Butadiene complexes with copper

Another approach to separate butadiene from other hydrocarbons is to use a solution containing cuprous ammonium acetate that forms a weak copper(I) complex with butadiene (243,244). The latter process has been used in a number of plants. 

The method of preparation of the copper (I) chloride-1,4-butadiene complex has been described by Gilliland and coworkers.3 The following procedure uses liquid 1,4-butadiene in contrast with the previous gas phase reactions. 

When CVD with copper(I) /3-diketonate complexes containing a Lewis base is carried out in the presence of hydrogen, deposition of metallic copper occurs by direct reduction with liberation of the Lewis-base ligand and formation of the corresponding -diketone, as was demonstrated for 10c (equation 6). In contrast, it is found that Cu(hfac)(l,3-butadiene) (lOg) deposits copper via disproportionation even in the presence of hydrogen . 

Poly(l,4-butadiene) segments prepared by the ruthenium-mediated ROMP of 1,5-cyclooctadiene can be incorporated into the ABA-type block copolymers with styrene (B-106) and MMA (B-107).397 The synthetic method is based on the copper-catalyzed radical polymerizations of styrene and MMA from the telechelic poly(butadiene) obtained by a bifunctional chain-transfer agent such as bis(allyl chloride) or bis-(2-bromopropionate) during the ROMP process. A more direct route to similar block copolymers is based on the use of a ruthenium carbene complex with a C—Br bond such as Ru-13 as described above.67 The complex induced simultaneous or tandem block copolymerizations of MMA and 1,5-cyclooctadiene to give B-108, which can be hydrogenated into B-109, in one pot, catalyzed by the ruthenium residue from Ru-13. 

Copper (I) complexes of olefins have been less widely studied but have been found to be analogous to silver(I) complexes in several ways. It was shown 54>, that solid cuprous chloride absorbed ethylene, propylene and isobutylene and solid cuprous bromide absorbed ethylene to give 1 1 complexes, while diole-fms (butadiene and isoprene) and acetylenes were reported S6> to form complexes with a 2 I copper olefin (or acetylene) stoichiometry. Andrews and... 

Electrical conductivity measurements have been reported on a wide range of polymers including carbon nanofibre reinforced HOPE [52], carbon black filled LDPE-ethylene methyl acrylate composites [28], carbon black filled HDPE [53], carbon black reinforced PP [27], talc filled PP [54], copper particle modified epoxy resins [55], epoxy and epoxy-haematite nanorod composites [56], polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) blends [57], polyacrylonitrile based carbon fibre/PC composites [58], PC/MnCli composite films [59], titanocene polyester derivatives of terephthalic acid [60], lithium trifluoromethane sulfonamide doped PS-block-polyethylene oxide (PEO) copolymers [61], boron containing PVA derived ceramic organic semiconductors [62], sodium lanthanum tetrafluoride complexed with PEO [63], PC, acrylonitrile butadiene [64], blends of polyethylene dioxythiophene/ polystyrene sulfonate, PVC and PEO [65], EVA copolymer/carbon fibre conductive composites [66], carbon nanofibre modified thermotropic liquid crystalline polymers [67], PPY [68], PPY/PP/montmorillonite composites [69], carbon fibre reinforced PDMS-PPY composites [29], PANI [70], epoxy resin/PANI dodecylbenzene sulfonic acid blends [71], PANI/PA 6,6 composites [72], carbon fibre EVA composites [66], HDPE carbon fibre nanocomposites [52] and PPS [73]. 

The ability of aqueous copper(I) solutions to absorb alkenes and alkynes is used industrially. In the steam cracking of naphtha into alkenes, which is carried out at 770°C/latm, the main product is ethene. Propene and lesser amounts of alkynes, 1,3-butadiene and butenes are also produced. A chilled aqueous ammoniacal copper(I) acetate solution is used as the absorber. The more unsaturated the hydrocarbon, the more stable is the complex. In the first stage the alkynes combine with copper, the complex is withdrawn and the alkynes liberated by heating. The copper solution is then recycled at a lower temperature to remove the 1,3-butadiene, allowing butanes and butenes to pass on. The 1,3-butadiene is freed by heating the solution of complex in a desorber and is finally fractionated. 

