Amine formation condensation reaction

Fabric Softeners, Surfactants and Bleach Activators. Mono- and bisamidoamines and their imidazoline counterparts are formed by the condensation reaction of one or two moles of a monobasic fatty acid (typically stearic or oleic) or their methyl esters with one mole of a polyamine. Imidazoline formation requires that the ethyleneamine have at least one segment in which a secondary amine group Hes adjacent to a primary amine group. These amidoamines and imidazolines form the basis for a wide range of fabric softeners, surfactants, and emulsifiers. Commonly used amines are DETA, TETA, and DMAPA, although most of the polyethylene and polypropane polyamines can be used. 

Condensa.tlon, This term covers all processes, not previously iacluded ia other process definitions, where water or hydrogen chloride is eliminated ia a reaction involving the combination of two or more molecules. The important condensation reactions are nitrogen and sulfur heterocycle formation, amide formation from acid chlorides, formation of substituted diphenyl amines, and misceUaneous cyclizations. 

The long known catalyses of some ketone condensation reactions by secondary amines, can be postulated to have their basis in the reactions of enamine intermediates with ketones. The unsuitability of methyl ketones for azeotropic enamine formation is based on this phenomenon. Recent studies in cyclization reactions have added further support to this concept (354). 

Direct amide formation in aqueous solution between carboxylic acids and amines can occur and the rates are first order in the anion of the acid and the basic form of the amine (Eq. 9.12).23 The second-order rate constant is independent of the acidity of the medium. The condensation reaction of glycine to form di- and triglycine occurs in aqueous solution... 

Amines can react with various carbonyl compounds and their derivatives in aqueous media to give the corresponding imine derivatives. These reactions have been discussed in related chapters. The synthetically most useful reaction of this type is the formation of imines and imine derivatives from the condensation of amines with aldehydes and ketones. Water is an excellent solvent for such condensation reactions. For example, water was found to be an ideal solvent for a high-yield, fast preparation of easily hydrolyzable 2-pyrrolecarbaldimines.23 In the presence of Cu2+, the reaction afforded the corresponding Cu(II) chelates (Eq. 11.19). 

Enthalpies are often used to describe the energetics of bond formations. For example, when an amide forms through the condensation reaction between an ester and an amine, the new C-N bond, has an enthalpy of formation of -293 kj/mole. The higher the negative value for the bond enthalpy of formation, the stronger the bond. An even more useful concept is the enthalpy of a reaction. For any reaction, we can use the fact that enthalpy is a state function. A state function is one whose value is independent of the path traveled. So, no matter how we approach a chemical reaction, the enthalpy of the reaction is always the same. The enthalpy of... 

A fused OZT was obtained in the course of the reduction of vicinal azido-thiocarbonates via formation of the intermediate amine, which attacks the thiocarbonyl group (Scheme 37). The condensation reaction proved faster than the deoxygenation process for the synthesis of 2 -amino-2, 3 -dideoxyuridine50 or methyl 3-amino-4,6-0-benzylidene-3-deoxy-2-0-phenoxythiocarbonyl-a-L-talopyranoside.51... 

A condensation reaction joins two molecules and splits out a small molecule. The small molecule is usually water. The formation of a peptide bond is an example of a condensation reaction. The conditions necessary for a condensation reaction vary with the functional groups involved. In most cases, a catalyst will be present. The two most common catalysts are acids and enzymes. Two alcohols will condense to form an ether. A carboxylic acid condenses with an alcohol to form an ester. A carboxylic acid condenses with an amine to form an amide. 

The formation of the technically important 2 -hydroxy-3 -naphthoylanilines (Naphthol AS derivatives) is accomplished primarily by a condensation reaction between 2-hydroxy-3-naphthoic acid and an aromatic amine in the presence of phosphorus trichloride at 70 to 80°C. Appropriate reaction media are organic solvents, such as toluene or xylene. In stoichiometric terms, one mole of 2-hydroxy-3-naphthoic acid reacts with 0.4 to 0.5 moles of phosphorus trichloride. The solution is allowed to cool to room temperature, then neutralized with a sodium carbonate solution, and the Naphthol AS derivative is isolated by filtration. Mechanistically, the reaction is thought to proceed via the phosphoazo compound (11) ... 

The condensation reactions of diacylfurazans and furoxans also provide a convenient means of constructing fused heterocyclic systems incorporating the 1,2,5-oxadiazole unit. Representative examples include the conversion of diaroylfuroxans into furoxano[3,4-r/]pyradizines (61) using hydrazine <92JHC87>, and the formation of furazano[3,4-c]pyridines (62) with primary amines and DBU <79S687>. 

Indeed, there were those who described the azide coupling method as racemization-free. [15l However, this viewpoint proved to be overly optimistic. In 1970, Sieber reported that during a synthesis of calcitonin M by the azide method, significant epimerization occurred during two of the segment condensation steps in one of these reactions 40% of the epimerized product was observed. 16 There is a crucial detail in the experimental procedure here. The workers used tert-butyl nitrite to convert a peptide hydrazide into a peptide azide, but did not isolate the azide as was typical for research at that time. Instead, they neutralized the active intermediate in situ with DIPEA and added the amino segment for acylation. This demonstrates another important theme in the control of epimerization, the presence of a tertiary amine in the reaction mixture, even if only as a neutralization equivalent, can result in the formation of epimerized products. Indeed, most observations of racemization during... 

