Lactonization of various diols, using transition metal-substituted keggin catalysts [PW11MO40]7-, (M= Co(II), Ni(II), Cu(II), Zn(II)

Potassium salts of the monosubstituted Keggin polyoxometalates, [PW11MO40]7-, (M= Co(II), Ni (II), Cu(II), Zn(II), were used as catalysts for lactonization of 1,4-butane diol, 1,6-hexane diol and 1,2-benzene dimethanol, in the presence of hydrogen peroxide as an oxidant. The effects of various parameters such as amount of the oxidant and diol, solvent type, temperature and reaction time have been studied. The results show that [PW11CoO40]7- as catalyst in chloroform produce the highest yield of lactone.