40870-70-0 BRN 2316303 CARBONIC ACID, (4,5-DIMETHYL-3,6-DIOXO-1,4-CYCLOHEXADIEN-1,2-DIYL)BIS(METHYLENE) Carbonic acid, (4,5-dimethyl-3,6-dioxo-1,4-cyclohexadien-1,2-diyl)bis(methylene)diphenyl ester