Ethene series

Allyl Chloride.—The halogen substitution products of propene and the higher hydrocarbons of the ethene series, when the substitution is in a carbon group not doubly linked, are of importance in the synthesis of derivatives in the same way as are the alkyl halides. 3-Chlor propene or propenyl chloride, CH2 = CH—CH2CI, is known also as allyl chloride, the radical (CH2 = CH—CH2—) being known as allyl. 

Ethylene and Ethylidene Compounds.—The fact that the symmetrical di-chlor ethane is readily prepared from ethylene, has given to it the name of ethylene chloride. To distinguish the two isomers by name the other, the unsymmetrical di-chlor ethane, has been called ethylidene chloride. In connection with our discussion of the constitution of the ethene series of unsaturated hydrocarbons (p. 154), we have used the constitution of ethylene chloride as proving the constitution of ethylene or ethene, as H2C = CH2. Isomerism of the character shown in these two di-chlor ethanes, as above explained, is found in all classes of di-substitution products of ethane, so that we may express the compounds by general formulas as follows ... 

Poly(ethylene-co-carbon monoxide) Alternating copolymer 500 CO, H2O, ethene, series of ketones with general structure R-[-C0-CH2-CH2-],-C0-R where R, R =-CH3, -CH2-CH3 or -CH=CH2 270... 

By 1866, based on eadier proposals, it was possible for Hofmann (41) to arrange hydrocarbons in series by their empirical formulas, ie, methane, CH4, and methene, CH2 ethane, ethene, C2H4, and ethine, C2H2 propane, C Hg, propene, C H, and propine, C H and quartane, C H q, quartene,... 

Note that there is no one-carbon alkene corresponding to methane, since hydrogen can never form more than one covalent bond, and there is no other carbon atom in the structural formula. Therefore, the first compound in the alkene series is ethene, while the corresponding two-carbon compound in the alkane series, ethane, is the second compound in the series, with methane the first. 

A five-column configuration of Such an analyser system is depicted in Figure 14.6. The first event in the process is the analysis of Hj by injection of the contents of sample loop 2 (SL2) onto column 5 (a packed molecular sieve column). Hydrogen is separated from the other compounds and detected by TCD 2, where nitrogen is used as a carrier gas. The next event is the injection of the contents of sample loop 1 (SLl), which is in series with SL2, onto column 1. After the separation of compounds up to and including C5, and backflushing the contents of column 1, all compounds above C5 (Q+) are detected by TCDl. The fraction up to and including C5 is directed to column 2, where air, CO, COj, Cj, and 2= (ethene) are separated from... 

You may recall that we discussed the bonding in ethene in Chapter 7. The double bond in ethene and other alkenes consists of a sigma bond and a pi bond. The ethene molecule is planar. There is no rotation about the double bond, since that would require breaking the pi bond. The bond angle in ethene is 120°, corresponding to sp2 hybridization about each carbon atom. The geometries of ethene and the next member of the alkene series, QHg, are shown in Figure 22.6. 

The alkene series of hydrocarbons is characterized by having one double bond in the carbon chain. The characteristic formula for members of the series is C H2 . Since there must be at least two carbon atoms present to have a carbon-to-carbon double bond, the first member of this series is ethene, C2H4, also known as ethylene. Propene (propylene), C,Hh, and butene (butylene), C4HK, are the next two members of the series. Note that the systematic names of these compounds denote the number of carbon atoms in the chain with the name derived from that of the alkane having the same number of carbon atoms (Table 21-2). Note also that the characteristic ending -ene is part of the name of each of these compounds. 

Alternatively, NIR spectroscopy has been applied to relate NIR data to mechanical properties [4], A multivariate data analysis was performed on a series of commercial ethene copolymers with 1-butene and 1-octene. For the density correlation, a coefficient of determination better than 99% was obtained, whereas this was 97.7% for the flexural modulus, and only 85% for the tensile strength. 

In the intermolecular series, Diels-Alder cycloaddition of ethene to the pyrazi-none heterodiene led to the expected bicyclic cycloadduct (Scheme 6.95 b) [195], The details of this transformation, performed in pre-pressurized reaction vessels, are described in Section 4.3.2 [196], Similar cycloaddition reactions have also been studied on a solid phase (Scheme 7.58) [197]. 

