Reaction Involving Acid Anhydrides

Acid anhydrides react with alcohols to form esters and carboxylic acids. A general equation representing this type of reaction is shown in the next sample reaction. 

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Although the majority of studies in this area involve five-membered ring cyclic anhydrides, a few pyrolytic reactions involving acyclic anhydrides have been reported. Thus, for example, FVP of 278 gives the alkylideneketene 279 with loss of trifluoroacetic acid142, while at 650 °C 280 loses both trifluoroacetic acid and cyclopentadiene to afford the indenylideneketene 281, which cyclizes by way of 282 to give 283143. FVP of... 

Like phenolphthalein, xanthene dyes are prepared in a condensation reaction involving phthalic anhydride. However, resorcinol is employed instead of phenol. The simplest representative of this family is C.I. Acid Yellow 73 (fluorescein), which is made via the sequence of steps shown in Fig. 13.109. Similarly, C.I. Acid Red 92 is made by the condensation of tetrachlorophthalic anhydride and resorcinol followed by bromination. 

Acid rain consists of acids formed by the reaction of acid anhydrides and water. List four acid anhydrides commonly involved in acid rain formation and the sources of each. 

High-yield aq lations of hindered alcohols are of considerable current interest [ 142 ]. Older methods for such reactions involve acetic anhydride, acetyl chloride, and the use of -butyUithium in the presence of an acid chloride. More contemporary approaches include catalysts such as DMAP [143], BujP [144], and 4-pyrrohdinopyridine (PPY),with DMAP being the most popular. Although both BujP and DMAP provide good yields of acylated alcohols, these catalysts have disadvantages. For example, BU3P has a low flash point and DMAP is fairly toxic. 

About half of the wodd production comes from methanol carbonylation and about one-third from acetaldehyde oxidation. Another tenth of the wodd capacity can be attributed to butane—naphtha Hquid-phase oxidation. Appreciable quantities of acetic acid are recovered from reactions involving peracetic acid. Precise statistics on acetic acid production are compHcated by recycling of acid from cellulose acetate and poly(vinyl alcohol) production. Acetic acid that is by-product from peracetic acid [79-21-0] is normally designated as virgin acid, yet acid from hydrolysis of cellulose acetate or poly(vinyl acetate) is designated recycle acid. Indeterrninate quantities of acetic acid are coproduced with acetic anhydride from coal-based carbon monoxide and unknown amounts are bartered or exchanged between corporations as a device to lessen transport costs. 

It was found inadvisable to use more than four molecules of form-amide [ (47) when R = H] per molecule of anthranilic acid and the condensation produces best results when the mixture is heated at 120 -130°C for 2 hr followed by further heating at 170°-180 C for 2 hr. Other variants of this reaction involve the use of ammonium o-acylaminobenzoates, anthranilic acid in the presence of nitriles and acetic anhydride, o-acetamidonitrile with acetic anhydride or hydrogen peroxide, anthranilic esters and aliphatic or aromatic amides or amidines, isatoic anhydride with amides or amidines, and anthranilic esters with aryl iminochlorides in acetoned The mechanism proposed by Bogert and Gotthelf has had experimental supporR and is represented in Scheme 12. 

The course of the reaction may involve either the acylation of the ketone to a -diketonic intermediate following thereupon the pathway in Section II, C, 2, a, or alternatively the condensation of two moles of ketone to yield an intermediate dypnone which then undergoes acylation following the pathway in Section II,C, l,a. Dilthey and Fischer thought the first alternative more plausible, on the basis of reaction yields, and this lead them to explore the pathway in Section II,C,2,a. Schneider and Ross and Diels and Alder believed that the second alternative operates. Both views are plausible since acylations of methyl ketones to S-diketones are known to take place in the conditions of this reaction, and dypnone ha.s been isolated from acetophenone on treatment with Friedel-Crafts catalysts, in the absence of an acid anhydride or chloride (an excess of catalyst... 

Blends based on polyolefins have been compatibilized by reactive extrusion where functionalized polyolefins are used to form copolymers that bridge the phases. Maleic anhydride modified polyolefins and acrylic acid modified polyolefins are the commonly used modified polymers used as the compatibilizer in polyolefin-polyamide systems. The chemical reaction involved in the formation of block copolymers by the reaction of the amine end group on nylon and anhydride groups or carboxylic groups on modified polyolefins is shown in Scheme 1. 

