Alkenes ethylene

Three membered rings that contain oxygen are called epoxides At one time epox ides were named as oxides of alkenes Ethylene oxide and propylene oxide for exam pie are the common names of two industrially important epoxides... 

The two simplest alkenes. Ethylene is planar, as is the —CH=CH2 region of piopene. 

Alkenes are hydrocarbons that contain one or more carbon-carbon double bonds. The simplest alkene, ethylene, is produced by plants to stimulate the ripening of fruit. Larger alkenes are abundant in the biological world and play a wide variety of roles. 

A few measurements are available that relate to the ion pair acidity of ethylene and some other alkenes. Ethylene is difficult to metallate directly, but vinyl bromides and iodides undergo facile transmetallation with alkyllithium reagents. Applequist and O Brien determined the equilibrium constants of transmetallation exchange reactions as a measure of relative acidity (equations 6 and 7)25. 

This 1,2-NH3 migration is the key step in the reorganization of the heavy atom skeleton which precedes pseudo-a-cleavage of ionized long-chain alkylamines (Scheme 3). The transition state for this process may be considered to resemble a tight complex of an ionized alkene (ethylene in the case of the archetypal /J-DI, CH2CH2NH3+) and NH3 (equation 9). This idea is consistent with the behaviour of adduct ions [C H2 NH3]+ generated by direct combination of the appropriate ionized alkene and NH3 58,59. 

Alkanes n-butene, isopentane, isooctane Cydoalkanes t dohezane, methylcyclopentane Olefins (sometimes called alkenes ) ethylene, propylene, butene Cydoolefins ( clohezene Alkynes acetylene Aromatics toluene, i ene CHLORINATED HYDROCARBONS ALDEHYDES, RCHO formaldehyde, acetaldehyde KETONES, RCX R " acetone, methylethylketone NITRIC OXIDE, NO ... 

First, the simplest of the alkenes, ethylene, or ethene, C2H4, is critically important for the ripening of frnit. This simple molecule is formed directly by fruit-forming plants. It is also used commercially to ripen fruit picked early during its storage and transport. It seems remarkable that such a simple molecule has such profound biological activity. 

Good selectivity in alkene (ethylene or butene) alkylation with isoparaffins has been reported for acidic chloroaluminates 140). The ionic liquids have also been... 

The oxidation of the simplest symmetrically substituted alkene, ethylene, is noteworthy in that an asymmetric spiro transition state is observed. When constrained to Cs symmetry with eqnal forming carbon-oxygen bond lengths, the energy increases by only 0.1 kcalmol. The spiro TS has the plane of the HO—ONO (or peracid) at right angles to the axis of the C=C bond. In an idealized spiro TS this angle is exactly 90°. While the formation of snlfoxides from snlhdes by peroxynitrons acid is well-established , epoxidations have not yet been observed in solution. 

TaUI nitrenes have been prepared by reduction of Tav nitrenes under argon (equation 59). The lability of the PMe3 ligands allowed the production of [Ta(NPh)ClL3(alkene)] (alkene = ethylene or styrene). 

The reaction of adamantane with lower alkenes (ethylene, propylene, and butylenes) in the presence of superacids [CF3SO3H or CF3SO3H—B(0S02CF3)3] shows the involvement of both alkylations.34 In the predominant reaction the 1-adamantyl cation formed through protolytic C—H bond ionization of adamantane adamanty-... 

The first results of anionic polymerization (the polymerization of 1,3-butadiene and isoprene induced by sodium and potassium) appeared in the literature in the early twentieth century.168,169 It was not until the pioneering work of Ziegler170 and Szwarc,171 however, that the real nature of the reaction was understood. Styrene derivatives and conjugated dienes are the most suitable unsaturated hydrocarbons for anionic polymerization. They are sufficiently electrophilic toward carbanionic centers and able to form stable carbanions on initiation. Simple alkenes (ethylene, propylene) do not undergo anionic polymerization and form only oligomers. Initiation is achieved by nucleophilic addition of organometallic compounds or via electron transfer reactions. Hydrocarbons (cylohexane, benzene) and ethers (diethyl ether, THF) are usually applied as the solvent in anionic polymerizations. 

Photocatalytic decomposition of water over various metal oxides to H2 and O2 is of current interest, representing an approach to the utilization of solar energy. This catalytic system catalyzes C—C bond fission and, to a lesser extent, the hydrogenation of multiple bonds. Titania220,221 and its binary oxides222 have been studied most in the hydrogenation of simple alkenes (ethylene, propylene and butenes). This photohydrogenation activity is,... 

Internal acetylenes, Ni-mediated reactions, 10, 546 Internal alkenes, ethylene co-polymers, 4, 1145 Internal alkynes in alder-ene reaction, 10, 567 intermolecular hydrosilylation with ruthenium, 10, 802 with yttrium, 10, 801 silylboration, 9, 163 silylformylation, 11, 483... 

