Intramolecular easily polarizable hydrogen bonds with anilides of 1-piperidine carboxylic acids

✍ Scribed by B. Brzeziński; G. Zundel

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 470 KB
• Volume: 53
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(78)80418-7

✦ Synopsis

IR spectra are plotted from anihdes of l-piperidine carbosylic acids CsH reN-(CHa),CONHCeHa-R in CHCla and CDCis solutions. In the cases of n =L and tz =4. weak intramolecular (NH ---N) hydrogen bonds are formed. An asymmetrical energy surface occurs and the proton is present at the N of the anilide group. In the cases of n=2 and n =3, intramolecular proton transfer hydrogen bonds of the types NRH---NP t_NR---I?NP are formed. In contmst to the intramo- IecuIarOH---N=+O----H+N bonds with l-piperidine carbosylic acids, these bonds do not cause IR continua but two bands: one in the region 3250-3190 and one in the region 2500-2450 cm-t_ The fact that, instead of IR continua, bands are observed is esplained by the folIowing: (I) these hydrogen bonds are relatively long; (2) they show only a narrow distribution of bond length; (3) the electrical fields at these bonds are small. since they are strongly screened.