Availability butadiene

Another potential use of homogeneous hydrogenation catalysts is the hydrogenation of dienes and trienes to monoolefins, where they display high specificity. Such an example is the conversion of the easily available butadiene dimers and trimers to polymer intermediates6. 

Indeed hydroaminomethylation is part of a new route to e-caprolactam. Starting with readily available butadiene it enables the first carbon-carbon bond formation, extending the carbon chain and introducing the aminogroup. In a sub-... 

This unique methodology has been applied to the preparation of synthetically useful building blocks and intermediates. Scheme 7 illustrates the stereocon-trolled synthesis of the dienamine derivative 26 starting with the readily available butadiene 25. Compound 26 undergoes intramolecular Diels-Alder reaction to afford the cfs-octahydroquinoline 27 as a single diastereomer [18]. 

Tsuji and colleagues have synthesized l,7-octadiene-3-one 62 from the readily available butadiene telomer 59 ° and have explored the utility of 62 in natur product synthesis, including two routes to 19-norsteroids. ... 

During the late 1940s and early 1950s interest was shown in copolymers of butadiene and methyl isopropenyl ketone, CH =C(CH3)C0CH3. The rubber was claimed to be superior to the then available butadiene-styrene rubbers in stress-strain properties, cut-growth resistance, tyre tread wear resistance and swelling in hydrocarbons. On the other hand low temperature properties and processability were said to be poorer. 

Multi-ton quantities of 1,5-hexadiene have been manufactured in alkene metathesis semi-works units and the process has been studied in a small specialty olefin pilot plant by the Phillips Company. Feedstocks for this process are the commerically available butadiene derivatives (1,5-cyclooc-tadiene and 1,5,9-cyclododecatriene). The use of excess ethylene and a... 

From the very beginning up to the 1960s, chloroprene was produced by the older energy-intensive acetylene process using acetylene, derived from calcium carbide [3]. The acetylene process had the additional disadvantage of high investment costs because of the difficulty of controlling the conversion of acetylene into chloroprene. The modern butadiene process, which is now used by nearly all chloroprene producers, is based on the readily available butadiene [3]. 

The correcnoii is only applietl in the del ank MM+ paraincier scheine. When MM+ pnranieiers are available in the inmp-sLr.txUtlbf) lile, the normal approach based on only atom types is used. Thus, the correction is applied Lo butadiene when all the atom types are, for example, but not when atom types are present and their corresponding parameters available in the parameter files. 

Analytical investigations may be undertaken to identify the presence of an ABS polymer, characterize the polymer, or identify nonpolymeric ingredients. Fourier transform infrared (ftir) spectroscopy is the method of choice to identify the presence of an ABS polymer and determine the acrylonitrile—butadiene—styrene ratio of the composite polymer (89,90). Confirmation of the presence of mbber domains is achieved by electron microscopy. Comparison with available physical property data serves to increase confidence in the identification or indicate the presence of unexpected stmctural features. Identification of ABS via pyrolysis gas chromatography (91) and dsc ((92) has also been reported. 

ElexibiHty allows the operator to pick and choose the most attractive feedstock available at a given point in time. The steam-cracking process produces not only ethylene, but other products as weU, such as propylene, butadiene, butylenes (a mixture of monounsaturated C-4 hydrocarbons), aromatics, etc. With ethane feedstock, only minimal quantities of other products ate produced. As the feedstocks become heavier (ie, as measured by higher molecular weights and boiling points), increasing quantities of other products are produced. The values of these other coproduced products affect the economic attractiveness and hence the choice of feedstock. 

Acrylonitrile—Butadiene—Styrene. Available only as sheet, ABS has good toughness and high impact resistance. It is readily therm oform able over a wide range of temperatures and can be deeply drawn. ABS has poor solvent resistance and low continuous-use temperature. It is often used in housings for office equipment (see Acrylonitrile polymers). 

Aliphatic Chemicals. The primary aliphatic hydrocarbons used in chemical manufacture are ethylene (qv), propjiene (qv), butadiene (qv), acetylene, and / -paraffins (see Hydrocarbons, acetylene). In order to be useflil as an intermediate, a hydrocarbon must have some reactivity. In practice, this means that those paraffins lighter than hexane have Httle use as intermediates. Table 5 gives 1991 production and sales from petroleum and natural gas. Information on uses of the C —C saturated hydrocarbons are available in the Hterature (see Hydrocarbons, C —C ). 

