Nitrogenous Bases with Carboxylic Acids

Nitrogenous Bases with Carboxylic Acids Diels-Alder Adducts 

A corrosion inhibitor with excellent film-forming and film-persistency characteristics is produced by first reacting Cig unsaturated fatty acids with maleic anhydride or fumaiic acid to produce the fatty acid Diels-Alder adduct or the fatty acid-ene reaction product [31]. This reaction product is further reacted in a condensation or hydrolyzation reaction with a polyalcohol to form an acid-anhydride ester corrosion inhibitor. The ester may be reacted with amines, metal hydroxides, metal oxides, ammonia, and combinations thereof to neutralize the ester. Surfactants may be added to tailor the inhibitor formulation to meet the specific needs of the user, that is, the corrosion inhibitor may be formulated to produce an oil-soluble, highly water-dispersible corrosion inhibitor or an oil-dispersible, water-soluble corrosion inhibitor. Suitable carrier solvents may be used as needed to disperse the corrosion inhibitor formulation. 

Similarly, a salt of an ethoxylated amine and a reaction product of an alcohol and a fatty acid maleic anhydride adduct produced by a reaction between maleic anhydride and an unsaturated fatty acid has been described [511]. 

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The most extensive studies of solid-state proton transfer have been undertaken on two types of systems - complexes (salts and cocrystals) of carboxylic acid with nitrogen bases, and carboxylic acid dimers. In the first case, the proton transfer occurs along the unsymmetrical H N, and in the other along a (usually) symmetrical O- -H- -O bond. As both these types of proton transfer can (in principle) also lead to tautomerization, we shall briefly expound the main finds of these studies. 

The present procedure is based on the method published by Fu, Birnbaum and Greenstein. The yields are increased by the very slow addition of an aqueous solution of sodium nitrite to the reaction mixture as well as by a nwdified work-up procedure, i.e, careful removal of nitrogen oxides and the final decomposition of their adducts with carboxylic acids by buffering with sodium carbonate. 

A process based on the use of an immobilized C. antarctica lipase (Novozym 435) has been developed in order to perform direct esterification of natural alcohols with carboxylic acids in a solvent-free system. Based on the system represented in Figure 11.2, the process had to overcome the problem of recycling the nitrogen, once the reaction was over. 

Heating 1,2,4-benzotriazines (128) with bases gives aniline, nitrogen and a carboxylic acid (60G1H3). 2-Substituted l,2,4-benzotriazin-3-ones (116) with potassium hydroxide in... 

Under suitable conditions, amide formation can take place between an amine and a carboxylic acid, an acyl halide, or an acid anhydride. Along with ammonia, primary and secondary amines yield amides with carboxylic acids or derivatives. Table 33.2 relates the nitrogen base with the amide class (based on the number of alkyl or aryl groups on the nitrogen of the amide). 

Due to its wide application in peptide synthesis, 1-hydroxybenzotriazole 849 is the most commonly used benzo-triazole derivative with hundreds of references in Chemical Abstracts each year. The utility of 849 (Scheme 183) rests essentially on its readiness to form esters with carboxylic acids in the presence of dehydrating agents. l-Hydroxy-7-azabenzotriazole 847 is also used in peptide coupling reactions, especially with sterically encumbered amines. The faster reaction rates and reduced racemization is attributed to base catalysis by the adjacent pyridine nitrogen 848 during the coupling reactions. 

A well-known purine is the central nervous stimulant (CNS) caffeine (9.134), which is found in coffee and chocolate. Its synthesis (Scheme 9.77) illustrates the technique of forming the fused imidazole ring of purines. It was noted in Chapter 4 that diaminobenzenes reacted with carboxylic acids or esters to form benzimidazoles this process is known as the Phillips synthesis. It is this reaction that is used to fuse imidazoles to pyrimidines. Here, the process is known as the Traube purine synthesis. The initially formed purine is tri-methylated with methyl chloride and base to form caffeine (9.134). Note that under these conditions it is the 7-nitrogen that is methylated. 

Three generations of latices as characterized by the type of surfactant used in manufacture have been defined (53). The first generation includes latices made with conventional (/) anionic surfactants like fatty acid soaps, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates (54) (2) nonionic surfactants like poly(ethylene oxide) or poly(vinyl alcohol) used to improve freeze—thaw and shear stabiUty and (J) cationic surfactants like amines, nitriles, and other nitrogen bases, rarely used because of incompatibiUty problems. Portiand cement latex modifiers are one example where cationic surfactants are used. Anionic surfactants yield smaller particles than nonionic surfactants (55). Often a combination of anionic surfactants or anionic and nonionic surfactants are used to provide improved stabiUty. The stabilizing abiUty of anionic fatty acid soaps diminishes at lower pH as the soaps revert to their acids. First-generation latices also suffer from the presence of soap on the polymer particles at the end of the polymerization. Steam and vacuum stripping methods are often used to remove the soap and unreacted monomer from the final product (56). 

Conversion of Amides into Carboxylic Acids Hydrolysis Amides undergo hydrolysis to yield carboxylic acids plus ammonia or an amine on heating in either aqueous acid or aqueous base. The conditions required for amide hydrolysis are more severe than those required for the hydrolysis of add chlorides or esters but the mechanisms are similar. Acidic hydrolysis reaction occurs by nucleophilic addition of water to the protonated amide, followed by transfer of a proton from oxygen to nitrogen to make the nitrogen a better leaving group and subsequent elimination. The steps are reversible, with the equilibrium shifted toward product by protonation of NH3 in the final step. 

Positive photoresists, by contrast, are based on water-soluble novolak resins with naphthalene diazoquinone sulfonate (NDS) as the photosensi-tiser. On photolysis the NDS causes a rearrangement in the polymer to yield nitrogen gas plus an indene carboxylic acid. This latter functional group considerably increases the solubility of the polymer, hence solubilising those areas of the polymer that had been exposed to light. 

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