Synthesis database: Lithium ethoxide synthesis

Lithium ethoxide can be synthesized by reacting ethanol with lithium metal. In a similar way, one can obtain ethoxides of other alkali metals as well. Alkoxides are used for many different purposes - one of them is also the synthesis of various ethers.

The reaction is as follows:

2Li + 2C₂H₅OH -> 2C₂H₅OLi + H₂

For the synthesis of this compound, along with ethanol and lithium, one also needs to prepare a flask or some other type of beaker in which the reaction will be carried out. In case the ethanol contains a small amount of water, it is also useful to have a funnel and some filter paper nearby, so that any eventually formed lithium hydroxide could be filtered and thereby separated from the lithium ethoxide solution.

In this case, the goal was to make a saturated solution of lithium ethoxide in ethanol. Because of that, 144 grams of ethanol (3.13 moles) was taken, and reacted with 2.9 grams of lithium (0.41 moles). The weight of the resulting ethoxide was approximately 21.3 grams. This amount of ethoxide was dissolved in the 125.1 grams (158.6 mL) of the remaining ethanol. The mentioned suggests that 100 mL of ethanol contained approximately 13.4 of lithium ethoxide. However, in reality, the amount of lithium ethoxide is a bit lower, since some of the lithium has reacted with traces of water present in the ethanol. Normally, 100 mL of ethanol can dissolve approximately 12.5 grams of this compund (at room temperature).

The reaction is not overly vigorous. However, the solution heats up somewhat. Because of that, it is a good idea to add the lithium slowly to the ethanol. In the end, a slightly yellow colored solution is obtained, which exhibits alkaline properties.