PREPARATION OF HYDROXY DERIVATIVES OF 7,12-DIMETHYLBENZ(A)ANTHRACENE- 8-HYDROXY-7,12-DIMETHYLBENZ(A)ANTHRACENE, 10-HYDROXY-7,12-DIMETHYLBENZ(A)ANTHRACENE, AND 11-HYDROXY-7,12-DIMETHYLBENZ(A)ANTHRACENE