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Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
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A comparative study on vibrational, conformational and electronic structure of 2-chloro-4-methyl-3-nitropyridine and

V Arjunan1, I Saravanan, Mariusz K Marchewka

  • 1Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry, India. varjunftir@yahoo.com

Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|March 27, 2012
PubMed

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Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
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The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...
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