Amide, protonated, formula

Hence, chalcogenoamidophosphinic acids of general formula R2P(E)NHR (27) can be considered as dichalcogenophosphinic acids with one of the chalcogen atoms replaced by an amido group. These amido species are still normally referred to as acids due to their acidic amide protons. They are accessible from reaction of thiophosphinic chlorides and primary amines (Equation 43) or from reaction of aminophosphines with elemental chalcogen... 

The total hydrolysis of phenylacetonitrile (Formula A in Figure 7.9) to phenylacetic acid (C) can be performed in one or two steps and both under acidic (following the mechanism in Figure 7.8) and basic conditions. In the latter case, the nucleophilic addition of a hydroxide ion to the nitrile carbon atom is the rate-determining step. This is how the imidic acid anion D is formed. Protonation (—> F), deprotonation (—> E) and reprotonation yield the amide B, which one can isolate or further hydrolyse under harsher conditions via the usual BAC2 mechanism (cf. Figure 6.24). 

According to Appendix 1, the pA"a value for a proton adjacent to an amide is approximately 30-35, and the pATa value for a proton adjacent to an aldehyde is approximately 20-25. Recognizing that there are two relevant functional groups (an aldehyde and an amide), the above formula gives us a pATa value of approximately 12.5-15. 

Deprotonation reactions. Ethylenediamine, H2NCH2CH2NH2, (abbreviated as en in writing formulas for complexes) forms many stable complexes with metal ions. One such complex is [Pt(en)2]2+. The amide ion will remove protons from the coordinated en so in liquid ammonia the reaction... 

The molecular formula was established as C13H20N4O7S, and was supported by the H and 13C NMR spectra (26). The structure of the highly water-soluble compound was deduced through spectral analysis. Amide (1650 cm-1) and sulfonyl (1345 and 1165 cm1) groups were observed in the IR spectrum. An olefinic proton (7.39 ppm) and an JV-methyl group were observed in the NMR spectrum, together with a pair of exchangeable methylene protons (4.29 and 4.82 ppm). Methylation afforded a methyl ester, which permitted solubility in pyridine and clarification of some of the NMR resonances. The structure of altemicidin as 78 was deduced... 

The position of the C-4 hydroxymethyl signals indicated the proximity of the protons to the amide carbonyl, thus supporting the evidence for the location of the benzamide at C-3. Hydrolysis of this alkaloid furnished dihydrocyclomicrophylline-F (194) 88a), the structure elucidation of which was reported earlier (c/. Vol. IX, p. 397). On the basis of these data structure 193 was assigned to iV -benzoyldihydrocyclo-microphylline-F. The correctness of the proposed structural formula (193) was proved by correlation with buxidine-F (see Section III, A, 5, g) 91). 

Figure 3. NMR spectra (15.4 MHz) of at natural abundance for a mixture of common solvents, as indicated from left to right dimethylformamide (amide), benzene, ethanol (hydroxyl), ethanol (methylene), dimethylformamide (methyl), acetone, ethanol (methyl), tetramethylsilane. The D in each formula is to emphasize that for a molecular species containing at natural abundance all other hydrogen is Key A, proton-coupled B, proton-decoupled. (From Ref. A.)...

The functional group created when the —OH of a carboxyl group is replaced by an NH group is called an amide (Section 1.3F). Draw the structural formula of acetamide, which is derived from acetic acid, and determine whether proton transfer to the amide group from HCl occurs preferentially on the amide o>ygen or the amide nitrogen. 

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