Urethane intermediates

The polyamide copolymer of dodecanoic acid with methylenedi(cyclohexylamine) (MDCHA, PACM) was sold as continuous filament yam fiber under the tradename QIANA. As late as 1981, over 145,000 t was produced using high percentages, typically 80%, of trans, trans MDCHA isomer. The low melting raffinate coproduct left after t,t isomer separation by fractional crystallisation was phosgenated to produce a Hquid aUphatic diisocyanate marketed by Du Pont as Hylene W. Upon terrnination of their QIANA commitment, Du Pont sold the urethane intermediate product rights to Mobay, who now markets the 20% trans, trans—50% cis, trans—30% cis, cis diisocyanate isomer mixture as Desmodur W. In addition to its use in polyamides and as an isocyanate precursor, methylenedi (cyclohexyl amine) is used directiy as an epoxy curative. The Hquid diamine mixture identified historically as PACM-20 is marketed as AMICURE PACM by Anchor Chemical for performance epoxies. 

Other Derivatives. Ethylene carbonate, made from the reaction of ethylene oxide and carbon dioxide, is used as a solvent. Acrylonitrile (qv) can be made from ethylene oxide via ethylene cyanohydrin however, this route has been entirely supplanted by more economic processes. Urethane intermediates can be produced using both ethylene oxide and propylene oxide in their stmctures (281) (see Urethane polymers). 

Key steps, as shown in Scheme 4-15, involve the formation of a urethane intermediate 37 by treating epoxide 36 with methyl isocyanate in the presence of sodium hydride. Intramolecular A-nucleophilic ring opening of oxirane affords oxazolidine 38. Subsequent treatment furnishes product 34. 

Polyurethane 541-D-101 Valspar Moisture-cured urethane intermediate coat... 

The holacosamine 7, a component of the cardiotonic glycosteroids holantiosine, holacurtine, folarosine and mitiphylline, has been obtained in a similar manner3. The required configuration at C-3 of protected holacosamine is obtained through halocyclization of the urethane intermediate 5. 

Spiropiperidine Alkaloids.—new synthetic pathway to ( )-perhydro-histrionicotoxin (27) (Scheme 5) has been elaborated. The final product is the intermediate (28), convertible to (27) as described earlier. A further synthetic entry into this ring system uses a Mannich-type spiro cyclization as key step and leads ultimately to racemic 2,7-epiperhydrohistrionicotoxin (29) (Scheme 6). The structure and stereochemistry of the urethane intermediate (30) were ascertained by X-ray diffraction analysis. ... 

Use Lubricants, plasticizers, paint and varnish vehicles, gelling agents, urethane intermediates, adhesives, cross-linking agents, humectants, textile fiber finishes, functional fluids, surface-active agents, dispersants and emulsifiers in foods, pharmaceuticals, cosmetic preparations. 

Figure 4. Cotton linters vs. urethane intermediates. Price index (12/1975 = 100).

Silicones and Urethane Intermediates Division—Section K1487,... 

Research and Development Department, Silicones and Urethane Intermediates Division, Union Carbide Corporation, South Charleston, WV 25303... 

Raney catalysts are used in a broad range of industrial hydrogenations. These include reductions of nitriles and dinitriles (e.g. for nylon intermediates), aldehydes (e.g. for sorbitol or alkane diols), olefins and alkynes (e.g. for monomer purification) and aromatic nitro compounds (e.g. for urethane intermediates). 

Epoxy intermediates Polycarbonate intermediates Polyester intermediates Urethane intermediates, flexible foam rigid foam... 

The formulations used in the manufacture of polyurethane elastomers are critical, as variations in the chemical composition of raw materials seriously affect properties. In particular, trace impurities can catalyze or inhibit the various reactions, changing network structures and hence final elastomer properties. For these reasons analytical tests to quantify the quality and reactivity of urethane intermediates have been developed and their use in urethane technology is essential. Additionally, characterization and identification of unknown polymers is frequently necessary. Finally, it is necessary to have procedures which characterize the structure and degree of crosslinking (where this applies) of polyurethane elastomers. 

Propionaldehyde is a reactant in the preparation of propanol, propionic acid and a urethane intermediate. It is used as a modifier in polyethylene manufacture, in the synthesis of slow release fertilizers, and in the preparation of favor and fragrance chemicals. 

Bis-(2-hydroxyethy)2,3-dibromopropylsuccinate, urethane intermediate, 174 Bis(2-hydroxyethyl)sulfide, use in polyesters, 492... 

There are also flame retardants chemically bound to the substrate, such as epoxy intermediates, polycarbonates, polyesters, and flexible or rigid urethane intermediates. 

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