Ethylene dibenzoate

A particularly relevant thermo-oxidative study on PET degradation and PBT reported the degradation products observed for ethylene dibenzoate [39], The products observed paralleled those of the photolysis and photo-oxidation reports discussed above with benzoic acid, vinyl benzoate, 2-hydroxyethylene dibenzoate, 2-carboxymethoxy benzoate and the coupling product, 1,4-butylene dibenzoate, being reported. The 2-hydroxyethylene dibenzoate and 2-carboxymethoxy... 

Goodings [38] used ethylene dibenzoate as a model compound for pyrolysis studies on PET. His results indicated that an important pyrolytic reaction in molten PET is cleavage of an internal ester linkage to form a carboxylic acid end group and a vinyl ester end group... 

CO, CHi. CO2, ethylene, acetylene, ethane. H2O. propylene, ethanal acetone, propanal, ethanol, benzene, toluene, ethylbenzene, styrene, p-vinyltoluene, benzaldehyde, p-ethyl-totuene acetophenone, methyl benzoate, vinyl benzoate, ethyl benzoate, p-methyl-acetophenone. benzoic acid, p-methyl vinyl benzoate, p-vinylacetophenone, propyl benzoate, p-ethyl vinyl benzoate, p-vinyl vinyl benzoate, biphenyl. 1-hydroxyethyl benzoate, diacetylbenzene. p-acetyl vinyl benzoate, divinyl terephthalate. ethyl vinyl terephthalate. ethyl vinyl terephthalate, p-acetyibenzoic acid, methyl 1-hydroxyethyl terephthalate. ethylene dibenzoate... 

A -Ethylcarbazole, 40, 41, 43 9-Ethyl-3-carbazolecarboxaldehyde, 17 A -Ethylcarbazole-3,6-dicarboxylic acid, 334 Ethylene earbonate, 360 Ethylene chlorohydrin, 312 Ethylenediamine tetraacetic acid, 143 Ethylene dibenzoate, 357 Ethylene dinaphthoate, 357 Ethylene glycol, 360... 

The kinetics of transesterification reaction in PET/ PEN blends was studied by the model compounds ethylene dibenzoate (BEB) and ethylene dinaphthoate (NEN). The exchange reaction between BEB and NEN was followed by H NMR spectroscopy [24]. 

Botelho and co-workers [56] studied the thermal breakdown of ethylene dibenzoate nnder nitrogen as a model compound for PET. From the evolved prodncts, these authors suggested that the degradation process takes place through hydrogen transfer reactions and homolytic reactions ... 

Studied by a number of authors, - with particular reference to the effects of reduced pressure and catalysts. A new solid-state polymerization route, the effects of acid impurities, and the role of depropagation reactions in polymerization as studied using ethylene dibenzoate as a model compound have also been reported. 

A comparative study has been conducted into the thermal and thermooxidative degradation of PET and PBT polymer films and their model compounds, ethylene dibenzoate and butylene dibenzoate, in an oxygen atmosphere at 160 °C 832485. On the basis of the compounds identified by GC-MS, a mechanism was proposed for the degradation of the model compounds that involves oxidation at the a-methylene carbon with the formation of unstable peroxides and carboxylic acids a.l53. From the studies performed under N2 at 160 °C, it was concluded that benzoic acid and esters are products of the thermal degradation as illustrated in Schemes 15 and 16, while benzoic and aliphatic acids, anhydride and alcohols were due to thermooxidative degradation. 

Scheme 15. Proposed thermal degradation mechanisms for ethylene dibenzoate during...

In the late 1970s several developments occurred causing renewed interest in poly(ethylene terephthalate) as a plastics material. These included the development of a new mouldable grade by ICI (Melinar) and the development of a blow moulding technique to produce biaxially oriented PET bottles. In addition there appeared a glass-fibre filled, ionomer nucleated, dibenzoate plasticised material by Du Pont (Rynite) (see Chapter 26). 

Polymeric pseudocrown ether networks have been generated in situ by the photopolymerization of poly(ethylene glycol) diacrylate transition metal complexes <00CM633>, and the effect of metal ion templation was evaluated. The 1,6,13,18-tetraoxa[6.6]paracyclophane-3,15-diyne (termed pyxophanes) was prepared from hydroquinone and l,4-dichlorobut-2-yne it forms size-selective 7i-complexes with alkali metal cations <00CC2377>. Dibenzo[ ]crown-m have been used in numerous elegant studies in which they were the needles that were threaded by diverse reagents the resultant... 

