R
   - C(-OH)(-R)
   - R.
   
   Notice that this compound has an extra organic group.
   
   This group has been added by the grignard reagent.
2. 2

   Step 2: See if the starting and target chemicals have any groups in common.

3. 3

   Step 3: If the starting chemical is a mixture

4. 4

   Step 4: look at which parts can be used.

5. 5

   Step 5: Draw a spider diagram.

6. 6

   Step 6: Learn how the functional groups react.

7. 7

   Step 7: Try with an example.

8. 8

   Step 8: Remove unnecessary functional groups.

9. 9

   Step 9: Add groups if needed.

10. 10

    Step 10: Join your groups.

11. 11

    Step 11: Use grignard reagent if you need to directly join two carbon chains.

Detailed Guide

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