Amides acidity and

Esterification, Amidation, and Acid Chloride Formation. Amino acids undergo these common reactions of the carboxyl group with due regard for the need for A/-protection. 

Carboxylic Acid Group. Sorbic acid undergoes the normal acid reactions forming salts, esters, amides, and acid chlorides. Industrially, the most important compound is the potassium salt because of stabiUty and high water solubiUty. Sodium sorbate [7757-81-5] (E,E form [42788-83-0]) is less stable and not commercially available. The calcium salt [7492-55-9] which has limited solubiUty, has use in packaging (qv) materials. 

In the case of esters, carboxylate anions, amides, and acid chlorides, the tetrahedral adduct may undergo elimination. The elimination forms a ketone, permitting a second addition step to occur. The rate at which breakdown of the tetrahedral adduct occurs is a function of the reactivity of the heteroatom substituent as a leaving group. The order of stability of the... 

Based on ether carboxylic acids it is possible in principle to make the same derivatives as with fatty acids, such as esters, amides, and acid chlorides. The hydrophilic chain in the molecule may confer special properties in comparison with the fatty acid derivatives. 

Both cis- and trans-chrysanthemic nitriles and amides were resolved into highly enantiopure amides and acids by Rhodococcus sp. whole cells [85]. The overall enantioselectivity of reactions of nitriles originated from the combined effects of a higher (lJ )-selective amidase and a (IJ )-selective nitrile hydratase (Figure 6.29). Chrysanthemic acids are related to constituents of pyrethrum flowers and insecticides. 

Each functional group of an amino acid exhibits all of its characteristic chemical reactions. For carboxylic acid groups, these reactions include the formation of esters, amides, and acid anhydrides for amino groups, acylation, amidation, and esterification and for —OH and —SH groups, oxidation and esterification. The most important reaction of amino acids is the formation of a peptide bond (shaded blue). 

Dynamic Kinetic Resolution for the Synthesis of Esters, Amides and Acids Using Lipases... 

Since chains of nylons having an even number of carbon atoms between the amide and acid groups pack better, some of their melting points are higher than comparable nylons with odd numbers of carbon atoms (Table 4.7). Further, the melting points decrease and the water resistance increases as the number of methylene groups between the amide and acid groups increases. 

Some studies seeking preferred conditions for this reaction have been made. Optimum yields are obtained when the amount of water present is appreciable, and it was noted that the rate of hydrogen evolution increases with increasing water content. A 75% formic acid system appears generally preferred. Under the reaction conditions examined by the submitters, olefins, ketones, esters, amides, and acids are inert, but nitro compounds are reduced to the formamide derivative. 

The zinc alkoxides of syn- or /7-3-(/3-hydroxyacyl)oxazolidin-2-ones underwent stereoselective rearrangement under mild conditions to afford syn- or /7-3-(2-hydroxyethyl)tetrahydro-l,3-oxazine-2,4-diones in good yields. The procedure was utilized in the synthesis of ( )-trisubstituted 0 ,/3-unsaturated amides and acids <2005OBC2976, 2005SL1090>. 

However, detection of the tetrahedral intermediate in the addition of a nucleophile to an ester, acid halide, amide or anhydride must be adduced from kinetic evidence, in particular the evidence of oxygen exchange in such an intermediate. Such tracer work has established the presence of symmetrical addition compounds in the hydrolysis of esters23, amides and acid chlorides24. Since the attempts to detect such intermediates have played a considerable part in the development of hydrolysis studies, it is worthwhile considering this point in some detail. 

Figure 10.5. Hofmann and Curtius degradation of support-bound amides and acids.

Oxidation of ,/l-unsaluraled nitriles, amide, and acids with pentachlorohydroxo-platinate(IV) in alkaline solution is first order in the oxidant, reductant and alkali. The oxidation takes place with an inner-sphere mechanism. A tentative mechanism involving a two-electron oxidation has been suggested and the activation parameters have been calculated.102... 

The reaction under consideration is typified by the formation of saturated carboxylic acids from olefins, carbon monoxide, and water. Other compounds have been used in place of olefins (alkyl halides, alcohols), and besides water, a variety of compounds containing active hydrogen may be employed. Thus, alcohols, thiols, amines, and acids give rise to esters, thio-esters, amides, and acid anhydrides, respectively (15). If the olefin and the active hydrogen are part of the same molecule, three or four atoms apart, cyclizations may occur to produce lactones, lactams, imides, etc. The cyclizations are formally equivalent to carbonylations, however, and will be considered later. 

Itraconazole (Sporanox, 13.11) is an approved antifungal (Figure 13.5). The drug has a log P value of 6.5, so its very low aqueous solubility is no surprise. Early efforts to improve the properties of itraconazole focused on making an acid salt. Because of the very weak basicity of all the nitrogens in itraconazole, the idea of an acid salt was soon abandoned. Cocrystals were then explored. A library of amides and acids were... 

Comparing the structure of the monomer with that of the polymer as shown in Table I, we see that the polymerization of the / -carboxy-methyl caprolactam must involve isomerization of the monomer ring system. This isomerization may be described by several possible processes, all of which are characterized by reaction between the amide and acid group of the / -carboxymethyl caprolactam. Based upon the results of our studies on the structure of this polymer (5) we may eliminate confidently those processes according to which the formation of the glutarimide moiety results either by intrachain cyclization or by trans-cyclization of certain intermediate polymer structures. The former would involve a polymer formed by a conventional ring opening polymerization ... 

Cyanide hydratase and cyanide dihydratase belongs to the nitrilase branch of nitrilase superfamily, using HCN as the only efficient substrate and producing amide and acid products, respectively. Microorganisms appear in fact to have evolved separate metabolic pathways for the hydrolysis of inorganic cyanide. Thus, most nitrilases (as well as nitrile hydratases) till now investigated do not display activity... 

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