Primary and Secondary Amides

For primary and secondary amides CUCI2, glyoxal, H2O, pH 3.5, reflux, 92% yield. "... 

Amides are reduced to amines because the nitrogen is a poorer leaving group than oxygen at the intermediate stage of the reduction. Primary and secondary amides are rapidly deprotonated by the strongly basic LiAlH4, so the addition step involves... 

This view has been challenged with more recent evidence indicating that AT-[(acyloxy)methyl] derivatives of both primary and secondary amides (8.170, Fig. 8.21) undergo decomposition by the same mechanisms, namely a) an acid-catalyzed process involving protonation followed by formation of an /V-acyliminium species (Fig. 8.21, Reaction a) b) a pH-independent heterolytic cleavage forming the same /V-acyliminium species (Fig. 8.21, Reaction b) and c) a base-catalyzed pathway, which for /V-[(acyloxy)methyl] derivatives of AT-methylamides is the normal mechanism (Fig. 8.21, Reaction c), but for AT-[(acyloxy)methyl] derivatives of primary amides involves substrate deprotonation followed by /V-acy limine formation (Fig. 8.21, Reaction d) [218],... 

What mainly differentiates /V-[ (acyloxy)methyl] derivatives of primary and secondary amides are the relative contributions of Reactions a-d as a function of pH, and, mainly the onset of the base-catalyzed Reactions c or d. Thus, the pathway for hydrolysis of derivatives of primary amides is pH-independent (Reaction b) at ca. pH 2-5, and is base-catalyzed (Reaction d) above pH 5, which explains the lability of primary amides at pH 7.4. In contrast, the base-catalyzed pathway for derivatives of secondary amides (Reaction c) is not important below pH 9-10, which is why these amides are relatively stable at pH 7.4 [218], This specific behavior, thus, eliminates 7V-[(acyloxy )methyl] derivatives as potential prodrugs for primary amides. 

Note that acids, and primary and secondary amides cannot be employed to generate enolate anions. With acids, the carboxylic acid group has pATa of about 3-5, so the carboxylic proton will be lost much more easily than the a-hydrogens. In primary and secondary amides, the N-H (pATa about 18) will be removed more readily than the a-hydrogens. Their acidity may be explained because of resonance stabilization of the anion. Tertiary amides might be used, however, since there are no other protons that are more acidic. 

The N-H protons of primary and secondary amides are slow to exchange and require heating or base catalysis and this is one way an amide functional group can be distinguished from other functional groups. 

Other Vibration Bands The C—N stretching band of primary amides occurs near 1400 cm-1. A broad, medium band in the 800-666 cm-1 region in the spectra of primary and secondary amides results from out-of-plane N—H wagging. 

One interesting feature of primary and secondary amide spectra is the... 

A wide range of linker groups are currently used with SynPhase crowns. They accommodate formation of the following functional groups upon cleavage carboxylic acids, primary and secondary amides, sulfonamides, alcohols, phenols, amines, anilines, anilides, hydroxymates, aldehydes, ketones, and thiols. 

Primary and secondary amides of the type RCONHj and RCONHR react with nitrous acid in the same way as do the corresponding primary and secondary amines. 

Figure 24-1 Infrared spectra of propanamide, /V-phenylethanamide, and W.W-dirnethylmethanarnide in chloroform solution. Notice the appearance of both free NH bands (sharp, 3300-3500 cm-1) and hydrogen-bonded NH bands (broad, 3100-3300 cm-1) for primary and secondary amides.

The at complex from DIB AH and butyllithium is a selective reducing agent.16 It is used tor the 1,2-reduction of acyclic and cyclic enones. Esters and lactones are reduced at room temperature to alcohols, and at -78 C to alcohols and aldehydes. Acid chlorides are rapidly reduced with excess reagent at -78 C to alcohols, but a mixture of alcohols, aldehydes, and acid chlorides results from use of an equimolar amount of reagent at -78 C. Acid anhydrides are reduced at -78 C to alcohols and carboxylic acids. Carboxylic acids and both primary and secondary amides are inert at room temperature, whereas tertiary amides (as in the present case) are reduced between 0 C and room temperature to aldehydes. The at complex rapidly reduces primary alkyl, benzylic, and allylic bromides, while tertiary alkyl and aryl halides are inert. Epoxides are reduced exclusively to the more highly substituted alcohols. Disulfides lead to thiols, but both sulfoxides and sulfones are inert. Moreover, this at complex from DIBAH and butyllithium is able to reduce ketones selectively in the presence of esters. 

