Primary amides, 31 Table

The melting points of the xanthylamides of a number of aliphatic primary amides are collected in Table 111,110. 

Many primary fatty amides which are available from various manufacturers are Hsted in Table 3. In 1986 approximately 55,000 metric tons of amides and bisamides were produced world wide (58), the majority of which are bisamides, followed in volume by primary amides. Most of these products are shipped in sohd form in bag or dmm quantities. Major producers of primary fatty amides are Akzo, Glyco, Humko, and Sherex. Bisamides are produced by Akzo, Milacron, and Syntex. There are over 100 producers of alkanolamides in the world, most of which are small specialized manufacturers to a specific industry. GAP, Henkel, Sherex, and Witco are among the principal producers. The most widely used alkanolamides are the Ai,Ai-bis(2-hydroxyethyl) fatty amides, mostly produced from middle-cut coco fatty acids (6% capryflc, 7% capric, 51% lauric, 19% myristic, 9% palmitic, and 2% stearic acids). An estimated 77,000 metric tons of alkanolamide was produced worldwide in 1986 (59). 

The trityl group was introduced on a primary amide, RCONH2, in the presence of a secondary amide with TrOH, AC2O, H2SO4, AcOH, 60°, 75% yield. It is stable to BOC removal with 1 N HCl in 50% isopropyl alcohol, 30 min, 50°, but can be cleaved with TFA. The following table gives the cleavage rates with TFA for a number of protected primary amides. 

Notice the ions at m/z 59, 44, and 72 in the mass spectrum ot hexanamide (Figure 7.1). Looking these up in the tables in Part 111 suggests an aliphatic primary amide. Looking at the mass spectrum... 

This procedure, which is based on the work of Ishii and co-workers, affords a mild and general method for converting a wide variety of esters to primary, secondary, and tertiary amides (Table 1). While the preparation of the tertiary amide, N,N-dimethylcyclohexanecarboxamide, described here is carried out in benzene, aluminum amides derived from ammonia and a variety of primary amines have been prepared by reaction with trimethylaluminum in dichloromethane and utilized for aminolysis in this solvent. Although 1 equivalent of the dimethylaluminum amides from amines was generally sufficient for high conversion within 5-48 hours, best results were obtained when 2 equivalents of the aluminum reagent from ammonia was used. Diethyl-aluminum amides can also effect aminolysis, but with considerably slower rates. 

Only a small number of heavier group 1 metal primary amides has been structurally characterized. Table 2 lists six compounds, three containing sodium and three containing cesium. The structures characterized contain the well-established M2N2 ring motif to build dimers 280 and 281, a tetrameric cubane 282, and polymers 283-285. The... 

Table 2 Crystallographically characterized heavy alkali metal primary amides...

Meyers and Shimano further expanded the scope of this methodology to include lithium amides as the nucleophile. The authors meticulously optimized the reaction conditions and determined the scope of the amide addition. Selected examples are listed in Table 8.32 (Scheme 8.163). The best results were obtained when THF was used as the solvent together with a stoichiometric amount of HMPA, relative to the lithium amide. The reaction was quite sensitive to the steric demand of the amide. Thus, lithium diethylamide give no product whereas lithium methyl n-pentylamide and lithium piperidide gave efficient reaction. Primary amides also failed to react. 

FIGURE 3.28. 2-methylpropanamide. A. The N—H stretch, coupled, primary amide, hydrogen bonded asymmetric, 3352 cm-1 symmetric, 3170 cm1. B. Aliphatic C—H stretch, 2960 cm-1. C. Overlap C=0 stretch, amide I band, 1640 cm-1 see Table 3.3. 

There have been several reviews on alkali metal amide structural chemistry. Most of these deal with lithium amides but there is also significant coverage of the heavier elements and other topics such as derivatives of primary amides and hydrazides. " Two comprehensive reviews for lithium amides and related salts published in 1991 and 1995 include extensive tables of structural data. There have also been reviews of the of lithium amides as well as of the extensive use of alkah metal... 

New polymer-supported reagents for sulfide transfer have been developed to avoid exposure to malodorous and toxic sulfur reagents. Ley et al.15 prepared a stable aminothiophosphate polystyrene resin for the conversion of secondary and tertiary amides to thioamides in high conversion and purity (Table III, entry 11). This procedure is extremely clean and affords the desired product with short reaction times in comparison to Law-esson s reagent. In addition, the aminothiophosphate resin dehydrates primary amides to nitriles. 

Use the one-letter abbreviations in Table 17.1. The one-letter representation of substance P is RPKPQQFFGLM-NH2. The -NH2 indicates that the C-terminal amino acid is present as the primary amide. 

Table I. Nitration of Primary Amides with Nitronium Tetrafluoroborate...

The primary amides of the group 2 elements, M(NH2)2, are nonmolecular species. " When the NH2 ligand is replaced by the bulky bis(trimethylsilyl)amido group, however, molecular complexes are formed. A complete set of structures has been obtained for Be through Ba (Table 11). The barium bis(trimethylsilyl)amides form a progression of compounds that illustrate the important relationship between ligand bulk and metal nuclearity. The base-free compound, [Ba N(SiMe3)2 ]2, exists as a dimer that can accommodate... 

Although the proposals advancing 4 and 6 as intermediates in the epoxidation explain most of the experimental data reported to date, there are a few remaining enigmas such as the reversal of enantioselectivity which accompanies the use of primary amide analogs of tartrates (Table 3) and when ferf-butyl hydroperoxide is replaced by triphenylmethyl hydroperoxide in epoxidations employing catalyst 840. 

Activation of aliphatic and aromatic carboxylic acids with sulfuric acid derivatives yields amides (Table 3). Sulfuryl chloride fluoride and primary amines or chlorosulfonyl isocyanate and secondary amines are used as reaction partners. 

In the N-phenyl case all of the secondary aryl amides were very weak or inactive. The biodata on the primary amides is shown in Table I. 

Although the chemical shifts of the exchangeable protons of the thioureas vary markedly with solvent, temperature and the presence of H20 in solution, the tables below indicate a trend in shift with the type of substitution of the thiourea nitrogen atoms. It is noted that the primary amide protons resonate at highest field (H2N-C(=S)-), that alkyl substituted secondary amide protons resonate at slightly lower field (R-NH-C(=S)-), and that the phenyl substituted secondary... 

The two exchangeable Primary Amide protons resonate at low field as either one or two very broad bands. The table of chemical shifts provided below indicates that the aliphatic Primary Amides resonate at slightly higher field than the aromatic compounds. The chemical shift(s) of these protons vary over a relatively wide range of values due to their sensitivity to the concentration of the sample solution, the solvent employed and the temperature at which the solution was examined, in addition to any possible hydrogen bonding effects and other structural considerations. 

As indicated in the following chemical shift tables, the primary amide compounds are not readily soluble in CDCI3 and usually require the use of DMSO-de or DMSO-d6/CDCI3 mixture (polysol) in order to obtain high quality carbon-13 spectra. 

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