Reactions of Olefins

A valuable indirect method of probing the Horiuti-Polanyi mechanism is the study and comparison of competitive rates of hydrogenation of olefins using both homogeneous and heterogeneous catalysts. Comparisons of individual rates 

Although various groups (27-29, 33, 34) have described kinetic analyses for competitive reactions on heterogeneous catalysts, the following suffices to demonstrate the complexities of the problem of hydrogenation of olefins. Applying steady state analysis to the system, 

If adsorption of olefin is competitive and equilibrium is set up between solution and surface 

It can easily be shown that integration of Eq. (5) affords a linear relationship between log CA and log CB with slope, or competition ratio,/ , as the multiple of constants within the square brackets. The ratio of Langmuir coefficients is obviously coupled with ratios of rate constants and alkyl reversal equilibrium constants. On the other hand, if alkyl reversal is very slow such that fc 3 k4 0H, then Eq. (4) reduces to 

R (b/c) = (A/c))- Graham et al. (30) found the same consistency for their data (Fig. 10) with the exception of the C6 and C8 mixture on Pt/Si02, and Hussey et al. (27) also report the same feature for this mixture. A probable clue to an 

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It was not fully realized until my breakthrough using superacids (vide infra) that, to suppress the deprotonation of alkyl cations to olefins and the subsequent formation of complex mixtures by reactions of olefins with alkyl cations, such as alkylation, oligomerization, polymerization, and cyclization, acids much stronger than those known and used in the past were needed. 

Rea.ctlons, Vinyl ethers undergo all of the expected reactions of olefinic compounds plus a number of reactions that are both usehil and... 

Aliphatic Aldehyde Syntheses. Friedel-Crafts-type aUphatic aldehyde syntheses are considerably rarer than those of aromatic aldehydes. However, the hydroformylation reaction of olefins (185) and the related oxo synthesis are effected by strong acid catalysts, eg, tetracarbonylhydrocobalt, HCo(CO)4 (see Oxo process). 

Thermally unstable cycHc trioxides, 1,2,3-trioxolanes or primary o2onides are prepared by reaction of olefins with o2one (64) (see Ozone). Dialkyl trioxides, ROOOR, have been obtained by coupling of alkoxy radicals, RO , with alkylperoxy radicals, ROO , at low temperatures. DiaLkyl trioxides are unstable above —30° C (63). Dialkyl tetraoxides, ROOOOR, have been similarly produced by coupling of two alkylperoxy radicals, ROO , at low temperatures. Dialkyl tetraoxides are unstable above —80°C (63). 

Glycol ethers can be prepared from isopropyl alcohol by reaction of olefin oxides, eg, ethylene oxide [75-21-8] (qv) or propylene oxide [75-56-9] (qv). Reactions such as that to produce 2-isoproxyethanol [109-59-1] (isopropyl CeUosolve) are generally cataly2ed by an alkaU hydroxide. 

Reaction of olefin oxides (epoxides) to produce poly(oxyalkylene) ether derivatives is the etherification of polyols of greatest commercial importance. Epoxides used include ethylene oxide, propylene oxide, and epichl orohydrin. The products of oxyalkylation have the same number of hydroxyl groups per mole as the starting polyol. Examples include the poly(oxypropylene) ethers of sorbitol (130) and lactitol (131), usually formed in the presence of an alkaline catalyst such as potassium hydroxide. Reaction of epichl orohydrin and isosorbide leads to the bisglycidyl ether (132). A polysubstituted carboxyethyl ether of mannitol has been obtained by the interaction of mannitol with acrylonitrile followed by hydrolysis of the intermediate cyanoethyl ether (133). 

OxythaHation reactions of olefins provide useful synthetic routes to products, eg, glycols, aldehydes, and ketones (31) ... 

Ghlorohydrination with er -All l Hypohalites. Olefins react with ethyl hypochlorite [624-85-1] to form the corresponding chlorohydrin (49). In 1938 both Shell Development Co. (50) and Arthur D. Litde, Inc. (51) patented the preparation of chlorohydrins by the reactions of olefins with tertiary alkyl hypochlorites. Examples with ethylene and propylene in the Shell patent reported chlorohydrin yields of greater than 95% with tert-huty hypochlorite [507-40-4]. 