Tetrahydrocarbazoles have been prepared in one-flask syntheses from indoles, ketones and maleic anhydride, with acid catalysis. The reactions involve a condensation of the indole 121 with the ketone or aldehyde, followed by in situ trapping of the vinylindole 122 with maleic anhydride to afford tetrahydrocarbazoles 123 after double bond isomerization <96T4555>. 

This reaction involves formation of a mixed anhydride-chloride of oxalic acid, which then decomposes, generating both C02 and CO. 

Highly reactive mixed anhydrides can also promote acylation. Phenylacetic acid reacts with alkenes to give 2-tetralones in TFAA-H3P04.55 This reaction involves an intramolecular Friedel-Crafts alkylation subsequent to the acylation. 

Friedel-Crafts acylation generally involves reaction of an acyl halide and Lewis acid such as A1C13, SbF5, or BF3. Bismuth(III) triflate is also a very active acylation catalyst.46 Acid anhydrides can also be used in some cases. For example, a combination... 

Catalysis in Transacylation Reactions. The principal objective of the study was to evaluate 4 as an effective organic soluble lipophilic catalyst for transacylation reactions of carboxylic and phosphoric acid derivatives in aqueous and two-phase aqueous-organic solvent media. Indeed 4 catalyzes the conversion of benzoyl chloride to benzoic anhydride in well-stirred suspensions of CH2CI2 and 1.0 M aqueous NaHCC>3 (Equations 1-3). The results are summarized in Table 1 where yields of isolated acid, anhydride and recovered acid chloride are reported. The reaction is believed to involve formation of the poly(benzoyloxypyridinium) ion intermediate (5) in the organic phase (Equation 1) and 5 then quickly reacts with bicarbonate ion and/or hydroxide ion at the interphase to form benzoate ion (Equation 2 and 3). Apparently most of the benzoate ion is trapped by additional 5 in the organic layer or at the interphase to produce benzoic anhydride (Equation 4), an example of normal phase-... 

Alternative paths for decomposition of the metal carboxylate can lead to ketones, acid anhydrides, esters, acid fluorides (1,11,22,68,77,78), and various coupling products (21,77,78), and aspects of these reactions have been reviewed (1,11). Competition from these routes is often substantial when thermal decomposition is carried out in the absence of a solvent (Section III,D), and their formation is attributable to homolytic pathways (11,21,77,78). Other alternative paths are reductive elimination rather than metal-carbon bond formation [Eq. (36)] (Section III,B) and formation of metal-oxygen rather than metal-carbon bonded compounds [e.g., Eqs. (107) (119) and (108) (120). Reactions (36) and (108) are reversible, and C02 activation (116) is involved in the reverse reactions (48,120). 

This study was prompted by a report that phthalimidoacetic acid (R = CH2C02H, see also Scheme 4.11, vide supra) could be synthesized by the reaction of phthalic anhydride with glycine in the absence of solvent, which involves the reaction between two solids [56], However, in this study [45], it was established that the synthesis of phthalimides under solvent-free reactions requires at least one liquid reactant in order to occur. This was possible when reacting a liquid amine (e.g. R = CH2Ph) or a solid with a sufficiently low melting point to melt rapidly under MW (e.g. R = (CH2)6OH, m.p. 56-58). In these cases, the reaction temperature was typically over 135 °C after 2 or 3 min of MW heating resulting in dissolution of phthalic anhydride in the molten... 

Respiratory hypersensitivity is an adverse reaction in the respiratory tract driven by immune mechanisms such as IgE antibody mediated allergic responses. Other less well understood mechanisms that have an immune component are also involved in respiratory hypersensitivity. OA is one outcome of respiratory hypersensitivity. Respiratory hypersensitivity and OA to proteins are primarily mediated by IgE antibody with subsequent inflammatory cell infiltrates. This same mechanism is responsible for OA to specific LMW chemicals such as the acid anhydrides and platinum salts. However, the role for IgE mediated responses in OA to other LMW chemicals such as the isocyanates and plicatic acid is poorly defined and other mechanisms may be responsible. 

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