Oxamide

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... 

The very low solubility of oxamide is almost undoubtedly the result of the extensively hydrogen-bonded nature of the crystalline compound (cf. E. M. Ayerst and J. R. C. Duke, Acta. Cryst. (1954), 7, 588). 

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°. 

B) Formamide, acetamide, oxamide, urea, benzamide, salicylamide thiourea. 

A large variety of organic compounds char without melting, e.g., starch, oxamide, sulphonic acids, uric acid, etc. 

Dissolve 0 2 g. of methyl oxalate in 10 ml. of water, add without delay 1 ml. of ammonia (d, o 88o) and shake a fine white precipitate of the insoluble oxamide is produced. A precipitate of oxamide is similarly produced when 2-3 drops of ammonia are added directly to 0 5 ml. of ethyl oxalate. 

A purple or rose pink coloration i produced when sodium hydroxide and dilute copper sulphate solution are added to compounds containing two -CONH- groups attached either to one another, or to the same nitrogen atom, or to the same carbon atom. It is therefore also given by oxamide, NHjCO CONH, malonamide, NHtCO-CH, CONH, and by proteins and peptides. In fact the -COKH - is often spoken of as the peptide linkage. 

Biuret test. Oxamide, having two CONHj groups, will give this test without any preliminary treatment (c/. urea). Shake o-i g. of oxamide with 1 ml, of 10% NaOH solution, add i drop of very dilute CuSO solution and mix well. A rose-pink coloration is produced. 

Sulphuric acid test. Heat 0-5 g, of oxamide with cone. HjSO. CO and COj are evolved. 

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. 

Di- and tri-chloroacetamide, oxamide, guanidine, and cyanoguanidine (dicyanodiamide) do not give satisfactory results. 

An interesting illustration is urea CO(NH2)2, m.p. 132°, which is very soluble in water, and oxamide (CONH2)2, m.p. 420°, which is sparingly soluble in water. 

The alkylurea 576 and oxamide 577 are formed by oxidative carbonylation of amines under CO pressure using Pd/C as a catalyst[518]. The urea formation proceeds under atmospheric pressure using PdCh and CuCl2[519]. The mono-and double carbonylations of / -aminoethanol (578 and 579) afford the cyclic carbamate (oxazolidinones) 580 and oxamide (morpholinediones) 581 [520,521]. 

Amides. For primary amides the suffix -amide is added to the systematic name of the parent acid. For example, CH3—CO—NHj is acetamide. Oxamide is retained for HjN—CO—CO—NHj. The name -carboxylic acid is replaced by -carboxamide. 

Qualitative Analysis. Several quaUtative analyses can be employed. For example, in the oxamide method (59), oxaUc acid is first heated at approximately 200°C with concentrated aqueous ammonia in a sealed tube. When thiobarbituric acid is added and heated to 140°C, a condensed compound of red color forms. The analysis limit is 1.6 pg. In the diphenylamine blue method (59,60), oxaUc acid is heated with diphenylamine to form a blue color, aniline blue. The analysis limit is 5 pg. 

Oxamide. This diamide [471 6-5] H2NCOCONH2, mol wt 80.07, is sparingly soluble in water and insoluble in various organic solvents. It... 

There are three reactions used for the production of oxamide ... 

The second and third reactions are economical, but the first is not. The second reaction is used in a process where HCN is oxidized to (CN)2 and hydrolyzed in the presence of a strong acid catalyst to give oxamide. The third reaction is employed in a newly developed process where diaLkyl oxalates are converted to oxamide by the ammonolysis reaction. This reaction easily proceeds without catalysts and quantitatively gives oxamide as a powder. 

Other Reaction Products. Nitrogen reaction fertilizers are commercially available that do not involve reactions between urea and aldehydes. These are oxamide and melamine. 

Oxa.mide. Oxamide [471 6-5] is a nonhygroscopic single compound. It has a molecular weight of 88.08, a nitrogen content of 31.8%, and is a white crystalline soHd with very limited solubiUty in water. Table 4 Hsts select physical properties. 

Following slow dissolution into the soil solution, oxamide undergoes stepwise hydrolysis to Hberate ammonia. Oxamic acid is formed in the first... 

Another method, utilized by Ube Industries, Ltd. (Japan), involves the oxidation of methanol and carbon monoxide to form an oxaUc diester. This then reacts with ammonia in a second step to form oxamide. 

Oxamide is produced commercially by Ube Industries, Ltd. (Japan) and a pilot process is being operated by Enichem (Italy). It is not produced domestically as a commercial fertilizer, although it was the subject of much research and development activity by the Tennessee Valley Authority s (TVA) National Fertilizer Research and Development Center. It is made in small quantities for industrial use by AUied Chemical, Hummel Chemical Co., and United Guardian, Inc. Oxamide has appHcation as a controlled release nitrogen source for the turf and specialty agricultural markets. 

Reactions of Organic Ruorine Compounds Table 30. Alkylboration of Oxamides [114 ... 

Add a few drops of concentrated ammonia. A while crystalline precipitate of oxamide rs formed, C20, (0CH3).2-1-... 

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