Methyl orange CAS 547-58-0

Methyl orange is orange powder or flaky crystal, insoluble in ethanol, slightly soluble in water, and easily soluble in hot water. It is generally used as an acid-base titration indicator with a concentration of 0.1% (dissolve 0.1 g of methyl orange in 100 ml of hot water). It exists in the form of sulfonic acid in an acidic solution. The dimethylamino group forms an internal salt, which converts a benzene ring into a quinoid structure and turns red. Methyl orange is yellow in the form of sulfonic acid sodium salt in neutral or alkaline solution, and the pH value of the discoloration range is 3.1 to 4.4.