A calorimetric and computational study of the thermochemistry of halogenated 1-phenylpyrrole derivatives

Energetics of 1-(aminophenyl)pyrroles: A joint calorimetric and computational study

“…As was already noticed for 1-phenylpyrrole and derivatives, [5][6][7][8] the steric repulsions between the H of the a-C of pyrrole ring and the H (in the case of the 3-and 4-isomers), or the -NH 2 group (for the 2-isomer) of the phenyl ring at the ortho position, are minimum when these three isomers take a twist orientation with dihedral angles between the phenyl and pyrrole planes of 52.3°for 1-(2-aminophenyl)pyrrole, 36.6°for 1-(3-aminophenyl)pyrrole, and 41.1°for 1-(4-aminophenyl)pyrrole. The phenyl/pyrrole dihedral angle is higher in the 2-isomer due to the steric interactions caused by the proximity of the amino group and the hydrogen atom of the C10 of the pyrrole ring.…”

“…By fitting the experimental data to the integrated form of this equation, ln(p/Pa) = a À b Á (T/K) À1 , the standard molar enthalpy of sublimation of 1-(2-aminophenyl)pyrrole, at the mean temperature of For 1-(2-aminophenyl)pyrrole, the value of D g cr C p;m considered was À50 J Á K À1 Á mol À1 [34], a value that has already been used in previous papers of other pyrrole derivatives [1,[3][4][5][6][7][8]. The standard molar enthalpy, D g cr H m , entropy, D g cr S m , and Gibbs energy of sublimation, D g cr G m , at T = 298.15 K , are presented in table 5.…”

“…Among these nitrogen heterocyclic compounds studied are acetylpyrroles and their derivatives [1][2][3], pyrrolecarboxylic acids [4], and phenylpyrrole derivatives [5][6][7][8]. Following the same line of investigation, we have studied now the energetics of (aminophenyl)pyrroles, whose structural formulae are depicted in figure 1.…”

Interplay of thermochemistry and structural chemistry, the journal (volume 24, 2013, issues 5–6) and the discipline

“…In addition, the enthalpies of formation of 1-(3,5-dichlorophenyl)pyrrole, 1-(3,5-dichlorophenyl)-2-methylpyrrole, 1-phenyl-3-pyrrolecarboxaldehyde, and 2-methyl-1-phenyl-3-pyrrolecarboxaldehyde were also calculated. The current authors previously studied a variety of other substituted 1-phenylpyrroles; accompanying the parent species [168,169] is its p-methyl [169], p-fluoro, chloro, and iodo derivatives [170]. It has long been known that 1-phenylpyrrole can be thermally isomerized to its 2-phenyl isomer [171], reflecting the fact that the 2-phenyl isomer is more stable.…”

Energetics and molecular structure of alkyl 1-methylpyrrolecarboxylates (alkyl=methyl or ethyl)

“…Experimental and computational thermodynamic studies of pyrrole derivatives, with different substituent groups [1][2][3][4][5][6][7][8][9][10][11][12][13], have been developed in our Research Group during the last few years, with the main goal to correlate the effects of the corresponding molecular structures on the energetic characteristics of the compounds. Pyrrole moiety is the structural core of the naturallyoccurring porphyrins, the tetrapyrrolic ''pigments of life'', which include the hemoglobin, porphyrins, corrins, vitamin B 12 , the bile pigments and chlorophyll, playing an important role in respiration and photosynthesis processes [14][15][16][17][18].…”