Olefins purification

J.C. Davis, R.J. Valus, R. Eshraghi and A.E. Velikoff, Facilitated Transport Membrane Hybrid Systems for Olefin Purification, Sep. Sci. Technol. 28, 463 (1993). 

Davis JC, Valus RJ, Eshraghi R, and Vilikoff AE. Facilitated transport membrane hybrid systems for olefin purification. Separation Science and Technology 1993 28(1-3) 463-476. 

As a general procedure if the olefin is impure, the oxymercura-tion-reduction process may include an olefin purification step. Alternatively, this process may be used to purify the olefin for other purposes. - In such cases, acetone is substituted for ether and, after oxymercuration for the same length of time as suggested above, the solution is poured with stirring into two volumes of water containing one equivalent each of sodium bicarbonate and sodium chloride. The mercury derivative is filtered, recrystallized from ethanol-water, ether, dioxane, or ethyl acetate-heptane and then either reduced as described above (in 70-80% yield) to produce pure alcohol, or deoxy-mercurated with cold 6N HCl, with ethereal lithium aluminum hydride (added cautiously), or high concentrations of alkali halides - to produce the pure olefin. 

Sorbents based on TT-complexation for olefin purification have been developed recently in the author s laboratory (Padin et al., 1999 Jayaraman et al., 2001 Padin et al., 2001 Takahashi et al., 2001a and 2001b). AgY and Cu(l)Y are the best sorbents. Although only vapor phase isotherms are reported in the literature cited above, these sorbents have been demonstrated successfully for the liquid-phase feeds in the field. Diene impurities below 1 ppm can be readily achieved. The isotherms are shown in Figures 8.12 and 8.13, for 1,3-butadiene and 1-butene. 

The sorbent that forms a 7r-complexation bond with molecules of a targeted component in a mixture is named 7r-complexation sorbent. The r-complexation bond is a type of weak and reversible chemical bond, the same type that binds oxygen to hemoglobin in our blood. This type of sorbent has been developed in the past decade, largely in the author s laboratory. Because they have shown a tremendous potential for a number of important applications in separation and purification, they are discussed separately in Chapter 8. This chapter also presents their applications for olefin/paraffin separations, olefin purification (by removal of dienes to <1 ppm, separation of CO, as well as aromatics from aliphatics. The particularly promising application of 7r-complexation sorbents for sulfur removal from transportation fuels (gasoline, diesel, and jet fuels) is discussed in Chapter 10. 

Alkylaluminums generally are thermally very stable thus they are able to be stably stored under an inert atmosphere at ambient temperatures. Straight-chain trialkyl-aluminum having C2—C4 compounds begin to decompose slowly according to the transformation shown in eqs. (7—11) and (7-12) at ca. 100°C. Branched-chain trialkylaluminum compounds, e.g., triisobutylaluminum, begin to decompose at ca. 50 °C [13]. These properties are utilized for the preparation of olefins, purification of aluminum metal and aluminum thin films [17]. 

Gas purifications H2O/olefin-containing cracked gas, natural gas, air, synthesis gas, etc sHica, alumina, zeoHte... 

With the improvement of refining and purification techniques, many pure olefinic monomers are available for polymerization. Under Lewis acid polymerization, such as with boron trifluoride, very light colored resins are routinely produced. These resins are based on monomers such as styrene, a-methylstryene, and vinyltoluene (mixed meta- and i ra-methylstyrene). More recently, purified i ra-methylstyrene has become commercially available and is used in resin synthesis. Low molecular weight thermoplastic resins produced from pure styrene have been available since the mid-1940s resins obtained from substituted styrenes are more recent. 

Table 3 provides typical specifications for isoprene that are suitable for Al—Ti polymerization (89). Traditional purification techniques including superfractionation and extractive distillation are used to provide an isoprene that is practically free of catalyst poisons. Acetylenes and 1,3-cyclopentadiene are the most difficult to remove, and distillation can be supplemented with chemical removal or partial hydrogenation. Generally speaking distillation is the preferred approach. Purity is not the main consideration because high quaUty polymer can be produced from monomer with relatively high levels of olefins and / -pentane. On the other hand, there must be less than 1 ppm of 1,3-cyclopentadiene. 

Another attractive commercial route to MEK is via direct oxidation of / -butenes (34—39) in a reaction analogous to the Wacker-Hoechst process for acetaldehyde production via ethylene oxidation. In the Wacker-Hoechst process the oxidation of olefins is conducted in an aqueous solution containing palladium and copper chlorides. However, unlike acetaldehyde production, / -butene oxidation has not proved commercially successflil because chlorinated butanones and butyraldehyde by-products form which both reduce yields and compHcate product purification, and also because titanium-lined equipment is required to withstand chloride corrosion. 

In the manufacture of 2-naphthalenol, 2-naphthalenesulfonic acid must be converted to its sodium salt this can be done by adding sodium chloride to the acid, and by neutralizing with aqueous sodium hydroxide or neutralizing with the sodium sulfite by-product obtained in the caustic fusion of the sulfonate. The cmde sulfonation product, without isolation or purification of 2-naphthalenesulfonic acid, is used to make 1,6-, 2,6-, and 2,7-naphthalenedisulfonic acids and 1,3,6-naphthalenetrisulfonic acid by further sulfonation. By nitration, 5- and 8-nitro-2-naphthalenesulfonic acids, [89-69-1] and [117-41-9] respectively, are obtained, which are intermediates for Cleve s acid. All are dye intermediates. The cmde sulfonation product can be condensed with formaldehyde or alcohols or olefins to make valuable wetting, dispersing, and tanning agents. 

