Thermodynamic Study of Chlorobenzonitrile Isomers: A Survey on the Polymorphism, Pseudosymmetry, and the Chloro···Cyano Interaction

Abstract

The relationships among structural and thermodynamic properties of 2-, 3-, and 4-chlorobenzonitrile were investigated, in the present work, using several experimental techniques (Knudsen effusion, differential scanning calorimetry, and combustion calorimetry) and computational studies. The CN···Cl intermolecular interactions are weaker in 2-chlorobenzonitrile, reflecting a lower enthalpy of sublimation. The two polymorphic forms of 4-chlorobenzonitrile were observed by differential scanning calorimetry and interpreted in terms of the strength of CN···Cl intermolecular interactions. The entropic differentiation due to the pseudosymmetry observed in the crystalline packing of 2-chlorobenzonitrile was evaluated. Using adequate working reactions and the respective standard molar enthalpies of formation, in the gaseous phase, the halogen-cyano intramolecular interaction was also evaluated. The theoretically estimated gas-phase enthalpies of formation were calculated using high-level ab initio molecular orbital calculations at the G3MP2B3 and MP2/cc-pVTZ levels of theory. The computed values support very well the experimental results obtained in this work.

Experimental Investigation on Physical, Thermal and Spectroscopic Properties of 2-Chlorobenzonitrile: Impact of Biofield Treatment

“…[33]. Besides, the molecules of 2-ClBN do not possess an organized structure as the molecular layers Properties of 2-Chlorobenzonitrile: Impact of Biofield Treatment are not perfectly overlapping with each other [34]. It is presumed that biofield energy may be absorbed by the treated 2-ClBN molecules that may lead to increasing the symmetry of 2-ClBN molecules by formation of a symmetrical crystalline long range pattern.…”

“…3). It was previously reported that 2-ClBN molecules possess CN---Cl intermolecular interactions but these interactions are weak in nature due to which 2-ClBN molecules possess lower enthalpy of sublimation as compared to other isomers [34]. It was hypothesized that biofield energy was absorbed by 2-ClBN molecules that possibly strengthened the intermolecular bonding between chlorine-cyano groups in 2-ClBN molecules.…”

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

“…Meaningful thermochemical comparison can be made with the related fluoro- [154], chloro- [155], and iodo-benzonitriles [156].…”

Benchmark thermochemistry of methylbenzonitriles: Experimental and theoretical study

“…Because of their rich chemistry, cyano substituted benzenes (i.e., benzonitriles) are important intermediates in organic synthesis [1]. While the thermochemical properties of some benzonitriles of interest are known [2][3][4][5][6][7], those for several other simple CN substituted benzenes have yet to be determined. This hinders our knowledge of these aromatic compounds, and prevents the quantitative study of the chemical reactions in which they take part.…”