Chemical/Physical. TCDD was dehalogenated by a solution of poly (ethylene glycol), potassium carbonate, and sodium peroxide. After 2 h at 85 °C, >99.9% of the applied TCDD decomposed. Chemical intermediates identified include tri-, di-, and chloro[Ae]dibenzo[l,4]dioxin, di-benzodioxin, hydrogen, carbon monoxide, methane, ethylene, and acetylene (Tundo et al., 1985). TCDD will not hydrolyze to any reasonable extent (Kollig, 1993). 

Uchida H, Kurakata Y, Sawamura H et al (2003) Purification and properties of an esterase from Aspergillus nomius HS-1 degrading ethylene glycol dibenzoate. EEMS Microbiol Lett 223 123-127... 

Additions to the ring are also named. For example, in dicyclohexano-18-Crown-6 the macrocyclic ring contains ethylenic carbon atoms that are also a part of cyclohexane rings, while dibenzo-18-Crown-6 has benzene rings at the same positions. In pyridino-18-Crown-6, the nitrogen from a pyridine ring replaces one of the oxygens. 

A bistricyclic ethylene with seven-membered central rings, 5,5 -bis-5//-dibenzo[a,d]cy-cloheptenylidene (16), has been found to give two stable steroisomers, one with syn- and the other with awft -folding89. An extreme case of yyw-folding is represented by 9,9, 10,10 -tetrahydrodianthracene (18)90, in which the anthracene rings in a bianthrylidene are bent backward to the extent of permitting double bonds between the 9,9 and 10,10 positions. 

Note 1 PVAC/P/C Polyvinyl acetate/plasticizer/chlorhexidine Note 2 PB/P/C Polybutyral/plasticizer/chlorhexidine Note 3 P Plasticizer (ethylene glycol dibenzoate)... 

Macrocyclic ligands have played an important part in the development of modern co-ordination chemistry. But what exactly is a macrocycle As far as a co-ordination chemist is concerned, the definition of Melson is probably the most useful. Melson stated that a macrocycle is a cyclic molecule with three or more potential donor atoms in a ring of at least nine atoms. Thus, ethylene oxide (6.1), 1,4-dithiane (6.2), cyclotetradecane (6.3) and cyclooctatetraene (6.4) are not commonly thought of as macrocycles (Fig. 6-1), whereas molecules such as cyclam (6.5), phthalocyanine (6.6), 1,4,7-trithiacyclononane (6.7) and dibenzo-18-crown-6 (6.8) fit the definition (Fig. 6-2). 

Similar reaction with benzaldehyde or pivalaldehyde led to 6-phenyl- and 6-/-butyl-dibenzo[//,g][l,3,6]trithiocins 133 in good yields (Scheme 34 <1998BCJ1187>). Reaction of bis(o-mercapto)phenyl sulfide with 1,2-rxr-dichloro-ethylene produced 6-methylenedibenzo[//,g][l,3,6]trithiocine 11 as a mixture with 18-membered product 134 instead of an expected nine-membered dibenzo[3/][l,4,7]trithionine <1999T10057>. 

Copolymers containing alternating l,4-bis(phenylethenyl)benzene, l,4-bis(phenylethenyl)-2,5-dimethoxybenzene or l,5-bis(phenylethenyl)naphthalene chromophores, and dibenzo-24-crown-8 spacers within the polymer backbone, best represented by 87, showed blue light emission in solution, and tunable photoluminescence and electroluminescence depending on the structure of the chromophore. Blends of these copolymers with a small amount of poly(ethylene oxide), and lithium salt as active layers, form efficient light-emitting electrochemical cells <2003JMC800>. 

A further variation has been proposed by Pless with the 10,ll-dihydro-5//-dibenzo[a,rf]cy-clohepten-5-yl derivative (dibenzosuberyl. Sub, 113), in which two phenyl groups are linked via an ethylene bridge.The Sub group represents an alternative to the more commonly used trityl group, since it is more stable under acidic conditions (stable even against 5 M HCl/ dioxane), but cleaved by various hydrogenolytic or acidolytic procedures, e.g. 10% TEA/... 

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