Microwave-induced, catalytic gas-phase reactions have primary been pursued by Wan [63, 64], Wan et al. [65] have used pulsed-microwave radiation (millisecond high-energy pulses) to study the reaction of methane in the absence of oxygen. The reaction was performed by use of a series of nickel catalysts. The structure of the products seemed to be function of both the catalyst and the power and frequency of microwave pulses. A Ni/Si02 catalyst has been reported to produce 93% ethyne, whereas under the same irradiation conditions a Ni powder catalyst produced 83% ethene and 8.5 % ethane, but no ethyne. 

The cationic character of the active site, proposed as long ago as 1961,32 has recently been confirmed by the synthesis of a wide series of group 4 metallocene cations able to polymerize ethene and propene without any aluminum cocatalyst.33 36 The finding by Ewen that C2H4(l-Ind)2ZrCl2/MAO... 

For a series of model acyl of the type [Pd(COMe)(C2H4)(P - P)]+ it has been found that the insertion of ethene into the Pd-acyl bond with formation of a /3-chelate (Eq. 20) is irreversible and that the energy barrier is ca. 12 kcal/mol [52,55,56]. From thermodynamic and kinetic data, Schultz et al. calculated that the insertion of ethene into a Pd-alkyl bond (double ethene insertion) could occur every ca. 105 CO insertions into the same bond [52], which accounts for the strict alternating chain growing. 

Another typical feature of these catalysts is the socalled chain walking . Prior to insertion of the next ethene molecule a series of P-hydride elimination and re-insertions can take place, which looks like a metal atom running along the chain. Insertion of ethene in a secondary alkyl chain leads to the formation of branches. During the isomerisation process palladium can even cross tertiary carbon atoms, since branches on branches are obtained. 

Tuazon, E.C., Aschmann, S.M., Arey, J., and Atkinson, R. Products of the gas-phase reactions of O3 with a series of methyl-substituted ethenes, Environ. Sci. Tecbnol, 31 (10) 3004-3009, 1997. 

Kinetic parameters k, often also and AS, occasionally AV ) for formation and dissociation of several pentacyanoferrate(II) complexes [Fe(CN)5L]" have been established. Ligands L include several S- and A-donor heterocycles,4-methyl- and 4-amino-pyridines, a series of alkylamines, 3- and 4-hydroxy- and 3- and 4-methoxy-pyridines, several amino acids, nicotinamide, " 4-pyridine aldoxime, 3-Me and 3-Ph sydnones, several bis-pyridine ligands,neutral, protonated, and methylated 4,4 -bipyridyl, 1,2-bis(4-pyridyl)ethane and traTO-l,2-bis0-pyridyl)ethene, pyrazine- 4,4 -bipyridyl- and bis(4-pyridyl)ethyne-pentaammine-cobalt(III), edta-ruthenium(III), and pentaammineruthenium-(II)and-(III) complexes of... 

In a series of studies, substituents were introduced or varied at the 2-positions of the thiophene rings of di(benzothienyl)ethenes. The reactions of 3-bromo-2(n-aIkyl)-l-benzothiophene with BuLi and octafluorocyclo-pentene gave bis(2-n-alkyl-l -benzothiophen-3-yl)perfluorocyclo-pentenes 60 containing alkyl substituents with a different chain length at position 2 of the benzothiophene ring. The authors stated that the Et-, Pr-, and Bu-containing derivatives exhibit photochromic properties even in the crystalline state (06JPP(A)162). 

The reaction of 2,5-disubstituted 3-furyl bromides with butyl-lithium and octafluorocyclopentene in dry tetrahydrofuran (THF) at —78°C gave bis(furyl)ethenes 82 (06JMC4690). Photochrome 83 (05JOC10323, 06EJ03105) (29-46% yield) and a series of its derivatives 84 (55-65%) containing different substituents at position 6 of the ben-zofuran ring were synthesized from 3-bromo-2-methyl-1-benzofuran (08JPP(A)146). 

Tuazon, E. C., S. M. Aschmann, J. Arey, and R. Atkinson, Products of the Gas-Phase Reactions of a Series of Methyl-Substituted Ethenes with the OH Radical, Enriron. Sci. Technoi, 32, 2106-2112 (1998a). 

Ethyne, ethene and ethane contain 10. 12 and 14 valence electrons, respectively. They are isoelectronic with N2, 02 and F., respectively. Along both series of molecules the central link becomes progressively weaker and the bond lengths increase. The carbon-carbon bond length increases from 121 pm in ethyne to 133 pm in ethene and to 155 pm in ethane. The corresponding bond enthalpy terms are 837, 612 and 348 kJ mol Data for the diatomic molecules is contained in the text. Discuss these data in terms of the VSEPR and MO treatments of the molecules. 

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