Normal butenes

The propylene-based chemicals, n- and isobutanol and 2-ethyl-1-hexanol [104-76-7] (2-EH) dominate the product spectmm. These chemicals represent 71% of the world s total oxo chemical capacity. In much of the developed world, plasticizers (qv), long based on 2-EH, are more often and more frequendy higher molecular weight, less volatile Cg, and C q alcohols such as isononyl alcohol, from dimerized normal butenes isodecanol, from propylene trimer and 2-propyl-1-heptanol, from / -butenes and aldol addition. Because of the competition from the higher molecular weight plasticizer alcohols,... 

Oxydehydrogenation of /i-Butenes. Normal butenes can be oxidatively dehydrogenated to butadiene in the presence of high concentration of steam with fairly high selectivity (234). The conversion is no longer limited by thermodynamics because of the oxidation of hydrogen to water. Reaction temperature is below about 600°C to minimise over oxidation. Pressure is about 34—103 kPa (5—15 psi). 

Normal butenes and isobutylene are separated by a selective reaction-extraction... 

The acid extract phase is separated, diluted with water, and heated to regenerate isobutylene. The isobutylene is then caustic and water washed to remove traces of acid, distillation dried, and rerun. The unreacted C4 stream, containing normal butenes, is also caustic washed before further processing. 

When high purity isobutylene is not required, the acid extract from the rich stage may be heated for a few minutes to 250-300°F, and then quickly cooled. Under these conditions the isobutylene dimerizes to form largely 2,4,4, trimethyl pentene-1. This is known as the dimer process and may be used to concentrate i-butenes for dehydrogenation feed, the isobutylene dimer being added to the motor gasoline pool. Trimers, as well as codimers with normal butenes are also produced. 

There are four butene isomers three unbranched, normal butenes (n-butenes) and a branched isobutene (2-methylpropene). The three n-butenes are 1-butene and cis- and trans- 2-butene. The following shows the four butylene isomers ... 

The kinetic measurements reported in the following sections are concerned with the polymerization of propylene the results obtained with this monomer can, however, be extended to other olefins (e.g., normal butene-1, pentene-1, or branched). For this reason, although we limit ourselves to recording measurements made with one monomer only and with two types of catalytic system, we have given the most general title to this paper. 

Butenes or butylenes are hydrocarbon alkenes that exist as four different isomers. Each isomer is a flammable gas at normal room temperature and one atmosphere pressure, but their boiling points indicate that butenes can be condensed at low ambient temperatures and/or increase pressure similar to propane and butane. The 2 designation in the names indicates the position of the double bond. The cis and trans labels indicate geometric isomerism. Geometric isomers are molecules that have similar atoms and bonds but different spatial arrangement of atoms. The structures indicate that three of the butenes are normal butenes, n-butenes, but that methylpropene is branched. Methylpropene is also called isobutene or isobutylene. Isobutenes are more reactive than n-butenes, and reaction mechanisms involving isobutenes differ from those of normal butenes. 

Most butenes are produced in the cracking process in refineries along with other C-4 fractions such as the butanes. Butenes are separated from other compounds and each other by several methods. Isobutene is separated from normal butanes by absorption in a sulfuric acid solution. Normal butenes can be separated from butanes by fractionation. The close boiling points of butanes and butenes make straight fractional distillation an inadequate separation... 

Another large use of normal butenes in the petrochemical industry is in the production of 1,3-butadiene (CH2 = CH = CH = CH2). In the process, a mixture of n-butenes, air, and steam is passed over a catalyst at a temperature of 500°C to 600°C. Butadiene is used extensively to produce synthetic rubbers (see Isoprene) in polymerization reactions. The greatest use of butadiene is for styrene-butadiene rubber, which contains about a 3 1 ratio of butadiene to styrene. Butadiene is also used as a chemical intermediate to produce other synthetic organics such as chloroprene, for adhesives, resins, and a variety of polymers. 

Normal butenes to butadiene, furan and maleic anhydride... 

More information is available about orientation, when a second alkyl group is introduced into the aromatic ring, and about relative rates. As might be expected, propene reacts more easily than ethylene [342,346] and isobutene more easily than propene [342]. Normal butenes are sometimes isomerised in the process practically the same product composition, consisting mainly of 2,2,4-trimethylpentane, is obtained in the alkylation of isobutane whether the olefin component is isobutene or 2-butene [339]. In the alkylation of aromatic hydrocarbons, this side reaction is negligible. 

