EFFECT OF SOLUTION ENVIRONMENT ON THE ABSORPTION MAXIMA OF SCHIFF BASES OF RETINAL *

Abstract— –Preliminary examination of the effect of solution environment on the electronic absorption spectrum of N‐retinylidene‐n‐butylamine(I) is reported. It is established that small amounts of CO2 dissolved in certain solvents cause the formation of the conjugate acid of I. This reaction is shown to be dependent on temperature and the concentration of CO2. The pKb of I in aqueous buffer was measured spectrophotometrically and found to be 8.71. Salts of I were prepared in a number of ways and their spectra were determined in selected solvents. The Λmax varies with method of preparation, and only one method gives reproducible results. The Λmnx is a function of the solvent in which the spectrum is determined. It was also found that the absorption maximum in wavenumbers is proportional to the negative logarithm of acid concentration.