The diamagnetic susceptibilities of phthalic acid and phthalic anhydride

Summary

• 1. The gram-molecular susceptibilities of carefully purified samples of phthalic acid and its anhydride are determined. The susceptibilities are: Phthalic acid, X_m=−81·24×10⁻⁶ Phthalic anhydride, X_m=−67·31×10⁻⁶ It is found that whereas the value of the gram-molecular susceptibility of phthalic acid found by Gray and Birse and ourselves is nearly equal, that for the anhydride is higher in our case.

• 2. The difference in gram-molecular susceptibilities of dibasic acids and their anhydrides is nearly equal to that of water with minor variations, possibly due to different structures attached to the anhydride rings.

• 3. The constitutive effect of the rings in the anhydrides of different dibasic acids has also been discussed.