when we are synthesis n-butyl bromide what impurities we can expect in the crude product?and how would these impurities react with concentrated sulfuric acid?and also how we can make t-butyl bromide?
barood
When synthesizing n-butyl bromide, some common impurities that can be present in the crude product include unreacted n-butanol (starting material), excess hydrogen bromide, and side reaction products such as isobutyl bromide and tert-butyl bromide.
These impurities may react with concentrated sulfuric acid differently:
1. Unreacted n-butanol: It would undergo esterification with concentrated sulfuric acid to form an alkyl hydrogen sulfate. The reaction can be represented as follows:
n-butanol + H2SO4 → n-butyl hydrogen sulfate
2. Excess hydrogen bromide: It would react with sulfuric acid to form hydrogen bromide adducts:
HBr + H2SO4 → HBr·H2SO4
3. Isobutyl bromide: It can undergo halogenation with sulfuric acid to form isobutylene and hydrogen bromide:
(CH3)2CHCH2Br + H2SO4 → (CH3)2C=CH2 + HBr
4. tert-Butyl bromide: It can also undergo halogenation with sulfuric acid to produce tert-butyl hydrogen sulfate and hydrogen bromide:
(CH3)3CBr + H2SO4 → (CH3)3COSO3H + HBr
To prepare tert-butyl bromide, you can follow the following synthetic route:
1. Begin with tert-butyl alcohol (2-methylpropan-2-ol).
2. Add hydrogen bromide (HBr) dropwise to the tert-butyl alcohol while maintaining a low temperature, typically around 0-5°C. This should be done in a well-ventilated fume hood due to the release of HBr gas.
3. After the addition is complete, warm the reaction mixture to room temperature and let it stir for a few hours to ensure complete reaction.
4. Extract the crude tert-butyl bromide using a suitable organic solvent such as diethyl ether.
5. Wash the organic layer with water to remove impurities and then dry it with anhydrous magnesium sulfate (or another drying agent).
6. After drying, evaporate the organic solvent to obtain pure tert-butyl bromide.
It is important to note that synthesizing organic compounds, including n-butyl bromide and tert-butyl bromide, should be conducted in a well-controlled laboratory environment by professionals with proper training and safety precautions in place.