Halides carboxylic acids

Acid chlorides are commonly made from acids by exchange with an excess of thionyl chloride or oxalyl chloride. Brief heating gives the acid chloride plus gaseous by-products (Eq. 6.14) [20]. Phosphorus tri- and pentachlorides are used similarly. The acid bromides are made with phosphorus tribromide or oxalyl bromide [20]. 

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Diaryl sulfones can be formed by treatment of aromatic compounds with aryl sulfonyl chlorides and a Friedel-Crafts catalyst. This reaction is analogous to Friedel-Crafts acylation with carboxylic acid halides (11-14). In a better procedure, the aromatic compound is treated with an aryl sulfonic acid and P2O5 in polypho-sphoric acid. Still another method uses an arylsulfonic trifluoromethanesulfonic anhydride (ArS020S02CF3) (generated in situ from ArS02Br and CF3S03Ag) without a catalyst. ... 

Carboxylic acid fluorides, intermediates in the pathway to trifluoromethyl derivatives, are readily formed in reactions of all types of carboxylic acids with sulfur tetrafluoride derivatives (see Section 8.2.4.). Little attention has been paid to fluorination of other carboxylic acid halides. Aroyl chlorides are converted into aroyl fluorides by treatment with sulfur tetrafluoride, e.g. formation of l,41 or to (trifluoromethyl)arenes, e.g. 2 and 3. in the presence of hydrogen fluoride.45 Chlorination of the aromatic ring occurs in some cases.41... 

Replacement of Halogens by Fluorine in Carboxylic Acid Halides... 

From Boron Halides. Using boron halides is not economically desirable because boron halides are made from boric acid. However, this method does provide a convenient laboratory synthesis of boric acid esters. The esterification of boron halides with alcohol is analogous to the classical conversion of carboxylic acid halides to carboxylic esters. Simple mixing of the reactants at room temperature or below in a solvent such as methylene chloride, chloroform, pentane, etc, yields hydrogen halide and the borate in high yield. 

This chapter deals with the kinetics and mechanisms of the hydrolysis of carboxylic acid derivatives of general formula RCOX. These include carboxylic acid halides, amides, and anhydrides with small sections on carboxylic acid cyanides etc. Many recent developments in this field have been made with acid derivatives in which R is not an aliphatic or aromatic group, for example, carbamic acid derivatives, and these are reported where relevant, as are reactions such as ethanolysis, aminolysis, etc. where they throw light on the mechanisms of hydrolysis. 

The acylating reagents commonly used are carboxylic acid halides, RCOC1, anhydrides, (RC0)20, or the acid itself, RC02H. A strong proton or other Lewis-acid catalyst is essential. The catalyst functions to generate the acyl cation ... 

Vinyl Substitutions with Carboxylic Acid Halides, Aryl Sulflnates and Arylsulfonyl Chlorides 856... 

Based on their chemical structure, the organic chemicals were divided into a number of categories alkanes, alkenes, amines, aromatic hydrocarbons, benzenes, carboxylic acids, halides, phenols, and sulfonic acid. Linear regression analysis has been applied using the method of least-squares fit. Each correlation required at least three datapoints, and the parameters chosen were important to ensure comparable experimental conditions. Most vital parameters in normalizing oxidation rate constants for QSAR analysis are the overall liquid volume used in the treatment system, the source of UV light, reactor type, specific data on substrate concentration, temperature, and pH of the solution during the experiment. 

This latter thought has an important consequence if compounds with C=0 double bonds are sorted in decreasing order of resonance stabilization of their C=0 group they are at the same time sorted according to their increasing propensity to enolization. So as the resonance stabilization of the C=0 double bond decreases from 22 kcal/mol to somewhere near zero in the order carboxylic acid amide > carboxylic acid ester/carboxylic acid > ketone > aldehyde > carboxylic acid chloride/-bromide, the enol content increases in this same order (Figure 12.2). These circumstances immediately explain why no enol reactions whatsoever are known of carboxylic acid amides, virtually none of normal carboxylic acid esters/carboxylic acids, but are commonly encountered with ketones, aldehydes and carboxylic acid halides. 

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