Anhydrides from alkenes

Temperature (°K) From maleic anhydride From alkene From product... 

A co-solvent that is poorly miscible with ionic liquids but highly miscible with the products can be added in the separation step (after the reaction) to facilitate the product separation. The Pd-mediated FFeck coupling of aryl halides or benzoic anhydride with alkenes, for example, can be performed in [BMIM][PFg], the products being extracted with cyclohexane. In this case, water can also be used as an extraction solvent, to remove the salt by-products formed in the reaction [18]. From a practical point of view, the addition of a co-solvent can result in cross-contamination, and it has to be separated from the products in a supplementary step (distillation). More interestingly, unreacted organic reactants themselves (if they have nonpolar character) can be recycled to the separation step and can be used as the extractant co-solvent. 

As with carboxylic acids obtained by palladium hydroxycarbonylation, their derivatives esters, amides, anhydrides and acyl halides are synthesized from alkenes, CO and HX (X = OR, NR2 etc.). The Pd-catalyzed methoxycarbonylation is one of the most studied reactions among this type of catalyzed carbonylations and has been reviewed and included in reports of homogeneous catalysis.625, 26 The methoxycarbonylation has been applied to many different substrates to obtain intermediates in organic syntheses as well as specific products. For instance, the reaction has been applied for methoxycarbonylation of alkynes666 Highly efficient homogeneous Pd cationic catalysts have been reported and the methoxycarbonylation of alkynes has been used to develop economically attractive and environmentally benign process for the production of methyl... 

Onsager inverted snowball theory (Com.) relation to Smoluchowski equation in, 35 relaxation time by, 34 rotational diffusion and, 36 Ozone in the atmosphere, 108 alkene reactions with, 108 Crigee intermediate from, 108 molozonide from, 108 ethylene reaction with, 109 acetaldehyde effect on, 113 formic anhydride from, 110 sulfur dioxide effect on, 113 sulfuric acid aerosols from, 114 infrared detection of, 108 tetramethylethylene (TME) reaction with, 117... 

Unsaturated acyliutn ions generated from alkenic acids or anhydrides react with alkenes to produce cy-clopentenones (equation 4i).88.i78-i8i with cycloheptene the major products arise from ring contraction. Again, it is unclear whether these reactions proceed via direct cyclization of (76) or a Nazarov cycliza-tion. 

Of the compounds we have dealt with so far, alcohols also dissolve in sulfuric acid. Alcohols can be distinguished from alkenes, however, by the fact that alcohols give a negative test with bromine in carbon tetrachloride and a negative Baeyer test—so long as we are not misled by impurities. Primary and secondary alcohols are oxidized by chromic anhydride, CrOa, in aqueous sulfuric acid within two seconds, the clear orange solution turns blue-green and becomes opaque. 

Unsaturated acylium ions generated from alkenic acids or anhydrides react with alkenes to produce cy-clopentenones (equation with cycloheptene the major products arise from ring contraction. 

Keteniminium salts arc an attractive alternative to ketenes for cycloaddition with alkenes to give cyclobutanones31-32. Keteniminium salts do not dimerize and are more electrophilic than ketenes. They can be easily prepared by treatment of a dialkyl amide with 2,4,6-trimethylpyri-dine (collidine) and triflic anhydride in an inert solvent or from an a-haloenamine and a Lewis acid. The cycloadditions of keteniminium salts with alkenes are stepwise, not concerted, so that products from syn addition to the alkene are not always obtained stereoselectively. Of greater concern is the fact that the major product from alkenes which can form a tertiary carbocation is the Kriedel-Crafts product. The cycloaddition procedure is therefore limited to mono- and 1,2-disubstituted alkenes. 

Ozonolysis of the alkene of C frees the carboxylic acid of D which reacts with carbonyl diimidazole E (CDl) in a nucleophilic substitution at the carbonyl group, with the relatively stable imidazole anion as the leaving group. The product is an activated ester , like an anhydride, from which the anion of nitromethane displaces the second molecule of imidazole to give the product F. 

Nitric acidlacetic anhydride Nitrations with acetyl nitrate 2-Acetoxynitro compounds and 3-nitroalkenes from alkenes... 

What roles do inorganic catalysts play in the following manufacturing processes (a) production of aldehydes from alkenes, (b) polymerization of propene, (c) production of acetic anhydride,... 

Pyrano[3,4-b]indol-3-ones are the most useful equivalents of the indol-2,3-quinodimethane synthon which are currently available for synthetic application. These compounds can be synthesized readily from indole-3-acetic acids and carboxylic anhydrides[5,6]. On heating with electrophilic alkenes or alkynes, adducts are formed which undergo decarboxylation to 1,2-dihydro-carbazoles or carbazoles, respectively. 

Table 3. Preparation of 2-Chloro-l,l,l trifIuorO 2-alkenes from Aldehydes, Zinc, and Acetic Anhydride [63]...

In 1970, it was disclosed that it is possible to achieve the conversion of dimethylformamide cyclic acetals, prepared in one step from vicinal diols, into alkenes through thermolysis in the presence of acetic anhydride." In the context of 31, this two-step process performs admirably and furnishes the desired trans alkene 33 in an overall yield of 40 % from 29. In the event, when diol 31 is heated in the presence of V, V-dimethylforrnamide dimethyl acetal, cyclic dimethylformamide acetal 32 forms. When this substance is heated further in the presence of acetic anhydride, an elimination reaction takes place to give trans olefin 33. Although the mechanism for the elimination step was not established, it was demonstrated in the original report that acetic acid, yV, V-dimethylacetamide, and carbon dioxide are produced in addition to the alkene product."... 

Alkenes can add to double bonds in a reaction different from those discussed in 15-19, which, however, is still formally the addition of RH to a double bond. This is called the ene reaction or the ene synthesis For the reaction to proceed without a catalyst, one of the components must be a reactive dienophile (see 15-58 for a definition of this word) such as maleic anhydride, but the other (which supplies the hydrogen) may be a simple alkene such as propene. Cyclopropene has also been used. ° The reaction is compatible with a variety of functional groups that can be appended to the ene and dienophile. N,N-Diallyl amides give an ene cyclization. 

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