General Chemistry Online: Methyl Orange

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Methyl Orange

Here is the structure of methyl orange in acidic solution:

Methyl orange in acidic solution.
Click the image for a 3D Chime structure.

The molecule absorbs blue-green light, which makes its solution appear red. Notice that the nitrogen bearing the positive charge is involved in a double bond.

In the basic form of methyl orange, a hydrogen ion is lost from the -NN- bridge between the rings, and the electrons formerly used to bind the hydrogen neutralize the positive charge on the terminal nitrogen, so that it is no longer able to pi-bond. Solutions of the methyl orange appear yellow in alkaline solution.

Methyl orange in basic solution.
Click the image for a 3D Chime structure.

General Chemistry Online! Methyl Orange