Wandlowski, Th. published the artcileStructural and Thermodynamic Aspects of Phase Transitions in Uracil Adlayers. A Chronocoulometric Study, Recommanded Product: 3-Methylpyrimidine-2,4(1H,3H)-dione, the publication is Langmuir (1996), 12(26), 6604-6615, database is CAplus.
The phase formation of uracil and 5 uracil alkyl derivatives on a Au (111) single crystal electrode from aqueous 0.05 M KClO4 was studied by using chronocoulometry, cyclic voltammetry, and phase-sensitive ac voltammetry. As a function of the applied electrode potential and/or the adsorbate concentration, uracil (U), 5-methyluracil (5-MU), and 5,6-dimethyluracil (5,6-DMU) exhibit 4 different adsorption regions. These are assigned to a “dilute” phase (I), a 2-dimensional condensed physisorbed film (II), a partial charge transfer/deprotonation region (III), and a chemisorbed film (IV). Substitution of the N (1)- and/or the N (3)-ring N with Me groups prevents the formation of the ordered physisorbed film II. In the case of 1-methyluracil (1-MU) and 3-methyluracil (3-MU), region I is followed immediately by regions III and IV. No indications for the latter 2 regions were found with 1,3-dimethyluracil, where both ring N atoms are blocked simultaneously with Me groups. Quant. thermodn. adsorption parameters (e.g., film pressure, Gibbs surface excess, Gibbs energy of adsorption, and electrosorption valence) were determined on the basis of chronocoulometric measurements for the “dilute” and the 2-dimensional condensed physisorbed film. All of these mols. are oriented parallel to the electrode surface in both ordered regions. The corresponding values of the Gibbs energies of adsorption ΔGI° and ΔGII° of the 6 uracil derivatives on Au (111) indicate weak chemisorption. On the basis of structural and energetic data, the formation of the 2D-condensed physisorbed film of U, 5-MU, and 5,6-DMU is interpreted as a replacement of residual interfacial H2O mols. accompanied by the creation of a 2D network of planar oriented and (via H bonds) interconnected mols. The adsorption and phase formation parameter obtained for the 6 uracil derivatives on Au (111) in regions I and II is complemented by anal. of selected (published) results on Ag (111) and Hg electrodes. No quant. thermodn. data were extracted in regions III and IV.
Langmuir published new progress about 608-34-4. 608-34-4 belongs to pyrimidines, auxiliary class Pyrimidine,Amide, name is 3-Methylpyrimidine-2,4(1H,3H)-dione, and the molecular formula is C19H14Cl2, Recommanded Product: 3-Methylpyrimidine-2,4(1H,3H)-dione.
Referemce:
https://pubchem.ncbi.nlm.nih.gov/compound/Pyrimidine,
Pyrimidine – Wikipedia