L,3-Diethyl-2-thiobarbituric acid

DMQPH = 6,7-dimethoxy-l-methyl-2(177j-quinoxalinone-3-proprionylcarboxylic acid hydrazide, HCPI = 2-(4-hydrazinocarbonylphenyl)-4,5-diphenyli-midazole, DBPM = 7V-[4 (6 dimethylamino-2-benzofuranyl)phenyl]maleimide, DNS-H = dansyl hydrazine, DBD H = 4 (AA -dimethylaminosulphonyl) 7-hydrazino-2,l,3-benzoxadiazole, DETBA = l,3-diethyl-2-thiobarbituric acid, DCIA = 7-dimethylamino-3- 4-[(iodoacetyl)amino]phenyl -4-methylcou marin, m-CED = 1, 2-bjs(3-chlorophenyl)ethylenediamine. 

In this study 5-(Quinoline-2-ylidene)-l,3-diethyl-2-thiobarbituric acid have been synthesized via Knoevenagel condensation reaction, the product solutions were prepared lO -lO M in CHCI3, THF, MeOH, DMF and DMSO. UVA IS spectra recorded and then compared at each other. Absorbance of the solutions were measured at 200-300 nm. The maximum absorbance value increased and a new absorption appeared at 400-500 nm. The samples were excited at 337 nm in order to measure fluorescence. The maximum emission was observed in MeOH at 398 nm. These values increased by time therefore, the samples were not stable in solution state. 

The Xr Scale. In 1964, Brooker and co-workers (346) suggested the use of the solvent induced bathochromic shifts of the 1,3 diethyl-5-[5-(2,3,6,7-tet-rahydro- 1H,5H- benzo- [(/]- quinolizin-9-yl)-l,3-neopentylene-2,4-pentadie-nylidene]-2-thiobarbituric acid (III) as measures of medium polarity. 

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