Alkenes telomerization

Ziegler process) and telomerization of alkenes to medium chain derivatives for detergents and fats. Both processes operate by insertion of an alkene into AIR bonds. 

The palladium-catalyzed hnear telomerization of 1,3-bntklienes provides a useful method for thepreparation of functionalized alkenes. A proposed catalytic cycle for the paliadinm-catalyzed... 

H risson and Chauvin (88) examined the metathesis between acyclic alkenes and cycloalkenes (telomerization) in the presence of two other tungsten-based catalysts, namely WOCl4-Sn(n-C4He)4 and WOCI4-... 

From studies of the telomerization between 1-alkenes and cycloalkenes another interesting result emerged. The expected triads were observed, but within each triad the ratio of the products varied between 1 10 1 and 1 20 1 (88). This is not consistent with the scheme of H6risson and Chauvin. However, with the scheme of Calderon, this can be explained if... 

The essential difference in chemical behavior of chlorides and bromides used as telogens (addends) can be distinctly seen when the reactions of chloro- and bromoacetates are compared. In addition and telomerization reactions monochloroacetates react with 1-alkenes exclusively at C-H bond [under initiation... 

These occur readily between electron-rich alkenes and electron-poor carbonyl compounds. The first example, reported in 1959 (64HC(19-2)729), was the formation of 4,4-diaryloxetane-2,2-dicarbonitriles by the room temperature reaction of 1,1-diarylethylenes and carbonyl cyanide. Continued investigation of this reaction shows that a telomerization product is also formed, the tetraphenylpentadienedinitrile (55) from 1,1-diphenylethylene and carbonyl cyanide. This may be interpreted to indicate that carbon-carbon bond formation may commence somewhat ahead of carbon-oxygen bond formation (75MI51302). This... 

Fluorinated radicals play a significant role in synthetic organo-fluorine chemistry, for example, in electrophilic radical addition to alkenes, single-electron transfer reactions (SET), telomerization of fluoroalkenes with perfluoroalkyl iodides, polymerization to fluoropolymers and copolymers, and thermal, photochemical and radiation destruction of fluorocarbons. Furthermore, such free radicals are of interest for studying structures, reaction kinetics and ESR spectroscopic parameters.38... 

Trialkylamines are used as additives in the telomerization of butadiene and water in a two-phase system (103). The catalyst comprises a palladium salt and tppms or tppts. The amines may build cationic surfactants under catalytic conditions and be capable of micelle formation. The products include up to five telomerization products (alcohols, alkenes, and ethers), and thus the reaction is nonselective. 

In the syringe pump method, the halide and the alkene acceptor are typically refluxed in benzene and a solution of tributyltin hydride and AIBN in benzene is added slowly over a period of hours by syringe drive. The exact concentration of tin hydride is not known but it remains low, provided that the chain continues at a rate more rapid than syringe pump addition. Telomerization may intervene if the tin hydride concentration falls too low. To insure that the chain continues, it is important to use a reactive atom donor (to maximize the rate of step 1) and to insure that a constant source of initiator is present.91... 

Comparison of the relative alkene reactivites reported in Section III.D.4 with known copolymerization parameters [57] indicates qualitative agreement between the two sets of data. It is thus possible to use the reactivity scales in Section III.D.4, for predicting approximate copolymerization parameters, but the calculation of accurate rate ratios in copolymerization suffers from the fact that alkene reactivities are not completely independent of the nature of the attacking carbocation. This is especially true if the propagation rates get close to the diffusion limit. It is not possible to directly measure propagation rate constants by investigating cationic telomerizations, but extrapolations to such data on the basis of Eq. (23) in Section V are conceivable. 

The investigations described in this chapter show that nature and concentration of the negative counterion has a great influence on the outcome of carbocationic telomerizations because of the different rates of ion-pair collapse and because of reionization of eventually produced 1 1 adducts from alkyl halides and alkenes. On the other hand, it was found that the rate of attack of a carbocation at an alkene is generally independent of the nature of the complex counterion and that free and paired carbocations react with equal rates. If this conclusion also holds for carbocationic polymerizations, a reinterpretation of many polymerization kinetics becomes necessary. 

