Olefins terminal double bond

The Wacker reaction can also be carried out for other olefins with terminal double bonds. With propene, for example, approximately 90% yield of acetone is obtained. 1-Butene gave approximately 80% yield of methyl ethyl ketone. 

Linear olefins (with terminal double bond or with internal double bond)... 

With this rule in mind the outcome of CM-reactions can often be predicted. In the synthesis of organotrifluoroborate 79 [143] the terminal double bond is a type 1 substrate, while the 1,1-disubstituted olefin can be considered type III. The reaction of 2-methyl-1,4-pentadiene 77 with type II cross-partner 78 furnishes 79 efficiently (only 2 mol% catalyst used) in good yields after two steps. 

Olefin metathesis can also be used in intermolecular reactions.299 For example, a variety of functionally substituted side chains were introduced by exchange with the terminal double bond in 5.300 These reactions gave E Z mixtures. 

Some remarks concerning the scope of the cobalt chelate catalysts 207 seem appropriate. Terminal double bonds in conjugation with vinyl, aryl and alkoxy-carbonyl groups are cyclopropanated selectively. No such reaction occurs with alkyl-substituted and cyclic olefins, cyclic and sterically hindered acyclic 1,3-dienes, vinyl ethers, allenes and phenylacetylene95). The cyclopropanation of electron-poor alkenes such as acrylonitrile and ethyl acrylate (optical yield in the presence of 207a r 33%) with ethyl diazoacetate deserve notice, as these components usually... 

The detailed composition, referring to classes of compounds, is shown for C6 in Figure 9.3 with and without precolumn hydrogenation. In addition to paraffins, there are olefins—mainly with terminal double bond—and small amounts of alcohols (and aldehydes). The low detection limit of gas chromatography (GC) analysis allows precise determination even of minor compounds and provides exhaustive composition data also for use in kinetic modeling. Because of the short sampling duration of ca. 0.1 s,8 time-resolved selectivity data are obtained. 

Boelhouwer s discovery (23) prompted a flurry of activity in this area. Baker applied the Boelhouwer catalyst to the metathesis of w-olefinic esters (88). At an ester/W molar ratio of 20/1 (68°C), symmetrical olefinic diesters were formed in 34-36% yields with concomitant elimination of ethylene. In addition, Baker identified products recovered in 3-8% yield corresponding to addition of HC1 across the terminal double bond. 

Hydroxylation of the terminal double bond in 140 followed by the esterification paved the way to phosphodiester 141, whereas Grubbs olefin metathesis followed by hydroxylation and esterification led to divalent phosphodiester 142. 

In the polystyrenes produced by cationic initiators most of the chain-ends are terminal indanyl groups, and olefinic groups are rare. As this terminal indanyl group cannot be aluminated like a double bond, the amount of tritium incorporated comes only from the initial AlBr2CH2CHPh-groups and the few residual terminal double bonds and it, therefore, represents (approximately) the total number of initiated chains. 

On the other hand, 4-vinylidene-l,3-oxazolidin-2-one 26 undergoes a facile [2 + 2]-cycloaddition with electron-deficient olefins regioselectively at the terminal double bond to furnish methylenecyclobutane derivatives [25]. 

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. 

Again, the exclusive formation of six-membered rings indicates that the cyclization takes place by the electrophilic attack of a cationic center, generated from the enol ester moiety to the olefinic double bond. The eventually conceivable oxidation of the terminal double bond seems to be negligible under the reaction conditions since the halve-wave oxidation potentials E1/2 of enol acetates are + 1.44 to - - 2.09 V vs. SCE in acetonitrile while those of 1-alkenes are + 2.70 to -1- 2.90 V vs. Ag/0.01 N AgC104 in acetonitrile and the cyclization reactions are carried out at anodic potentials of mainly 1.8 to 2.0 V vs. SCE. 

The hydrogen atom adds to the terminal double-bonded carbon atom of the acceptor molecule or to that double-bonded carbon atom which has the smallest alkyl group the olefin radical adds to the adjoining double-bonded carbon atom. When the acceptor olefin contains a tertiary double-bonded carbon atom, the olefin radical from the donor always becomes attached to it. 

Rule A. Olefins having a terminal double bond (e.g., 1-butene) are less stable than straight chain olefins having an internal double bond (e.g., 2-butene) and tend to yield a latter type under the influence of heat, catalyst, and other methods of activation (Whitmore and Herndon, 65 Whitmore and Homeyer, 44). 

The new Brownsville, Tex., plant for the manufacture of synthetic liquid fuels from natural gas makes use of this reaction to increase the octane number of its product by as much as 20 units. Synthetic naphtha produced over iron catalyst is highly olefinic and contains substantial amounts of straight-chain isomers with terminal double bonds (8). The shifting of these double bonds toward the center of the molecule may be accomplished by vapor-phase treatment employing synthetic cracking catalyst in the fluid state, under mild catalytic cracking conditions. Oxygenated compounds also present are converted under the isomerization conditions to hydrocarbons and water. 

Nonconjugated dienes, namely, allenes and isolated dienes, react preferentially on the terminal double bond.10 Hydrogenation of 1,2-butadiene over palladium yields 1-butene and d.s-2-butene as the main products with moderate discrimination of the two double bonds.68 Deuteration experiments indicated that the dominant syn addition to either the 1,2- or the 2,3-olefinic bond occurs. Different vinyl and Jt-allyl intermediates were invoked to interpret the results.69 70... 

