Insertions double ethylene

Double insertion of ethylene into aniline with the aid of rhodium(III) chloride hydrate gives the cyclization product, 2-methylquinoline (Eq. 3) [10]. Forcing reaction conditions and the use of an excess amount of aniline were required for this catalytic reaction. 

Poly(ethylene oxide). Although AH j is more than double that of polyethylene, the effect is offset by an even greater increase for AS j. The latter may be due to increased chain flexibility in the liquid caused by the regular insertion of ether oxygens along the chain backbone. 

Secondly, the carbon framework holding the exocyclic double bonds could be extended. This is demonstrated by naphtharadialene 5, a highly reactive intermediate which has been generated by thermal dehydrochlorination from either the tetrachloride 178 or its isomer 179106. Radialene 5 has not been detected as such in these eliminations rather, its temporary formation was inferred from the isolation of the thermolysis product 180 which was isolated in 15% yield (equation 25). Formally, 5 may also be regarded as an [8]radialene into whose center an ethylene unit has been inserted. In principle, other center units—cyclobutadiene, suitable aromatic systems—may be introduced in this manner, thus generating a plethora of novel radialene structures. 

All these reactions are promoted by Pd(II) species, and can be stoichiometric (Eq. 10) or catalytic (Eqs. 11-13, in the presence of Cu(II) salts or other oxidizing agents). 3-Chloropropionyl chloride from ethylene is conceivably formed through PdCl2 addition to the double bond followed by CO insertion and reductive elimination (Scheme 2). 

Recoil UC atoms have been produced by nuclear transformations and allowed to react with ethylene.15 Both Q1/)) and C(3P) atoms are formed, and both add to the double bond and insert into the vinylic C—H bond. The resulting hot singlet adducts relax primarily to allene and methylacetylene, whereas the hot triplet adducts decompose to acetylene or are stabilized as carbenes, which mainly add to more ethylene to yield various C5 products. 

Reactions of the recoil C1] with several olefins have been studied, including ethylene, propylene, cyclopentene, and cfs-butene-2, as well as with several paraffins. The type of products observed indicated the existence of several general modes of interaction, such as CH bond insertion, interactions with CC double bonds, formation of methylene-C11. The most important single product in all systems is acetylene, presumably formed by CH insertion and subsequent decomposition of the intermediate. Direct interaction with double bonds is shown by the fact that, for example, in the case of propylene, yields of stable carbon atom addition products were significantly higher than in the case of propane. The same was true for ethylene and ethane. 

Oxidative cyclization is another type of oxidative addition without bond cleavage. Two molecules of ethylene undergo transition metal-catalysed addition. The intermolecular reaction is initiated by 7i-complexation of the two double bonds, followed by cyclization to form the metallacyclopentane 12. This is called oxidative cyclization. The oxidative cyclization of the a,co-diene 13 affords the metallacyclopentane 14, which undergoes further transformations. Similarly, the oxidative cyclization of the a,co-enyne 15 affords the metallacyclopentene 16. Formation of the five-membered ring 18 occurs stepwise (12, 14 and 16 likewise) and can be understood by the formation of the metallacyclopropene or metallacyclopropane 17. Then the insertion of alkyne or alkene to the three-membered ring 17 produces the metallacyclopentadiene or metallacyclopentane 18. 

Random ethylene/propylene copolymers are amorphous and represent an interesting class of synthetic elastomers. The introduction of double bonds, useful for sulphur vulcanisation in the copolymer, can be achieved by copolymerisation of ethylene and propylene with non-conjugated dienes containing only one double bond capable of insertion for instance, 1,4-hexadiene, dicy-clopentadiene and 5-ethylidene-2-norbornene (endocyclic double bond)... 

Cycloolefins having rings with more than four carbon atoms do not homo-polymerise in the presence of Ziegler-Natta catalysts based on titanium or vanadium compounds as precursors and alkylaluminium activators. However, these cycloolefins may copolymerise with ethylene via the double bonds while preserving the cycloolefin ring ethylene is able to compensate the steric hindrance at the Ca atom of the growing chain after and before the 1,2-insertion of the cycloolefin [2],... 

Functionalised a-olefins capable of undergoing insertion polymerisation with Ziegler-Natta catalysts are, in principle, monomers in which the heteroatom (X) does not electronically interact with the double bond to be polymerised in such monomers, the heteroatom is separated from the double bond CH2=CH-(CH2)x X [326,384,518,522-528], Monomers with the heteroatom directly bound to the double bond, i.e. those of the CH2=CH-X type, may also undergo polymerization, but when the heteroatom is silicon or tin (X= Si, Sn) [522-526], Representative examples of the insertion polymerisation of functionalised a-olefins and their copolymerisation with ethylene and a-olefins in the presence of heterogeneous Ziegler-Natta catalysts are shown in Table 3.7 [2,241,326,384,518,522-528],... 

The ruthenacyclopentene intermediate can also undergo insertion of ethylene to give a ruthenacycloheptene. Subsequent unexpectedly observed /1-hydride elimination occurred and led then to cyclization products with a propenylidene substituent [79] (Eq. 58). Various enynes.with substituents on triple or double bonds, have been cyclized to form carbocyclic and heterocyclic compounds in good yields. 

A second method of production utilizes the Ziegler-Natta TiCl4 catalyst with liquid cocatalysts such as an alkyl aluminum halide. This is a reactive catalyst that must be prepared at the exclusion of air and water. The alkyl group of the co-catalyst coordinates with the Ti+3 site. The polymer grows by insertion of the ethylene into the double bond of the adsorbed polymer on another site. 

The polymerization tests with ethylene and 1-olefines as well as with dienes showed a good ability of the metallocene catalyst for copolymerization. Interesting results from practical and theoretical point of view could be gained in the copolymerization of ethylene and 1,5-hexadiene. During polymerization first a complexation of one of the double bonds of 1,5-hexadiene takes place at the vacant coordination side of the transition metal. After insertion into the polymer chain the complexation of the second double bond occurs followed by intramolecular cyclisation of the 5-membered ring. Analysis of the 13C-NMR spectra reveals an incorporation of 4.2 mole% 1,5-hexadiene and a predominance of trans rings caused by the diastereoselectivity of the cyclisation step. 

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