The fact that there is carbonyl-oxygen exchange in primary and secondary amides is in accord with the principle of stereoelectronic control but it does not constitute a proof since these experimental results can be explained without the use of this principle. 

Amides. All amides are characterised by a strong carbonyl absorption band, referred to as the amide I band. Primary and secondary amides additionally show bands arising from N—H stretching and bending vibrations. The N—H... 

As a consequence of the mesomeric effect, the amide carbonyl group has less double bond character than that of a normal ketonic carbonyl group and it would be expected to absorb at lower frequency. This is found to be the case primary and secondary amides absorb strongly near 1690 cm-1 in dilute solution and at somewhat lower frequency in the solid phase. Tertiary amides are not affected by hydrogen bonding and show strong absorption at 1670-1630 cm-1 irrespective of the physical state of the sample. 

Bands resulting from the primary and secondary N—H bending vibrations appear near 1650 cm-1 and 1550 cm-1 respectively in the solid phase, and the large difference in these amide II bands enables primary and secondary amides to be distinguished. The 1550 cm -1 band is not a simple N—H bending mode, but is believed to result from coupling of this deformation with a C—N stretching vibration. 

Epoxy resins are solidified by the polyaddition mechanism by primary and secondary amides di- and polyamides, polybasic acids and their anhydrides, monomer and oligomer isocyanates, poly-... 

Other amide compounds were also identified from radiolysis of DEHDMBA (A(iV-di(2-ethylhexyl)-3,3-dimethyl butanamide) and mixtures of DEHBA [N.N-di(2-ethylhexyl)- -butanamide]-DEHiBA V,V-di(2-cthylhcxyl)-i,vo-butanamide] in TPH by CPG-FTIR light primary and secondary amides and functionalized tertiary amides with high molecular masses (196). Carboxylic acids represented a large... 

The parameter HB, as defined above, is the number of donor hydrogen atoms in a hydrogen-bonding molecule. Compounds subject to hydrogen bonding include alcohols, phenols, carboxylic acids, and primary and secondary amides. 

Conformations of primary, secondary, and tertiary amides of (R,R)-tartaric acid, both symmetrically and asymmetrically substituted, have been studied ciys-tallographically [22, 24, 29, 30-40] Moreover, ab initio studies up to MP2 / 6-31G //RHF/6-31G level [41] for both the diamide and N,N,N ,N -tctramcthyl-diamide of (/ ,/ [-tartaric acid have been carried out [20, 22]. X-ray results have shown that primary and secondary amides of (R,R [-tartaric acid tend to adopt a conformation with the extended carbon chain - the Taa structure. In this Taa conformation both the a-hydroxy-amide moieties form planes and the structure gains stabilization from hydrogen bonding between donors, the NH, and acceptors, the proximal OH groups. Moreover, the Taa structure is favorably stabilized by the attraction of antiparallel local dipoles formed along distal C H and Csp2=0 bonds [18, 21, 22],... 

The conversion of primary and secondary amides by treating with the system SiCl —NaN ( into 1,5-disubstituted tetrazoles 5 through intermediate imidoyl azides 150 has been used <2002RJ01370, 2004RJ0443, 2004RJ01528, 2004RJ01532> for the preparation of tetrazoles of various structures, in particular, bis- and tris-tetrazoles 507 and 508. 

The first step in this reaction is formation of the allyl trichloroacetimide 8 formed from allyl alcohol 3 by reaction with trichloroacetonitrile. The allyl amides 9 are formed by the [3,3]-sigmatropic rearrangement of 8, followed by hydrolysis. The reaction proceeds with good yield for primary and secondary amides however, for products where the amide nitrogen is bound to a tertiary carbon atom the yields are generally low. 

Primary and secondary amides have N—H bonds that give infrared stretching absorptions in the region 3200 to 3500 cm-1. These absorptions fall in the same region as the broad O—H absorption of an alcohol, but the amide N—H absorptions are usually sharper. In primary amides (R—CO—NH2), there are two N—H bonds, and two sharp peaks occur... 

---