Alkenes reaction conditions

Methylene compound Alkene Reaction conditions % yield... 

Alkene Reaction Conditions Product Yield m. p. Refer-... 

Diazirine Alkene Reaction Conditions Product Ratio of Isomers Yield (%) Ref... 

Entry o o Alkene Reaction Conditions Product d.r. Yield Ref... 

The first report of oxidative carbonylation is the reaction of alkenes with CO in benzene in the presence of PdCh to afford the /3-chloroacyl chloride 224[12,206]. The oxidative carbonylation of alkene in alcohol gives the q, f3-unsaturated ester 225 and /3-alkoxy ester 226 by monocarbonylation, and succinate 111 by dicarbonylation depending on the reaction conditions[207-209]. The scope of the reaction has been studied[210]. Succinate formation takes... 

Cyclic alkenes give different regioisomers depending on the reaction conditions owing to double bond isomerization caused by syii elimination of Pd—H species and its readdition. The following three reaction conditions were tested for the reaction of cycloheptene (35)[18,38] ... 

Hydroxy-THISs react with electron-deficient alkynes to give nonisol-able adducts that extrude carbonyl sulfide, affording pyrroles (23). Compound 16 (X = 0) seems particularly reactive (Scheme 16) (25). The cycloaddition to benzyne yields isoindoles in low- yield. Further cyclo-addition between isoindole and benzyne leads to an iminoanthracene as the main product (Scheme 17). The cycloadducts derived from electron-deficient alkenes are stable (23, 25) unless highly strained. Thus the two adducts, 18a (R = H, R = COOMe) and 18b (R = COOMe, R = H), formed from 7, both extrude furan and COS under the reaction conditions producing the pyrroles (19. R = H or COOMe) (Scheme 18). Similarly, the cycloadduct formed between 16 (X = 0) and dimethylfumarate... 

Wnte structural formulas for all the alkene products that could reasonably be formed from each of the following compounds under the indicated reaction conditions Where more than one alkene is produced specify the one that is the major product... 

Dimerization in concentrated sulfuric acid occurs mainly with those alkenes that form tertiary carbocations In some cases reaction conditions can be developed that favor the formation of higher molecular weight polymers Because these reactions proceed by way of carbocation intermediates the process is referred to as cationic polymerization We made special mention m Section 5 1 of the enormous volume of ethylene and propene production in the petrochemical industry The accompanying box summarizes the principal uses of these alkenes Most of the ethylene is converted to polyethylene, a high molecular weight polymer of ethylene Polyethylene cannot be prepared by cationic polymerization but is the simplest example of a polymer that is produced on a large scale by free radical polymerization... 

In the following section we 11 see another method for converting alkynes to alkenes The reaction conditions are very different from those of Lindlar hydrogenation So IS the stereochemistry... 

A useful alternative to catalytic partial hydrogenation for converting alkynes to alkenes IS reduction by a Group I metal (lithium sodium or potassium) m liquid ammonia The unique feature of metal-ammonia reduction is that it converts alkynes to trans alkenes whereas catalytic hydrogenation yields cis alkenes Thus from the same alkyne one can prepare either a cis or a trans alkene by choosing the appropriate reaction conditions... 

DiisononylPhthalate andDiisodeeylPhthalate. These primary plasticizers are produced by esterification of 0x0 alcohols of carbon chain length nine and ten. The 0x0 alcohols are produced through the carbonylation of alkenes (olefins). The carbonylation process (eq. 3) adds a carbon unit to an alkene chain by reaction with carbon monoxide and hydrogen with heat, pressure, and catalyst. In this way a Cg alkene is carbonylated to yield a alcohol a alkene is carbonylated to produce a C q alcohol. Due to the distribution of the C=C double bond ia the alkene and the varyiag effectiveness of certain catalysts, the position of the added carbon atom can vary and an isomer distribution is generally created ia such a reaction the nature of this distribution depends on the reaction conditions. Consequendy these alcohols are termed iso-alcohols and the subsequent phthalates iso-phthalates, an unfortunate designation ia view of possible confusion with esters of isophthaUc acid. 

N- Aminoaziridines have been converted to alkenes by reaction with a variety of oxidizing agents (70JA1784). Usually, the deamination reaction is stereospecific. The oxidation of l-amino-2,3-diphenylaziridines with manganese dioxide, however, was not stereospecific. The trans compound gives entirely frans-stilbene, whereas the cfs-aziridine forms a mixture of 85% trans- and 15% c -aikene. cw-Stilbene is not isomerized to trans under the reaction conditions, and the results are explained in terms of an azamine intermediate which can isomerize through a tautomeric equilibrium. 

Except for the biochemical exanple just cited, the stnactures of all of the alcohols in Section 5.9 (including those in Problem 5.13) were such that each one could give only a single alkene by p elimination. What about elimination in alcohols such as 2-methyl-2-butanol, in which dehydration can occur in two different directions to give alkenes that are constitutional isomers Here, a double bond can be generated between C-1 and C-2 or between C-2 and C-3. Both processes occur but not nearly to the sane extent. Under the usual reaction conditions 2-methyl-2-butene is the major product, and 2-methyl-1-butene the minor one. 

Dimerization in concentrated sulfuric acid occurs mainly with those alkenes that fonn tertiary carbocations. In some cases reaction conditions can be developed that favor the formation of higher molecular-weight polymers. Because these reactions proceed by way of carbocation intermediates, the process is refened to as cationic polymerization. 

Experiments show that both alkenes and ketones undergo acid-catalyzed reactions. Alkene reactions usually require use of a very strong acid, H2SO4 or HX, while ketone reactions occur under milder conditions. This suggests that ketones are stronger bases, and that their conjugate acids enjoy special stabilization. 

The two transition states in Figs 8.5 and 8.6 correspond in principle to a metal-catalyzed carho-Diels-Alder reaction under normal electron-demand reaction conditions and a hetero-Diels-Alder reaction with inverse electron-demand of an en-one with an alkene. The calculations by Houk et al. [6] indicated that with the basis set used there were no significant difference in the reaction course. 

The Baylis-Hillman reaction is usually carried out under mild conditions (0°C or room temperature). The reaction time varies from a few minutes to even days. With the proper catalyst, good yields are possible. In the absence of an aldehyde or ketone as the electrophilic component, a dimerization of the activated alkene can take place under the influence of the catalyst, as also observed as a side reaction under the usual reaction conditions ... 

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