Abstract The photochemical behaviour of 1, 1, 4, 4-tetramethyl-2, 3-dioxotetralin (I) in the presence of oxygen has been thoroughly investigated in the solvents methanol and benzene. Products which are formed as a result of the presence of oxygen include α, α?-o- phenylenediisobutyric anhydride (II), α, α?-o-phenylenediisobutyric acid (III), the peroxy acid lactone (XXI), the lactone (XXV), α-(o-isopropenyl) phenylisobutyric acid (XXVII), and the ...