Chemical Uses. In Europe, products such as ethylene, acetaldehyde, acetic acid, acetone, butadiene, and isoprene have been manufactured from acetylene at one time. Wartime shortages or raw material restrictions were the basis for the choice of process. Coking coal was readily available in Europe and acetylene was easily accessible via calcium carbide. 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

Economic considerations in the 1990s favor recovering butadiene from by-products in the manufacture of ethylene. Butadiene is a by-product in the C4 streams from the cracking process. Depending on the feedstocks used in the production of ethylene, the yield of butadiene varies. Eor use in polymerization, the butadiene must be purified to 994-%. Cmde butadiene is separated from C and C components by distillation. Separation of butadiene from other C constituents is accomplished by salt complexing/solvent extraction. Among the solvents used commercially are acetonitrile, dimethyl acetamide, dimethylform amide, and /V-methylpyrrolidinone (13). Based on the available cmde C streams, the worldwide forecasted production is as follows 1995, 6,712,000 1996, 6,939,000 1997, 7,166,000 and 1998, 7,483,000 metric tons (14). As of January 1996, the 1995 actual total was 6,637,000 t. 

Butadiene copolymers are mainly prepared to yield mbbers (see Styrene-butadiene rubber). Many commercially significant latex paints are based on styrene—butadiene copolymers (see Coatings Paint). In latex paint the weight ratio S B is usually 60 40 with high conversion. Most of the block copolymers prepared by anionic catalysts, eg, butyUithium, are also elastomers. However, some of these block copolymers are thermoplastic mbbers, which behave like cross-linked mbbers at room temperature but show regular thermoplastic flow at elevated temperatures (45,46). Diblock (styrene—butadiene (SB)) and triblock (styrene—butadiene—styrene (SBS)) copolymers are commercially available. Typically, they are blended with PS to achieve a desirable property, eg, improved clarity/flexibiHty (see Polymerblends) (46). These block copolymers represent a class of new and interesting polymeric materials (47,48). Of particular interest are their morphologies (49—52), solution properties (53,54), and mechanical behavior (55,56). 

Styrene—butadiene block copolymers are made with anionic chain carriers, and low molecular weight PS is made by a cationic mechanism (110). Analytical standards are available for PS prepared by all four mechanisms (see Initiators). 

Butadiene is primarily shipped in pressurized containers via railroads or tankers. U.S. shipments of butadiene, which is classified as a flammable compressed gas, are regulated by the Department of Transportation (254). Most other countries have adopted their own regulations (30). Other information on the handling of butadiene is also available (255). As a result of the extensive emphasis on proper and timely responses to chemical spills, a comprehensive handbook from the National Fire Protection Association is available (256). 

Symposium on Toxicology, Carcinogenesis, and Human Health Effects of 1,3-Butadiene (265). Detailed comparisons of various personal monitoring devices are available (266), and control of occupational exposure to 1,3-butadiene has been reviewed (267). ... 

The vinylacetylene [689-97-4] route to chloroprene has been described elsewhere (14). It is no longer practical because of costs except where inexpensive by-product acetylene and existing equipment ate available (see Acetylene-DERIVED chemicals). In the production of chloroprene from butadiene [106-99-0], there are three essential steps, chlorination, isomerization, and caustic dehydrochlorination of the 3,3-dichloro-l-butene, as shown by the following equations Chlorination... 

Third Monomers. In order to achieve certain property improvements, nitrile mbber producers add a third monomer to the emulsion polymerization process. When methacrylic acid is added to the polymer stmcture, a carboxylated nitrile mbber with greatly enhanced abrasion properties is achieved (9). Carboxylated nitrile mbber carries the ASTM designation of XNBR. Cross-linking monomers, eg, divinylbenzene or ethylene glycol dimethacrylate, produce precross-linked mbbers with low nerve and die swell. To avoid extraction losses of antioxidant as a result of contact with fluids duriag service, grades of NBR are available that have utilized a special third monomer that contains an antioxidant moiety (10). FiaaHy, terpolymers prepared from 1,3-butadiene, acrylonitrile, and isoprene are also commercially available. 

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