Reference of 120-61-6, These common heterocyclic compound, 120-61-6, name is Dimethyl terephthalate, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
Reference of 120-61-6, These common heterocyclic compound, 120-61-6, name is Dimethyl terephthalate, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
In the examples described below, the equipment used consisted of a one-liter base fitted with a heating mantel, magnetic stirrer bar, temperature sensor, and 10 Penn State-packed distillation column. The top of the column was fitted with a variable rate take-off head to allow selective removal of the methanol.Each example was run under typical reaction conditions by conducting the reaction at reflux while removing methanol via the packed column at a take-off ratio of 1:4. At the completion of the reaction, the excess alcohol was then stripped from the base after replacing the fractionating column with a 3 Vigreux column and applying vacuum to a final pressure of 18 mm Hg. The crude product was treated with 2.5% aqueous NaOH to neutralize the TIPT catalyst and washed twice with deionized water. The material was then suction filtered through a glass fiber filter circle coated with Dicalite filter-aid. The product was subsequently dried at a final base temperature of 120 C. at 1 mm Hg and held one hour. After cooling to 90 C., activated carbon (0.2 wt. %) was added and held at this temperature while stirring for one hour. The final product was isolate by filtration through a glass fiber filter coated with Dicalite filter-aid; The reaction was conducted in accordance with the chemical equation generally illustrated above on page 3 and was designed to produce a product derived from a 50:50 mole percent mixture of n-butanol and isobutanol.The reactor system was charged with 436.9 g (2.25 mol, MW=194.19) of dimethyl terephthalate, 207.5 g (2.8 mol, MW=74.12) of n-butanol, 207.5 g (2.8 mol, MW=74.12) of isobutanol and 223 ppm (0.19 g) of tetraisopropoxy titanate (TIPT). The reaction progress is summarized in the Table 1 below; The product was stripped as summarized in Table 2 below; After neutralization, drying, carbon treatment and final filtration in accordance with the above-describe general work-up procedure, the isolated product weighed 547.7 g. The theoretical amount of product is 626.28 g for an 87.5% isolated yield; The reaction described in Example 1 was repeated to produce a product derived from a 75:25 mole percent mixture of n-butanol and isobutanol, respectively. The reactor system was charged with 233 g (1.2 mol, MW=194.19) of dimethyl terephthalate, 200.1 g (2.78 mol, MW=74.12) of n-butanol, 66.7 g (0.9 mol, MW=74.12) of isobutanol and 220 ppm (0.11 g) of TIPT. The reaction progress is summarized in the Table 3 below; The product was stripped as summarized in Example 1 above and isolated as a clear liquid after neutralization, drying, carbon treatment and final filtration; The reaction described in Example 1 was repeated to produce a product derived from a 25:75 mole percent mixture of n-butanol and isobutanol, respectively. The reactor system was charged with 233 g (1.2 mol, MW=194.19) of dimethyl terephthalate, 66.7 g (0.9 mol, MW=74.12) of n-butanol, 200.1 g (2.7 mol, MW=74.12) of isobutanol and 280 ppm (0.14 g) of TIPT. The reaction progress is summarized in the Table 4 below; The product was stripped as summarized in Example 1 above and isolated as a partially solid material after neutralization, drying, carbon treatment and final filtration. Since the goal was to develop lower freezing products, no further work was done with this material.Each sample was analyzed by capillary gas chromatography (uncorrected area percent values reported). The results are summarized in Table 5 below; Two of the above materials (158-01, 163-01) along with pure DBT were submitted for a DSC point study. This study incorporated heat-cool-heat cycles in an hermetically sealed stainless steel pan. The scan rate was 2 C./min. in helium. FIG. 1 is the warm-up cycle for pure DBT.The results show a complex freezing point behavior. For the 75:25 DBT/DIBT mixture:1. On the first warm-up, there are two crystallization events at -66 and -42 followed by a minor melting event at -5 and a major one at 6.2. On the second warm-up, it goes through two crystallization events at -35 and -29 followed by a minor melting event at -5 and a major one at 6.3. The freezing point peaked at around -42 (super cooled).For the 50:50 mixture:1. The freezing point peaked at around -22 C. (super cooled).2. On the first warm-up it goes through two low-temperature events: crystallized at -56 and melted at -17 followed with another melting at -6 and a final melting event at 8.3. On the second warm-up, it goes through one crystallization event at -15 and one melt event at -8 followed with a minor melting event at 10.Of the two, the 50:50 looks the best in that there is a smaller melting event at the warmer region (minor at 8-10 vs. major at 6 for 75:25). On the other hand, the 75:25 seems to super cool to a lower temperature than the 50:50 (-42 vs. -22).Note that the DBT super cooled to -7 before freezing, as shown in FIG. 5
The synthetic route of 120-61-6 has been constantly updated, and we look forward to future research findings.
Reference:
Patent; Eastman Chemical Company; US7361779; (2008); B1;,
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