Amine, infrared absorptions

Formation of an amide is also indicated in the reaction of PCTFE with Cr(CO)6 and the primary amine, benzylamine. The infrared absorption spectrum shows an N-H stretch centered at 3400 cm, aromatic C-H stretches at 3063 and 3030 cm1, aliphatic C-H stretches at 2933 and 2876 cm1, a broad amide I/amide II band ranging from 1680-1580 cm1, and a C-N stretch at 1454 cm1. The C-Cl stretch at 970 cm1 also shows a significant decrease in... 

Fig. 1. (a) A chemical structure of a 2.5th generation carboxylic acid-terminated poly(amido amine) (PAMAM) dendrimer. (b) Transmission surface enhanced infrared absorption spectra (SEIRAS) of dendrimer adlayers prepared at 30 min adsorption from aqueous solutions (0.01 wt.%) of a dendrimer at different pHs. Numerical values are pHs of the solutions, (c) Adsorption-desorption profiles as a function of time at different pHs and adlayer thicknesses at adsorption and desorption equilibrium as a function of pH for aqueous solutions (0.1 wt.%) of the dendrimer. The symbols, j and J, in the top figure denote start of adsorption and desorption, respectively. In the bottom figure, filled circle and opened square denote adlayer thicknesses at adsorption and desorption equilibrium, respectively. The dark tie denotes the calculated dendrimer size width. A solid curve is drawn to be visual, (d) Schematic illustration of dendrimers adsorbed at different pHs. Reprinted with permission from Ref. [69], 2006, American Scientific Publishers. 

The infrared absorption spectra of these compounds showed, however, that the compounds do not have the structure of type IV, but that the structure is in fact of the aldehyde-amine, addition type (V) that is, the compounds are analogous to aldehyde-ammonia compounds. The expected... 

Convert the following infrared absorption values from wavenumbers to micrometei (al A cyclopentanone, 1755 cm" (b) An amine, 3250 cm ... 

The near-infrared absorption of primary, secondary and tertiary aliphatic and aromatic amines has been studied extensively since 192530,31 in order to define the spectroscopic properties of the NH bond in a large number of amines. 

The weak absorption at 304 0 cm in the infrared spectrum would be indicative of the N-H stretch of secondary amines. The absorption at 1380 would be indicative of an ethyl, methyl, isopropyl or t-butyl group. The broad absorption at 1120 would be indicative of a C-N stretch, while the broad absorptions at 750 cm and 700 cm would be indicative of a monosubstituted benzene ring. Unfortunately one can only interpret infrared spectra if one is familiar with the various group characteristic peaks. There are no "easy" ways of interpreting ir spectra. 

Finally, we call attention to the remarkable stability of the complexes of nitrophenols ° and FAD (entries 48-51, Table II). This stability may be due to protonation of the adenine moiety of FAD by the phenols. Briegleb and Delle ° have detected salt formation in complexes of aromatic amines and picric acid (piT 1.8-10 ). They used infrared absorption spectroscopy and detected a typical salt band at 3.4 ju (2910 cm ). 

Toluene solutions of trilaurylammoniumchloride in equilibrium with dilute hydrochloric acid contain an amount of water which corresponds to amine salt monohydrate. In contact with hydrochloric acid of increasing concentration, the organic phase extracts increasing amounts of excess acid, whereas the water content decreases. From distribution studies with acidic concentrated chloride solutions, it can be concluded that the extraction of excess acid is due mainly to amine dihydrochloride formation. The water content is independent of excess acid present in the organic phase, and is proportional to the water activity. Physicochemical investigations of the organic phases (infrared absorption, conductivity, cryoscopic measurements) confirm the interpretation of analytical data as to amine dihydrochloride formation and to amine salt hydration. 

It was shown in section II.D.l that chemical methods for the analysis of groups attached to the nitrogen atom require drastic treatment. On the other hand i.r., n.m,r., and mass spectroscopy afford excellent methods for such studies. In sections II.B.6.b, II.C.1 l.a, and II.D.2 certain structural features of saturated amines yielding absorption bands in the infrared region were mentioned already, and no further treatment of i.r. spectroscopy will be made here. 

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