SODIUM TEREPHTHALATE

Sodium terephthalate can be used alone in place of the free acid. 

Another possibility to use PET recyclate for food applications is the URRC process (United Resource Recovery Corporation). In this method the cleaned PET flakes are covered with concentrated caustic soda. After evaporation of the water in a rotary kiln the sodium hydroxide etches the surface of the PET at a temperature of more than 200°C. The resulting sodium terephthalate is removed by washing. The remaining flakes are used for the production of bottle preforms. Since 2000 several plants in Switzerland and Germany have been established [1],... 

Base-catalyzed hydrolysis of PET can be used to obtain TPA and oxalic acid [19], PET is completely hydrolyzed to TPA and EG at 250°C in concentrated aqueous NaOH solution. Then EG is converted to oxalic acid and CO2 by the introduction of oxygen. Since the sodium terephthalate formed is stable to oxidation, the yield of TPA reaches 100%. EG is converted to oxalic acid by base-catalyzed oxidation with a maximum yield of 61% ... 

Base-catalyzed hydrolysis always leads to the TPA salt of the cation used. Releasing the salt by neutralization leads to large amounts of waste salts such as NaCl or Na2S04 or a complicated treatment of the sodium terephthalate. Figure 25.7 shows the neutralization scheme for sodium terephthalate with CO2 for the UnPET process. All components run in cycles. Just TPA, EG, CO2 and water are released. This product treatment needs five... 

Figure 25.7 UnPET process and neutralization of Na2Tp (sodium terephthalate) with CO2 avoiding the production of salts...

Hexamethylcyclotrisiloxane (D3) (Toshiba Silicone Co.) was distilled over CaHa-Butyllithium (Nacalai Tesque, 1.6mol/L in hexane) was filtered with a G4 glass filter. A lithium salt of bis[p-(dimethylhydroxysilyl)phenyl]ether was prepared according to the method detailed elsewhere. 3-Trimethylsiloxypropyldimethylchlorosilane, 2., was prepared by the method detailed elsewhere. Tetrahydrofuran (THF) (Nacalai Tesque) was distilled firom the blue sodium/benzophenone solution. 1-Methylpyrrolidine (Nacalai Tesque) was distilled over CaH2. Tosyl chloride and dimethylaminopyridine (Nacalai Tesque) were recrystallized firom ethyl acetate. Mono and plurifunctional carboxylates used in the present study were sodium benzoate, sodium terephthalate, sodium and lithium salts of trimesic acid and pyrromelitic acid. They were either purchased or prepared by the standard neutralization method with sodium or lithium hydroxides. Deionized water (chromatography grade, Nacalai Tesque) was used as received. 

The photophysical property investigation of MOF-5 by Alvaro et al. initiated the study of MOFs as photocatalysts [56]. MOF-5 can emit light with an emission maximum at 540 nm under excitation of 350 ran. Whilst the localised excited electrons have a hfetime of 5 ps, the delocalised excited electrons have a lifetime of 30 ps. By investigating the transient absorption spectra of the moiety (sodium terephthalate) with additional Zn + in solution, it is revealed that a ligand-to-metal... 

The high yields of ethyl ester obtainable from the product attest its purity. A mixture of 50 g. of terephthalic acid, 500 ml. of absolute ethyl alcohol, and 25 ml. of sulfuric acid was boiled for 16 hours and then distilled to half its volume and poured into dilute aqueous sodium carbonate. There was obtained 56.7 g. of diethyl terephthalate (m.p. 42-44°), and from the wash water there was recovered 4.6 g. of terephthalic acid these materials account for 93.3% of the original substance. 

Terephthalic acid has been obtained from a great many /)-disubstituted derivatives of benzene or cyclohexane by oxidation with permanganate, chromic acid, or nitric acid. The following routes appear to have preparative value from />-toluic acid, />-methylacetophenone,2 or dihydro-/)-tolualdehyde by oxidation with permanganate from f>-cymene by oxidation with sodium dichromate and sulfuric acid from />-dibromobenzene or from /i-chloro- or -bromobenzoic acid by heating at 250° with potassium and cuprous cyanides and from />-dibromo-benzene, butyllithium, and carbon dioxide. ... 

Smaller diameter columns are especially useful when expensive solvents are used. Figure 11.3 shows the analysis of poly (1,4-butylene terephthalate) using a Waters Alliance narrow-bore GPC system, quantitated against narrow polymethylmethacrylate standards. In this case, the solvent used is hexaflu-oro-2-isopropanol with 0.05 M sodium trifluoroacetic acid at a flow rate of... 

