THE INTERACTION OF P-BENZOQUINONE WITH AMINO-ACIDS IN THE SOLID-STATE- A SPECTROSCOPIC INVESTIGATION

In the present work the results of a study of the solid state reaction between p-benzoquinone (PBQ) and some amino acids are reported. By gr inding equimolar amounts of PBQ and amino acid, a purple solid was obt ained, whose optical spectrum displayed a broad band centered at ca. 5 62 nm, for arginine. In addition, the solid product showed the presenc e of a radical species, whose identity seems to be different from the one reported in the aqueous solution reaction of the same reagents. In the solid state, the estimated radical concentration is at least two orders of magnitude greater than that estimated in the case of the pre vious study in solution. The resonance Raman spectrum also indicates t hat a different chromophore is involved as compared with the one repor ted in solution. All these points seem to indicate that the reaction m echanism in the solid state, although not yet clarified, is not the sa me from the one reported from the aqueous solution investigation.