Base catalysis is most effective with alkali metals dispersed on solid supports or, in the homogeneous form, as aldoxides, amides, and so on. Small amounts of promoters form organoalkali comnpounds that really contribute the catalytic power. Basic ion exchange resins also are usebil. Base-catalyzed processes include isomerization and oligomerization of olefins, reactions of olefins with aromatics, and hydrogenation of polynuclear aromatics. 

Hydroformylation, or the 0X0 process, is the reaction of olefins with CO and H9 to make aldehydes, which may subsequently be converted to higher alcohols. The catalyst base is cobalt naph-thenate, which transforms to cobalt hydrocarbonyl in place. A rhodium complex that is more stable and mnctions at a lower temperature is also used. 

Reaction of Olefins with Lead Tetrafiuoride in Situ... 

Reaction of Olefins with N-Bromoacetamide-Hydrogen Fluoride... 

The most common method of epoxidation is the reaction of olefins with per-acids. For over twenty years, perbenzoic acid and monoperphthalic acid have been the most frequently used reagents. Recently, m-chloroperbenzoic acid has proved to be an equally efficient reagent which is commercially available (Aldrich Chemicals). The general electrophilic addition mechanism of the peracid-olefin reaction is currently believed to involve either an intra-molecularly bonded spiro species (1) or a 1,3-dipolar adduct of a carbonyl oxide, cf. (2). The electrophilic addition reaction is sensitive to steric effects. 

In contrast, additions of fluorine and carbon to fluormated olefins are widely investigated The best known processes involve reactions of olefins with fluoride ion to generate carbanionic intermediates [203] that are trapped in situ by carbon-based electrophiles. 

The reaction of olefins,alcohols,and epoxides > with or at high temperatures over catalysts such as... 

The reactions of olefins with peracids to form epoxides allows for the selective oxidation of carbon-carbon double bonds in the presence of other functional groups which may be subject to oxidation (for example, hydroxyl groups). The epoxides that result are easily cleaved by strong acids to diols or half-esters of diols and are therefore useful intermediates in the synthesis of polyfunctional compounds. 

Thus, suppression of the radical-chain thermal destruction reaction of olefins necessitates an addition of substances having the ability to react with active macroradicals and to yield inactive or low-reactivity products. 

Kennedy, J. P. and Rengachary, S. Correlation Between Cationic Model and Polymerization Reactions of Olefins. Vol. 14, pp. 1 —48. 

If cobalt carbonylpyridine catalyst systems are used, the formation of unbranched carboxylic acids is strongly favored not only by reaction of a-olefins but also by reaction of olefins with internal double bonds ( contrathermo-dynamic double-bond isomerization) [59]. The cobalt carbonylpyridine catalyst of the hydrocarboxylation reaction resembles the cobalt carbonyl-terf-phos-phine catalysts of the hydroformylation reaction. The reactivity of the cobalt-pyridine system in the hydrocarboxylation reaction is remarkable higher than the cobalt-phosphine system in the hydroformylation reaction, especially in the case of olefins with internal double bonds. This reaction had not found an industrial application until now. 

Micellar catalysis to enhance or diminish the rate of chemical reactions is well known [97]. Of somewhat greater interest is the influence of micelles on competing reactions, e.g., proton-catalyzed reactions. An example related to the effect of alkanesulfonates is the epoxidation of simple aliphatic olefins. The reaction of olefins and hydrogen peroxide catalyzed by strongly acidic Mo(VI)... 

Alcohol sulfates were first obtained either by the reaction of olefins with sulfuric acid or by sulfation of alcohols produced by hydrogenolysis of oils and fats with sulfuric acid. With the advent of petrochemistry and the progress of chemistry and chemical engineering, alcohol sulfates and their derivatives have become one of the most important surfactants and are produced in large amounts using techniques different from those originally used. They are based on a wide range of alcohols and have found applications in almost all domestic and industrial sectors. 

