Alkylation of ethylene

Table 5.3-4 Alkylation of ethylene and 2-butene with isobutane. Semicontinuous pilot-plant results...

Ethyl fluoride shows more tendency to ionize in antimony pentafluoride, than does methyl fluoride. The solutions in neat antimony pentafluoride are, however, not stable and a rapid formation of t-butyl and t-hexyl cations is observed. This observation indicates self alkylation of ethylene formed in equilibrium of equation (2). 

MEEDNA was first prepd by Franchimont Klohbie (Ref 4) by alkylation of ethylene-din itramine. fO.NHHW PH. PH. NTH ... 

The thermal alkylation of ethylene-isobutane mixtures at high pressures in the gas phase has been studied in the presence and absence of HCl, and it has been found that HCl can (a) dramatically increase the total yield of alkylate, (b) increase the fraction of the alkylate which is C6 rather than C8> and (c) both increase and decrease the ratio of 2-methyl pentane to 2J2-dimethylbutane in the C6 fraction of the alkylate, this latter depending on the amount of HCl used. All of these effects can be explained readily in terms of the generally accepted free radical mechanism of thermal alkylation, provided one assumes that HCl acts as a catalyst for those reaction steps that involve transfer of a hydrogen atom between a free radical and a hydrocarbon. 

While it has been less generally recognized, there are free radical reaction systems in which hydrogen atom transfer between radicals is not rate controlling but does control the selectivity with which the various possible reaction products are formed. This chapter is a study of the effect of HCl on such a reaction system, the thermal alkylation of ethylene. (The effect of HCl upon this reaction was first disclosed in one of the authors patents (4). Several years after this disclosure, Schmerling (6) published a paper which, though differing in many details, showed... 

Properties Colorless liquid. Bp 57.9C, d 0.66164 (20C), fp-128.41C, refr index 1.37495 (20C), flash p -20F (-28.9C), autoign temp 788F (420C). Derivation Alkylation of ethylene with isobutane using aluminum chloride catalyst. 

Derivation By the thermal or catalytic union (alkylation) of ethylene and isobutane, both recovered from refinery gases. 

Alkylation reactions are exothermic. The initial alkylation of ethylene to benzene and each successive alkylation reaction generate roughly the same amount of heat (Table 2). 

Acid catalysts are used to promote the alkylation of ethylene to benzene. Acid catalysts suitable for benzene alkylation include protonic acids (i.e., H2SO4, HF, and H3PO4), Friedel-Crafts catalysts (i.e., AICI3 and BF3), and more recently, solid acid catalysts. Solid acid catalysts used for the commercial manufacture of EB are typically zeolitic molecular sieves and materials such as ZSM-5, faujasite, MCM-22, and zeolite beta. Zeolites physical and chemical properties can be modified to optimize the activity, selectivity, and stability of the catalysts. This flexibility of zeolites has made them the preferred catalyst of choice. 

Aluminum chloride has been known for a long time to catalyze this reaction. H owever, its high acidity leads to low selectivity for alkylate. Acidic chloroaluminates proved to be interesting alternative catalysts and solvents [28] because it is possible to tune their Lewis acidity by adjusting their composition. The alkylation of ethylene or butene with isobutane has been performed in continuous-flow pilot plant operation at IFF. The feed, a mixture of olefin and isobutane, is pumped continuously into the well-stirred reactor, which contains the IL catalyst In the case of ethylene, which is less reactive than butene, [pyridine, HClj/AlClj (1 2 molar ratio) IL proved to be the best candidate. The reaction can be run at room temperature and provides good quality alkylate (2,3-dimethylbutanes is the major product) over a period of 300 h (MON = 90-94 RON = 98-101). 

Experiments with conversion of MeOH in the presence of benzene [109,123], alkylation of ethylene with toluene [124], and alkylation of ethylene with ethylbenzene [125], over zeolite catalysts, show high yields and conversions to the corresponding ethylated analogs. This suggests that ethylene oligomerization and methylation (alkylation of ethylene by methanol) reactions are not very important under MTO conditions. So, the ethylene is relatively inert compared to other olefins under MTO conditions. 

Several solid acid catalysts were tested in the laboratory for the alkylation of ethylene with isobutane following the introduction of the sulfuric acid alkylation process." These were mostly derived from aluminum chloride or boron trifluoride and were never used in the full-scale production of alkylates. 

Me3CCH2CMe2C H40H. M.p. 8l-83"C, b.p. 286-288°C. Made by alkylation of phenol. Forms oil-soluble resins with methanal (salts used as oil additives) and surfactants (with ethylene oxide). 

The copolymers of ethylene and propylene (OCVP) are obtained by coordination catalysis using a derivative of vanadium and a derivative of an aluminum alkyl. Molar compositions of ethylene and propylene are usually on the order 45 and 55%. 

Homologous mono-alkyl ethers of ethylene glycol, such as monoethyl glycol (or 2-ethoxyethanol), HOC2H4OC2H5, form excellent solvents as they combine to a large extent the solvent properties of alcohols and ethers. The monoethyl and the monomethyl members have the technical names of ethyl cellosolve and methyl cellosolve respectively. Dioxan... 

Mono-alkyl ethers of ethylene glycol, ROCHjCHjOH. The mono methyl, ethyl and n-butyl ethers are inexpensive and are known as methyl cellosolve, cellosolve, and butyl cellosolve respectively. They are completely miscible with water, and are excellent solvents. The commercial products are purified by drying over anhydrous potassium carbonate or anhydrous calcium sulphate, followed by fractionation after... 

