Alpha-Hexene

Chemical Designations - Synonyms alpha-Hexene Chemical Formula CH3(CH2)3CH=CH2. Observable Characteristics - Physical State (as shipped) Liquid Color Colorless Odor Mild, pleasant. 

Alpha-Hexene 1-Hexene Isobutyl Acetate Isobutyl Acetate... 

The latest of three ethylene recovery plants was started in 1991. Sasol sold almost 300,000 t of ethylene in 1992. Sasol also produces polypropylene at Secunda from propylene produced at Sasol Two. In 1992 Sasol started constmction of a linear alpha olefin plant at Secunda to be completed in 1994 (40). Initial production is expected to be 100,000 t/yr pentene and hexene. Sasol also has a project under constmction to extract and purify krypton and xenon from the air separation plants at Sasol Two. Other potential new products under consideration at Sasol are acrylonitrile, acetic acid, acetates, and alkylamines. 

SASOL. SASOL, South Africa, has constmcted a plant to recover 50,000 tons each of 1-pentene and 1-hexene by extractive distillation from Fischer-Tropsch hydrocarbons produced from coal-based synthesis gas. The company is marketing both products primarily as comonomers for LLDPE and HDPE (see Olefin polymers). Although there is still no developed market for 1-pentene in the mid-1990s, the 1-hexene market is well estabhshed. The Fischer-Tropsch technology produces a geometric carbon-number distribution of various odd and even, linear, branched, and alpha and internal olefins however, with additional investment, other odd and even carbon numbers can also be recovered. The Fischer-Tropsch plants were originally constmcted to produce gasoline and other hydrocarbon fuels to fill the lack of petroleum resources in South Africa. 

Kalyan et al. [56] have also studied the effect of alpha-olefin comonomers on the rheological properties and processing of LLDPE. The characteristics of the resins are shown in Table 2. It is found that 1-octene-based LLDPE has the lowest shear viscosity as compared to 1-butene- and 1-hexene-based polymers (Fig. 9). Decrease in power consumption, pressure before the die, temperature in the die, and increase in output has also been found according to shear viscosities of the polymers during tubular film extrusion. 

In 2004 Caporali investigated the hydroformylation of 1-hexene and cyclohexene using HRh(CO)(PPh3)3 [61]. The collected data indicated that the rate-determining step in the hydroformylation cycle depends upon the structure of the olefin. With an alpha-olefin like 1-hexene, the slowest step seems to be the hydrogenolysis of the acyl rhodium complex. In the presence of cyclohexene as a model for an internal olefin, the rate-determining step is the reaction of the olefin with the rhodium hydride complex (intermediate II in Fig. 6). 

This chemistry is sometimes accomplished simultaneously in one reactor and sometimes in two separate reactors. In the former, the triethyl aluminum catalyst is lost in the latter, it is recycled. Sometimes the displacement compound is butene-1 or hexene-1, depending on the chain length of the final alpha olefin desired and the change in operating conditions necessary to effect the displacement reaction. 

DOT classifies butene-1 as a flammable compressed gas, hexene, and octene as flammable liquids, and decene-1 as a combustible liquid. All four must carry required shipping placards. The remaining alpha olefins are not regulated by the DOT. 

The lions share, 80-90%, of the alpha olefins produced in. the United States are used In five areas as comonomers in LLDPE (linear low density polyethylene) and HDPE (high density polyethylene), plasticizer alcohols, polyalpha olefins for use in synthetic lubricants, detergent alcohols, and surfactants. The comonomer demand started out exclusively as butene-1, but it is shifting toward hexene-1 and octene-1. Similarly, the specification... 

LLDPE can be produced with less than 300 psi and at about 100°C. It is actually a copolymer of ethylene with about 8% 10% of an alpha-olefin such as 1-butene, 1-pentene, 1-hexene, or 1-octene. Through control of the nature and amount of alpha-olefin, we are able to produce materials with densities and properties between those of LDPE and HDPE. LLDPE does not contain the long branches found in LDPE. 

Today, new copolymers are making use of the hard-soft block strategy where the hard segment is a block portion as PE that readily crystallizes forming a physical cross-link. The soft segment consists of blocks formed from alpha-olefins, such as 1-butene, 1-hexene, and 1-octane, where the substituted alkane-arm discourages crystallization. 

Random copolymers of ethylene and 1-butene or propylene are more flexible and more resistant to environmental stress cracking than ldpe. Some of the newer commercial lldpe plastics are copolymers of ethylene and alpha alkenes, such as 1-hexene. 

