In order to study the keto and enol forms of cyanuric acid derivatives in the solid state, we have synthesized bis(2,4-benzyloxy)-6-(5H)-one-1,3,5-triazine, 1. Computational investigations indicate that keto form is more stable than enol form in both gas phase and solution phase
by 9.69–11.18 kcal mol−1 IR and crystallographic analysis shows that 1 exists in keto form in the solid state also. To obtain the enol form in the solid state, we adopted co-crystallization with
an organic base. The crystal structures of both keto/amine and the enol/imine forms (in a co-crystal) are reported.
[Show abstract][Hide abstract] ABSTRACT: In the crystal of triclinic symmetry the title compound contains four independent molecules, which differ in the conformation
of the aliphatic carbon chain (T, G
−) and in the helicity (M or P) of the N-(1,8-naphthaloyl)-2-aminobenzoate (NAB) unit. Quantum chemical MP2 calculations showed that isolated molecules favor helicity
of NAB bichromophores most likely due to attractive interactions between local dipoles formed along carbonyl bonds, such that
the helical arrangement of O=C–C–C–N–C=O fragments is stabilized by intramolecular interactions between terminal anti-parallel
local carbonyl dipoles. In the crystal structure, columnar stacking of the anti-parallel 1,8-naphalimide rings is observed.
In a column the neighboring NAB units display opposite helicity.
[Show abstract][Hide abstract] ABSTRACT: AbstractIn the current study we relate the contents of the journal of “Structural Chemistry” for the calendar year 2006 to thermochemistry.
Each paper is briefly summarized and supplemented by a comment which explicitly interrelates the content of the study to chemical
[Show abstract][Hide abstract] ABSTRACT: The electrospray ionization collisionally activated dissociation (CAD) mass spectra of protonated 2,4,6-tris(benzylamino)-1,3,5-triazine (1) and 2,4,6-tris(benzyloxy)-1,3,5-triazine (6) show abundant product ion of m/z 181 (C(14) H(13)(+)). The likely structure for C(14) H(13)(+) is α-[2-methylphenyl]benzyl cation, indicating that one of the benzyl groups must migrate to another prior to dissociation of the protonated molecule. The collision energy is high for the 'N' analog (1) but low for the 'O' analog (6) indicating that the fragmentation processes of 1 requires high energy. The other major fragmentations are [M + H-toluene](+) and [M + H-benzene](+) for compounds 1 and 6, respectively. The protonated 2,4,6-tris(4-methylbenzylamino)-1,3,5-triazine (4) exhibits competitive eliminations of p-xylene and 3,6-dimethylenecyclohexa-1,4-diene. Moreover, protonated 2,4,6-tris(1-phenylethylamino)-1,3,5-triazine (5) dissociates via three successive losses of styrene. Density functional theory (DFT) calculations indicate that an ion/neutral complex (INC) between benzyl cation and the rest of the molecule is unstable, but the protonated molecules of 1 and 6 rearrange to an intermediate by the migration of a benzyl group to the ring 'N'. Subsequent shift of a second benzyl group generates an INC for the protonated molecule of 1 and its product ions can be explained from this intermediate. The shift of a second benzyl group to the ring carbon of the first benzyl group followed by an H-shift from ring carbon to 'O' generates the key intermediate for the formation of the ion of m/z 181 from the protonated molecule of 6. The proposed mechanisms are supported by high resolution mass spectrometry data, deuterium-labeling and CAD experiments combined with DFT calculations.
Journal of Mass Spectrometry 07/2012; 47(7):860-8. DOI:10.1002/jms.3037 · 2.38 Impact Factor
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