7-[4-(Diethylamino)-2-ethoxyphenyl]-7-(1-ethyl-2-methyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one

• CAS: 69898-40-4
• Catalog Number: ACM69898404
• Category: Main Products
• Molecular Weight: 483.60132
• Molecular Formula: C₃₀H₃₃N₃O₃
• Synonyms: 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(1-ethyl-2-methyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one ;3-(1-Ethyl-2-methylindol-3-yl)-3-(2-ethoxy-4-N,N-diethylaminophenyl)-4-aza-1(3H)-isobenzofuranone;3-(4-Diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphtha;3-(4-Diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methyl-1H-indol-3-yl)-4-azaphthalide;7-[4-(Diethylamino)-2-ethoxyphenyl]-7-(1-ethyl-2-methyl-1H-indole-3-yl)furo[3,4-b]pyridine-5(7H)-one;WinCon Blue 63 (7-[4-(diethylaMino)-2-ethoxyphenyl]-7-(1-ethyl-2-Methyl-1H-indol-3-yl) furo[3,4-b]pyridin-5(7H)-one );WinCon-Blue 63; 7-[4-(diethylaMino)-2-ethoxyphenyl]-7-(1-ethyl-2-Methyl-1;MB1
• IUPAC Name: 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(1-ethyl-2-methylindol-3-yl)furo[3,4-b]pyridin-5-one
• SMILES: CCN1C(=C(C2=CC=CC=C21)C3(C4=C(C=CC=N4)C(=O)O3)C5=C(C=C(C=C5)N(CC)CC)OCC)C
• InChI Key: RCVMSMLWRJESQC-UHFFFAOYSA-N
• Boiling Point: 669.1ºC at 760 mmHg
• Flash Point: 358.5ºC
• Density: 1.17g/cm³
• EC Number: 274-194-2
• Exact Mass: 483.25200

Case Study

Blue-63 as a Phthalide-Type Thermochromic Dye for Thermodynamic Characterization of Lactone-Zwitterion Equilibria in Aqueous Alcohol Solutions

Kim, J.-U., et al. (2015). Bulletin of the Korean Chemical Society, 36, 1980-1984.

Blue-63, 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(1-ethyl-2-methyl-1H-indol-3-yl)furo[3,4-b]pyridin-5(7H)-one, a phthalide-type leuco dye, functions as a reversible thermochromic probe whose temperature-dependent lactone-zwitterion equilibrium enables the quantitative determination of thermodynamic parameters through visible absorption spectroscopy.
Experimental Protocol: Blue-63 was synthesized via Friedel-Crafts condensation of quinolinic anhydride with N-ethyl-2-methylindoline and N,N-diethyl-3-phenetidine using zinc chloride catalyst in acetic acid-acetic anhydride, yielding a white crystalline product (72 percent, mp 358.3 degrees C). Stock solutions at 1.0 times 10^-3 M were prepared in methyl, ethyl, propyl, and butyl alcohols. UV-visible absorption spectra were recorded over the range 20.0 to 60.0 degrees C, monitoring the colored zwitterion band near 584 nm. Equilibrium constants were derived from absorbance changes, and enthalpy, entropy, and Gibbs energy changes were calculated using the van't Hoff equation.
Performance Evaluation: The visible absorption peak of Blue-63 decreased with increasing temperature in all alcohol solvents, confirming a shift toward the colorless lactone form at elevated temperatures. The enthalpy change in methanol was 21.77 kJ/mol. Equilibrium constants decreased systematically with longer alcohol carbon chains: 2.72 (methanol), 1.46 (ethanol), 1.28 (propanol), and 0.68 (butanol) at 293.15 K. A red shift in the absorption maximum was observed from 577.6 nm in methanol to 583.8 nm in butanol, attributed to reduced solvent polarity weakening electronic conjugation in the zwitterionic form.