The chemical compound O -Phthaldialdehyde, also known as Phthalaldehyde, is an aromatic building block with the molecular formula C8H6O2 and a molecular weight of 134.13 g/mol. It has a Melting Point of 55.8 °C and a Boiling Point of 83 °C at 0.8 mm Hg. This substance has a relative Vapour Density of 4.6 compared to air. Due to its flammability and toxicity, it carries the GHS signal word "Danger" and hazard statements for both flammable solids and acute oral toxicity.

• CAS Number: 643-79-8
• Molecular Formula: C8H6O2
• Molecular Weight: 134.13
• Exact Mass: 134.036779430
• Boiling Point: Boiling Point: 83 °C at 0.8 mm Hg
• Melting Point: 55.8 °C
• Density: Relative Vapour Density (air = 1): 4.6
• GHS Signal Word: Danger
• Hazard Statements:
• H228 (44.3%): Flammable solid [Danger Flammable solids]
• H301: Toxic if swallowed [Danger Acute toxicity, oral]