1) After the reaction, the mixture was poured into 50 ml of water and washed to remove other water-soluble components. For example, the reactant sulfuric acid can form fake salt with ether and dissolve in the ether layer. After adding water, sulfuric acid will be dissolved in water, and the sulfuric acid in the ether layer will be removed, and the residual n-butanol will also be partially dissolved in water, thus removing impurities; At the same time, the water generated by the reaction is limited, which is not conducive to the liquid separation operation. After adding water, the stratification is obvious, and the large amount is convenient for operation and reduces the error;

2) washing with 5% NaOH solution can still remove the residual acid, because the acid will not be completely washed off by the previous washing, and it needs to be washed with alkali again to remove it;

3) In general teaching experiments, CaCl _ 2 solid is used for drying instead of washing and rinsing with CaCl _ 2 solution, so as to remove a very small amount of water left after liquid separation. Please pay attention to repeat, or ask the tutor directly if this step is reasonable. If CaCl2 _ 2 _ 2 solution is used, it is difficult to distill it later.

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