14H-Dibenzo[a,j]xanthene was easily synthesized by heating alkali (K or Na) 2-naphthyloxide under CO and CO2 pressure.
A convenient one-pot−two-step process for chemical recycling of waste PET to produce terephthalohydroxamic acid (TPHA) and terephthalohydrazide (TPHD) was proposed. Decomposition of PET pellets to the corresponding oligomeric mixture in boiling ethylene glycol, followed by its treatment with hydroxylamine and hydrazine at room temperature in 1 h, produced >90% overall yields of TPHA and TPHD, respectively.
Scheme 11). Crown 3 was prepared with some modifications by the method developed by Bradshaw and co-workers for obtaining similar ~rowns.6~~ A mixture of 401 mg (1.31 "01) of 7,256 mg (1.31 mmol) of dimethyl 2,6-pyridinedicarboxylate, and 35 mg (0.65 mmol) of NaOCHS was combined with 120 mL of dry benzene in a flask equipped with a Soxhlet apparatus. Molecular sieves (4 A, 10 g) were placed in the extraction thimble, and the mixture was refluxed through the Soxhlet for 32 h. Because the TLC (THF/isopropyl ether (1/8)) showed that the diester was consumed but not the diol, another 100 mg (0.51 "01) of diester was added and the mixture was refluxed for another 24 h. The cold mixture was acidified with 0.2 mL of glacial acetic acid, and the solvent was removed under reduced pressure. Ice (10 g) and 50 mL of CH2C12 were added to the residue, the resulting mixture was shaken, and the phases were separated. The organic phase was dried (MgS04) and filtered, and the solvent was evaporated under reduced pressure. The residue was purified by column chromatography on silica gel (THF/toluene (1/8)). The resulting solid was recrystallized from hexane to give 85 mg (15%) of white crystals: mp 96-97 OC; [ a ] %~ -24.33' (c = 0.825, benzene); ' H NMR 6 1.05 (18 H, a), 3.38-3.87 (12 H, m), 5.2 (2 H, t, J = 8 Hz), 7.95 (1 H, t), 8.12 (2 H, d, J = 10 Hz); Determination of log K Values by the Direct lH NMR Method. The log K values listed in Table I1 were determined as re~0rted.l~ A sample containing a few milligrams of macrocycle in a known volume of solvent was first loaded into the probe, and a spectrum was taken. The sample was then unloaded, added to the sample tube with a small amount of the ammonium salt, and reloaded into the probe, and another spectrum was taken.This process was repeated until no significant change was observed in successive ' H NMFt spectra. Usually 8-12 spectra were taken for each log K determination. The crown ether concentrations were -0.01-0.015 M and the ammonium salt concentrations varied from 0.0 M to -0.06 M for each of the experiments. In such experiment, an accurately weighed quantity of the crown ether was dissolved in a known volume of solvent at 25.0 O C . The analytical balance used was calibrated for accuracy using a standard weight from the National Institute of Standards and Technology. The salt concentrations were calculated on the M i of the integral ratio of a particular ammonium salt signal to a particular crown ether signal in the spectra. In order to obtain a quantitative integration, the time delay between the two pulses for each NMFt acquisition was set long enough to allow sufficient relaxation of the signals of interest. The log K values were then calculated from the differences in chemical shift values as reported.1° Acknowledgment.Alkylation of potassium 2-naphthyl oxide with glyoxal in aqueous media formed 1,2-dihydronaphtho[2,1-b]furan-1,2-diol(l). Without isolation of 1, acidification of this reaction mixture with aqueous HCl led to three products, i.e., the lactone of (2-hyd...
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