In 1995, Porter et al. [34] reported the first excellent results for free radical addition to an electron-deficient alkene by use of chiral zinc complexes. Reaction of the oxa-zolidinone 9 with tert-butyl iodide and allyltributylstannane 30 in the presence of Zn(OTf)2 and a chiral bis(oxazoline) ligand 12 gave the adduct 44 in 92 % yield with 90 % ee (Sch. 18). The chiral bis(oxazoline) complexes derived from ZnCl2 or Mg(OTf)2 gave racemic products. In this reaction, lower allyltin/alkene ratios gave substantially more telomeric products, and a [3 + 2] adduct 45 of the oxazolidinone 9 and the allylstannane 30 was obtained at temperatures above 0 °C. 

These latter reactions resemble linear telomerizations of alkenes (see Section 1.5.8.3.1.). 

Fluorinated alkenes are able to insert into weak C-H bonds of various compounds branched alkanes, haloforms, alcohols, ethers, aldehydes and their corresponding ketals. These reactions usually involve the use of UV irradiation or radical-initiation catalysts, such as peroxides or azobisisonitriles. Variable amounts of telomeric products are also formed. Under the influence of /-irradiation (60Co source), one-to-one adducts are obtained predominantly. Attack of the intermediate radical occurs preferentially on the less-hindered carbon of the fluorinated alkenc. 

Review W. Reim, A. Behr, M. Roper, Alkene and alkyne oligomerization, cyclooligomerization and telomerization reactions, in Comprehensive Organometallic Chemistry, (Eds. G. Wilkinson, F. G. A. Stone, E. W. Abel), I rgamon, Oxford, 1984. 

Electrophilic substitution of r/ -allyl complexes, especially those of Si and Sn, has found extensive synthetic applications, but the overall transformation is stoichiometric with regard to the amount of the metal atom. A catalytically useful reaction of r/ -allyl intermediate was involved in telomerization of 1,3-dienes in the presence of Pd catalyst shown in Scheme 8.41. r/ -Allylmetal complexes were reactive with not only H+ but also electrophilic alkenes (e.g. Scheme 8.72) [62,133]. Recent development in Pd-catalyzed amphiphilic allylation of alkenes and imines (e.g. Scheme 8.73) relied on the high susceptibility of Pd-bound r -allyl ligand to the attack of unsaturated carbon electrophile [134]. 

These unusual properties were the basis of the fluorous biphasic catalysis process (FBC) first published in 1994 by Horvdth and Rdbai and demonstrated using hydroformylation chemistry as a pertinent example (7, 2) in a 1991 Ph.D. thesis, that was unfortunately not readily available to the homogeneous catalysis community nor published in the open literature, M. Vogt, under the guidance of his Ph.D. advisor, W. Keim, of the Rheinisch-WestflUischen Technischen Hochschule in Aachen, Germany, presented the first conceptual aspects of the FBC approach with an emphasis on oligomerization of alkenes, oxidation of alkenes, hydroformylation of olefins, and telomerization of dienes (5, 4). 

Palladium(I) intermediates have been proposed for the telomerization of butadiene with acetic acid yielding acetoxyoctadienes, and in a recent review the involvement of Pd(I) has been snggested for processes in which Pd(II) had been formerly suggested. These processes include alkene isomerization, methoxycarbonylation of alkynes to acrylic esters, and the aryloxycarbonylation of allyl alcohol. 

Dimerization, Telomerization, Polymerization, and Alkylation of Olefins. Reactions of alkenes and dienes are of tremendous interest and ionic liquids offer new possibilities in this field too (282,283). 

Ethylene provides a good example of a petrochemical feedstock for the synthesis of lipids and polyketides. It can be oligomerized to provide a variety of alkenes into which functionalization can be introduced by hydration, oxidation, hydroformylation, and so on. Of course, telomerization can be used to provide functionalized materials directly. 

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