Tentative schemes for the naphthoquinonic ring biosynthesis are presented, involving o-carboxyphenylpyruvic acid as an intermediate. A possible derivative of this intermediate, o-carboxy[1-14C]phenylacetic acid was synthesized, but could not be incorporated in dihydromenaquinone-9, lawsone or juglone....
We have measured calorimetrically the enthalpies of solution of superconducting YBa2Cu3O7δ (δ = 0.09) which has a Tc(off-set) of 90 K and semiconducting Y2BaCuO5 in IN HCl aqueous solution at 298 K. The standard enthalpies of formation of YBa2Cu3O7δ and Y2BaCuO5 have been ...