Amides, from acid derivatives types

Ladenburg said Gerhardt and Chiozza derived the acid amides from a mixed type NH + H 0, but Japp said that they (1854) represent them as substituted ammonium hydroxide, e.g. succinamic acid is the hydrate of an ammonium in which 2 atoms of hydrogen are replaced by their equivalent of succinyl ... 

Substances of this type have hitherto received little attention. One of the reasons appears to be the limited possibilities of preparation. The only known method of preparation, described by Woolley et ai./ proceeds from the derivatives of 4-aminoimidazole-5-carboxylic acid. The amide of this acid (142) is treated with nitrous acid to yield 4-hydroxyimidazo [4,5-d]-i -triazine (2-azahypoxanthine) (143), the amidine (144) yielding the 4-amino derivative (2-azaadenine) (145) under the same conditions. 2-Azahypoxanthine was probably obtained in the same way earlier but was not identified. ... 

Of the methods used for converting amides to aldehydes the one utilizing lithium triethoxyaluminohydride is most universal, can be applied to many types of amides and gives highest yields. In this way it parallels other methods for the preparation of aldehydes from acids or their derivatives (p. 148). 

There are several types of chiral derivatizing reagents commonly used depending on the functional group involved. For amines, the formation of an amide from reaction with an acyl halide [147,148], chloroformate reaction to form a carbamate [149], and reaction with isocyanate to form the corresponding urea are common reactions [150]. Carboxyl groups can be effectively esterified with chiral alcohols [151-153]. Isocynates have been used as reagents for enantiomer separation of amino acids, iV-methylamino acids, and 3-hydroxy acids [154]. In addition to the above-mentioned reactions, many others have been used in the formation of derivatives for use on a variety of packed and capillary columns. For a more comprehensive list, refer to References 155-159. 

The manufacture of the large variety of polyamides (commonly referred to as nylons) occurs through polycondensation of amino carboxylic acids (or functional derivatives of them, e.g. lactams) and from diamines and dicarboxylic acids. Labeling the amino groups with A and the carboxyl groups with B allows differentiation of the different chemical structures between the two types AB (from amino carboxylic acids) and AA-BB (from diamines and dicarboxylic acids). The number of C atoms in the monomers acts as a code number for the identification of the polyamides. The polycaprolactam manufactured from caprolactam (type AB) is then called polyamide 6 (PA 6). The number of carbon atoms in the diamine is given first for type AA-BB followed by the number of atoms in the dicarboxylic acid, e.g. PA 66 for polyhexamethylenedia-dipic amide from hexamethylenediamine and adipic acid. For copolymers the components are separated by a slash, e.g. PA 66/6 (90 10) is a copolymer composed of 90 parts PA 66 and 10 parts PA 6. 

Similarly, mercury-nitrogen compounds may resemble either salts or acid-base type adducts. Saltlike compounds of this type include the familiar white amino compound, Cl—Hg—NH2, and analogous compounds formed from organic amines, for example, Cl—Hg—NHCH3 organic amides and imides also are known to form mercury derivatives, descriptions of which appear in more comprehensive works. 

Amides and Imides, Orgonlc. An organic amide is a compt contg the monovalent -CO.NH, radical (eg, acetamide CHj.CO.NH], oxamide HjN.CO.CO.NH], benzamide C(H, CONH], etc). An organic imide is a compd of the general formula R NH in which R is an acyl radical such as CH,CO—. Another type of imide is a compd derived from acid anhydrides in which one oxygen is reolaced... 

The use of ethoxycarbonyl-protected amino acids as well as methoxycarbonyl derivatives for peptide synthesis was reported in 1903 by Fischer, although the protecting groups in related peptide derivatives could not be cleaved without affecting the peptide bonds,f since urethanes derived from aliphatic primary alcohols are about as stable as the amide bond. Thus, this type of carbamate can only be used for reversible protection of amino groups, at least in... 

There have been two major approaches towards achieving selective reduction of carboxylic acid derivatives to aldehydes (or derivatives) by hydrides. Firstly, hydride reagents themselves have been modified as, for example, sodium borohydride and sodium cyanoborohydride. Sometimes these modifications have led to finely tuned reducing agents, as with the dimethyl sulfide adduct of thexylbromoborane (see later). Secondly, the type of carboxylic acid derivative has been modified for the optimum yield of aldehyde. For example, amides have been made from an assortment of amines in efforts to maximize yields of aldehyde. Best yields of aldehydes are obtained usually by a combination of modified hydride reagent with a modified carboxylic acid derivative. 

Most of the local anesthetic agents in current medical use are of the.se types (Tables 20-2 and 20-. ). The benzoic acid derivatives are esters that were developed from cocaine, while the aniline derivatives are amides developed ftom iso-gramine. Both types of derivative have chemical structutes that normally have the general format ... 

As mentioned before, any substance in the preceding list can be readily transformed into a substance to its right that is, the more reactive derivative types (acyl halides) can be directly transformed into less reactive derivative types (esters and amides). Every type can be made directly from carboxylic acid (hence the name of this subsection) but carboxylic acid can also be made from any of these types. 

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