Another isomer-separation process which has been announced Is called OlefinSlv (13) This process separates iso-butene from normal butenes in a manner similar to IsoSiv. 

Oxidation of olefins other than ethylene occurs more slowly and often in lower yields. Propylene is oxidized selectively to acetone,516,519 and normal butenes give methyl ethyl ketone.519 Higher olefins generally produce mixtures as a result of olefin isomerization.520 Aqueous solutions of other Group VIII metal salts, such as Pt(II), Ir(III), Ru(III), and Rh(III) oxidize olefins in an analogous manner to Pd(II), although at significantly lower rates.512... 

Tessag Edeleanu GmbH Butanol, secondary Normal butenes rich C4 cut and water Catalytic direct hydration. Catalyst is cation exchange resin 3 1995... 

Olefin Isomerization. Olefin isomerization plays an important role in butene-isobutane alkylation reaction mechanisms. Normal butenes are largely isomerized to isobutene before alkylation. This is believed to take place in ionic form, i.e., immediately following olefin protonation, since a number of olefins have been found to odd HF across their double bonds quite readily at room temperature (Grosse and Linn, 1938). Thus, the likelihood of olefin molecules being present for very long under alkylation conditions is not great. 

The following facts are the basis for butene isomerization (I) There is a basic similarity in the composition of alkylates produced from all four butene isomers. (2) Alkylate molecules, once formed, are relatively stable under alkylation conditions and do not isomerize to any appreciable extent alkylate fractions having the same carbon number ore not equilibrated (see Table I). (3) Thermodynamic equilibrium between the butene olefins highly favors isobutene formation at alkylation temperatures. (4) Normal butenes p>roduce only small and variable amounts of normal butane, thus indicating only a small and variable amount of chain initiation from normal butenes. Yet the alkylate composition shows a high concentration of trimethylpentanes and a low concentration of dimethylhexanes. (5) A few of the octane isomers can be explai.ned only by isomerization of the eight-carbon skeletal structure this isomerization occurs while isobutene dimer is in ionic form. For example, 2,3,3- and 2,3,4-trimethylpentanes... 

Normal Butene Reactions. Under alkylation conditions, all four butene isomers are believed to undergo isomerization, dimerization, and co-dimerization when first coming in contact with HF catalyst, i.e., immediately following protonation. These are very rapid, Ionic reactions and take place competitively along with isobutane alkylation. Alkylate compositions from the four butenes are basically similar (see Table VII). However, l-butene produces a C3 fraction containing nearly two times... 

The normal butenes were pyrolyzed in the presence of steam in a nonisothermal flow reactor at 730°-980°C and contact times between 0.04 and 0.15 sec to obtain conversion covering the range between 3% and 99%. Isomerization reactions accompanied the decomposition of these olefins however, the decomposition was the dominant reaction under these conditions. Pyrolysis of 1-butene is faster than that of either cis- or trans-2-butene. Methane, propylene, and butadiene are initial as well as major products from the pyrolysis of the n-butenes. Hydrogen is an initial product only from the 2-butenes. Ethylene appears to be an initial product only from 1-butene it becomes the most prominent product at high conversions. Over the range of conditions of potential practical interest, the experimental rate expressions for the disappearance of the respective butene isomers, have been derived. 

Results from this laboratory for steam pyrolysis of isobutene were reported earlier (I), and this chapter describes the pyrolysis of the three normal butene isomers 1-butene, m-2-butene, and trans-2-butene. Reaction schemes are derived from the product distributions, and kinetic parameters are established. 

Alkylation of aromatics and aliphatics, e.g., ethylbenzene from ethylene and benzene, cumene from propylene and benzene, alkylation of isobutane with normal butenes... 

Refineries that have access to isobutylene streams from steam cracking may face the problem that the existing alkylation and possibly catalytic condensation units cannot take the normal butenes which are contained in the pyrolysis stream. 

Skeletal isomerization of normal butenes is an active research domain, but has not yet found an industrial realization. 

Butene, homopolymer PIB Polybutene Poly-a-butylene U.S, National L. Polymer formed by polymerization of a mixture of iso and normal butenes. Thermoplastic resin used as tackifier, strengthener, and extender in adhesives, as plasticizer for rubber, as vehicle and fugitive binder for coatings, Amoco Lubricants Ashland BP Chem. Harcros. 

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