Making a Halogenoalkane
- One way in which a halogenoalkane can be made, is to start with an alcohol and then replace the ľOH group with a halogen atom:
- The preparation of an organic compound usually occurs in four stages:
- The carrying out of the reaction.
- Separating out the required product from the reaction mixture.
- Purifying the product.
- Testing the product to check that it is a pure sample of the required compound.
Carrying out the reaction
Separating the product from the reaction mixture
- The mixture contains the product 2-chloro-2-methylpropane, 2-methylpropan-2-ol, HCl, and water.
- There should be two layers in the separating funnel, one containing the organic substances, and the other the inorganic substances.
- We want to collect the organic substances, so the bottom layer is filtered off.
Purifying and testing the product
- Most of the impurities should have been removed, except for a small amount of 2-methylpropan-2-ol, which will be dissolved in the 2-chloro-2-methylpropane.
- This can be separated by carrying out a distillation, as 2-chloro-2-methylpropane has a lower boiling point than 2-methylpropan-2-ol.
- The product can now be tested to ensure that it is pure.
Useful books for revision:
Revise AS Chemistry for Salters (Written by experienced examiners and teachers of Salter's chemistry)
Revise AS Chemistry for Salters (OCR) (Salters Advanced Chemistry)