Cis-2-Butene oxide

Common names of epoxides are derived by giving the name of the alkene from which the epoxide is formally derived followed by the word oxide an example is cis-2-butene oxide. 

Comparison of activation enthalpies for neutral hydrolysis of substituted oxi-ranes (propene oxide and butane oxides) [53] clearly demonstrates the preference of Beta pathways corresponding to the attack of water molecule on more substituted carbon atom (Fig. 10.13). Activation enthalpies lowering has been ascertained in the series ethene oxide>trans-2-butene oxide cis-2-butene oxide propene oxide > isobutene oxide. 

From the results of other authors should be mentioned the observation of a similar effect, e.g. in the oxidation of olefins on nickel oxide (118), where the retardation of the reaction of 1-butene by cis-2-butene was greater than the effect of 1-butene on the reaction of m-2-butene the ratio of the adsorption coefficients Kcia h/Kwas 1.45. In a study on hydrogenation over C03O4 it was reported (109) that the reactivities of ethylene and propylene were nearly the same (1.17 in favor of propylene), when measured separately, whereas the ratio of adsorption coefficients was 8.4 in favor of ethylene. This led in the competitive arrangement to preferential hydrogenation of ethylene. A similar phenomenon occurs in the catalytic reduction of nitric oxide and sulfur dioxide by carbon monoxide (120a). 

Pd/Cu zeolite Y associations were found to be selective catalysts for oxidation of olefins in the presence of steam at temperatures ranging from 373 to 433K [22-30]. Acetone and acetaldehyde were obtained by propylene and ethylene oxidation, with selectivities of at least 90%. Neither Pd/Y nor Cu/Y showed good activity in these reactions. The conversion of different olefins under the same experimental conditions decreases in the following order [23] ethylene > propylene > 1-butene > cis-2-butene - trans-2-butene. 

For many reactions the type of intermediate that is involved may be deduced from a study of a family of reactants. For example, by noting that in allylic oxidation the order of reactivity is isobutene > trans-2-butene > cis-2-butene > 1-butene one may deduce that an allyl radical or cation is an intermediate. For other oxidations, if the reaction rate order is primary > secondary > tertiary, then an anionic intermediate is implicated. However, care must be taken that the formation of the intermediate is involved in the ratedetermining step and that there are no adsorption equilibrium effects. To rule out the latter, the reaction should be carried out at conditions of low coverage. 

Fig. 1. The temperature programmed desorption profiles for a-Fe203 (a) Blank desorption without adsorbates (b) ris-2-butene adsorption (c) butadiene adsorption (d) cis-2-butene adsorption from a catalyst depleted of selective oxidation sites. From ref. 5, reprinted with permission, copyright 1979 by the American Chemical Society.

The separation of the two sets of desorption products may indicate that they are from different sites. That is, branching of the selective and nonselec-tive oxidation takes place on adsorption of butene. This can be confirmed if the two sets of products can be varied independently. This is shown by two experiments. The first experiment makes use of the fact that butene and butadiene adsorb on the same sites. Butadiene is first adsorbed onto the catalyst (5). The catalyst is then heated to 210°C, desorbing all of the unreacted butadiene, but leaving on the surface the precursors of the combustion products. Since desorption of the unreacted butadiene does not involve a net chemical reaction, the adsorpton sites involved are not affected. The catalyst is then cooled to 22°C, and cis-2-butene is adsorbed. If selective oxidation and combustion take place on the same site, the adsorbed butene would undergo both reactions. If they take place on separate sites, and butene adsorbs only on the selective oxidation site (because the combustion site is covered by species from butadiene adsorption), the adsorbed butene would form only butadiene. Subsequent desorption yields a profile similar to that for a single adsorption of ds-2-butene (Fig.l, curve b). More importantly, within experimental errors, the amount of butadiene evolved is the same as in a ds-2-butene adsorption experiment, and the amount of C02 evolved is the same as in a butadiene adsorption experiment. Thus, the adsorbed butene forms only butadiene. These results show that under these experimental conditions (i.e., in the absence of gas-phase oxygen), the production of butadiene and carbon dioxide takes place on separate sites. 

Results of a variation of this experiment yield the same conclusion (5). A catalyst is first adsorbed with butadiene, and the unreacted butadiene is desorbed by heating to 210°C. Then a pulse of cis-2-butene is passed over the catalyst at this temperature. The production of butadiene from this pulse is the same as that from an untreated catalyst. Thus, the preadsorbed precursors of combustion products do not affect the selective oxidation reaction. 

The second experiment is to perform adsorption-desorption of butene on a catalyst that is depleted of selective oxidation sites. When 10 pulses of cis-2-butene are passed over a catalyst at 210°C (5), which is a temperature too low for the production of C02, the catalyst is reduced. The number of selective oxidation sites is substantially reduced as is evident by the much lower conversion to butadiene in the last pulse. Then the oxide is cooled to 22°C, and cis-2-butene is adsorbed. The resulting desorption profile is shown in Fig. 1, curve d. Clearly, there is no more butadiene production, while the combustion products are produced in a somewhat larger quantity. These results again support the conclusion that the selective oxidation and the combustion sites are independent. 

