The solvent still is a widely used technique to generate moisture, oxygen, and p

Question

The solvent still is a widely used technique to generate moisture, oxygen, and peroxide free solvents. In a THF solvent still, what chemical should be used as the drying reagent (to remove water, oxygen etc.)? What is used as indicator? When the color of the indicator turns from ______ to ______, it means the THF is no longer in an oxygen or moisture free condition. What are potential risks and the safety procedures regarding the usage of a THF solvent still? If it catches a fire, what type of fire extinguisher should be used?

Explanation / Answer

What is used as indicator? sodium and Benzophenone

When the color of the indicator turns from white to dark blue ,

What are potential risks and the safety procedures ?

handling sodium wire is very tedious thing since it catches fire very easily. sodium will be coated with wax layer that should be dissolved in hexane then we will make sodium wire. As well we have to keep methanol near incase any little bit sodium is spilled that can be quenched with methanol .

If it catches a fire, what type of fire extinguisher should be used?

Type D fire extinguisher especially made for metal fire that should be used

Procedure

THF (Tetrahydrofuran): distilled from sodium benzophenone ketyl. Add sodium wire and benzophenone to a volume of THF, heat at reflux/under nitrogen for several hours until the solvent turns deep blue in colour. This indicates the solvent is dry, and you can distill off the volume you require. With time the still will turn orange, this indicates that it is time to make a new one!

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