Oxamide, preparation

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... 

Carry out this preparation in precisely the same way as the above preparation of oxamide, using 2 ml. (2-4 g.) of benzoyl chloride instead of the ethyl oxalate, and observing the same precautions. Considerably more heat is generated in this reaction therefore hold the cork very securely in position during the shaking. After vigorous shaking for 15 minutes, no trace of oily benzoyl chloride remains. Filter off the fine flakes of benzamide, wash with cold water, and then recrystallise from hot water yield, 1-5 g. Colourless crystals, m.p. 130°. 

Benzenediamine (288) and the unstable oxamide equivalent (289), prepared in situ by chlorination of bis(dimethylamino)acetylene, gave 2,3-bis(dimethyl amino)quinoxaline (290) (no details). ... 

The complex and sometimes competing issues of solubility, stability, and reactivity of reagents designed for purely aqueous POCL were addressed by Barnett et al. [21,22], who furthered the development of the trifluormethylsulfonyl-substituted oxamide class of reagents. They prepared disulfonic acid functionalised oxamides (see Fig. 4), which were found to possess a considerably improved degree of stability at both ambient and low temperature when compared to METQ, in addition to showing some promise as potential reagents in analytical applications. 

Several of this group are explosives of moderate to considerable sensitivity to impact or friction and need careful handling. Fluorodinitromethane and fluorodini-troethanol are also vesicant [ 1 ]—[4]. l-Fluoro-l,l-dinitro derivatives of ethane, butane, 2-butene and 2-phenylethane are explosive [5], Among the preparations of a series of energetic and explosive compounds, that of N, N, N, A /-tctrakis(2-fluoro-2,2-dinitroethyl)oxamide is especially hazardous, as it involves heating an undiluted explosive to a high temperature [6],... 

The reaction is slightly exothermic. At this stage, lithium butanetelluroate (BuTeLi) is formed. (The checkers noted a deep red color as the BuLi was added.) BuTeLi should be prepared slightly in excess to the carbamoyl chloride. The subsequent step produces carbamoyllithium that may react with any excess carbamoyl chloride to give an undesired oxamide by-product. 

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 . 

A mixture of concentrated sulfuric and nitric acids has been used for the A-nitration of amides and ureas. A, A -Dinitro-A,A -bis(2-hydroxyethyl)oxamide dinitrate (NENO) (11) is prepared from the action of mixed acid on A, A -bis(2-hydroxyethyl)oxamide (61), itself prepared from the condensation of diethyloxalate with two equivalents of ethanolamine. Niuo-sylsulfuric acid is an inhibitor of A-nitration and so nitrous acid should be rigorously excluded. The reaction of (61) with absolute nitric acid results in 6>-nitration of the hydroxy groups but no A-nitration, and consequently, (62) is isolated as the sole product. 

A rapid method of preparation of [Mn(NH20H)2Cl2] has been reported that is easily carried out and does not require the use of hydroxylamine. It involves treatment of manganese(ii) carbonate with hydroxylamine hydrochloride in boiling water. The complexes formed between Mn and tetramethyl- and tetraethyl-dithio-oxamide have been investigated by the Job method MnL3X2 (X = C10 or FeCl4 ) were observed. ... 

Benzotriazoles are neutral acylating agents, successfully used for the preparation of amides, oxamides and hydrazides The acylbenzotriazoles 95a-d are prepared from carboxylic acids 94a-d by reaction with l-methanesulfonyl-l//-benzotriazole (Scheme 51). Reaction of 1-benzoyl-l//-benzotriazole with hydroxylamine hydrochloride in the... 

Ethylene oxamide was prepared earlier by van Alphen [21]. It cannot be nitrated either with nitric acid alone (98 %) or with mixed nitric and sulphuric acids. 

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 ... 

Vogl et al. 59-60> prepared regular copolyamide membranes. They condensation-polymerized isophthaloylchloride with N,N -bis(2-aminoethyl)oxamide, which was prepared from ethylenediamine and diethyloxalate, to give the polymer 14. The salt rejection of the membrane was 77.5 99.0% for 1% aqueous solution of NaCl at 25 °C and 70 kg/cm2 but the water flux was not very high. 

Reaction LXXXIX. Hydrolysis of Nitriles to Amides. (B., 18, 355.)— When nitriles are heated with acids or alkalis they are hydrolysed to the corresponding acids passing intermediately through the amides. It is possible only in a few instances (e.g., oxamide) to stop the hydrolysis at this intermediate stage, unless alkaline hydrogen peroxide is employed, when the amide is obtained in almost theoretical yield. Both methods of hydrolysis are illustrated in the following preparations. 

