Principle:
Ethyl iodide is usually reacted with ethanol, iodine and red phosphorus, but the reaction is slow, and it needs to be heated in a reflux device for several hours.
Supplies:
Flask, straight condenser, beaker, red phosphorus, alcohol, iodine crystals, zeolite, 5% NaOH solution, anhydrous calcium chloride.
Operation:
2 g of red phosphorus and 25 ml of alcohol were added to a 125 ml flask, and 18 g of finely divided iodine crystals were added in portions under shaking, followed by the addition of 3 zeolites. A straight condenser was placed on the flask and allowed to reflux for half an hour by heating in a water bath. After the reaction is completed, the mixture is cooled, and the reflux straight condenser is discharged, and then the condenser is replaced with a common distillation apparatus. It should be noted that the receiver should be filled in a cold water bath to prevent the produced iodoethane from being volatilized.
The iodoethane was distilled off in a boiling water bath. The distillate can be transferred to a separatory funnel and browned as the liquid contains iodine. First wash the mixed ethanol with distilled water, then wash the free iodine with a small amount of 5% NaOH solution, and dry it with anhydrous calcium chloride in a condenser, then put it on a water bath for distillation, then there is iodine. When ethane is present, a fraction of 70 - 74 ℃ (343-347 K) can be collected. Pure ethyl iodide is a colorless oily liquid with a boiling point of 72.3 °C.
Remarks:
1. When preparing ethyl iodide, add iodine once. However, the added iodine should not be excessive, and the reaction will be exothermic, which will increase the temperature. Therefore, keep the reactants at 20 ℃ to prevent a large amount of volatile substances from being distilled out to cause loss. Iodoethane should be stored in a brown closed bottle to prevent problems with lightening and loss of volatilization.
2. The outlet tube of the distiller should be inserted under the water surface, and always pay attention to prevent back suction.
3. The experiment is not well controlled, and the purity of
iodoethane will have an effect. Methyl iodide is a highly toxic substance, and iodoethane also has certain toxicity. Please pay attention to safety protection.