For the general condensation reaction of secondary amines with ketones to yield enamines, pyrrolidine, piperidine, or morpholine is generally used. The rate of enamine formation depends on the basicity of the secondary amine and the steric environment of the carbonyl group [12a, b, 29], Pyrrolidine, which is more basic, usually reacts faster than morpholine. The investigation of piperazine, a disecondary amine, has only been reported recently by Benzing [45, 46] and Sandler [41]. Surprisingly, the reaction of excess -butyraldehyde with piperazine in tetrahydrofuran at — 20°C to 0°C gave mainly AM-butenyl-piperazine [41] (see Eq. 13). 

The condensation of primary amines with aldehydes and ketones gives products known as imines which contain a C=N double bond. These compounds rapidly decompose or polymerize unless there is at least an aryl group bonded to the nitrogen or to the carbon atom. The latter imines are called Schiff bases, since their synthesis was first reported by Schiff.1 The most common method of obtaining a Schiff base (4) is straightforward, as indicated in the condensation reaction (1) between (1) and (2) with the formation of an intermediate hemiaminal (3). 

Schiff bases having two nitrogen atoms as donors may be derived either from condensation of dialdehydes and diketones with two molecules of an amine, or from reaction of diamines with aldehydes or ketones. In Section 20.1.2.1, it has been pointed out that coordination through the N atom may occur only under particular circumstances. However, in the case of diimines the formation of chelate rings stabilizes the metal-nitrogen bond. Thus, they can form both mono-41 and bis-chelate42 complexes. 

A great variety of aza macrocycle complexes have been formed by condensation reactions in the presence of a metal ion, often termed template reactions . The majority of such reactions have inline formation as the ring-closing step. Fourteen- and, to a lesser extent, sixteen-membered tetraaza macrocycles predominate, and nickel(II) and copper(II) are the most widely active metal ions. Only a selection of the more general types of reaction can be described here, and some closely related, but non metal-ion-promoted, reactions will be included for convenience. The reactions are classified according to the nature of the carbonyl and amine reactants. 

Possibly the most important condensation reaction is that between a carboxylic acid and an amine to give an amide. A great many methods are known by which this formal dehydration process may be carried out, almost all of which involve the two step sequence (i) activation of CO2H COX, where X is a leaving group and (ii) aminolysis of RCOX. Japanese workers have recently advocated the use of 2,2-dichloro-5-(2-phenylethyl)-4-trimethylsilyl-3-furanone (1, "DPTF") for carboxyl activation, and its use for peptide formation is illustrated by the representative conversion 2 —> 3. The byproduct formed from DPTF in these reactions is 5-(2-phenylethyl)-4-trimethylsilylfuran-2,3-dione. 

Formation of C—N bonds is frequently achieved by condensation reactions between amines and aldehydes or ketones. A typical nucleophilic addition is followed by elimination of water to give an imine or Schiff base [Figure 2.12(a)], Of almost equal importance is the reversal of this process, i.e. the hydrolysis of imines to amines and alde-hydes/ketones [Figure 2.12(b)], The imine so produced, or more likely its protonated form the... 

Mixing of an aminosilane with silica gel results in a fast adsorption, by hydrogen bonding of the amine to a surface hydroxyl group.2 After adsorption, the amine group can catalyze the condensation of the silicon side of the molecule with a surface silanol. Thus siloxane bonds with the surface may be formed in the absence of water.3,4 For other silanes the siloxane bond formation requires an initial hydrolysis of the ethoxy groups or the addition of an amine in the reaction mixture.5 This general reaction scheme has been presented in chapter 8. Here we will go into further detail on the types of interaction of the aminosilane with the silica surface and the characterization of the bonded silane species. 

Reymond and Chen88 have investigated the same set of antibodies for their ability to catalyze bimolecular aldol condensation reactions. The antibodies were assayed individually at pH 8.0 for the formation of aldol 111 from aldehyde 109 and acetone. None catalyzed the direct reaction, but in the presence of amine 110 three anti-52a and three anti-52b antibodies showed modest activity. In analogy with natural type I aldolase enzymes, the reaction is believed to occur by formation of an enamine from acetone and the amine, followed by rate-determining condensation of the enamine with the aldehyde. As in the previous example, the catalyst, which was characterized in detail, is not very efficient in absolute terms ( cat = 3 x 10-6 s 1 for the anti-52b antibody 72D4), but it is approximately 600 times more effective than amine alone. Moreover, the reactions with the antibody are stereoselective The enamine adds only to the si face of the aldehyde to give... 

The growth of the polymer chains (polymerization) may be described by a condensation reaction between the anhydride and amine functions as depicted here for the formation of a linear dimer ... 

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