Diethyl terephthalate

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. 

Diethyl terephthalate [636-09-0] M 222.2, m 44 , 142 /2mm, 302 /760mm. Crystd from toluene and distd under reduced pressure. 

In analogy to the transesterification of diethyl terephthalate used in the preparation of commercially important polyester fibers such as Dacron (24), a transesterification reaction waus successfully employed for the preparation of poly(N-acylhydroxyproline esters) (Scheme 1). 

In the case of the polyesters Smith and Dole s (1956) study of the monomeric analogs of polyethylene terephthalate, namely, dimethyl and diethyl terephthalate, in which they found 39.5 and 26.6 cal g-1 for the heats of fusion, respt., was of aid in supporting their conclusion that Edgar and Hill s (1952) estimate of the heat of fusion of polyethylene terephthalate from the use of the copolymer Eq. (6), namely 11.5 cal g-1, must be definitely too low. It should be pointed out that Edgar and Hill were also uncertain as to the correctness of the value 11.5 cal g-1. 

Dimethyl phthalate Diethyl phthalate Dipropyl phthalate Diisopropyl phthalate Dibutyl phthalate Diethyl isophthalate Dimethyl isophthalate Diethyl terephthalate Dimethyl terephthalate... 

Presumably for similar reasons, cathodic reduction of diethyl terephthalate and diethyl furan- and thiophene-2,5-dicarboxylate [51-53] in a buffered ethanolic solution of pH 4.2 affords the aldehyde ester under controlled potential electrolysis (CPE) conditions (in the interval between —1.50 and —1.65 V). Diethyloxalate [77] is reduced at a mercury cathode in acidic medium to give the ethyl hemiacetal of ethyl glyoxylate (38-50% yield). In contrast, diethyl and monoethyl phthalate gave phthalide under similar conditions [21,78]. 

Diethyl terephthalate [636-09-0] toluene and distd under reduced pressure. 

The information drawn from polarizability and polarization studies seems, in general, to compare reasonably with that from other physical methods, if the natures of these methods are borne in mind. The techniques of X-ray, neutron and electron diffraction and microwave spectroscopy provide metrical structural details of the highest precision relating to the crystalline or gaseous states flexible molecules in solution may be expected to adopt conformations between the extremes found in the states mentioned. Thus dimethyl oxalate, diethyl terephthalate, 1,2-dibromoethane, and 1,4-dimethoxybenzene all exhibit dipole moments as solutes, but nevertheless assume trans—and therefore nonpolar—forms in their solid phases (cf. Chemical Society Tables, 1958). Accordingly it is difficult to assess the correctness of the findings summarized in Table 23 when available, results secured in other ways have been quoted in the papers cited. 

Alcoholysis of PET via methanolysis or ethanolysis yields dimethyl terephthalate and diethyl terephthalate respectively (Jie et al., 2006 Kurokawa et al., 2003). The reaction can also be carried out under supercritical conditions (Castro et al., 2006 Goto, 2009). 

Fig. 2 Chemical structures of the PET model compounds ethylene glycol dibenzyl ester (BEB), Z>is(benzoyloxyethyl) terephthalate (PET trimer), diethyl terephthalate (DET), and Z>is-(p-methylbenzoic acid)-ethylene glycol ester (PET dimer)...

Oligomeric PET model compounds have been widely used to study enzymatic hydrolysis of PET, since their degradation is faster and easier to analyze compared to a polymeric substrate. Diethyl terephthalate (DET), diethyl p-phthalate (DP), h/i(benzoyloxyethyl) terephthalate (PET trimer), ethylene glycol dibenzyl ester (BEB), and hA-(p-methylbenzoic acid)-ethylene glycol ester (PET dimer) have been employed (Eig. 2). Their degradation by PET hydrolases from Fusarium solani [27, 38], T. insolens [1, 5, 48, 101], P. mendocina [25, 49], T. fusca [26, 27, 38], Burkholderia cepacia [26, 27, 38], Aspergillus oryzae [103], Bacillus spp. [87], and porcine liver esterase [109, 110] has been reported, and the corresponding hydrolysis products have been partially characterized (Table 1). 

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