Iersel ML, Ploemen JP, Struik I, van Amersfoort C, Keyzer AE, Schefferlie JG, van Bladeren PJ. 1996. Inhibition of glutathione S-transferase activity in human melanoma cells by alpha,beta-unsaturated carbonyl derivatives. Effects of acrolein, cinnamaldehyde, citral, crotonaldehyde, curcumin, ethacrynic acid, and trans-2-hexenal. Chem Biol Interact 102 117-132. 

Linear alpha olefins can be copolymerized with polyethylene to form linear low-density polyethylene (LLDPE) and 1-hexene (C6) and 1-octene (C8) are especially useful for this purpose. In addition, linear alpha olefins are used to make detergent alcohols, oxo alcohols for plasticizers, lubricants, lube oil additives, and surfactants are other important products from linear alpha olefins. 

It has been assumed that the remaining products are formed by some sort of free radical chain mechanism, but no generalized mechanism like that of Rice s for paraffin pyrolysis has been proposed. Tanaka et al. have been able to simulate product distributions for shorter olefins—up to hexene (10). We shall describe a model for higher alpha-olefin pyrolysis and use it to account for the products from the cracking of several olefins. 

There is little rate data available for addition and abstraction reactions involving higher alpha-olefins. Where such data are available, they have usually been obtained from lower temperature studies (12,13,14), However, the available information indicates that addition should be competitive with abstraction in the temperature range of this study. For example, Steacie s data for ethyl radical reactions with 1-hexene and 1-heptene indicate that at 525°C, the addition rate would be about seven-tenths of the abstraction rate. For dodecene, one would expect this ratio to decrease because of the increase in abstractable hydrogen, but addition should still be a significant pathway. For methyl radicals and H atoms, available data (13,14) indicate that addition is somewhat faster relative to abstraction. 

CIC The main flavouring components are alpha-and beta-ionone with their floral, violet and typical perfumy, raspberry, woody character. l-(4-hydroxyphenyl)butan-2-one imparts the fruity, sweet raspberry body. (Z)-3-hexenal is responsible for the fresh, green topnote and 2,5-dimethyl-4 hydroxy-furan-3(2H)-one adds the overripe, almost cooked fruit jammy body. 

Polyolefins—specifically, polyalpha olefins—are made from polymerizing alpha olefins where the double bond is located at the alpha carbon atom. Figure 7.7 shows 1-hexene. The double bond is located between the first and second carbon atoms and, as a result, they have flexible alkyl branching groups on every opposite carbon in the chain. The flexibility due to the different configurations makes crystallization difficult. Because polyalpha olefins are able to remain flexible at lower temperatures, they are ideal as a synthetic motor oil. Some advantages versus disadvantages of synthetics are shown in Table 7.4... 

Description Polymer-grade ethylene is oligomerized in a liquid-phase reactor (1) with a liquid homogeneous catalyst designed for high activity and selectivity. Liquid effluent and spent catalyst are then separated (2) the liquid is distilled (3) for recycling unreacted ethylene to the reactor, then fractionated (4) in order to produce high-purity alpha olefins. Spent catalyst is treated to remove volatile hydrocarbons before safe disposal. The table below illustrates the superior purities attainable (wt%) with the Alpha-Select process n-Butene-1 >99 n-Hexene-1 >98 n-Octene-1 >96 n-Decene-1 >92... 

C12 19, and C16+ 5% and dimer composition was 86% alpha-, and 14% beta-isobutene propylene product hexene 45%, nonenes 40% and oligomers higher than C9 15% increasing temperature increases the amount of > 9 fraction Gasoline and diesel hydrocarbons 94 ... 

Another key limitation of Z-N catalysts is the inability to incorporate very high levels of alpha-olefin comonomer such as 1-butene, 1-hexene, or 1-octene to make the density less than about 0.885 g/cm. The lowest density Z-N catalyzed VLDPE resin commercially available today (FLEXOMER from The Dow Chemical Company) has a target density of 0.885 g/cm (approximately 20 wt% crystallinity). Due to this, Z-N catalyzed VLDPE resins cannot be used in applications requiring very low modulus, low shore A hardness (density less than 0.885 g/cm ). Note that logarithm of modulus of polyethylene resins is related to density (degree of crystallinity) ... 

Besides bio-based ethylene additional bio-based alpha-olefin co-monomers will be required in order to tailor the various polyethylene grades to a required performance. It will require bio-based ethylene to be di-, tri- or tetramerized to form 1-butene, 1-hexene or 1-octene [43 7]. 

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