Interest in synthetic naphthenic acid has grown as the supply of natural product has fluctuated. Oxidation of naphthene-based hydrocarbons has been studied extensively (35—37), but no commercially viable processes are known. Extensive purification schemes must be employed to maximize naphthene content in the feedstock and remove hydroxy acids and nonacidic by-products from the oxidation product. Free-radical addition of carboxylic acids to olefins (38,39) and addition of unsaturated fatty acids to cycloparaffins (40) have also been studied but have not been commercialized. 

The largest use of NMP is in extraction of aromatics from lube oils. In this appHcation, it has been replacing phenol and, to some extent, furfural. Other petrochemical uses involve separation and recovery of aromatics from mixed feedstocks recovery and purification of acetylenes, olefins, and diolefins removal of sulfur compounds from natural and refinery gases and dehydration of natural gas. 

Monomers for manufacture of butyl mbber are 2-methylpropene [115-11-7] (isobutylene) and 2-methyl-l.3-butadiene [78-79-5] (isoprene) (see Olefins). Polybutenes are copolymers of isobutylene and / -butenes from mixed-C olefin-containing streams. For the production of high mol wt butyl mbber, isobutylene must be of >99.5 wt % purity, and isoprene of >98 wt % purity is used. Water and oxygenated organic compounds iaterfere with the cationic polymerization mechanism, and are minimized by feed purification systems. 

These are regenerative methods since the systems in question can usually be made from olefins. Employed in this way, they are frequently useful in the isolation, purification or protection of olefins. Alternatively, independent routes to the difunctional system are available and constitute legitimate olefin syntheses. 

The "acyl effect" proves crucial in the formation of the perhydroazulene systems cyclization can only take place with the presence of an acyl group on the TMM portion whereas the parent hydrocarbon fails. For example, treatment of substrate (51) with the palladium catalyst gave a mixture of the bicyclic compounds (52) and (53) in 51% yield. The formation of endocyclic olefin (52) is presumed to occur when the first formed (53) was exposed to silica gel during purification [22]. This intramolecular cycloaddition strategy was utilized in a highly diastereoselec-tive preparation of a key intermediate (54) in the total synthesis of (-)-isoclavuker-in A (55) (Scheme 2.16) [21]. 

In an alternative syntliesis of panaatistaliti (S7) by Trost et al. [52], fSdieme 9.15) addilioti of tlie Grlgtiatd teagetil 63 [53] lo a mixture of tlie azide 62 and copper cyanide reprodudbly gave tlie desired adduct 64. Because of tlie difliciilties associated witli purification of adduct, tlie overall yield of tlie two steps ftlie next being diliydroxylation of tlie olefin) was 6 296. 

In a typical procedure61144 the sulfonyl chloride in ether is added to an etheral solution of the diazoalkane and triethylamine. Filtration and evaporation gives the relatively pure thiirane dioxide. Further purification can be easily achieved by recrystallizations preferentially below room temperature in order to avoid fragmentation of the product into sulfur dioxide and the olefin. In general, when the temperature of the above reaction is lowered, the yields are improved without a drastic decrease in reactivity144. Many thiirane dioxides have been successfully synthesized through this method and a detailed list of them can be found elsewhere2. 

Rhodium catalyzed carbonylations of olefins and methanol can be operated in the absence of an alkyl iodide or hydrogen iodide if the carbonylation is operated in the presence of iodide-based ionic liquids. In this chapter, we will describe the historical development of these non-alkyl halide containing processes beginning with the carbonylation of ethylene to propionic acid in which the omission of alkyl hahde led to an improvement in the selectivity. We will further describe extension of the nonalkyl halide based carbonylation to the carbonylation of MeOH (producing acetic acid) in both a batch and continuous mode of operation. In the continuous mode, the best ionic liquids for carbonylation of MeOH were based on pyridinium and polyalkylated pyridinium iodide derivatives. Removing the highly toxic alkyl halide represents safer, potentially lower cost, process with less complex product purification. 

Synthesis of Allylic Alcohol Xa. A 3.84 g sample of olefin VII was treated with m-chloroperoxybenzoic acid (MCPBA) in dichloromethane for 1.5 hours at 0°C and 2.5 hours at 20°C. The NMR spectrum of the crude product indicated a mixture of approximately 75% epoxide VIII and 25% IX (structural assignments based upon assumed epoxidation preferentially from the less hindered side). Purification by column chromatography furnished 0.61 g of IX and 2.58 g of VIII. The separation was performed for characterization purposes the crude epoxidation mixture was suitable for subsequent transformations. 

This sequence has been proposed as a novel approach to olefin separation and purification. Ffowever, there is disagreement about the reversibility of the reaction because it has been shown that irreversible reduction to the dianionic complex occurs through an ECE process.1082 A convenient new route to 1,2-enedithiolate complexes of Ni has been reported, which starts from the bisfhydrosulfldo) complex [Ni(dppe)(SFI)2] and various a-bromoketoues(heterocycle-C(0)CH2Br). 

Because of the unique properties of the cyclopropane ring, cyclopropylbenzene is a compound of considerable interest. Only one of the alternative methods 9 for the preparation of this compound has been reported to give more than 32% yield the procedure described affords an olefin-free product without a relatively laborious purification process. By its utilization of readily available starting materials, and by its applicability to the preparation of large quantities of product, this method of synthesis provides easy access to many cyclopropylbenzene derivatives.12... 

---