Some amides do not dissolve in glacial acetic acid in such cases a mixture of 2 ml of glacial acetic acid and 3 ml of water may be used as a solvent for the reaction. Urea may be characterised as the di-xanthyl derivative (m.p. 274 °C) prepared in acetic acid. Di- and tri-chloroacetamide, oxamide, and salicylamide do not give satisfactory results. 

Complexes of several S-donor ligands have also been reported. The reaction of dithio-oxamide and its tetramethyl and tetraethyl derivatives with zinc, cadmium, and mercury halides leads to complexes of stoicheiometry MLX2 (M = Zn, Cd, or Hg X = Cl, Br, or I).64,65 M—S bonding is involved i.r. spectra show that the zinc and mercury complexes are four-co-ordinate, while the cadmium complexes are octahedral with halogen bridges. The complexes [ML3][C104]2 have also been prepared and do not contain co-ordinated perchlorate. The complexes ZnL (H2L = dithio-oxamide, NiV-dimethyl- and IVA -dicyclohexyl-dithio-oxamide) have been isolated,66 and consist of linear chains containing four-co-ordinate zinc. 

A more direct way for the preparation of carbamoyl and thiocarbamoyllithiums started from carbamoyl and thiocarbamoyl chlorides 119 and used lithium powder and a catalytic amount of naphthalene (3 mol%)113,114. The lithiation was performed at —78°C in the presence of carbonyl compounds and imines as electrophiles to yield products 120 (Scheme 32). Phenyl isocyanate and DMF afforded oxamides in modest yields (21 and 42%, respectively). 

Rubeanic acid (0-5%). Dissolve 0-5 g rubeanic acid [or dithio-oxamide] NH2, CS.CS.NH2 in 95 per cent ethanol and dilute the solvent to 100 ml. The solution decomposes rapidly and should be prepared freshly each time. 

Rubeanic acid (0 02%). Dissolve 20 mg rubeanic acid (dithio-oxamide), NH2.CS.CS.NH2, in 100 ml glacial acetic acid. The reagent should be prepared freshly. 

Tetra-N-isopropyl oxamide derivatives of the current invention have been prepared (4). 

With solutions of lower pH all the major observations made by Masson have been confirmed. In preparative work at these higher acidities, oxamide has been reported to be formed, probably through intermediate formation of cy-... 

To prepare the 2-trifluoromethyl derivative of hypoxanthine 17, 5-aminoimidazole-4-carb-oxamide hydrochloride is refluxed with trifluoroacetamide. ... 

Chloroimidazoles (2) prepared from A -disubstituted oxamides or from //-foimylglycine amides... 

Bredereck and Schmotzer (1044), from diaminomaleonitrile (DAMN hydrogen cyanide tetramer) and oxalyl chloride, prepared 2,3-dicyano-5,6-dihydroxy-pyrazine but Stetten and Fox (1049) could not prepare 23-diamino-5-hydroxy-pyrazine from glycine amide and oxamide. Section 11.3 lists preparations from a, -diamino or a, -diimino compounds and reagents other than a,0-dicarbonyl compounds (384) with additional data (1050) and oxidation of 23-dichloro-quinoxaline with hot aqueous potassium permanganate gave 23-dicarboxy-5,6-dihydroxypyrazine (1051). 

Preparations of some A-substituted 2-oxo-l, 2-dihydropyrazines have been discussed in Section 11.2 from the reactions of di-, tri-, and tetrapeptides with glyoxal (380-382) and Cheeseman and co-workers (1111) have described the preparation of 1-benzyl-3-hydroxy-2-oxo-l, 2-dihydropyrazine (83) (and similarly its 1-methyl analogue) from ethyl A-(2, 2 -dimethoxyethyl)oxamate and benzyl-amine through A-benzyl-A -(2, 2-dimethoxyethyl)oxamide (84) by the application of a standard procedure (482). 

The preparation of oxamide is easily accomplished in the laboratory. On heating anhydrous oxalic acid with absolute alcohol and then distilling di-ethyl oxalate is obtained. On adding concentrated ammonium hydroxide to this the oxamide is thrown down at once as an abundant white precipitate. 

Another reaction by which both oxamic acid and oxamide may be prepared is by heating the ammonium salt of oxalic acid. The reaction takes place in two steps. Firsts by the loss of one molecule of water the ammonium salt of oxamic acid is formed. Second, by the loss of another molecule of water, this is converted into oxamide, as follows ... 

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