Dimethyl terephthalate, structure

Poly(butylene Terephthalate). Poly(butylene terephthalate) is prepared in a condensation reaction between dimethyl terephthalate and 1,4-butanediol and its repeating unit has the general structure... 

PTT is made by the melt polycondensation of PDO with either terephthalic acid or dimethyl terephthalate. The chemical structure is shown in Figure 11.1. It is also called 3GT in the polyester industry, with G and T standing for glycol and terephthalate, respectively. The number preceding G stands for the number of methylene units in the glycol moiety. In the literature, polypropylene terephthalate) (PPT) is also frequently encountered however, this nomenclature does not distinguish whether the glycol moiety is made from a branched 1,2-propanediol or a linear 1,3-propanediol. Another abbreviation sometimes used in the literature is PTMT, which could be confused with poly(tetramethylene terephthalate),... 

The PET polymer structure can also be generated from the reaction of ethylene glycol and dimethyl terephthalate, with methyl alcohol as the byproduct. A few producers still use this route. The aromatic rings coupled with short aliphatic chains are responsible for a relatively stiff polymer molecule, as compared with more aliphatic structures such as polyolefin or polyamide. The lack of segment mobility in the polymer chains results in relatively high thermal stability, as will be discussed later. 

Chemically, Dacron and Mylar are polymers made from a ring structure called dimethyl terephthalate and ethylene glycol (HO-CH2CH2-OH). The polymer unit is called polyethylene terephthalate, or PET. Dacron fiber is used in tires and fabrics, and is even used to repair blood vessels. Mylar is used in magnetic recording tape. In the 1960s, it was used in huge balloons that were sent into orbit around Earth. Plastic soda containers are made of PET. 

Thermoplastic copolyester elastomers are generally block copolymers produced from short-chain aliphatic diols, aromatic diacids, and polyalkylene ether-diols. They are often called polyesterether or polyester elastomers. The most significant commercial product is the copolymer from butane-1,4-diol, dimethyl terephthalate, and polytetramethylene ether glycol [25190-06-1/, which produces a segmented block copolyesterether with the following structure. 

Health and Safety Issues. Polyesterether elastomers derived from dimethyl terephthalate, butanediol, and Ptmeg are not hazardous according to the published Materials Safety Data Sheets (MSDS) for this elastomer. Polymers of a similar structure containing isophthalic acid are also not considered hazardous. For other copolymer elastomers, the MSDS put out by suppliers should be consulted by potential users before evaluation. One environmental advantage of thermoplastic elastomers of this type is that they are melt-reprocessible and thus scrap and off-specification material and even obselete parts can be easily recycled. Up to 25% by weight of recycled material can be incorporated (see Recycling, plastics). 

With the advances in experimental solid-state NMR and computational resources (both software and computing power), it is now possible to use both the experimental and computational results (sometimes in a complementary way) to study biologically important macromolecules such as proteins. The quantum-chemical computation (particularly by density functional theory) of NMR parameters in solids has found important application in protein structure determination.30-36 Tesche and Haeberlen37 calculated the proton chemical shift tensor of the methyl groups in dimethyl terephthalate and found the theoretical results were in good agreement with the multiple pulse experiment. 

Kodef polyester is formed by transesterification of dimethyl terephthalate with 1,4-di(hydroxy methyficyclohexane. Draw the structure of Kodel . 

Polyester fibers, similar to polyamide fibers, represent another important family of fiber. Polyester fiber was discovered in England in 1941 and commercialized in 1950. Two common trade names of polyester are Dacron in the US and Terylene in the UK. The term polyester fiber represents a family of fibers made of polyethylene terephthalate. Dimethyl terephthalate is reacted with ethylene glycol in the presence of a catalyst, antimony oxide, to produce polyethylene terephthalate or polyester. The chain repeat structure of PET is given in Fig. 4.6. Although polyesters can be both thermosetting and thermoplastic, the term polyester has become synonymous with PET. Note that the PET chain structure is different from the simpler structure of nylon or polyethylene. In PET, the aromatic ring and its associated C-C bonds provide a rigidity to the structure. The polyester structure is also bulkier than that of nylon or polyethylene. These factors make polyester less flexible than nylon and polyethylene, and the crystallization rate of PET slower than that of nylon or polyethylene. Thus, when polyester is cooled from the melt, an appreciable amount of crystallization does not result. 

Kodel . Polyester staple and filament fiber. Prepn From dimethyl terephthalate and 1,4 -cyelohexanedi methanol Kibler et at, U.S. pat, 2,901,466 (1959 to Eastman Kodak). Review and structure R. W, Moncrieff,... 

A polyester from terephthalic acid and 1,2-dimethylol cyclohexane is produced mainly for use in fibers. This polymer is also formed from dimethyl terephthalate and the diol by a transesterification reaction. The material has the following structure ... 

PTT is a semicrystalline polymer synthesized by the condensation of PDO with either terephthalic acid or dimethyl terephthalate. The unique, semicrystalhne molecular structure of PTT features a pronounced kink , as shown in Fig. 10... 

PolyCtrimethylene terephthalate) (PTT, also abbreviated as 3GT) is an aromatic polyester made by the melt poly condensation of 1,3-propanediol (PDO) with either terephthalic acid (TPA) or dimethyl terephthalate (DMT). Although available commercially only since 1998, it was one of the three polyesters first synthesized by Whinfield and Dickson (1) in 1941. Two of which, the so-called even-munhered polyCethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) for the number of methylene units in their chemical structures, are well-estabhshed high volume polymers. However, the odd-numbered PTT remained an obscure polymer. It was never commercialized until recently because PDO was very expensive and was available only as a small volume line chemical. 

Polyesters contain carboxylic ester linkages (-0-C0-) in the backbone. Polyesters are synthesized by reaction of a diol and a dicarbonic acid, e.g. poly(ethylene terephthalate) (PET) by polycondenastion of ethylene glycol and dimethyl terephthalate. Poly(butylene terephthalate) (PBT) is produced by reaction with butylene glycol. Structures of PET and PBT are shown in Fig. 2.2.7. 

As indicated previously, poly(ethylene terephthalate) is by far the most important linear saturated polymer at the present time. However, one closely related polymer is also produced commercially. This material, poly(cyclo-hexane-1,4-dimethylene terephthalate) is prepared from dimethyl terephthalate and 1,4-dimethylolcyclohexane and has the following structure ... 

Draw the structure of the polymer you would expect to obtain from reaction of dimethyl terephthalate with a triol such as glycerol. What structural feature would this new polymer have that was not present in Dacron How do you think this new feature might affect the properties of the polymer ... 

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