. Can. J. Chem. 55, 4028 (1977).Protonation constants of several a-mercapto-a-aryl acrylic acids and constants for formation of complexes between these ligands and bivalent metal cations were determined by computerassisted analysis of pH-titration data. Ligand-metal ion mixtures in 50% (v/v) dioxane-water and in water, I = 0.1 M (NaC104) were titrated at 25'C with sodium hydroxide. Initial estimates of complex formation constants were refined with the SCOGS program. The ligands were shown to conlplex zinc(I1) and nickel(I1) metal ions avidly. These ligands potently inhibited the metal-dependent enzymes alkaline phosphatase, carboxypeptidase A, coeruloplasmin, and thermolysin. Partition of zinc(I1) between aqueous and n-butanol or n-octanol phases was enhanced in favor of the organic phase by several of these complexants.
This material did react with hydrazine to give an amino product (18) and subsequently a benzoyl derivative. However, neither of these has so far been purified or otherwise adequately characterized.«-Propyl 2-Thiazolothiazolecarbamate (19). To 2-thiazolothiazolecarbonyl hydrazide (12, 710 mg, 3.55 mmol) in 20 ml of aqueous hydrochloric acid, stirred with 400 ml of ether at 10°, was added 420 mg (5.9 mmol) of sodium nitrite. A precipitate of the azide was formed but was extracted by the ether as stirring was continued for 15 min. The ether phase and an ether extract of the aqueous phase was dried (magnesium sulfate and then Drierite) and then diluted with 100 ml of «-propyl alcohol. The ether was distilled and the alcohol solution was refluxed for 1 hr, concentrated to 10 ml, and allowed to stand at 20°. There was obtained 470 mg (55 %) of the «-propyl carbamate ( 19), mp 185-192°. The material was dissolved in ether, the solution was filtered and diluted with propyl alcohol, and the ether distilled to give colorless crystals, mp 192-194°. This process was repeated twice followed by sublimation (115-123°, 0.01 mm) for the analytical sample: mp 198-200.5°; uv Xmax 289 (log e = 4.22), 246 µ (log e = 3.78); ir Xmax
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