Anhydrides acid-base chemistry

Acid amide herbicides Acid anhydrides Acid azine dyes Acid-base catalysis Acid-base chemistry Acid Black [1064-48-8]... 

This approach emphasizes the acid- and basic-anhydride aspects of acid-base chemistry, certainly useful though often neglected. The Lux-Flood base is a basic anhydride ... 

Consider the oxides MgO and CO2. For each oxide, tell whether it is a basic anhydride or an acidic anhydride. Write an equation for each to demonstrate its acid-base chemistry. 

Although there has been much discussion of the chemistry of cellulose acetylation, it is now generally agreed that the sulfuric acid is not a catalyst in the normal sense of the word, but rather that it reacts with the cellulose to form a sulfo ester. The acetic anhydride is the reactant that provides the acetate groups for esterification. The acetylation mixture consists of the output from the acetic anhydride recovery unit, being about 60 percent acetic acid and 40 percent acetic anhydride, in an amount 5-10 percent above the stoichiometric requirement, to which has been added 10-14 percent sulfuric acid based on the weight of cellulose used. The reaction is exothermic and requires that the heat be dissipated. 

Commercial petrochemical processes using syngas or carbon monoxide are based on four principal classes of reactions phosgenation, Reppe chemistry, hydroformylations, and Koch carbonylations. Phosgenation is a key step in the manufacture of polyurethanes, polycarbonates, and monoisocyanates. Reppe chemistry is the basis for acetic acid and acetic anhydride production as well as formic acid and methyl methacrylate synthesis. Hydroformylations utilize syngas in the oxo synthesis to make a wide variety of aldehydes and long-chain alcohols. The fourth class of reactions are Koch carbonylations. Koch carbonylations are used commercially to produce neo acids which are specialty products that serve markets similar to 0X0 alcohols. 

This chapter will discuss methods for the preparation of esters, acid chlorides, anhydrides, and amides from carboxylic acids, based on acyl substitution reactions. Acyl substitution reactions of carboxylic acid derivatives will include hydrolysis, interconversion of one acid derivative into another, and reactions with strong nucleophiles such as organometallic reagents. In addition, the chemistry of dicarboxylic acid derivatives will be discussed, as well as cyclic esters, amides, and anhydrides. Sulfonic acid derivatives will be introduced as well as sulfate esters and phosphate esters. Finally, nitriles will be shown to be acid derivatives by virtue of their reactivity. 

One of the most important aspects of the chemistry of oxides is their acid-base properties. Many oxides are basic or acidic anhydrides that is, they are compounds that are formed by the removal of water from a corresponding base or acid. A comparison of Figures 11.10 and 11.11 shows that the ionic oxides are usually basic anhydrides, whereas the covalent oxides are usually acidic anhydrides. Some oxides of the semimetals are amphoteric anhydrides, capable of acting as either an acid or a base, depending on the circumstances. Accordingly, if we list the oxides of a given period—say, the third— we find an orderly progression of their acid-base characteristics as shown below ... 

Besides halides and triflates, other electrophiles can be applied to Heck reactions. The first classical alternative was diazonium salts. Reactions proceed in the absence of phosphine (partly due to the fact that phosphines result in uncontrolled decomposition of the diazonium salt). The Heck reaction using these species can be useful in cases when mild conditions are required. Alternatively, iodonium salts behave in a similar manner to diazonium salts and show better tolerance to bases. " The reactions take place at ambient temperature and so are once again most useful in situations when mild conditions are required. Some main group metallie eompounds such as lead(IV) and thallium(III) have also been shown to undergo Heck-type chemistry and can be useful in specific cases. Of particular interest is the fact that acid chlorides and anhydrides can be employed in Heck chemistry, the use which was pioneered by Blaser and Spencer in 1982. " The process involves oxidative addition of palladium into the C-X bond followed by decarbonylation to yield the intermediate ArPdX species, de Vries has exploited this reaction, demonstrating the use of benzoic anhydride (105) as an effective arylating agent. ... 

Before providing an overview of the acid-base properties of metal oxide surfaces, a brief systematic description of their bulk and stmctural properties and surface chemistry is needed. According to basic inorganic chemistry concepts, the oxides of non-metals as well as the oxides of the metals in very high oxidation states are defined as acidic oxides and anhydrides, respectively, the oxides of metals as basic oxides, and the oxides having both acidic and basic characters are denoted as amphoteric. 

The Eastman acetic anhydride [108-24-7] process provides an extension of carbonylation chemistry to carboxyUc acid esters. The process is based on technology developed independendy in the 1970s by Eastman and Halcon SD. The Eastman acetic anhydride process involves carbonylation of methyl acetate [79-20-9] produced from coal-derived methanol and acetic acid [64-19-7]. 

The discovery that Lewis acids can promote Diels-Alder reactions has become a powerful tool in synthetic organic chemistry. Yates and Eaton [4] first reported the remarkable acceleration of the reactions of anthracene with maleic anhydride, 1,4-benzoquinone and dimethyl fumarate catalyzed by aluminum chloride. The presence of the Lewis-acid catalyst allows the cycloadditions to be carried out under mild conditions, reactions with low reactive dienes and dienophiles are made possible, and the stereoselectivity, regioselectivity and site selectivity of the cycloaddition reaction can be modified [5]. Consequently, increasing attention has been given to these catalysts in order to develop new regio- and stereoselective synthetic routes based on the Diels-Alder reaction. 

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