Some measurements of this property have been made in a range of electrically conducting polymers. These include epoxy resin/polyaniline-dodecylbenzene sulfonic acid blends [38], polystyrene-black polyphenylene oxide copolymers [38], semiconductor-based polypyrroles [33], titanocene polyesters [40], boron-containing polyvinyl alcohol [41], copper-filled epoxy resin [42], polyethylidene dioxy thiophene-polystyrene sulfonate, polyvinyl chloride, polyethylene oxide [43], polycarbonate/acrylonitrile-butadiene-styrene composites [44], polyethylene oxide complexes with sodium lanthanum tetra-fluoride [45], chlorine-substituted polyaniline [46], polyvinyl pyrolidine-polyvinyl alcohol coupled with potassium bromate tetrafluoromethane sulfonamide [47], doped polystyrene block polyethylene [38, 39], polypyrrole [48], polyaniline-polyamide composites [49], and polydimethyl siloxane-polypyrrole composites [50]. 

Sketch (a) the transition state for a concerted metal atom-assisted 3,9 hydride shift (b) two PNP ligands (c) the ligand used for selective dimerization of butadiene (d) a general structure for molybdenum- and tungsten-based metathesis precatalyst (e) a six-coordinate rathenium precatalyst for metathesis (f) a solid isolated from the reaction between Pd(OAc)j plus PRj (R = o-tolyl) (g) a T-shaped palladium complex and a two-coordinate palladium complex with a monodentate phosphine (h) an iron complex with a seven-membered metallacycle (i) the transition state for metal-catalyzed cyclopropanation (j) a rhodium and a copper precatalyst used in cyclopropanation reactions. 

Transmetalation from Zr to Cu is a highly beneficial process as it combines the ease of preparation of organozirconocenes from alkenes and alkynes with the wide scope of organocopper reagents in organic synthesis. Schwartz and coworkers were first to demonstrate transmetalation to Cu in their report on the reductive dimerization of alkenylzirconocenes [94]. Virgili et al. used this transformation to prepare dialkoxy-1,3-butadienes [95]. The copper-mediated coupling of alkenylzirconocene 85 and phenethynyl bromide was reported to yield 86 [96] (Scheme 19). The latter two reactions can also be mediated by ox-ovanadium complexes [97]. 

The butadiene complexes of the copper(l) halides are prepared by the direct reaction of anhydrous copper(I) halides with butadiene at —10°, in the absence of solvents [21]. Also, the complexes [Olefin PdCh] , where the olefin is straight chain, may be prepared by direct interaction at room temperature of palladium dichloride and the olefin in a liquid state [2Ia]. 

Transmetallation is not restricted to palladium and has been extended to rhodium and copper, so far. [(CODjRhClJj promotes the room-temperature JKOcycli-zation of cross-conjugated chroma- and tungsta-amino-l-metalla-l,3,5-hexatrienes with alkynes to give vinylcyclopentadienes as single isomers [96]. Alternatively, vinylcyclopentadienes are also formed from l-alken-3-ynes and 4-amino-l-metalla-1,3-butadiene complexes of chromium and tungsten RhClj 3 HjO in methanol turns out to be the most efficient (pre)catalyst (Scheme 11.44) [97]. 

Chiral BOX-zinc(II) complexes can also catalyze the cycloaddition reaction of glyoxylates with, e.g., 2,3-dimethyl-l,3-butadiene and 1,3-cyclohexadiene [36]. The reaction gave for the former diene a higher cycloaddition product/ene product ratio compared with the corresponding chiral copper(II) complexes the ee, however, was slightly reduced. For the reaction of 1,3-cyclohexadiene slightly lower yield and ee were also found. 