Effect of Preadsorbed Oxygen on the Oxidation of cis-2-Butene in Adsorption-Desorption Experiments -6... 

Epoxidation of cis-2-butene-l,4-diones.3 Enediones that can assume the all s-cis-conformation (A) are oxidized by Mo05 H20 HMPT (2 equiv.) stereospecif-ically to cw-2,3-epoxybutane-l,4-diones (1). 

In nonprotic solvents, alkenes are stoichiometrically oxidized by Vv-peroxo complexes to epoxides and consecutive oxidative cleavage products in a nonstereoselective fashion. For example, cis-2-butene gave an approximately 2 1 mixture of cis- and trans-epoxides (equation 37). The reactivity of alkenes increases with their nucleophilic nature. Alkenes containing phenyl substituents such as styrene, a- and jS-methylstyrene are also very reactive and mainly give oxidative cleavage products. 

For instance, the reaction of cis- and tra/w-2-butene oxide with aluminium chloride yields mainly erythro- and threo-chlorohydrin (after hydrolysis) respectively [66]. 

Clauson-Kaas suggested a variation of this method.88 cis-2-Butene-1,4-diol is oxidized by chromic acid to the monoaldehyde, which is... 

The aminocyclitol moiety was synthesized in a stereocontrolled manner from cis-2-butene-l,4-diol (Scheme 40)112 by conversion into epoxide 321 via Sharpless asymmetric epoxidation in 88% yield.111 Oxidation of 321 with IBX, followed by a Wittig reaction with methyl-triphenylphosphonium bromide and KHMDS, produced alkene 322. Dihydroxylation of the double bond of 322 with OSO4 gave the diol 323, which underwent protection of the primary hydroxyl group as the TBDMS ether to furnish 324. The secondary alcohol of 324 was oxidized with Dess-Martin periodinane to... 

Oxidation of terminal alkenes may be carried out in benzene-water in the presence of cetyltrimethy-lammonium bromide at 80 C ° although cyclodextrins are better phase-transfer agents. In the presence of a catalytic amount of -cyclodextrin, 1-decene and cis-2-butene were oxidized at 65 C to 2-decanone (61%) and 2-butanone (76%) respectively. Selective oxidation of linear Cg-Cio terminal alkenes took place at 75 C in the presence of a-cyclodextrin in water, but a low yield was obtained with 1-do-decene. 

The oxidation is highly stereoselective. Thus cis-2-butene gives mainly the meso-compound (3), and trans-2-hutcne gives mainly the (//-compound (4). Cyclohexene is converted mainly into the cix-compound (S). 

Vapor-deposited carbon atoms have been known to reduce epoxides to alkenes but with low stereoselectivity, whereas chemically generated carbon atoms, by thermal decomposition of S-tetrazolediazo-nium chloride (2), deoxygenate cis- and franr-2-butene oxide with a high degree of retention of stereochemistry. ... 

In both cases, under open-circuit operation (I = 0, no electrochemical rate), there is a catalytic rate, ro, of ethylene consumption for oxidation to CO2 (Fig. 47) or of 1 -butene consumption owing to reduction to butane and isomerization to cis-2-butene and trans-2-butene (Fig. 47). 

In the experiment shown in Fig. 47, it is A = 74000 and p = 26, that is, the rate of C2H4 oxidation increases by a factor of 25 and the increase in the rate of O consumption is 74000 times larger than the rate, I/2F, of O2- supply to the catalyst. In the experiment shown in Fig. 48, the maximum p values for the production of cis-2-butene, trans-2-butene, and butene are of the order of 50 and the corresponding maximum A values are of the order of 40 for cis-2-butene formation, 10 for trans-2-butene formation, and less than 1 for butene formation. Thus, each proton supplied to the Pd catalyst can cause the isomerization of up to 40 1-butene molecules to cis-2-butene and up to 10 1-butene molecules to trans-2-butene, whereas the hydrogenation of 1-butene to butane is electrocatalytic, that is, Faradaic. 

Fig. 3. FT-IR spectra of (a) surface species arising from cis-2-butene adsorption on MgFe204 at r.t. (b) liquid cis-2-butene (c) surface species arising from 1,3-butadiene adsorption on MgFe204 (d) liquid 1,3-butadiene. The bars denote the species arising from reactive adsorption of cis-2-butene, i.e. but-3-en-2-oxides, and but-2-en-l-oxides.

Arylation of the 4,7-dihydro-l,3-dioxepin system 68 (easily derived from cis-2-butene-l,4-diol), once again using the triflate, was reported by Shibasaki et al. in 1994 [57]. The reaction is significant in that the resulting enol ethers are easily converted (by hydrolysis and then oxidation of the intermediate lactol) to chiral P-aryl-y-butyrolactones 70, which are themselves useful synthetic intermediates (Scheme 18) [58]. Also noteworthy is the important role played by added molecular sieves (MS), which enhance both chemical yield and ee. This was the first time that such an effect had been noted for the AHR. 

Figure 4> GN2 and Gteom vs. nitrous oxide concentration for cis-2-butene (0.25M) in benzene. X, Gisom O, GA 2...

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