What is the white precipitate that forms when benzophenone is added to your grignard solution?

Phenols have a general acidic character and they react with Grignard solutions similarly to how water would react. The product is that the Mg group of the Grignard reaction is replaced with a H (that is easily available due to the acidity of phenols) and we have that Mg (OH) X is created. The grignard solution is: R-Mg-X. This metal hydroxide creates a white solid compound that is not soluble in ether and it is what you should see after adding phenol to the solution.