Monosubstituted amides

In a later paper Speziale and Smith 109) investigated the reaction of trivalent phosphorus compounds with N-monosubstituted a-trichloro-acetamides and a-trichloroacetamide. The products were imidoyl chlorides (129) and dichloroacetonitrile (130), respectively. The intermediacy of enamines (131) was assumed. For the monosubstituted amides the enamine... 

In contrast with the oxocarboxylic acids, which readily participate in tautomeric equilibria in solution, their open-chain and cyclic N-unsubsti-tuted and A-monosubstituted amide isomers are more stable. In most cases, the tautomeric equilibrium (Scheme 3) is not observed in neutral aprotic solvents at ambient temperature. In protic solvents, e.g., CD3OD, intercon-... 

Free acids require still an additional hydride equivalent because their acidic hydrogens combine with one hydride ion of lithium aluminum hydride forming acyloxy trihydroaluminate ion. Complete reduction of free carboxylic acids to alcohols requires 0.75 mol of lithium aluminum hydride. The same amount is needed for reduction of monosubstituted amides to secondary amines. Unsubstituted amides require one full mole of lithium aluminum hydride since one half reacts with two acidic hydrogens while the second half achieves the reduction. 

Monosubstituted amides can be converted into N-nitroso derivatives by use of a sufficiently powerful nitrosating agent, such as ni-... 

Some examples of photolytic intramolecular [2 + 2] cycloadditions which lead to the formation of lactones and lactams are sketched in Scheme 9.9. The allyl ester and N-monosubstituted amide do not undergo cydization, probably because of the high energy of the required E conformers. Cydization of the homoallyl ester does,... 

The partial double bond character of the C-N bond is even more pronounced in amides than in aromatic amines. As a result, the rotation barrier of the C-N bond in amides often lies in the range 15-20 kcal/mol. In N-monosubstituted amides (LXXVI), two low-energy conformers exist, namely the (Z)- and ( )-forms. In a number of derivatives, the (Z)-isomer is found to represent 90-100% of the total,... 

IR, Raman characteristic bands of monosubstituted amides, low frequencies. 

Idoux, J.P., Scandrett, J.M. and Sikorski, J.A. (1977). Conformational Influence of Nonacyl Groups on Acyl Group Properties in N-Monosubstituted Amides and in Other Carboxylic Acid Derivatives a 7-Position Proximity Effect. J.Am.Chem.Soc., 99,4577-4583. 

Aldehyde synthesis. The reduction of an N-monosubstituted amide (1) probably proceeds by addition to the carbonyl group and formation of a geminal amino... 

REACTIONS OF CARBONYL DIFLUORIDE WITH Af-MONOSUBSTITUTED AMIDES [571,632]... 

We are therefore led to make the following correlations for NH frequencies in monosubstituted amides ... 

Here again the effect of dilution has been studied by Richards and Thompson (1947), by Mizushima and others (1950), and by Darmon and Sutherland (unpublished). The effects found were similar to those observed on the C=0 frequency in carboxylic acids (Davies and Sutherland, 1938). Thus in concentrated solutions, in pure liquids, or in the solid state where hydrogen bonding is bound to be prevalent, this band lies at a markedly lower frequency than for dilute solutions the difference in this CO frequency being about 40 cm. i (Fig. 1). It should be noticed that this is less than the change in the NH stretching frequency, which was several hundred cm. Typical values for this frequency in a simple monosubstituted amide are ... 

Imidoyl chlorides of aromatic carboxylic acids ( ). An equimolar mixture of the N-monosubstituted amide and phosphorus pentachloride is heated for 15-180 min at 60-140 C. After completion of the reaction, which is indicated by the cessation of hydrogen chloride evolution, the phosphoryl chloride is removed under reduced pressure, and the remaining imidoyl chloride is distilled under vacuum. The reported yield ranges from 41-96%, but generally yields of 80-90% are obtained. 

Only a few data exist for the higher monosubstituted amides. Fuchs, Bear and Rodewald have measured heats of solution of several uniunivalent electrolytes in iV-ethylacetamide (NEA) including some tetraalkylammonium salts and others containing complex anions. They observe that for some salts, particularly tetraphenylarsonium chloride and sodium tetraphenylborate, the heat of solution varies markedly with concentration. While they suggest that the cause may be the result of ion-pair formation, they offer no convincing evidence. 

Open-chain secondary N-monosubstituted amides display the C=0 stretching band from 1680 to 1630 cm " Mn the solid state, and from 1700 to 1650 cm " Mn dilute solution. This band has been studied extensively, but the correlations are mainly applicable to solids (Randall et al, 1949 Thompson et al, in Clarke et al, 1949). The groups substituted on the nitrogen produce inductive and conjugation effects which influence the C=0 frequency. For example, N-chloroacetamide has its carbonyl band at 1705cm" (Gierer, 1953), while N-aryl substituted amides absorb near 1700cm" (Richards and Thompson, 1947). Jones and Sandorfy (1956) have discussed the amide I band in N,N-disubstituted amides (tertiary amides, see Table... 

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