SolutionsAdditional Topics
1. What comes with the product?
At the end of a reaction, which three kinds of substances usually accompany the desired product?
- By-products from side reactions or decomposition.
- Reagents that did not react (starting material).
- Salts and impurities from the reaction medium.
2. Choose the method
Which method would you use in each case? a) To separate two liquids boiling at 78 °C and 100 °C. b) To separate benzoic acid from naphthalene, both dissolved in ether. c) To find out which functional groups an unknown, already purified compound has.
- Fractional distillation: the boiling points are very close.
- Acid-base extraction: with aqueous NaOH the acid passes into the water as sodium benzoate and the naphthalene stays in the ether.
- Infrared (IR) spectroscopy.