Secondary amines and amides

Primary and secondary amines and amides are first chlorinated at nitrogen by the chlorine released by the gradually decomposing calcium hypochlorite. Excess chlorine gas is then selectively reduced in the TLC layer by gaseous formaldehyde. The reactive chloramines produced in the chromatogram zones then oxidize iodide to iodine, which reacts with the starch to yield an intense blue iodine-starch inclusion complex. 

D. With Ammonia, Primary and Secondary Amines, and Amides... 

The reaction of chlorodiphenoxymethane with dimethylamine yields the amide acetal (459 equation 214). Dialkoxymethyl groups can be transferred by means of dialkoxyalkyltriethylammonium tetraflu-oroborate (460 equation 215) to primary amines and amides, amidines, secondary amines and amides once or twice to give amide acetals (461) and (462) Azodiazoles, e.g. (463) and (464) (Scheme 85), add to ketene dimethylacetal to give lactam acetals. ... 

Secondary and primary amines also undergo N-oxygenation and the first isolable metabolites are hydroxylamines (reactions 3-A and 4-A, respectively). Again, reversibility is documented (reactions 3-B and 4-B). These compounds can be aliphatic or aromatic amines, and the same metabolic pathway occurs in secondary and primary amides (i.e., R = acyl), whereas tertiary amides seem to be resistant to N-oxygenation. The oxidation of secondary amines and amides usually stops at the hydroxylamine/hydroxylamide level, but formation of short-lived nitroxides (not shown) has been reported. 

As opposed to secondary amines and amides, their primary analogs can be oxidized to nitroso metabolites (reaction 4-C), but further oxidation of the latter compoundsto nitro compounds does not seem to occur in vivo. In contrast, aromatic nitro compounds can be reduced to primary amines through reactions... 

Primary and secondary amines and amides have N—H bonds, and one might expect that they could on occasion behave as acids (proton donors). 

NH bending Intensity generally weak In conjunction with bands in the 3300 cm region, this band is used to characterize secondary amines and amides. This band, like the N-H stretching band in the 3300 cm region, may be very weak in secondary amines. 

Carboxylic acids Primary and secondary amines and amides 3400-2400 m 62... 

It will also reduce acid chlorides, acid anhydrides and aldehydes to primary alcohols, ketones to secondary alcohols, and amides to the corresponding amines R-CONHi -> R CHiNH. Nitro-hydrocarbons if aromatic are... 

Dimethyl Sulphate Method for hydroxy compounds and for primary and secondary amines, acid amides, etc. The substance is dissolved or suspended in water, a small excess (above the theoretical) of sodium hydroxide added and then the theoretical quantity of dimethyl sulphate, the mixture being finally shaken without external warming. Methylation is usually rapid, the dimethyl sulphate being converted to methyl hydrogen sulphate... 

Inhibition of Nitrosamine Formation. Nitrites can react with secondary amines and A/-substituted amides under the acidic conditions of the stomach to form /V-nitrosamines and A/-nitrosamides. These compounds are collectively called N-nitroso compounds. There is strong circumstantial evidence that in vivo A/-nitroso compounds production contributes to the etiology of cancer of the stomach (135,136), esophagus (136,137), and nasopharynx (136,138). Ascorbic acid consumption is negatively correlated with the incidence of these cancers, due to ascorbic acid inhibition of in vivo A/-nitroso compound formation (139). The concentration of A/-nitroso compounds formed in the stomach depends on the nitrate and nitrite intake. 

Cyanopyridazines add ammonia, primary and secondary amines and hydroxylamine to give amidines or amidoximes. Substituted amides, thioamides and carboximidates can be also prepared. With hydrazine, 3-pyridazinylcarbohydrazide imide is formed and addition of methylmagnesium iodide with subsequent hydrolysis of the imine affords the corresponding pyridazinyl methyl ketone. 

Treatment of acyl pyrroles with primary and secondary amines affords amides. ... 

Proline is the only amino acid in Table 27.1 that is a secondary amine, and its presence in a peptide chain introduces an amide nitrogen that has no hydrogen available for hydrogen bonding. This disrupts the network of hydrogen bonds and divides the peptide into two separate regions of a helix. The presence of proline is often associated with a bend in the peptide chain. 

While the usual eonsequence of hydration of enamines is eleavage to a secondary amine and an aldehyde or ketone, numerous cases of stable carbinolamines are known (102), particularly in examples derived from cyclic enamines. The selective terminal hydration (505) of a cross-conjugated dienamine-vinylogous amide is an interesting example which gives an indication of the increased stabilization of the vinylogous amide as compared to simple enamines, which is also seen in the decreased nucleophilicity of the conjugated amino olefin-carbonyl system. 

Reaction between secondary amines or amides and nitrous acid... 

The detection limits for primary and secondary amines and for the amides are 10 to 60 ng substance per chromatogram zone [1]. The detection limits on layers with fluorescence indicators are about double the amount of substance [1]. 

When the -OH of a carboxylic acid is replaced by an -NH2, the compound produced is an amide. Amides are neutral to mildly basic compounds. They can be made from acids, acid chlorides, acid anhydrides, and esters by reaction with ammonia or primary and secondary amines. The amide linkage is found in polyamide resins such as nylon. 

In classical organic chemistry, nltrosamlnes were considered only as the reaction products of secondary amines with an acidified solution of a nitrite salt or ester. Today, it is recognized that nitrosamines can be produced from primary, secondary, and tertiary amines, and nltrosamides from secondary amides. Douglass et al. (34) have published a good review of nitrosamine formation. For the purposes of this presentation, it will suffice to say that amine and amide precursors for nitrosation reactions to form N-nitroso compounds are indeed ubiquitous in our food supply, environment, and par-... 

Hard evidence for the first category seems to be nonexistent. An educated guess on the potential hazards would combine residue technology [how much of a secondary amine (or amide, urea, carbamate, etc.) might a person consume or otherwise be exposed to ], nitrosation chemistry (what would be the yield of in vivo nitrosation of the pesticide thus consumed ), and toxicology (what would be the toxicological effect and potency of the nitroso compound thus formed ). Frequently, these questions, which simplify to, "What dose—eg., in mg/kg—of a pesticide-derived nitroso compound might a person be exposed to and what would be the result if he were " are not carefully considered. 

After cooling and dilution with methyl-Cellosolve (2-methoxyethanol), acetic anhydride is slowly added (in order to convert the secondary amine to amide) and the solution is cooled to room temperature. Finally, the resulting tertiary amine, representing the original unsaturate, is titrated with 0.5 N perchloric acid in methyl-Cellosolve, either visually (with thymol blue + xylene cyanol... 

Amides prepared from secondary amines and acylchloride/imidazole,[391 carboxylic acid/oxalyldiimidazole,[41 ] carboxylic acid/sulfinyldiimidazole[61 ] or isolated imidazo-... 

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