Abstract
N,N-dioctyl-azepanium, -piperidinium and -pyrrolidinium bromides 1-3, have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p) approach have been presented. Both FTIR and Raman spectra of 1-3 are consistent with the calculated structures in the gas phase. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants confirm the optimized geometry.
Highlights
Quaternary ammonium compounds (QACs) were introduced as antimicrobial agents by Domagk over seventy years ago [1]
The second generation of QACs was obtained by substitution of the aromatic ring in alkylbenzyldimethylammonium chlorides by chlorine or alkyl groups to get products like alkyldimethylethylbenzylammonium chloride with C12, 50%; C14, 30%; C16, 17% and C18, 3% alkyl distribution
The mixture of dialkyldimethylamoonium chloride with benzalkonium chloride (C12, 40%; C14, 50%; C16, 10%) is the newest blend of quaternary ammonium salts which represents the fifth generation of QACs [2]
Summary
Quaternary ammonium compounds (QACs) were introduced as antimicrobial agents by Domagk over seventy years ago [1]. The second generation of QACs was obtained by substitution of the aromatic ring in alkylbenzyldimethylammonium chlorides by chlorine or alkyl groups to get products like alkyldimethylethylbenzylammonium chloride with C12, 50%; C14, 30%; C16, 17% and C18, 3% alkyl distribution. One of the new groups with good antimicrobial activity are the cyclic quaternary ammonium salts [3]. Some cyclic quaternary ammonium salts have previously been obtained by intramolecular cyclisation of amine derivatives [4,5,6,7,8,9]. Another way, i.e. reaction of alkyl halides with cyclic amines, can lead to chiral cyclic quaternary ammonium salts [10]
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