Propylene derivatives

The main use of propylene is for polymerization to polypropylene, a process similar to the manufacture of high-density polyethylene (i.e., a low-pressure, catalytic process). Textile hhers made from polypropylene are relatively low-cost and have particularly good properties, such as high resistance to abrasion and soiling for use in furniture upholstery and indoor/outdoor carpeting. 

Three major non-polymer propylene derivatives are isopropanol, acetone, and acrylic acid. Isopropanol (isopropyl alcohol) is used mainly as a solvent. It has been made from propylene by reaction with sulfuric acid and water for at least the last 75 years, making its manufacture the oldest, still-running commercial organic chemical process. It is used in household rubbing alcohol because, unlike ethanol, it is unfit for human consumption even in small amounts. About 25 % of the isopropanol produced is used for making acetone, in competition with a route based on isopropylbenzene. 

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Most organopentacyanides are stable towards [Co(CN)jH], with the exception of allyl complexes which react to liberate propylene derivatives (105). This is one of the steps in the homogeneous hydrogenation of butadienes catalyzed by cobalt cyanide complexes (see Section VII,A). 

Several studies now exist which add credence to Casey s attractive proposal that metallocyclobutanes intervene in metathesis and cyclopro-panation reactions. Additionally, metallocyclobutanes have been observed to interconvert to propylene derivatives by way of /3-hydrogen transfer reactions. It is not well established, however, whether precoordination of the reacting olefin is required in all these processes. The proposed interrelation of these reactions may be formally presented as follows ... 

The fact that Schrock s proposed metallocyclobutanes decomposed to propylene derivatives rather than cyclopropanes was fortunate in that further information resulted regarding the stereochemistry of the olefin reaction with the carbene carbon, as now the /3-carbon from the metal-locycle precursor retained its identity. The reaction course was consistent with nucleophilic attack of the carbene carbon on the complexed olefin, despite potential steric hindrance from the bulky carbene. Decomposition via pathways f-h in Eq. (26) was clearly confirmed in studies utilizing deuterated olefins (67). 

One of the propylene derivatives displays the same effects to a lesser degree. The propylene carbonate coupling constants are solvent invariant. 

Chemicals obtained from jjetroleum having four carbons are manufactured at a considerably lower scale than ethylene or propylene derivatives. Only five C4 compounds— butadiene, acetic acid, vinyl acetate, isobutylene, and methyl /-butyl ether (MTBE)— appear in the top 50. The manufacture of butadiene and isobutylene, as well as the separation of other C4 compounds from petroleum, is described in Chapter 8, Sections 3-5. Acetic acid was discussed as a derivative of ethylene in Chapter 9, Section 3 and is discussed as a derivative of methane in Chapter 12, Section 3. Vinyl acetate was discussed in Chapter 9, Section 4. A few important derivatives of C4 chemistiy will be briefly mentioned here as well as MTBE. 

There are nine chemicals in the top 50 that are manufactured from benzene. These are listed in Table 11.1. Two of these, ethylbenzene and styrene, have already been discussed in Chapter 9, Sections 5 and 6, since they are also derivatives of ethylene. Three others—cumene, acetone, and bisphenol A— were covered in Chapter 10, Sections 3-5, when propylene derivatives were studied. Although the three carbons of acetone do not formally come from benzene, its primary manufacturing method is from cumene, which is made by reaction of benzene and propylene. These compounds need not be discussed further at this point. That leaves phenol, cyclohexane, adipic acid, and nitrobenzene. Figure 11.1 summarizes the synthesis of important chemicals made from benzene. Caprolactam is the monomer for nylon 6 and is included because of it importance. 

Application The Uhde Sleam Active Reforming STAR process produces (a) propylene as feedstock for polypropylene, propylene oxide, cumene, acrylonitrile or other propylene derivatives, and (b) butylenes as feedstock for methyl tertiary butyl ether (MTBE), alkylate, isooctane, polybutylenes or other butylene derivatives. 

Reaction of potassium triazolyldithiocarbonate with dibromopropane leads to substituted [l,2,4]triazolo[l,5-c]-[l,3,5]thiadiazocine-5-thione 143 in poor yield (Equation 28 <1994JHC997>). The major products of this transformation were uncyclized 3-bromopropyldithiocarbonate (20%) and bis-substituted propylene derivative (16%). 

The number of derivatives commercially produced from this group of aromatic substrates is extensive, many targeted as monomers for polymerization to the large-volume fibers and plastics. Some of these, the ethylbenzene to styrene sequence and cumene to phenol, have already been discussed in connection with ethylene and propylene derivatives. Details of some further representative examples of major products are outlined here. 

Propylene. Unlike ethylene, propylene production does not represent the requirement for propylene derivatives. With few exceptions, propylene is not made on purpose but is obtained as a by-product of other processes. More specifically, large quantities of relatively low purity (40-70%) propylene are produced in refineries as a by-product of gasoline manufacture. Additionally, significant quantities of higher purity propylene originate in olefins plants, where ethylene is the primary product. However, only polymer-grade propylene (>99% pure) can in any way be considered an on-purpose product. To better understand... 

Somewhat surprisingly, the structure of the propylene derivative, [ Cu(H20)2(o-phen) Cu(o-phen)2 (Mo50i5)(03PCH2CH2CH2P03)], shown in Figure 11,... 

Another important process connected with propylene derivatives is the hydrodimerization of acrylonitrile, which has been developed commercially by Monsanto, up to a total installed capacity exceeding 2000.000 t y with plants located in the US and in Europe. This process easily withstands the competition with the concurrent chemical processes by using cheaper raw materials presenting minor problems of pollution and affording higher operational safety. Adiponitrile is hydrogenated to hexamethyl-enediamine, which is used in the manufacture of polyamides, and, to a lesser extent, of polyurethanes. 

Propylene-derived alkyl benzenes were pretty much phased out in the 1960s because of their exceptional (and undesirable) biological stabUity and were replaced by the linear alkyl benzenes prepared from linear olefins or intermediate chlorinated paraffins. These products, like the tetrapropylenes, have a chain length that may range from Cg to Cie, variously distributed according to the specific preparation procedure and the properties desired in the final surfactant. The nominal carbon values for most commercial products are Cg and Cg alkyl groups. 

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