4-Ethynylbenzoic acid may be used in the synthesis of N-(4-ethynylphenylcarbonyl) L-glutamic acid diethyl ester, a precursor for synthesizing glutamic acid-based dendritic helical poly(phenylacetylene)s. It can also be used to prepare zinc porphyrins attached to various cyclic aromatic hydrocarbon substituents, which can act as potential photo-sensitizers for dye-sensitized solar cells (DSSCs). This product was previously listed as CBR01612.
Synthesis of 4-ethynylbenzoic acid: Methyl 4-[(trimethylsilyl)ethynyl]benzoate (714 mg, 3.07 mmol) was dissolved in a methanol solution of 4% KOH (w:v, 30 mL) and the reaction was carried out at reflux overnight. Upon completion of the reaction, the pH of the reaction solution was adjusted to 2-3 with 6N HCl (detected by pH paper), followed by extraction with ethyl acetate (EtOAc) twice. The organic layers were combined, dried with anhydrous sodium sulfate (Na2SO4), and concentrated under reduced pressure to afford 4-ethynylbenzoic acid (427 mg, 2.92 mmol, 95% yield) as a brown solid.1H-NMR (d6-acetone, 500 MHz) δ (ppm): 7.62 (d, J = 16.2 Hz, 2H); 8.03 (d, J = 16.3 Hz 2H).
[1] Journal of the American Chemical Society, 2009, vol. 131, # 30, p. 10692 - 10700
[2] Patent: US2013/65248, 2013, A1. Location in patent: Page/Page column
[3] Patent: US9290791, 2016, B2
[4] Journal of Medicinal Chemistry, 2015, vol. 58, # 11, p. 4851 - 4856
[5] Journal of Medicinal Chemistry, 2012, vol. 55, # 22, p. 9562 - 9575
