Original sentence: The black potassium salt K4C6O6 was prepared by West and Niu in 1962.and the greenish-black sodium salt Na4C6O6 was described by Fatiadi and Sanger in the same year
Edited sentence: The black tetrapotassium salt K4C6O6 was prepared by West and Niu in 1962, by reacting THBQ with potassium methanoate in methanol.The dark purple and insoluble dipotassium salt K2C6H2O6 was prepared by Preisler and Berger in 1942, by oxidizing inositol with nitric acid and reacting the result with potassium carbonate in the presence of oxygen.The greenish-black sodium salt Na4C6O6 was described by Fatiadi and Sanger in 1962