Tetra methylene

Schollenberger added 2% of a polycarbodiimide additive to the same poly(tetra-methylene adipate) urethane with the high level of acid (AN = 3.66). After 9 weeks of 70°C water immersion, the urethane was reported to retain 84% of its original strength. Carbodiimides react quickly with residual acid to form an acyl urea, removing the acid catalysis contributing to the hydrolysis. New carbodiimides have been developed to prevent hydrolysis of polyester thermoplastics. Carbodiimides are also reported to react with residual water, which may contribute to hydrolysis when the urethane is exposed to high temperatures in an extruder [90]. 

There has been considerable interest in the structure and properties of poly(tetra-methylene terephthalate) 4GT, stemming from the observation that when the oriented polymer is stretched, the crystalline regions are transformed from one structure to a new one30,3l). It appears from the X-ray diffraction data that in the structure... 

Helgeson, Tarnowski Cram, 1979). X-ray diffraction confirms that a similar structure occurs in the solid state in this instance, the tetra-methylene diammonium ion is the guest (the dipositive charge on the complex is balanced by a pair of uncoordinated hexafluorophosphate counter ions) (Goldberg, 1977). 

Mercury Mercury complexed with ammonium tetra methylene- Chloroform extract analysed by < 5 ng/1 Hg absolute dithiocarbamate, extracted with chloroform graphite tube AAS... 

To conclude the matter of monoferrocene molecules we consider those cases in which the cyclopentadienyl substituents form bridges between the two rings. Such derivatives are named ferrocenophanes. The best known ferrocenophanes are those which contain saturated (tri- or tetra-methylene) carbon chains. Like ferrocenes, these molecules also exhibit reversible one-electron oxidation to the corresponding ferrocenium ions. 

Calculations based on this second model give the observed value for the entropy of activation. In addition, this model may be used to account for the observed isotope effect (Benson and Nangia, 1963). If the tetra-methylene biradical is involved then it is to be expected that appropriately substituted cyclobutanes might undergo cis-trans isomerization reactions. This will be referred to again later. One final point should be mentioned in connection with biradical intermediates in both cyclopropane and cyclobutane reactions. This concerns the absence of any effect of radical inhibitors on these systems, when it might be expected that they would interact with the biradicals. In fact calculations show that, under the conditions of formation, the biradicals have extremely short lifetimes sec) and hence, unless radical inhibitors are... 

Ferrocenylacetonitrile, 40, 4S Ferrous sulfate, oxidation ferf-butyl alcohol to a,a,a, a -tetramethyl tetra-methylene glycol by hydrogen peroxide and, 40, 90 Fluoboric acid as catalyst for diazomethane etherifications, 41, 9,10 Formaldehyde, reaction with diethyl malonate to form diethyl bis-(hydroxymethyl)malonate, 40, 27... 

If R1 and R2 are a tri- or tetra-methylene bridge then the products (127) are heterocyclic propellanes (78CI(L)95>. Photolysis of the sulfone (128) eliminates sulfur dioxide to give a 47r-electron system which can be trapped by N- phenylmaleimide (Scheme 41) (78JOC3374). 

Abstract. Three independent determinations have been made of the crystalline structure of the a-phase of poly (tetra-methylene terephthalate). The data on which these determinations have been based are used to asses the contributions to the uncertainties of the structural parameters caused by errors in the unit cell parameters, structure factors, and bond parameters. The effects of differences in the model from which refinement is started are also assessed. The major contribution to uncertainty arises from errors in the structure factors (the "R-factor" between structure factor sets from two different laboratories can be greater than 20%) but errors in bond parameters also make a sizeable contribution. Hamilton s test indicates that one of the structure factor sets used in this study is less inaccurate than the other two and using this the best model satisfying all the other data is estimated together with the uncertainties in its parameters. 

Two series of polyether polyurethanes (PU) based on hydroquinone bis (P-hydroxyethyl) ether (HQEE) or 1,4-butanediol (BDO) as a chain extender were prepared by the one step bulk polymerisation process. By varying the mole ratio of poly tetra methylene oxide (PTMO) extender (with Mn = 1000 and Mn = 2000) and 4,4 -diphenylene methane diisocyanate (MDI) the two series of HQEE (PUlOOOHj, PU 1000H2, PU2000Hj,... 

In the polyurethane industry, the polymeric glycols are prepared by anionic polymerization of epoxides such as ethylene oxide and propylene oxide. Poly(tetra-methylene glycol), which was prepared by polymerization of tetrahydrofuran, was subjected to chain extension by reaction with diisocyanate (polyurethane formation) and with dimethyl terephthalate (polyester by alcoholysis). 

