Oxamide, preparation reactions

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°. 

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 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. 

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... 

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. 

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). 

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 ... 

Bis(TV-substituted)-cyclams have been prepared by a variety of reactions. Dioxo- or diiminecy-clams can be bis-substituted and then reduced. Starting from cyclam, 1,8-dimethyl-cyclam (108) can be prepared and further /ra ,v-bis-substi luted to form (109) (Scheme 28). The formamidinium salt (110) is 1,11-bis-substituted (111), and then hydrolyzed to form (112).107 The bicyclic oxamide (113) is 1,4-bis-substituted (114), and then hydrolyzed to form (115).108 Substitution for (30), R2 = Me, (CH2)2NH2, etc. produces /nmv-bis/V-substituted 2,6-pyridiyl macrocycles. 

Imidazoles.—Formation. Several new syntheses of imidazoles from isocyanides have been reported these include the formation of 1-alkyl-imidazoles (396) by the action of primary amines on 2-isocyano-2-tosylstyrene, PhCH=C-(NOTos, the cyclization of the enamine Me2NCH=C(NC)C02Me to compound (397) in the presence of methyl iodide,and the preparation of the ethers or thioethers (398) from isocyano-cyanides R CH(NC)CN by their reaction with alcohols or thiols R XH, respectively.Aromatic aldehydes are converted into 2-aryl-4,5-dichloroimidazoles (399) by the combined action of cyanogen and hydrochloric acid. 5-Acetyl-4-methylimidazole (400) results when form-amido-acetylacetone, AC2CHNHCHO, is heated with formamide and formic acid. Exhaustive chlorination of tetramethyldithio-oxamide leads to the tri-chloro-imidazolium cation (401). ... 

Oxamides, dialkyl oxalate esters, and oxamic add esters can be prepared by Pd-catalyzed double carbonylation of secondary amines and alcohols via incorporation of two molecules of carbon monoxide into amines and/or alcohols. Pd-catalyzed double carbonylation reactions of amines in the absence or presence of alcohol were reported earlier to give ox-amides and oxamic acid ester.t i t Selective formation of oxamides has been achieved by double carbonylation of secondary amines in the presence of iodide ion and dioxygen catalyzed by Pd(OAc>2 (Eq. 

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