Tetramethylene units

The macrocyclic bis(oximato)borates 130-131 and its tetramethylene analogue 132 are derivatives of the bisborylated dioxime complexes discussed above, in which one of the OBR2O groups has been substituted by a trimethylene or tetramethylene unit, respectively (Fig. 35). 

The (co)polymerization of dienes can be a good method for the preparation of polymers with reactive vinyl groups, a method that enables the preparation of polymers possessing plural vinyl groups per polymer chain. A fluorinated bis(phenoxy-imine) Ti complex was shown by Coates and co-workers to convert 1,5-hexadiene to poly(methylene-l,3-cyclopentane-fti-3-vinyl tetramethylene), which contained multiple vinyl groups. As already discussed, Saito et al. and others revealed that bis(phenoxy-imine) Ti complexes favored secondary insertion. " This is probably responsible for the formation of 3-vinyl tetramethylene units. Likewise, the same catalyst system can form sPP-/ -poly(methylene-l,3-cyclopentane-z -3-vinyl tetramethylene) from propylene and 1,5-hexadiene. Very recently. 

Complex 87 was used for propylene-1-hexene co-polymerization. It has been suggested that blocks of iPP and poly-1-hexene were joined to form a poly(iPP-rti-iPH) block co-polymers.1070 Propylene and 1,5-hexadiene have been copolymerized with the 138/MAO catalyst.1229 The NMR spectroscopy indicated that the propylene homosequences are remarkably syndiotactic. As in the case of hexadiene homopolymerization with the same catalyst (see Figure 55), the hexadiene is incorporated as methylene-1,3-cyclopentane or 3-vinyl-tetramethylene units. Lower propylene concentration favored the formation of methylene-1,3-cyclopentane units, while higher propylene concentration favored 3-vinyl-tetramethylene units. Furthermore, an sEE-block-pcAyOP-co-HE)) diblock co-polymer was synthesized by first polymerizing propylene to sPP for 2h and then adding 1,5-hexadiene for 6 additional h.1229... 

Many polyamines are now available from Aldrich, Fluka, Phaltz and Bauer, Sigma, and TCI chemical companies. The available compounds include tri-and tetraamines with a mix of ethylene, trimethylene, and tetramethylene units between the nitrogen atoms. Of particular interest are tetraamines where the two internal amines are tertiary and the terminal amines are secondary. These compounds can be used in the ring closure reaction to form the peraza-crowns. 

As normally polymerized, PVF melts between IH5 and 210 °C and contains 12 18% inverted monomer units ft is normally considered a thermoplastic, but because of its instability above its melting point, it cannot be processed by conventional thermoplastic techniques Instead it is generally extruded into films in a solvent swollen (organosol) form and the solvent is subsequently evaporated and recovered Such films can be onented further to achieve specific mechanical properties PVF films are exceptionally weather and radiabon resistant considenng their modest fluonne content PVF is insoluble below 100 °C but, at higher temperatures, it dissolves in polar solvents like amides, ketones, tetramethylene sulfone, and tetramethylurea Resistance to acids and bases at room temperature IS good [1, 29 ... 

From DMT and 1,4-tetramethylene diamine, a dimethylesterdiamide unit (T4T-dimethyl) is prepared as described above for T6T-dimethyl (Example 22a). The T4T-dimethyl has a Tm of265° C and a AHm of 152 J/g. 

Conversely, Tamao and co-workers constrained the Si chain in oligosilanes with 4, 6, 8, and 10 Si atoms to adopt an alternating cisoid- and ////-conformation using two tetramethylene tethers to further link the silicon atoms in each disilane unit, producing oligomers by the route shown in Scheme 2.1... 

Extending this methodology, Tamao and co-workers recently prepared a pentasilane, 4, containing a central trisilane unit constrained to the all-anti conformation by tethering with bis(tetramethylene) groups, as confirmed by single crystal X-ray diffraction.14... 

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),... 

Cyclophanes consist of a class of artificial hosts featured with well-defined hydrophobic cavities constructed by aromatic rings incorporated in their macrocy-clic structures, and also with high design versatility because they are totally synthetic.The first direct evidence of the formation of an inclusion complex with an organic guest was obtained for tetraazacyclophane 62, the cavity of which is constructed with diphenylmethane units bridged by tetramethylene chains. 

Part I of this series explored the structure-property relationships of tetramethylene terephthalate/polyether terephthalate copolymers as a function of variations in the chemical structure, molecular weight, and concentration of the polyether units (10). Of the polyether monomers tested, poly (tetramethylene ether) glycol of molecular weight approximately 1000 was found to provide copolymers having the best overall combination of physical properties and ease of synthesis. 

The work reported here is concerned with the syntheses and properties of polyether-ester block copolymers containing poly (tetramethylene ether) units of molecular weight of approximately 1000 as the amorphous polyether blocks and a variety of esters as the crystallizable hard segments. The purpose of this study is to correlate changes in synthesis and properties of these thermoplastic and elastomeric copolymers with changes in the concentration and nature of the ester segments, particularly the types of diol and diacid. 

Copolymer compositions are expressed as weight percentages of the ester units with the remainder being polyether-ester units. For instance, 40% tetramethylene terephthalate/PTME terephthalate copolymer represents a block copolymer containing 40 wt % of tetramethylene terephthalate units and by difference 60 wt % of poly(tetramethylene ether) terephthalate units. 

Sulfolane A process for removing aromatic hydrocarbons from petroleum fractions by liquid-liquid extraction using sulfolane (tetramethylene sulfone tetrahydrothiophene-1,1-dioxide) at approximately 190°C. Developed by Shell Development Company in 1959 and first commercialized in 1962 now licensed through UOP. By 2005, 134 units had been licensed worldwide. The process replaced the Udex process. Sulfolane is used for another purpose in the Sulfinol process. 

Structure, properties. PTHF is a linear elastomer with the following repeat unit [—OCH2CH2CH2CH2—]. Poly(tetrahydrofuran) is also named poly(tetramethylene oxide) (PTMO) and the official name is poly(-oxy-1,4-butane diyl). For PTHF diols the usual names are poly(tetrameth-ylene ether) glycols (PTMEG). 

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