Acidity ethene

Ethyl bromide, H NMR spectrum, 503—504 Ethyl butanoate, Claisen condensation of, 851 Ethyl chloride, 48, 156. See also Chloroethane Ethyl cinnamate, 788 Ethyl cyanoacetate, 857 Ethylene, 168. See also Ethene acidity of, 343, 345, 552 biosynthesis of, 168 bond dissociation energies in, 343 bonding in, 14, 38-40, 47, 54, 170-171,... 

C2He04S, Et0)(H0)S02. Oily acidic liquid. Soluble in water and slowly hydrolysed by it to ethanol and sulphuric acid. Prepared by passing ethene into concentrated sulphuric acid or by heating ethanol and sulphuric acid. Gives ethene when heated alone, and diethyl sulphate when heated with ethanol at 140 C. Forms crystalline metallic salts which are soluble in water. 

Using ethene in ethanoic acid at 70-80 C it is possible to prepare vinyl acetate (ethenyl ethanoate) in good yields. 

Bond Distances, Bond Angles, and Bond Energies in Ethane, Ethene, and Ethyne (Table 9 1, p 342) Stmctures of a-Ammo Acids (Table 27 1, pp 1054-1055)... 

Synthesis ofp-Ethyltoluene. j )i7n7-Ethyltoluene, the feedstock for j )-methylstyrene, is difficult to separate from the products of toluene alkylation with ethane using conventional acidic catalysts. The unique configurational diffusion effect of ZSM-5 permits -dialkylbenzenes to be produced in one step. In the alkylation of toluene with ethene over a chemically modified ZSM-5, -ethyltoluene is obtained at 97% purity (58). 

Alcohols undergo dehydration in supercritical and hot water (41). Tertiary alcohols require no catalyst, but secondary and primary alcohols require an acid catalyst. With 0.01 MH2SO4 as a catalyst, ethanol eliminates water at 385°C and 34.5 MPa to form ethene. Reaction occurs in tens of seconds. Only a small amount of diethyl ether forms as a side reaction. 

A more efficient agent than peroxy compounds for the epoxidation of fluoro-olefins with nonfluonnated double bond is the hypofluorous acid-acetomtrile complex [22] Perfluoroalkylethenes react with this agent at room temperature within 2-3 h with moderate yields (equation 13), whereas olefins with strongly electron-deficient double bond or electron-poor, sterically hindered olefins, for example l,2-bis(perfluorobutyl)ethene and perfluoro-(l-alkylethyl)ethenes, are practically inert [22] Epoxidation of a mixture of 3 perfluoroalkyl-1-propenes at 0 C IS finished after 10 mm in 80% yield [22] The trifluorovinyl group in partially fluorinated dienes is not affected by this agent [22] (equation 13)... 

A common property of coordinated alkenes is their susceptibility to attack by nucleophiles such as OH , OMe , MeC02, and Cl , and it has long been known that Zeise s salt is slowly attacked by non-acidic water to give MeCHO and Pt metal, while corresponding Pd complexes are even more reactive. This forms the basis of the Wacker process (developed by J. Smidt and his colleagues at Wacker Chemie, 1959-60) for converting ethene (ethylene) into ethanal (acetaldehyde) — see Panel overleaf. 

Bond density surfaces are also superior to conventional models when it comes te describing chemical reactions. Chemical reactions can involve many changes in chemica bonding, and conventional formulas are not sufficiently flexible to describe what happen (conventional plastic models are even worse). For example, heating ethyl fonnate t( high temperatures causes this molecule to fragment into two new molecules, foraii( acid and ethene. A conventional formula can show which bonds are affected by ths reaction, but it cannot tell us if these changes occur all at once, sequentially, or in soms other fashion. 

Attempted dehydrocyclization of the 6-acylhydrazinopyrimidine 65 by heating with polyphosphoric acid led, instead, to pyrimidine ring rupture, yielding the l,l-diamino-2-nitro-2-(3-phenyl-l,2,4-triazol-5-yl)ethene 66. Cyclocondensation of the latter with triethyl orthoformate gave the fully aromatic triazolopyrimidine 67 (94JHC1171) (Scheme 23). 

Another common reaction is the chlorination of alkenes to give 1,2-dihaloalka-nes. Patell et al. reported that the addition of chlorine to ethene in acidic chloroalu-minate(III) ionic liquids gave 1,2-dichloroethane [68]. Under these conditions, the imidazole ring of imidazolium ionic liquid is chlorinated. Initially, the chlorination occurs at the 4- and 5-positions of the imidazole ring, and is followed by much slower chlorination at the 2-position. This does not affect the outcome of the alkene chlorination reaction and it was found that the chlorinated imidazolium ionic liquids are excellent catalysts for the reaction (Scheme 5.1-39). 

Cracking and isomerization reactions occur readily in acidic chloroaluminate(III) ionic liquids. A remarkable example of this is the reaction of poly(ethene), which is converted into a mixture of gaseous alkanes of formula (C Ff2n+2, where n = 3-5) and cyclic alkanes with a hydrogen to carbon ratio of less than two (Figure 5.1-4, Scheme 5.1-68) [99]. 

The first example of homogeneous transition metal catalysis in an ionic liquid was the platinum-catalyzed hydroformylation of ethene in tetraethylammonium trichlorostannate (mp. 78 °C), described by Parshall in 1972 (Scheme 5.2-1, a)) [1]. In 1987, Knifton reported the ruthenium- and cobalt-catalyzed hydroformylation of internal and terminal alkenes in molten [Bu4P]Br, a salt that falls under the now accepted definition for an ionic liquid (see Scheme 5.2-1, b)) [2]. The first applications of room-temperature ionic liquids in homogeneous transition metal catalysis were described in 1990 by Chauvin et al. and by Wilkes et ak. Wilkes et al. used weekly acidic chloroaluminate melts and studied ethylene polymerization in them with Ziegler-Natta catalysts (Scheme 5.2-1, c)) [3]. Chauvin s group dissolved nickel catalysts in weakly acidic chloroaluminate melts and investigated the resulting ionic catalyst solutions for the dimerization of propene (Scheme 5.2-1, d)) [4]. 

Closely related catalytic systems have also been used for the selective dimerization of ethene to butenes [99]. Dupont et al. dissolved [Ni(MeCN)<3][BF4]2 in the slightly acidic [BMIM]Cl/AlCl3/AlEtCl2 chloroaluminate system (ratio = 1 1.2 0.25) and obtained 100 % butenes at -10 °C and 18 bar ethylene pressure (TOF = 1731 h Y Unfortunately, the more valuable 1-butene was not produced selectively, with a mixture of all linear butene isomers (i.e., 1-butene, cis-2-butene, trans-2-butene) being obtained. 

The use of acidic chloroaluminates as alternative liquid acid catalysts for the allcy-lation of light olefins with isobutane, for the production of high octane number gasoline blending components, is also a challenge. This reaction has been performed in a continuous flow pilot plant operation at IFP [44] in a reactor vessel similar to that used for dimerization. The feed, a mixture of olefin and isobutane, is pumped continuously into the well stirred reactor containing the ionic liquid catalyst. In the case of ethene, which is less reactive than butene, [pyridinium]Cl/AlCl3 (1 2 molar ratio) ionic liquid proved to be the best candidate (Table 5.3-4). 

As we saw earlier (Section 22.4), ethanol can be made from ethene by adding water in the presence of an acid catalyst. This process is referred to as hydration ... 

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