Correlation of Biodegradability with Atomic Charge Difference and Superdelocalizability

Abstract

Five-day BOD values have been correlated with the difference in the modulus of atomic charge (Δ∣δ∣_X−Y) across a functional group bond X−Y within a congeneric series of compounds. For different congeneric series, the regression coefficients and intercepts of the correlation equations are very similar, so that the equations can be combined. Hence for 112 compounds comprising alcohols, phenols, ketones, carboxylic acids, ethers and sulfonates, we obtain: BOD = 1.105 × 10³ Δ∣δ∣_X−Y + 1.906, with r² = 0.978 and s = 4.308. It is shown that the electrophilic superdelocalizability on the carbon atom to which the functional group is attached correlates well with BOD, suggesting that the atom is the reactive centre controlling attack on a molecule.