The Collaborative International Dictionary of English v.0.48:

Disacquaint \Dis`ac*quaint"\, v. t. [Pref. dis- + acquaint: cf.
   OF. desacointier.]
   To render unacquainted; to make unfamiliar. [Obs.]
   [1913 Webster]

         While my sick heart
         With dismal smart
         Is disacquainted never.                  --Herrick.
   [1913 Webster]