The dithionitronium cation SNS+ (as the AsFg salt) underwent quantitative concerted symmetry-allowed cycloaddition reactions with alkenes (ethylene, methylethylene, trans- and +r-l,2-dimethylethylene, 1,1-dimethyl-ethylene, tetramethylethylene, and norbornene) to give 1,3,2-dithiazolidine cations 76 (Equation 20) <1996JCD1997>. 

The two simplest alkenes, ethylene (ethene) and propylene (propene), are the organic compounds that are produced in the largest amounts by the U.S. chemical in-... 

Fig. 7 Yardstick-plots (Eq. 1) of the graphitized black N220g obtained with a series of alkenes (ethylene, propylene, iso-butylene) (filled symbols) and alkanes (ethane, propane, iso-butane) (open symbols). Adsorption temperatures are chosen as evaporation points at vapor pressures p0 103 mbar (lower curves) and po 104 mbar (upper curves) of the condensed gases, respectively...

The first (green) alkene has a disubstituted double bond. The second (blue) alkene is mono-substituted, and the red alkene (ethylene) has an unsubstituted double bond. We predict that the red products will be favored. 

The most important representatives are the lowest 1-alkenes, ethylene and propene. Ethylene is not particularly easily polymerized by radical or ionic mechanisms. Its importance as a monomer was greatly enhanced by the discovery of coordination polymerizations. Propene is oligomerized by radical and ionic initiators. This explains the importance of Natta s modification [1] of Ziegler [2,3] catalysts, enabling inferior raw materials to yield high-quality polymers. 

Delocalization of bonding electrons in the transition complex is an important event. In the absence of this far-reaching delocalization, even the most acid alkenes, ethylene and propene only undergo both radical and ionic polymerization reluctantly. 

Mechanistically, as elucidated by Schmerling (19) and as illustrated for isobutane-ethylene (alkane-alkene) alkylation (Scheme 1), the reaction is initiated by protonation of the alkene (ethylene) to form a very acidic primary ethyl cation (step 1) which rapidly abstracts a hydride ion from an isobutane molecule to generate the chain carrying t-butyl cation (step 2). This can then alkylate another molecule of ethylene to form the secondary-2-methyl-t-butyl carbenium ion (step 3). This cation rapidly undergoes a... 

Complexes of formula [(jj -arene)Rh(CO)L]PF6 (arene = CeHg, C6H5CF3, CeHsOMe, mesifylene, l,3,5-(MeO)3C6H3 L = PPF3) are readily formed by displacement of the weakly bound solvent from [Rh(COE)(L)(acetone)2] PFe by the arene, and the COE ligand can be then replaced by the more strongly bonding alkene ethylene. Treatment... 

Application of the Pauson-Khand reaction to simple acylic alkenes has been limited by both low reactivity and lack of regiocontrol in incorporation of the alkene. Among simple alkenes, ethylene provides the most consistently useful results. Yields with terminal alkynes range from 30-60% (equations 9,15 and 16) internal alkynes have also been used with some success (equation 10). Forcing conditions (toluene, 130-160 C, 6()-80 atm, autoclave) are usually required for best results, although it has been recently demonstrated that the reaction proceeds, albeit slowly, at reduced pressures and temperatures (equation 17). ... 

Epoxides are also named as alkene oxides, since they are often prepared by adding an O atom to an alkene (Chapter 12). To name an epoxide this way, mentally replace the epoxide oxygen by a double bond, name the alkene (Section 10.3), and then add the word oxide. For example, the common name for oxirane is ethylene oxide, since it is an epoxide derived from the alkene ethylene. We will use this common method of naming epoxides after the details of alkene nomenclature are presented in Chapter 10. 

Common names are seldom used except for three simple alkenes ethylene, propylene, and isobutylene. The various alkenes of a given carbon number are, however, sometimes referred to collectively as the pentylenes amylenes), hexylenes, heptylenes, and so on. (One sometimes encounters the naming of alkenes as derivatives of ethylene as, for example, tetramethylethylene for (CH3)20—C(CH3)2.) Most alkenes are named by the lUPAC system. 

Bromine (Br2) is brown, and one of the classic tests for alkenes is that they turn a brown aqueous solution of bromine colourless. Alkenes decolourize bromine water alkenes react with bromine. The product of the reaction is a dibromoalkane, and the reaction below shows what happens with the simplest alkene, ethylene (ethene). 

When we draw a similar resonance structure for an ,/3-unsaturated carbonyl compound, however, the positive charge is allylic and can be shared by the jS carbon. In other words, the /3 carbon of an ,j8-unsaturated carbonyl compound is an electrophilic site and can react with nucleophiles. A comparison of electrostatic potential maps of ethylene with an a,/3-unsaturated ketone shows that the double-bond carbon atoms of the unsaturated ketone are more positive (more green) than those of the isolated alkene ethylene. 

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