Polk et al. reported27 that PET fibers could be hydrolyzed with 5% aqueous sodium hydroxide at 80°C in the presence of trioctylmethylammonium bromide in 60 min to obtain terephthalic acid in 93% yield. The results of catalytic depolymerization of PET without agitation are listed in Table 10.1. The results of catalytic depolymerization of PET with agitation are listed in Table 10.2. As expected, agitation shortened the time required for 100% conversion. Results (Table 10.1) for the quaternary salts with a halide counterion were promising. Phenyltrimethylammonium chloride (PTMAC) was chosen to ascertain whether steric effects would hinder catalytic activity. Bulky alkyl groups of the quaternary ammonium compounds were expected to hinder close approach of the catalyst to the somewhat hidden carbonyl groups of the fiber structure. The results indicate that steric hindrance is not a problem for PET hydrolysis under this set of conditions since the depolymerization results were substantially lower for PTMAC than for die more sterically hindered quaternary salts. 

To a stainless steel reactor equipped with a heating mantle, a charging port, a condenser for removing ethylene glycol, an inert gas inlet, and a sampling valve were added 400 g of bis(2-hydroxyethyl)terephthalate, 136 g of ethylene glycol, and 0.035 g (or 0.225 g) of sodium acetate trihydrate. The temperature was raised to between 190 and 200°C in 1 h and then 454 g of waste polyester... 

Example 2. Reactor Experiment.66 Waste PET (110 g), 800 g of ethylene glycol, and 93 g of 50% aqueous sodium hydroxide were introduced into a reactor. The reaction mixture was heated to 170° C with agitation while collecting distillate (mostly water with some ethylene glycol). The slurry, which consisted of disodium terephthalate in ethylene glycol, was filtered at a temperature of 170° C in a vacuum filter. The disodium terephthalate obtained was pressed as dry as possible and the ethylene glycol was recovered. The filter cake was washed with room temperature EG to remove impurities and to cool the disodium terephthalate to less than 100° C, followed by washing with a saturated solution of disodium terephthalate in water (maintained at 90-100° C). 

PETP flakes produced from used soft drinks bottles were subjected to alkaline hydrolysis in aqueous sodium hydroxide. A phase transfer catalyst (trioctylmethylammonium bromide) was used to enable the depolymerisation reaction to take place at room temperature and under mild conditions. The effects of temperature, alkali concentration, PETP particle size, PETP concentration and catalyst to PETP ratio on the reaction kinetics were studied. The disodium terephthalate produced was treated with sulphuric to give terephthalic acid of high purity. A simple theoretical model was developed to describe the hydrolysis rate. 17 refs. 

We previously reported that brominated aromatic phosphate esters are highly effective flame retardants for polymers containing oxygen such as polycarbonates and polyesters (9). Data were reported for use of this phosphate ester in polycarbonates, polyesters and blends. In some polymer systems, antimony oxide or sodium antimonate could be deleted. This paper is a continuation of that work and expands into polycarbonate alloys with polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and acrylonitrile-butadiene-styrene (ABS). 

The best preparative method of obtaining terephthalic acid is to oxidise the sodium salt of p-toluic acid with permanganate at the temperature of the water bath. In the same way toluene can be converted into benzoic acid, and an important technical example of this reaction is the oxidation, of o-tolylsulphonamide to saccharin. 

While this is an effective nucleation mechanism for PET, the efficiency of this system is not stable and decreases significantly with melt mixing (compounding) time. This instability is due to a disproportion reaction in which the sodium chain ends react with each other to give disodium terephthalate. The subsequent decrease in ionic chain end concentration is directly linked to the loss in nucleation efficiency. 

Pure ethylene glycol is dried by refluxing for 1 h in the presence of 2 wt% metallic sodium and is then distilled. Dimethyl terephthalate is recrystallized from methanol and carefully dried in vacuum (mp 141-142 °C). 

Terephthalic acid [100-21-0] M 166.1, sublimes >300 without melting. Purified via the sodium salt which, after crystn from water, was reconverted to the acid by acidification with mineral acid. Terephthaloyl chloride [100-20-9] M 203.0, m 80-82 . Crystd from dry hexane. o-Terphenyl [84-15-1] M 230.3, m 57-58 ,... 

Terephthalic acid [100-21-0] M 166.1, sublimes >300° without melting. Purified via the sodium salt which, after crystn from water, was reconverted to the acid by acidification with mineral acid. 

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