Oxamidic ester

Poly(parabanic acids) are close relatives of poly(hydantoins). They are also known as 2,4,5-triketoimidazolidine polymers. They can be produced by several processes, for example, from oxamidic esters and (capped) isocyanates ... 

Oxamide differs from most aliphatic acid amides in being almost insoluble in water, and therefore can be readily prepared from the diethyl ester by Method 2(a). Place a mixture of 5 ml. of concentrated [d o-88o) ammonia solution and 5 ml. of water in a 25 ml. conical flask, for which a welTfitting cork is available. (The large excess of... 

Almost insoluble in cold water. Higher alcohols (including benzyl alcohol), higher phenols (e.g., naphthols), metaformaldehyde, paraldehyde, aromatic aldehydes, higher ketones (including acetophenone), aromatic acids, most esters, ethers, oxamide and domatic amides, sulphonamides, aromatic imides, aromatic nitriles, aromatic acid anhydrides, aromatic acid chlorides, sulphonyl chlorides, starch, aromatic amines, anilides, tyrosine, cystine, nitrocompounds, uric acid, halogeno-hydrocarbons, hydrocarbons. 

Of the common esters, methyl oxalate (solid, m.p. 54°) and ethyl oxalate (liquid) give amides almost immediately upon shaking with concentrated ammonia solution. The resulting oxamide, m.p. 417°, is valueless as a derivative. The esters may, however, be easily hydrolysed and identified as above. 

The majority of [4+1] methods has been extensively reviewed in CHEC(1984) and CHEC-II(1996) and includes conversion of aliphatic 1,2-diamines, 1,2-diimines and dioximes, cyanogen, 2-aminoacetamides, 2-aminoacetamidine, ethyl oxamidates, 2-cyano-2-oximino acetamides, and cyanoformamide and its esters. Below, the recent developments over the last decade are highlighted. 

In 1965, Rauhut et al. [73] reviewed the oxalyl chloride CL system and showed that oxalyl esters could be used for this system instead of oxalyl chloride. Since then, they synthesized a number of oxalates including oxamides and established a new, potent luminescent system, namely the peroxyoxalate CL (PO CL) system. Much work has been carried out to synthesize suitable oxalic compounds. The first study dealing with different reagents was published in 1967 by Rauhut et al. [98] for the American Cyanamid Company with the purpose of developing... 

The direct conversion of alcohols and amines into carbamate esters by oxidative carbonylation is also an attractive process from an industrial point of view, since carbamates are useful intermediates for the production of polyurethanes. Many efforts have, therefore, been devoted to the development of efficient catalysts able to operate under relatively mild conditions. The reaction, when applied to amino alcohols, allows a convenient synthesis of cyclic urethanes. Several transition metal complexes, based on Pd [218— 239], Cu [240-242], Au [243,244], Os [245], Rh [237,238,246,247], Co [248], Mn [249], Ru [224,250-252], Pt [238] are able to promote the process. The formation of ureas, oxamates, or oxamides as byproducts can in some cases lower the selectivity towards carbamates. 

Under appropriate conditions, alcohols and amines can undergo an oxidative double carbonylation process, with formation of oxalate esters (Eq. 34), oxamate esters (Eq. 35) or oxamides (Eq. 36). These reactions are usually catalyzed by Pd(II) species and take place trough the intermediate formation of bis(alkoxycarbonyl)palladium, (alkoxycarbonyl)(carbamoyl)palladium or bis(carbamoyl)palladium complexes, as shown in Scheme 29 (NuH, Nu H = alcohol or amine) [227,231,267,293-300]. 

Diisopropenyl oxalate results from the addition of oxalic acid to propyne. The ester condenses with all types of amines under ruthenium catalysis to yield the corresponding ester amides or oxamides, depending on the amounts of amines used (equation 104)327. 

A number of secondary high explosives containing both nitramine and nitrate ester functionality have been reported. Aliphatic examples include A-nitrodiethanolamine dinitrate (DINA) (110), prepared from the nitration of diethanolamine with nitric acid-acetic anhydride in the presence of zinc chloride,and A,A -dinitro-A,A -bis(2-hydroxyethyl)oxamide dinitrate (NENO) (111), prepared from the mixed acid nitration of A,lV -bis(2-hydroxyethyl) oxamide . 

In a subsequent reaction, the oxalate can be hydrogenated to ethylene glycol. Oxalate esters can also be reacted with NH3 giving oxamides, a fertilizer. 

Esters of this constitution include di(hydroxyethyl)-oxamide dinitrate [107] and di-(/9,y-dihydroxypropyl)-oxamide tetranitrate. The latter was first prepared by Domanski and Skudrzyk [103] by heating an oxalic add ester with dihydroxy-propylamine to form an amide which was then nitrated, as shown below ... 

There have been many reported chiral stationary phases for use in both packed and capillary gas chromatography. Most of these phases are of the carbonyl-bis-L-valine isopropyl ester, diamide, and peptide phase types. The most common phase is Chirasil-Val from Alltech Applied Science Laboratories (State College, PA). This phase is ideal for the separation of a variety of enantiomers including amino acids, sugars, amines, and peptides. The phase is composed of L-valine-tert-butylamide linked through a car-oxamide group to a polysiloxane backbone every seven dimethylsiloxane units apart. 

Four main types of antioxidants are commonly used in polypropylene stabilizer systems although many other types of chemical compounds have been suggested. These types include hindered phenolics, thiodi-propionate esters, aryl phosphites, and ultraviolet absorbers such as the hydroxybenzophenones and benzotriazoles. Other chemicals which have been reported include aromatic amines such as p-phenylenediamine, hydrocarbon borates, aminophenols, Zn and other metal dithiocarbamates, thiophosphates, and thiophosphites, mercaptals, chromium salt complexes, tin-sulfur compounds, triazoles, silicone polymers, carbon black, nickel phenolates, thiurams, oxamides, metal stearates, Cu, Zn, Cd, and Pb salts of benzimidazoles, succinic acid anhydride, and others. The polymeric phenolic phosphites described here are another type. 

Pyrrole-2-c oxamide, lV,iV-dimethyl-conformation, 4, 194 Pyrrole-3-carboxamide, N,iV-dimethyl-conformation, 4, 194 Pyrrolecarboxamides synthesis, 4, 242 Pyrrole-2-carboxamides synthesis, 4, 148, 360 Pyrrolecarboxylhydrazides Curtius degradation, 4, 362 Pyrrole-2-carboxylic acid, l-benzyl-3-hydroxy-ethyl ester... 

Gabriel synthesis. Following Al-alkylation of the oxamide, selective saponification removes the ethyl ester to afford RNHCOOBn. The N-Boc derivative is similarly transformed. 

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