Amine and Carboxylic Ester

There are some side reactions that may occur when using EDC with proteins. In addition to reacting with carboxylates, EDC itself can form a stable complex with exposed sulfhydryl groups (Carraway and Triplett, 1970). Tyrosine residues can react with EDC, most likely through the phe-nolate ionized form of its side chain (Carraway and Koshland, 1968). The imidazolyl group of histidine may react with sulfo-NHS esters, resulting in an active carbonyl imidazole group which subsequently hydrolyzes (Cuatrecasas and Parikh, 1972). Finally, EDC may promote unwanted polymerization due to the usual abundance of both amines and carboxylates on protein molecules. 

Although more studies have been devoted to the mechanism of the acylation of amines with carboxylic esters than with other reagents, the mechanistic details are not yet entirely clear.898 In its broad outlines, the mechanism appears to be essentially BAC2.899 Under the normal basic conditions, the reaction is general base-catalyzed,900 indicating that a proton is being transferred in the rate-determining step and that two molecules of amine are in-... 

Attempts to react enol(ate)s of esters with aliphatic aldehydes are doomed as the aldehyde will simply condense with itself. If the ester is replaced by a malonate 60, there is so much enol(ate) from the (5-dicarbonyl compound that the reaction is good. This style of aldol reaction is often called a Knoevenagel reaction10 and needs only a buffered mixture of amine and carboxylic acid. The enol reacts with the aldehyde 61 in the usual way and enolisation of the product 62 usually means that dehydration occurs under the conditions of the reaction. 

Amino acids exhibit chemical reactions that are typical of both amines and carboxylic acids. For example, the acid can be converted to an ester by the Fischer method. This reaction requires the use of an excess of acid because one equivalent is needed to react with the amino group of the product. As another example, the amine can be converted to an amide by reaction with acetic anhydride. Additional examples are provided by the reactions that are used in the preparation of peptides from amino acids described in Section 26.7 ... 

In NPC, analytes retentions generally increase in the following sequence alkane < alkenes < aromatic hydrocarbons = chloroalkanes < sulfides < ethers < ketones = aldehyde = esters < alcohols < amides carboxylic acids [16]. The retention also depends to some extent on the... 

This reagent also reduces nitro, nitrile, and amide derivatives to amines, and carboxylic acids and anhydrides to alcohols. The yields of these reductions arc nearly quantitative. Esters and halobenzene derivatives are not reduced. 

Other phenol derivatives that are used to form the backbone of an epoxy resin include bisphenol E, bisphenol F, resorcinol, brominated bisphenols, and more highly functionalized molecules such as tetrakisphenylolethane. Alcohols, amines, and carboxylic acids may be combined with epichlorohydrin to give a range of diglycidyl ether based epoxy resins. Non-aromatic, commercially available epoxides are produced by peracid epoxidation of alkenes and dienes, such as vinyl cyclohexene and esters of cyclohexane carboxylic acids [23]. The chemical formulas for two common uncured polymers are shown below ... 

The C 0 bonds of ethers, acetals, and esters are cleaved with iodotrimethylsilane (eq (39)) [36]. Various halosilanes, silylamines, and N,0-bis(trimethylsilyl)acetamide are used not only for the protection of alcohols, amines, and carboxylic acids but also for the conversion of them to the volatilizable compounds for GC analysis (eq (40)) [37]. Silyltriflates act as silating agents as well as Lewis acids (eq (41)) [38]. 

Aminations of alkyl halides and carboxylic esters are performed with organotin amides, which are also employed for the preparation of enamines (eq (118)) [113],... 

Tetrahydrofuran polymerization is initiated by a nucleophilic attack of the free electrons on the oxygen atom in THF by tertiary oxonium salts, carbon-onium salts, and superacid esters. The polymer is formed in the propagation step by a SN2 mechanism. The termination step uses common nucleophiles such as water, alcohols, amines, and carboxylic acids. 

Rollman (4 3) synthesized a series of polymer-bonded metalloporphyrins. Functionalized tetraphenyIporphyrines were attached to porous polystyrene resins via amine, carbonyl and ester linkages and metal ions (Co,Ni,Cu,Zn) were then incorporated into the structures. The porphyrin polymers that contained both oxidation (Co) and proton-acceptor sites (amine and carboxylate groups) were effective catalysts for the oxidation of thiols to disulfides. When the catalyst was exposed to a refinery stream containing only 180 ppm mercaptan sulfur, deactivation occurred. Deactivation was thought to occur via oxidation of the porphyrins by free radicals known to be present in such catalytic systems. 

Just as simple esters and amides can be made by condensation reactions, polyesters such as Dacron and Mylar are made by reacting diols with dicarboxylic acids (Figure 13.15 A). Similarly, polyamides such as nylon form from amines and carboxylic acids. Starting from anhydrides and amines, polyimides can be formed. These structures tend to be extremely stable, and so are valuable in high temperature applications. 

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