No abstract

Trihydroxy-3-methylbenzoic acid was obtained by NaHCO 3 carboxylation of 2,4,6-trihydroxytoluene. The heterocyclization and esterifi cation of the above acid were studied.

2,4,6-trihydroxytoluene (methylphloroglucinol) is a promising reagent in organic synthesis, after development out getting it from 2,4,6-trinitrotoluene. We previously synthesized of derivatives of 5,7-dihydroxy-2H-1-benzopyran-2-ones by the interaction of 2,4,6-trihydroxytoluene and 2,4,6 -trihydroxy-3-methylbenzoic acid with polyfunctional carbonyl compounds. The first time, a detailed analysis of the electronic absorption and fluorescence spectra of derivatives of 5,7-dihydroxy-2H-1-benzopyran-2-ones is carried out. In the electronic absorption spectra of the studied compounds, the absorption in the long-wavelength region of the spectrum is determined by electronic transitions with intramolecular charge carry. The possibility of controlling the bathochromic or hypsochromic shift of the long-wavelength absorption band by introducing substituents of various electronic nature into the molecule has been revealed. It was shown that some of the studied compounds have pronounced luminescence in the blue-green region of the spectrum (390–508 nm) with a quantum yield of 9–40%. The highest quantum yield (38%) was achieved when the 5,7-dihydroxy-2H-1-benzopyran-2-one carboxyl group was introduced into position 6. The bromination of this compound leads to a decrease in the quantum yield to 9.5 % The introduction into the 3 position of 5,7-dihydroxy-4,8-dimethylchromen-2-one phenyl substituted fragment along with O-acylation leads to a sharp decrease in the quantum yield. It is concluded that the studied objects are promising as basic structures for the search for new biosensors.

No abstract

Ten new complexes of 2,4,6–trihydroxy-3-methyl benzoic acid (methylphloroglucinol, L1) and 2,4,6–trihydroxy benzoic acid (phloroglucinol, L2) are isolated in the solid state, and their formulae were detected.The spectroscopic methods indicate that the coordination of  L1 and L2 to the metallic ions occurs through one of the O-atom of the deprotonated carboxylic group and an O atom of the non-deprotonated neighboring hydroxy-group (bidentate chelating coordination). The schemes of the structure of complexes are proposed.The complex formation in solution is studied, and formation constants are calculated. It is shown that for the metal complexes of the 1st transitional series, the formation constants for the complexes are arranged as Mn(II) < Co(II) < Ni(II) < Cu(II) > Zn(II). The obtained results correlate with the Irving-Williams Series.