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Chlorinated Solvents and Solvent Stabilizers
Published in Thomas K.G. Mohr, William H. DiGuiseppi, Janet K. Anderson, James W. Hatton, Jeremy Bishop, Barrie Selcoe, William B. Kappleman, Environmental Investigation and Remediation, 2020
Pure 1,4-dioxane is susceptible to forming peroxides over time when stored. The compound 1,3-dioxolane will also combine with oxygen from the air to form explosive peroxides. Methyl chloroform stabilized with 1,4-dioxane or 1,3-dioxolane can develop peroxides or acidity during storage; however, 1,4-dioxane develops peroxides to a lesser extent than 1,3-dioxolane (Manner, 1977).
INDUSTRIAL ORGANIC SOLVENTS
Published in Nicholas P. Cheremisinoff, Industrial Solvents Handbook, Revised And Expanded, 2003
1,3-Dioxolane is also used as an inhibitor for certain chlorinated solvents. 1,4- Dioxane, the six-member cyclic diethcr, is used as an aluminum inhibitor in chlorinated solvents like 1,1,1-trichlorocthanc and as a solvent for certain resins and polymers.
Synthesis and properties of benzoxazole-terminated mesogenic compounds containing tolane with high birefringence and large dielectric anisotropy
Published in Liquid Crystals, 2021
Ning Xie, Shenghua Du, Ran Chen, Guoqing Liu, Pei Chen, Qiang Weng, Jie Wang, Aiai Gao, Xinbing Chen, Zhongwei An
2.90 g of 2-[4-[4-pentyloxyphenyl]ethynyl]-2,6-difluorophenyl]-1,3-dioxolane (7.80 mmol), 54.21 g of formic acid (1178.57 mmol) and 80 mL of tetrahydrofuran were added to a 250 mL single-necked flask equipped with a magnetic stirrer and condenser. After the mixture was stirred at 60°C for 6 h, the system is cooled to room temperature. The mixture is diluted with water, then extracted three times with dichloromethane. The combined organic phase was washed three times with saturated ammonium chloride solution, then dried over anhydrous magnesium sulphate. The organic phase was concentrated, then recrystallised from absolute ethanol to give purity above 98% (HPLC). Pale white solid was obtained with yield 87%. 1H-NMR (400 MHz, CDCl3, TMS): δ (ppm) 10.30 (s, 1H), 7.46 (m, 2H), 7.08 (m, 2H), 6.88 (m, 2H), 3.97 (t, 2H, J = 6.58 Hz), 1.79 (m, 2H), 1.41 (m, 4H), 0.93 (t, 3H, J = 7.08 Hz). IR (KBr) v (cm−1): 2945, 2871, 2208 (–C≡C–), 1697, 1602, 1514, 1469, 1417, 1290, 1253, 1103. 1016, 838, 730, 540. EI-MS m/z (rel. int.): 328 (M+, 97), 258 (100), 229 (26), 201 (21), 43 (94).
FeNP-loaded coal-bearing kaolin catalysts for the direct esterification of benzoic acid with cyclic ether via C(sp3)-H bond activation
Published in Green Chemistry Letters and Reviews, 2021
Urenhu Bao, Tegshi Muschin, Agula Bao, Yong-Sheng Bao, Meilin Jia
In this work, to realize an atom economic, step economic, and environmentally sustainable green catalytic system, iron salts and abundant nonmetal minerals of coal-bearing kaolin were used to successfully synthesize FeNP-loaded kaolin heterogeneous catalysts. From the TEM images, the iron nanoparticle size was 3.1 nm, and both TEM and SEM elemental mappings showed that iron was distributed uniformly on kaolin. Both the fresh and used catalysts showed binding energies in the Fe 2P XPS spectra at 710.8 eV, which is attributed to the FeIII 2p3/2 peak. The catalytic activity for the C(sp3)-H bond activation in a CDC reaction was determined using a model reaction of the direct esterification of benzoic acid with cyclic ether. The model reaction showed efficient catalytic activity for various substituted benzoic acids with 1,4-dioxane and 1,3-dioxolane. The catalyst can be reused and remains active after 5 cycles. The prepared catalyst is easy to separate and recycle and is preferred for green catalysis in the C(sp3)-H activation CDC reaction, thus having the potential to be an alternative to homogeneous iron catalysts.
Benzoxazole-based nematic liquid crystals containing ethynyl and two lateral fluorine atoms with large birefringence
Published in Liquid Crystals, 2021
Mengting Zhang, Shenghua Du, Diao Yuan, Pei Chen, Guoqing Liu, Jiazhen Dang, Xinbing Chen, Zhongwei An
2.45 g of 2-[4-[4-octyloxyphenyl]ethynyl]-2,3-difluorophenyl]-1,3-dioxolane (5.91 mmol), 41.36 g of formic acid (893.23 mmol) and 80 mL of tetrahydrofuran were added to a 250 mL single-necked flask equipped with a magnetic stirrer and condenser. After the mixture was stirred at 60°C for 6 h, the system is cooled to room temperature. The mixture is diluted with water, then extracted three times with dichloromethane. The combined organic phase was washed three times with saturated ammonium chloride solution, then dried over anhydrous magnesium sulfate. The organic phase was concentrated, then recrystallized from absolute ethanol to give purity above 98% for GC measurement. Pale white solid was obtained with yield 81%. 1H-NMR (400 MHz, CDCl3, TMS): δ (ppm) 10.30 (s, 1H), 7.60-7.55 (m, 1H), 7.52-7.41 (m, 2H), 7.36-7.30 (m, 1H), 6.91-6.83 (m, 2H), 4.01-3.93 (d, 3JH-H=6.63 Hz), 1.85-1.73 (m, 2H), 1.50-1.40 (m, 2H), 1.39-1.28 (m, 8H), 0.93-0.86 (d, 3JH-H=7.16 Hz). IR (KBr) v (cm−1): 2924, 2858, 2208, 1692, 1607, 1516, 1461, 1388, 1291, 1255, 1109, 1018, 830, 757, 526. EI-MS m/z (rel. int.): 370.14 (M+, 25.12), 258.03 (100), 229.03 (7), 201.05 (50).