Di-alkyl ethers of ethylene glycol, ROCHjCHjOR. The dimethyl ether, b.p. 85°/760 mm., is miscible with water, is a good solvent for organic compounds, and is an excellent inert reaction medium. The diethyl ether (diethyl cdloaolve), b.p. 121-57760 mm., is partially miscible with water (21 per cent, at 20°). 

Ethyl /m s -2-butenyl sulfone (86) together with some ethyl vinyl sulfone are obtained by the reaction of ethylene and. SO2 in wet benzene using PdCl2. SO2 behaves mechanistically similarly to CO in this reaction[66]. Hydrosulfination of alkenes with SO2 and H2 is catalyzed by the Pd(dppp) complex. The sulfinic acid 87 is a primary product, which reacts further to give the. S-alkyl alkanethiosulfonates 88 as the major product, and 89 and the sulfonic acid 90 as minor products[67]. 

In a widely used industnal process the mixture of ethylene and propene that is obtained by dehydrogenation of natural gas is passed into concentrated sulfunc acid Water is added and the solution IS heated to hydrolyze the alkyl hydrogen sulfate The product is almost exclusively a sin gle alcohol Is this alcohol ethanol 1 propanol or 2 propanoH Why is this particular one formed almost exclusively" ... 

The EB present in recovered mixed xylenes is largely converted to xylenes or benzene. The EB used to make styrene is predominately manufactured by the alkylation of benzene with ethylene. 

The elimination of alcohol from P-alkoxypropionates can also be carried out by passing the alkyl P-alkoxypropionate at 200—400°C over metal phosphates, sihcates, metal oxide catalysts (99), or base-treated zeoHtes (98). In addition to the route via oxidative carbonylation of ethylene, alkyl P-alkoxypropionates can be prepared by reaction of dialkoxy methane and ketene (100). 

For example, ia the iadustriaHy important alkylation of benzene with ethylene to ethylbenzene, polyethylbenzenes are also produced. The overall formation of polysubstituted products is minimized by recycling the higher ethylation products for the ethylation of fresh benzene (14). By adding the calculated equiUbrium amount of polyethylbenzene to the benzene feed, a high conversion of ethylene to monoethylbenzene can be achieved (15) (see also... 

ALKYLATION OF ALIPHATIC COMPOUNDS The first reported alkylation of branched-chain alkanes by ethylene, over aluminum chloride (69), made it possible to alkylate alkanes (except methane and ethane) with straight chain or branched alkenes. 

When usiag HF TaF ia a flow system for alkylation of excess ethane with ethylene (ia a 9 1 molar ratio), only / -butane was obtained isobutane was not detectable even by gas chromatography (72). Only direct O -alkylation can account for these results. If the ethyl cation alkylated ethylene, the reaction would proceed through butyl cations, inevitably lea ding also to the formation of isobutane (through /-butyl cation). 

Cyclic Polyolefins (GPO) and Gycloolefin Copolymers (GOG). Japanese and European companies are developing amorphous cycHc polyolefins as substrate materials for optical data storage (213—217). The materials are based on dicyclopentadiene and/or tetracyclododecene (10), where R = H, alkyl, or COOCH. Products are formed by Ziegler-Natta polymerization with addition of ethylene or propylene (11) or so-called metathesis polymerization and hydrogenation (12), (101,216). These products may stiU contain about 10% of the dicycHc stmcture (216). 

Uses. Magnesium alkyls are used as polymerization catalysts for alpha-alkenes and dienes, such as the polymerization of ethylene (qv), and in combination with aluminum alkyls and the transition-metal haUdes (16—18). Magnesium alkyls have been used in conjunction with other compounds in the polymerization of alkene oxides, alkene sulfides, acrylonitrile (qv), and polar vinyl monomers (19—22). Magnesium alkyls can be used as a Hquid detergents (23). Also, magnesium alkyls have been used as fuel additives and for the suppression of soot in combustion of residual furnace oil (24). 

Other Higher Oleiins. Linear a-olefins, such as 1-hexene and 1-octene, are produced by catalytic oligomerization of ethylene with triethyl aluminum (6) or with nickel-based catalysts (7—9) (see Olefins, higher). Olefins with branched alkyl groups are usually produced by catalytic dehydration of corresponding alcohols. For example, 3-methyl-1-butene is produced from isoamyl alcohol using base-treated alumina (15). 

Olefin distribution in the Albemarle stoichiometric process tends to foUow the Poisson equation, where is the mole fraction of alkyl groups in whichp ethylene units have been added, and n is the average number of ethylene units added for an equal amount of aluminum. 

The solvent is 28 CC-olefins recycled from the fractionation section. Effluent from the reactors includes product a-olefins, unreacted ethylene, aluminum alkyls of the same carbon number distribution as the product olefins, and polymer. The effluent is flashed to remove ethylene, filtered to remove polyethylene, and treated to reduce the aluminum alkyls in the stream. In the original plant operation, these aluminum alkyls were not removed, resulting in the formation of paraffins (- 1.4%) when the reactor effluent was treated with caustic to kill the catalyst. In the new plant, however, it is likely that these aluminum alkyls are transalkylated with ethylene by adding a catalyst such as 60 ppm of a nickel compound, eg, nickel octanoate (6). The new plant contains a caustic wash section and the product olefins still contain some paraffins ( 0.5%). After treatment with caustic, cmde olefins are sent to a water wash to remove sodium and aluminum salts. 

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