Mono-olefins (un) react with solid copper(I) halides to form unstable complexes of the type [CuX(un)] (X = Cl, Br), which dissociate into their constituents above 0° (67, 138). Dienes (e.g., butadiene, isoprene, pipery-lene, bicyclo[2,2,l]hepta-2,5-diene, and cyclopolyolefins) form more stable complexes of the type [Cu2X2(diene)J (1,63, 67,138,192), in which a copper atom is attached to each C C bond industrial processes to separate dienes from mono-olefins and paraffins are based on this difference in stability (8). Complexes of the type [Cu(un)]+, [CuCl(un)], and [CuCl2(un)] have been shown to exist in dilute acid solution (15, 67, 138). 

A copper(O) complex, electro-generated from Cu(acac)2, is able to undergo an oxidative addition with benzyl and allyl bromides. Further reduction leads to the coupling products bibenzyl and 1,5-hexadienes Methyl-3-hexene-l,6-dicarb-oxylate can be prepared from butadiene and CO by electroreduction if di-Fe dicyclopentadienyl tetracarbonyl is used as redox catalyst Electro-generated low-valent tungsten species are able to reductively dimerize benzaldehyde to stilbene according to Eq. 83. The reduction potential was controlled at the third wave of the WClg catalyst (V = -1900 mV/SCE)... 

Dichloro[cate a-2-methyl-l,4-butadiene]dicopper(I) (B) can be prepared from direct reaction between isoprene and copper(I) chloride, analogously to the synthesis of the complex between butadiene and CuCl.12 The advantage of the synthesis described here is that the product is not contaminated with unreacted CuCl, and can be obtained as high-quality crystals instead of a microcrystalline powder. 

Although the diastereocontrolled cyclopropanation generally uses a chiral diazo compound, there is one exception in which a chiral olefin was used to react with an achiral diazo compound. Thus, copper catalysed cyclopropanation of chiral butadiene iron tricarbonyl complex 150 with methyl diazoacetate provided a 1 1 mixture of the trans (151) and cis (152) isomers (equation 132). The diastereomeric excess of both trans and cis are 90% and the decomplexation can be easily achieved by treating the adduct with trimethyl nitroxide in dichloromethane188. 

Gaseous 1,4-butadiene is liquefied with a slush of Dry Ice in trichloroethylene, with provisions made to protect the liquid hydrocarbon from condensation of atmospheric moisture. Anhydrous copper(I) chloride is added to the liquid diolefin and the mixture allowed to stand at —10° for 1 hour. The excess butadiene is evaporated off at room temperature and the complex remains as a pale yellow solid. J... 

A number of transition metal ion-exchange zeolites are active for acetylene trimerization (159, 160), and the criterion for activity appears to be an even, partially filled d-orbital, i.e., d8 (Ni2 +, Co+), d( (Fe2+), d4 (Cr2 + ). This has led to the suggestion that the mechanism must involve a complex in which there is simultaneous coordination of two acetylene molecules to the transition metal ion. The active oxidation state for CuNaY butadiene cyclodimerization catalysts has been unambiguously defined as monovalent copper (172-180). The d10 electronic configuration of Cu+ is consistent with the fact that isoelectronic complexes of Ni° and Pd° are active homogeneous catalysts for this reaction. The almost quantitative cyclodimerization selec-... 

Transition metal coordination of Cu(II) carboxylate groups and pyridine groups was employed as a means of coupling a telechelic butadiene-base polymer with a randomly functionalized styrenic polymer. Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) indicated partial miscibility of the two polymers and Fourier transform infrared (FTIR) spectroscopy demonstrated that interactions occurred on a molecular level. When compared with blends of PSVP and the free acid derivative of CTB, the compositions based on the transition metal complex had improved dimensional stability at elevated temperatures, though there remains some question as to the stability of the copper salt to hydrolysis. Electron spin resonance (ESR) spectroscopy showed that only the... 

---