Physical properties are related to ester-segment structure and concentration in thermoplastic polyether-ester elastomers prepared hy melt transesterification of poly(tetra-methylene ether) glycol with various diols and aromatic diesters. Diols used were 1,4-benzenedimethanol, 1,4-cyclo-hexanedimethanol, and the linear, aliphatic a,m-diols from ethylene glycol to 1,10-decane-diol. Esters used were terephthalate, isophthalate, 4,4 -biphenyldicarboxylate, 2,6-naphthalenedicarboxylate, and m-terphenyl-4,4"-dicarboxyl-ate. Ester-segment structure was found to affect many copolymer properties including ease of synthesis, molecular weight obtained, crystallization rate, elastic recovery, and tensile and tear strengths. 

Alkylene 4,4 -Biphenyldicarboxylate/PTME 4,4 -Biphenyldicarbox-ylate Copolymers. Tetramethylene 4,4 -biphenyldicarboxylate/PTME 4,4 -biphenyldicarboxylate copolymers containing 20 and 30% tetra-methylene 4,4 -biphenyldicarboxylate were prepared without incident (Table VI). Attempts to prepare similar copolymers containing 40 and 50% tetramethylene 4,4 -biphenyldicarboxylate led to problems with phase separation in the melt during the copolymerizations. 

Bicyclo[4.4.1]undec-l(ll)-ene (28), however, exhibits different behavior, for it dimerizes in 95% yield to form structure (29). Whether this process involves hydrogen atom transfer from a tetra-methylene diradical, or an unusual pericyclic reaction reminiscent of an ene reaction, remains unclear. 

Stereochemical studies add great support to the proposition that [2 + 2] cycload tions involve tetra-methylene diradical intermediates, for these additions e place with partial or complete loss of cis/trans stereochemical relationships present in alkene reactants, llie dimerization of acrylonitrile, for example, studied with ci5-l,2-dideuteriocyanoethylene (42), gives six distinct [2 + 2] adducts the distribution of deuterium labels in the df-l,2-dicyanocyclobutane products are given in structures (43), (44) and (45) an analogous set of three trans stereoisomers is formed. Recovered starting material shows partial loss of stereochemical integrity. 

The process is not limited to mcthylation, Thus reaction of aniline (I) with tetra-methylene sulfide in the general procedure followed by Raney nickel desulfurization gives ori/jo-n-butylaniline (5) in satisfactory overall yield. 

Dry hydrogen bromide [Org. Syntheses Coll. Vol. 2, 338 (1943)] is passed into tetrahydrofuran [Org. Syntheses Coll. Vol. 2, 566 (1943)] under a reflux condenser until the temperature of the reaction mixture reaches 150", at which point the theoretical quantity of hydrogen bromide has been taken up. The reaction mixture is steam-distilled, and the distillate is extracted with ether. Distillation of the ethereal solution after drying gives a 63% yield of tetra-methylene bromide, b.p. 62-63°/3 mm. 

FIGURE 5-7 Some unusual in/ramolccular H bonds. This page o-carboxybcnzcnc-phosphoric acid o-hydroxyphcnylacctylcnc spiro(4,4) nonanediol(l,6) a-hy-droxyethylferroccne Tcrramycin ethylenediamine-tetra (methylene-phos-... 

Imines.—The compounds so formed and containing the group (—NH—), are known as imines. The four carbon imine given above is named pjrrrolidine, and the di-amine from which it is formed, as tetra-methylene di-amine, also as putrescine. It is found as a putrefaction product of animal flesh. The analogous five carbon compounds are, penta-methylene di-amine, or, cadaverine, and the imine is piperidine. The last compound is found in pepper in combination as the alkaloid, piperine. 

CsHe Tri-methylene C4H8 Tetra-methylene C5H10 Penta-methylene C6H12 Hexa-methylene... 

Poly-methylenes, Cycle ParaflSns.—The names tetra-methylene or cyclo butane, hexa-methylene or cycle hexane, etc., are analogous to tri-methlyene or cyclo propane. For the homologous series the names poly-methylenes or cyclo parafi s are used. 

Pyrrolidine may be synthesized from tetra-methylene di-amine, putrescine (p. 194), by the loss of ammonia. 

The constitution of pyrridine is established by numerous syntheses. The only one we shall mention is the one from cadaverine or penta-methylene di-amine. The corresponding tetra-methylene di-amine, as already stated (p. 855), loses ammonia and yields pyrrolidine, the saturated hydrogenated pyrrole. By an exactly similar reaction penta-methylene di-amine loses ammonia and yields the saturated hydrogenated pyridine which is known as piperidine. 

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