The first synthesis of a crown ether (Section 11.16) by C. J. Pedersen (of the DuPont Company)

Question:

The first synthesis of a crown ether (Section 11.16) by C. J. Pedersen (of the DuPont Company) involved treating 1, 2-benzenediol with di(2-chloroethyl) ether, (ClCH2CH2) 2O, in the presence of NaOH. The product was a compound called dibenzo-18-crown-6. Give the structure of dibenzo-18-crown-6 and provide a plausible mechanism for its formation.