Extending the Solvent Acidiy Scale to Highly Acidic Organic Solvents: The Unique Photophysical Behaviour of 3,6-Diethyltetrazine
The SA scale, developed previously for weakly acidic solvents, was extended to include the most acidic solvents (haloalcohols and carboxylic acids) by using a unique solvatochromic probe (3,6-diethyl-1,2,4,5-tetrazine). The proposed new solvent scale has a number of advantages over widely used alternatives such as that based on Gutmann's acceptor number (AN). As shown in this paper, SA data provide an accurate description of the effect of solvent acidity on various chemical properties.