Oligomers 2-butene

With Lewis acids as catalysts, compounds containing more than one alkoxy group on a carbon atom add across vinyl ether double bonds. Acetals give 3-alkoxyacetals since the products are also acetals, they can react further with excess vinyl ether to give oligomers (228—230). Orthoformic esters give diacetals of malonaldehyde (231). With Lewis acids and mercuric salts as catalysts, vinyl ethers add in similar fashion to give acetals of 3-butenal (232,233). 

The dehydrogenation of 2-butanol is conducted in a multitube vapor-phase reactor over a zinc oxide (20—23), copper (24—27), or brass (28) catalyst, at temperatures of 250—400°C, and pressures slightly above atmospheric. The reaction is endothermic and heat is suppHed from a heat-transfer fluid on the shell side of the reactor. A typical process flow sheet is shown in Figure 1 (29). Catalyst life is three to five years operating in three to six month cycles between oxidative reactivations (30). Catalyst life is impaired by exposure to water, butene oligomers, and di-j -butyl ether (27). 

Propjiene (qv) [115-07-1] is the predominant 0x0 process olefin feedstock. Ethylene (qv) [74-85-1J, as well as a wide variety of terminal, internal, and mixed olefin streams, are also hydroformylated commercially. Branched-chain olefins include octenes, nonenes, and dodecenes from fractionation of oligomers of C —C olefins as well as octenes from dimerization and codimerization of isobutylene and 1- and 2-butenes (see Butylenes). 

Several additives were tested in the case of the Ni(acac)2/P(n-Bu)3/AlEt3/addihve (1/3/3/10) system. BF3.0Et2 or TiCl4 or morpholinium chloride induces the fully se-lechve formahon of 3-(N-morpholino)-l-butene without formahon of 1 2 telomers or oligomers (Eq. 4.46) [180]. 

The reaction of ethylene at -20°C and 1 atm with the phosphine-free catalyst prepared from 77-allylnickel chloride and ethylaluminum dichloride in chlorobenzene results in the rapid formation of a mixture of ethylene dimers with lesser amounts of higher oligomers. The dimer fraction consists mainly of 2-butenes and the trimer fraction of 3-methylpentenes and 2-ethyl-1-butene as well as a minor amount of hexene (97). From the composition of the products it can be concluded that the displacement reaction predominates over the insertion reaction when using the phosphine-free catalyst and that the direction of addition of both the H—Ni and C2H5—Ni species is mainly of the Ni — C2 type. 

Adapted from Sasidharan and Kumar (258). Reaction conditions 2,3-dimethyl-2-butene, 10 mmol H202 (31 wt% aqueous solution), 10 mmol catalyst, 20wt% with respect to substrate water (as dispersion medium), 5 mL temperature, 333 K reaction time, 6 h. a The figures in the parentheses represent the Si/Ti ratios. b DMB, 2, 3-dimethyl-2-butanol and others include oligomers. 

The only solid acidic catalyst which has given high polymers at an appreciable rate at low temperatures, and which has been studied in some detail, is that described by Wichterle [41, 42]. This was prepared as follows A 10 per cent solution in hexane of aluminium tri-(s- or t-butoxide) was saturated with boron fluoride at room temperature, and excess boron fluoride was removed from the precipitate by pumping off about half the hexane. Two moles of boron fluoride were absorbed per atom of aluminium, and butene oligomers equivalent to two-thirds of the alkoxy groups were found in the solution the resulting solid had hardly any catalytic activity. When titanium tetrachloride was added to the suspension in hexane, an extremely active catalyst was formed but the supernatant liquid phase had no catalytic activity. The DP of the polymers formed by the catalyst prepared from the s-butoxide was much lower than that of polymers formed with a catalyst prepared from the r-butoxidc. 

The mechanism of the reaction is still obscure but our results are probably compatible with those of Pepper and Barton [23] who found that the rate of disappearance of unsaturation, when 1,3-diphenyl butene-1 (distyrene) reacted with perchloric acid, was of second order in olefin and in acid. Unfortunately they did not investigate whether any saturated products other than the cyclised dimer were formed, although they found some higher oligomers. 

Propene- and butene-oligomers are complex mixtures. A typical isomer distribution is shown in Fig. 24. According to the thermodynamical stability the double bonds are distributed along the chain, terminal double bonds are present only in traces. To get predominant terminal products, a catalyst must provide extremely fast terminal hydroformylation activity for the traces of terminal olefins, a high isomerization activity to supply the terminal double bonds as fast as they are consumed, and low hydroformylation activity for internal double bonds. 

Ruthenium complexes B also undergo fast reaction with terminal alkenes, but only slow or no reaction with internal alkenes. Sterically demanding olefins such as, e.g., 3,3-dimethyl-l-butene, or conjugated or cumulated dienes cannot be metathesized with complexes B. These catalysts generally have a higher tendency to form cyclic oligomers from dienes than do molybdenum-based catalysts. With enol ethers and enamines irreversible formation of catalytically inactive complexes occurs [582] (see Section 2.1.9). Isomerization of allyl ethers to enol ethers has been observed with complexes B [582]. 

This reaction may account in part for the oligomers obtained in the polymerization of pro-pene, 1-butene, and other 1-alkenes where the propagation reaction is not highly favorable (due to the low stability of the propagating carbocation). Unreactive 1-alkenes and 2-alkenes have been used to control polymer molecular weight in cationic polymerization of reactive monomers, presumably by hydride transfer to the unreactive monomer. The importance of hydride ion transfer from monomer is not established for the more reactive monomers. For example, hydride transfer by monomer is less likely a mode of chain termination compared to proton transfer to monomer for isobutylene polymerization since the tertiary carbocation formed by proton transfer is more stable than the allyl carbocation formed by hydride transfer. Similar considerations apply to the polymerizations of other reactive monomers. Hydride transfer is not a possibility for those monomers without easily transferable hydrogens, such as A-vinylcarbazole, styrene, vinyl ethers, and coumarone. 

A novel homogeneous process for the catalytic rearrangement of 3,4-epoxy-l-butene to 2,5-dihydrofuran has been successfully developed and scaled-up to production scale. A tri(n-alkyl)tin iodide and tetra-(n-alkyl)phosphonium iodide co-catalyst system was developed which met the many requirements for process operation. The production of a minor, non-volatile side product (oligomer) was the dominating factor in the design of catalysts. Liquid-liquid extraction provided the needed catalyst-oligomer separation process. 

A block copolymer consisting of poly(cthylcnc-b-butene) oligomer and N,lf -di mcth I pyrrolidinium chloride, ( ), was prepared by Koroskenyi et al. 

Fourier-transform IR spectra show that the main products of butyl alcohol dehydration, when they are adsorbed on HZSM-5 in quantities smaller than or equal to the number of the active sites, are water and butene oligomers, the... 

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