The reaction of olefin sulfation and its possibilities has been extensively studied [3-10] and it was used to produce alcohol sulfates. Dry distillation of spermaceti gives palmitic acid and cetene-1, which can be sulfated with sulfuric acid to give cetyl-2 sulfate [11]. Other surfactants were obtained from olefins produced from natural substances, such as alcohol sulfates by sulfation of olefins from decarboxylation of oleic acid [12], by sulfation of olefins made by dehydrating hydroabietyl alcohol, by direct sulfation of abietyl alcohol [13,14], or by sulfation of natural terpenes [15]. 

Rather low yields were obtained by reaction of olefins with phosphorous acid in the presence of free radical catalysts. The reactants were dissolved in 50% aqueous dioxane, dibenzoyl peroxide was added, and the solution was heated for 6 h at 90°C [93,94] see Eq. (66) ... 

Another reaction for synthesizing phosphinic acid derivatives was described by Jungermann and coworkers [173-176], It is based on the reaction of olefins with phosphorus trichloride in the presence of a Friedel-Crafts catalyst, according to Eq. (106) ... 

Recently Nafion-H was successfully used in the Diels-Alder reaction of olefin acetals with isoprene and cyclopentadiene (Scheme 4.27). The reactions work well in DCM at room temperature and Nafion-H did not cleave the acetal group [96]. The recovered Nafion-H was used four or five times without affecting the yield of the cycloadducts. 

E. Reactions of Carbon-Carbon Double Bonds Among the most important reactions of olefinic compounds are those involving the carbon-carbon double bond. It is convenient to divide phenomena occurring... 

Vicinal iodo carboxylates may also be prepared from the reaction of olefins either with iodine and potassium iodate in acetic acid/ or with N-iodosuccinimide and a carboxylic acid in chloroform. " A number of new procedures for effecting the hydroxylation or acyloxylation of olefins in a manner similar to the Prevost or Woodward-Prevost reactions include the following iodo acetoxylation with iodine and potassium chlorate in acetic acid followed by acetolysis with potassium acetate reaction with iV-bromoacetamide and silver acetate in acetic acid reaction with thallium(III) acetate in acetic acid and reaction with iodine tris(trifluoroacetate) in pentane. ... 

Reactions of alkyl halides with alkaU metal phosphides [39-41], addition reactions of olefins with PHj [42] or the pyrolytic cleavage of P-0 bonds in RPO2H2 [43] are also reported for the preparation of alkyl/aryl functionalized primary... 

Pyridine-based N-containing ligands have been tested in order to extend the scope of the copper-catalyzed cyclopropanation reaction of olefins. Chelucci et al. [33] have carefully examined and reviewed [34] the efficiency of a number of chiral pyridine derivatives as bidentate Hgands (mainly 2,2 -bipyridines, 2,2 6, 2 -terpyridines, phenanthrolines and aminopyridine) in the copper-catalyzed cyclopropanation of styrene by ethyl diazoacetate. The corresponding copper complexes proved to be only moderately active and enantios-elective (ee up to 32% for a C2-symmetric bipyridine). The same authors prepared other chiral ligands with nitrogen donors such as 2,2 -bipyridines 21, 5,6-dihydro-1,10-phenanthrolines 22, and 1,10-phenanthrolines 23 (see Scheme 14) [35]. 

The 5,6-disubstituted dihydropyran 2049 is converted by iodosobenzene diacetate and Me3SiBr 16 or Mc3Sil 17 in pyridine to the 3-bromo (or 3-iodo) compounds 2050 in 79 or 84% yield, respectively [198] (Scheme 12.59). Reaction of olefins such as cyclohexene (or enol ethers) with iodosobenzene diacetate, tetra-... 

Addition of TCS 14 to CH2l2/Zn, which contains up to 0.04 mol% of lead impurity, improves the Simmons-Smith reaction of olefins such as cyclooctene to give up to 96% of the cyclopropane 2103 [36] (Scheme 13.12). 

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