Infrared spectra of amines

Infrared spectra of amines and carbon dioxide adducts of amines... 

The IEs on amine basicity are also due to changes in vibrational frequencies, not only computationally but also experimentally. Gas-phase IEs of O.lOkcalmol-1 per CD3 group on basicities of methylamine, dimethy-lamine, and trimethylamine can be reproduced by ab initio force constants for C-H stretching, which increase on TV-protonation.100 Infrared spectra of amines show characteristic bands (called Bohlmann bands ) in the 2700-2800 cm-1 region, lower than the 2900 cm-1 of a typical C-H stretch.169,170 Upon /V-protonation these bands revert to a typical, higher frequency. Therefore the zero-point energy of the C-H increases on... 

Infrared The absorptions of interest in the infrared spectra of amines are those associated with N—H vibrations. Primary alkyl- and arylamines exhibit two peaks in the range 3000-3500 cm which are due to symmetric and antisymmetric N—H stretching modes. 

The infrared spectra of amines show one or two N-H stretches in the 3500-3200 cm-1 region. Primary amines usually have two bands, while secondary amines usually have one band. Obviously, since there are no N-H bonds, tertiary amines have no N-H stretch. The bands are small and sharp in comparison the corresponding alcohol peaks. 

After this we embarked upon a comprehensive study of the infrared spectra of amine complexes of platinum and palladium. By we, I don t just mean Joe, the leader, and myself, but Alan Williams, George Gamlen, Bernard Shaw and last, but far from least, Luigi Venanzi who had the gift of being able to synthesise any compound you could think of which might have an interesting infrared spectrum. Incidentally I remember him not just for his chemical skills but as the most... 

Take et al studied the infrared spectra of amines adsorbed on montmorillonite pillared with AI2O3 or Z1O2 and calcined at 723 K. From the intensities of the bands due to adsorbed pyridine, the number of Bronsted and Lewis acid sites on the AI2O3 — pillared montmorillonite were estimated to be 0.36 and 0.93 mmol g", respectively, and those on the Zr02 pillared material to be 0.32 and 0.92 mmol g , respectively. Competitive adsorption of pyridine and isoamyl amine revealed that about 30 percent of Brensted acid sites was located on the external surface of the pillared montmorillonites. 

Section 22 19 The N—H stretching frequency of primary and secondary amines appears m the infrared m the 3000-3500 cm region In the NMR spectra of amines protons and carbons of the type H—C—N are more shielded than H—C—O... 

The present authors have found that the preparation of 7V-acetyl aziridine derivates provides the most secure method of differentiating aziridines from primary amines which are alternate reaction products in a number of cases. The infrared spectra of the former derivatives show only a peak at 1690 cm" for a tertiary amide peaks at ca. 3440 and 1530 cm" indicative of a secondary amide are absent. Acetylation also shifts the aziridine ring protons to a lower field in the NMR by ca. 1 ppm relative to the parent aziridine. The A"-acetyl aziridines are hydrolyzed with 3% methanolic potassium hydroxide. " Published NMR spectra of several 16j5,17j -aziridines reveal resonance patterns resembling those of the respective epoxides. " ... 

The intermediacy of an aminal in the formation of enamines from ketones and secondary amines is not usually proposed. The only direct evidence for this is the infrared spectra of the reaction mixtures produced when dimethyl-or diethylamine was allowed to react with cyclohexanone or cyclopentanone... 

Similarity with cobalt is also apparent in the affinity of Rh and iH for ammonia and amines. The kinetic inertness of the ammines of Rh has led to the use of several of them in studies of the trans effect (p. 1163) in octahedral complexes, while the ammines of Ir are so stable as to withstand boiling in aqueous alkali. Stable complexes such as [M(C204)3], [M(acac)3] and [M(CN)5] are formed by all three metals. Force constants obtained from the infrared spectra of the hexacyano complexes indicate that the M--C bond strength increases in the order Co < Rh < [r. Like cobalt, rhodium too forms bridged superoxides such as the blue, paramagnetic, fCl(py)4Rh-02-Rh(py)4Cll produced by aerial oxidation of aqueous ethanolic solutions of RhCL and pyridine.In fact it seems likely that many of the species produced by oxidation of aqueous solutions of Rh and presumed to contain the metal in higher oxidation states, are actually superoxides of Rh . ... 

Only equivocal chemical evidence appears to be available for the unsubstituted aminoimidazoles. The failure of 2-aminoimidazole to undergo diazotization was originally interpreted to indicate that it existed in the imino form more recently, the 4-amino analog has been reported to behave as a normal aromatic amine. The infrared spectra of substituted aminoimidazoles of type 192 193 were con-... 

Figure 2. Infrared spectra of a Na" and exchanged clays following the uptake of cyclohexylamine. Absorptions at 1585 and 1525 cnT are characteristic of the neutral and protonated amine species, respectively.

Powell, D. B., Scott, J. G. Infrared spectra of the thiophosphates of tris(ethylenedi-amine)cobalt(IIl). Spectrochim. Acta28A, 1067 (1972). 

Figure 1. Comparison of the IR spectra of amine salts taken in KBr pellets on a Perkin-Elmer 337 Grating Infrared Spectrometer. AB, AS, and DAD are 1,4-diaminobutane, 3-aminopropyltriethoxysilane, and 1,12-diaminododecane, respectively [2].

The infrared spectra of solid M-2-naphthyl- and AT-o-tolyl-n-glucosyl-amine are considered by Legay as giving evidence for these compounds having a Schiff-base structure. Both give a peak at 6.05 n, usually caused by ... 

An analogous reaction can be effected for primary amine products. The similarities in the infrared spectra of the anions in the sodium and alkylammonium salts support the structures proposed for these products. The stabilities and properties of the products obtained from various amines have been described (12). When hindered amines are employed, no product is obtained, presumably because of a steric effect. By analogy with the structure of S03N202 , the following structure is proposed for the anion. 

Methylation and acetylation provide confirmatory evidence for the assignment of various bands to aliphatic components in the humic substances (Wagner and Stevenson, 1965 Flaig et al., 1975 Stevenson, 1982). The presence of amine groups in a peat fulvic acid has been confirmed by observing the changes in the infrared spectra of the sample following reaction with nitrous acid (MacCarthy and O Cinneide, 1974). 

Fig. 16. Infrared spectra of polyf-y-benzyl glutamate) formed in polymerization of S-87%rNCA by hexyl-amine in dimethylformamide (48). Number of samples corresponds to that in Table 10...

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