I remember using both 95% ethanol and absolute ethanol quite a few times. You'd need absolute ethanol for a reaction that would fail if water was present, such as a Grignard reaction. I can't remember whether the absolute ethanol was in an ordinary bottle or the type with a rubber septum (where you keep the liquid under nitrogen to avoid contact with air). If the ethanol was to be used as a reagent, a septum bottle would be more appropriate.
http://boards.straightdope.com/sdmb/showpost.php?p=5314683&postcount=10
First, why would one use ethanol for a Grignard reaction? If a Grignard is destroyed by water (as suggested by the poster) then wouldn't a Grignard also be destroyed by ethanol?
I'm guessing that the poster just forgot all his chemistry. Ironic for someone posting on a message board that proclaims to be "fighting ignorance since 1973."
Second (assuming that one could somehow run a Grignard reaction in ethanol), do you really need anhydrous ethanol for Grignard reactions to work? Why not just use a slight excess of Grignard to account for the water present in 95% ethanol? Seems to me that anhydrous ethanol would be pretty expensive given that the usual distillation methods wouldn't get you from 95% ethanol to 100% ethanol.
Finally, is there a reaction in which using excess Grignard to account for acidic protons wouldn't chemically work in some way?