# NaI in acetone v/s acetone and water

When NaI is in acetone and we have R-X, then I replaces X by Finklestein mechanism (Sn2 => Inversion). But when we have acetone and water, why do we get a racemic mixture?

• The Wilipedia data indicate that $\ce{NaI}$ has between one-third and one-fourth as soluble in acetone as in water. Another factor could be dissociation of the salt (thus availability of the iodide ion for multiple exchange reactions), which is less in most nonaqueous solvents than in water. – Oscar Lanzi Jun 18 '16 at 12:55