G. I. Koldobskii

Tetrazoles. 10. Acid-base properties of 5,5′-ditetrazolyls

The constants of detachment (pKa 1.41 and 4.25) and addition (pKBH −5.47 and −10.91) of protons for 5,5′-ditetrazolyl and of protonation of 1,1′-diphenyl-5,5′-ditetrazolyl (pKBH+ −7.47) in aqueous solutions were determined by spectrophotometric and potentiometric methods. By comparison of the acid-base properties of the two compounds it was established that the latter exists in the trans form.

Tetrazoles. 13. Protonation of tetrazolylacetic acids

The protonation of isomeric 1H-, 2H-, and 5H-tetrazolylacetic acids, as well as a series of 5-aryl-1H- and 5-aryl-2H-tetrazolylacetic acids, in aqueous sulfuric acid solutions was studied by IR, UV, and PMR spectroscopy. It is shown that all of the investigated tetrazolylacetic acids are protonated in the tetrazole ring at sulfuric acid concentrations up to 96%; the proton adds to the nitrogen atom in the 4 position.