Carbonic acid amides

Urea can be considered the amide of carbamic acid, NH2COOH, or the diamide of carbonic acid, CO(OH)2. At room temperature, urea is colorless, odorless, and tasteless. Properties are shown ia Tables 1—4. Dissolved ia water, it hydrolyzes very slowly to ammonium carbamate (1) and eventually decomposes to ammonia and carbon dioxide (qv). This reaction is the basis for the use of urea as fertilizer (qv). 

Dialkylphosphonoacetic acid esters react with p-aminobenzoic acid to anilides. The potassium salt of the diamyl ester is said to be surface-active [126]. Phosphorus organic carbonic acid amides can also be obtained by the following reaction [127] see Eq. (76). 

Carbonic acid amides are known for their good surface-active properties. In particular, alkanolamides are produced on a large scale. But relatively little is known about the synthesis of alkanephosphonic acid amides. Therefore surface-active properties and different ways of synthesizing alkanephosphonic acid bisdialkylamides were investigated [121]. There are three ways to obtain these derivatives ... 

Thus unsubstituted (R=H) and substituted (R = alkyl) non-stabilized diyiides 1 react with phenylisocyanate and dicyclohexylcarbodiimide (R NCX), leading to the formation of new monoylide type intermediates. These last ones react in situ with carbonyl compounds through a Wittig type reaction leading respectively to a,)8-unsaturated amides 2 and amidines 3, with a high E stereoselectivity, the double bond being di- or tri-substituted [48,49]. By a similar reactional pathway, diyiides also react with carbonic acid derivatives, with the synthesis as final products of -a,/l-unsaturated esters 4 and acids 5 [50]. 

Biochemical tests are usually performed after pure cultures have been obtained. The standard indole, methyl red, Voges-Proskauer, citrate, and litmus milk tests may be used to show important physiological characteristics. To study the functional diversity of bacteria, the utilization of carbohydrates, amines, amides, carboxylic acids, amino acids, polymers, and other carbon and nitrogen sources can be tested.28 Dilution-based most-probable number (MPN) techniques with phospholipid fatty acids as biomarkers have been employed for studying different bacterial species in lakes.40 The patterns of antibiotic resistance in bacteria isolated from natural waters have been useful for identifying sources of water pollution.34... 

Owing to the acyl group to which it is bound, the amino-group loses its basic character almost entirely. Salts of the amides with strong acids are indeed known, but such salts are immediately and completely decomposed into their constituents by water. Only urea, the diamide of carbonic acid, forms stable salts, the existence of which is made possible by the second NHa-group. 

Carbon dioxide is a symmetrical, linear triatomic molecule (0 = C=0) with a zero dipole moment. The carbon-to-hydrogen bond distances are about 1.16A, which is about 0.06A shorter than typical carbonyl double bonds. This shorter bond length was interpreted by Pauling to indicate that greater resonance stabilization occurs with CO2 than with aldehydes, ketones, or amides. When combined with water, carbonic acid (H2CO3) forms, and depending on the pH of the solution, carbonic acid loses one or two protons to form bicarbonate and carbonate, respectively. The various thermodynamic parameters of these reactions are shown in Table I. 

Since chains of nylons having an even number of carbon atoms between the amide and acid groups pack better, some of their melting points are higher than comparable nylons with odd numbers of carbon atoms (Table 4.7). Further, the melting points decrease and the water resistance increases as the number of methylene groups between the amide and acid groups increases. 

Most important are quantitative solid-state reactions of cyclic carbonic acid derivatives with gaseous or solid amines. These give open-chain amides that can be recyclized in various cases to new products of preparative interest. 

The carbonyl group consists of a carbon atom double-bonded to an oxygen atom. It occurs in the organic compounds known as ketones, aldehydes, amides, carboxylic acids, and esters. 

Intramolecular rotations in carboxylic and carbonic acid amides have been thoroughly investigated by 1H NMR [108]. The thermodynamic data for rotation in N,N-di-methyltrichloroacetamide as obtained by 1H and 13C 1H NMR agree quite well CH AG294 = 76.5 kJ/mol 13C AG BB = 73.6 kJ/mol) [109]. 

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