Evidence of variables that influence the relative rates of reaction of olefins and alcohols was obtained from experiments with compounds that have both olefinic and alcoholic functions and by the competitive oxidation of mixtures of olefins and alcohols. The data of Table VI show that when the double bond has no substituents, as in allyl alcohol, but-3-en-l-ol, or 2-methylbut-3-en-l-ol, only the epoxide is formed but when the double bond has substituents, the epoxida-tion rate is decreased and ketone and aldehyde products from the oxidation of the OH group are formed. This effect is more pronounced with a greater degree of substitution. Since the double bond and the OH group are part of the same molecule, the difference must arise from the different abilities of the reactants to coordinate and react at the titanium center restricted transition-state shape selectivity is a possibility. The terminal double bond, sterically less hindered, interacts strongly with titanium, preventing coordination of the competing OH... 

Secondary alcohol 11 is first protected as a silyl ether with TBS chloride, after which the terminal double bond is ozonized. The resulting methyl ketone is subsequently converted stereoselectively with a Homer-Wadswonh-Emnions reaction21 into olefin 13. This reaction sequence leads to tram selectivity in the formation of the terminal double bond in 13. 

Ring closure occurs during the nexi step, which takes the form of an olefin metathesis. The two terminal double bonds in 50 are coupled together with release of ethene (58), thereby closing the ring to 17. 

Considering functionalized olefins first, only three two-carbon reactants are listed above. Ethylene itself can give only terminal double bonds when elimination is facile and triethylamine functions as the base. If nucleophilic secondary amines are necessary, ethylene produces internal amines almost entirely. Aryl halides react well with ethylene to produce styrene derivatives. 

Derivatives of acyclic olefins can be used as chain transfer agents in these polymerizations. The most effective are those with a terminal double bond. For example, in the ROMP of 248 catalysed by [Ru(H20)6](0Ts)2 the transfer constant (klr/kp) for CH2=CHCH2CH20H is 0.21. The size of the polymer particles produced by emulsion polymerization of 248, using RUCI3 with a non-ionic surfactant, is of the order of 0.03 /zm577. 

ADMET is a step growth polymerization in which all double bonds present can react in secondary metathesis events. However, olefin metathesis can be performed in a very selective manner by correct choice of the olefinic partner, and thus, the ADMET of a,co-dienes containing two different olefins (one of which has low homodimerization tendency) can lead to a head-to-tail ADMET polymerization. In this regard, terminal double bonds have been classified as Type I olefins (fast homodimerization) and acrylates as Type II (unlikely homodimerization), and it has been shown that CM reactions between Types I and II olefins take place with high CM selectivity [142], This has been applied in the ADMET of a monomer derived from 10-undecenol containing an acrylate and a terminal double bond (undec-10-en-l-yl acrylate) [143]. Thus, the ADMET of undec-10-en-l-yl acrylate in the presence of 0.5 mol% of C5 at 40°C provided a polymer with 97% of CM selectivity. The high selectivity of this reaction was used for the synthesis of block copolymers and star-shaped polymers using mono- and multifunctional acrylates as selective chain stoppers. 

The reaction occurs via the formation of the intermediate adduct 126 and a mixture of /Z-isomeric alkenes 127 (for R1 = R2 = R3 = R4 = H, the yield is 29 and 11%, respectively). The reaction product is formed by intramolecular cyclization of olefins initiated by bases (water, Na2C03, NaOH) in tetrahydrofuran (xylene). The authors did not give any interpretation of the reaction route. One can assume that the reaction proceeds by the following scheme. Under the action of bases, olefins undergo elimination of hydrogen fluoride and the formation of compound 128 containing a terminal double bond. 

Monoethanolamine reacts with perfluoro-2-methylpent-2-ene in the presence of triethylamine, forming 7-fluoro-5-pentafluoroethyl-6-trifluoro-methyl-2,3-dihydro[l,4]oxazepin 135 (OlJFC(llO)l 1). If the compound has bulky substituents in the -position relative to the amino group, attack at the internal double bond is sterically hindered, and the internal olefin isomerizes in the presence of the base to the terminal olefin. The attack of the N-nucleophilic center of monoethanolamine occurs at the carbon atom of the terminal double bond, giving 5-fhioro-3,3-dimethyl-7-pentafluoroethyl-6-trifhioromethyl-2,3-dihydro[l,4]-oxazepin 136 or 137 as the major product. 

AU four of the elementary reactions in a cationic polymerization involve electrophilic or cationic intermediates. Thus, initiation, propagation, transfer, and termination may be classified as either nucleophilic substitution, electrophilic addition, elimination, rearrangement, or possibly as a pericyclic reaction. Initiation occurs in alkene polymerizations by either addition of acid to the alkene, or by ionization of a covalent initiator followed by addition of the resulting carbocationic intermediate to an olefin s double bond. Although initiation is an electrophilic addition (AdE) reaction in... 

Due to the large differences in reactivities of the comonomers the chains are mostly composed of isobutene units with minor amounts of 1-butene and traces of the even less reactive Z-2-butene. They are linear and present several types of unsaturations. Spontaneous termination and transfer involving proton abstraction lead to the expected and largely predominant exo/endo terminal double bonds (A, B) but some other tri- and tetrasubstituted olefinic structures (C, D) together with internal vinyli-denes were also detected by H and nC NMR spectroscopy [30-34]. 

Cyclohexene exists only as internal cw-olefin and is moderately reactive. In contrast, -hexene, regardless of whether charged as 1- or internal olefin or a mixture of these, is quickly isomerized to a near-equilibrium mixture containing some 5 to 10% of the isomer with terminal double bond, whose reactivity is about two orders of magnitude higher than those with internal ones. Accordingly, -hexene is more reactive than cyclohexene with only internal double-bond positions. Lastly, neohexene (3,3 -dimethyl-l-butene) has its double bond locked in the terminal position —no double bond can exist adjacent to a quaternary carbon atom—and so should have the highest reactivity if not sterically hindered. (This is an unsubstantiated prediction, as the hydroformylation reactivity of that olefin seems not to have been studied to date.)... 

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