Vibrational frequencies of an α para-dichlorobenzene crystal are calculated. By solving an inverse spectral problem, the series of force constants of an isolated p-C6H4Cl2 molecule were found. It was shown that this series can be carried over to the crystal model. This means that during crystallization, the electronic structure of a p-C6H4Cl2 molecule stays constant. Intermolecular interaction was modeled upon pseudo-bonds. Force constants were estimated from the calculation of intermolecular interaction energy, by the way of a Monte-Carlo simulation. Vibrational dynamics of the crystal and isolate molecule were analyzed. Absorption bands sensitive to the crystallization of the molecule were found.

A theoretical study of the γα and αβ phase transitions of p-dichlorobenzene with the aim of elucidating the effect of crystal forces on these transitions is presented. Our calculations are in agreement with experience concerning the necessities of microactivities for the nucleation. The Monte Carlo technique efficiently simulates the growth of the nucleus since the final positions of the molecules correspond to the positions given by the crystal structure with a statistical weight of about 30–40%.

It is shown that paraisopropylcalix [4] arene selectively complexes paraxylene from a 1:1:1 mixture of the three xylene isomers. The crystal structures of the complexes of paraisopropylcalix [4] arene with ortho and meta xylenes are isomorphous, crystallizing in the monoclinic group Cc. The complex with paraxylene is tetragonal (group P4/n). In the solid state, the macrocycle loses its 4 symmetry when complexed with ortho or meta xylene. Calculation of intra and intermolecular energies shows that the supramolecular energies are very similar, as are the macrocycle conformation energies of all three complexes. The result is that the phenomenon of molecular recognition observed can either be attributed to the greater number of efficient approaches between paraxylene and the macrocycle, due to its symmetry, in comparison to the other two isomers, or to the higher crystallization rate of the paraxylene complex in the considered medium. These conclusions are in agreement with the fact that crystallization with o- and m-xylene takes place after a much longer time than with p-xylene.

MMP2 calculations have been carried out to calculate the energies of activation for the interconversion of the p-isopropylcalix[4]arene conformers. They show that most of the barrier to inversion is to disrupt the circular hydrogen bonding.

This communication reports our studies on the solid state reactivity of 4-ethoxy-2-phenyl-1, 3-thiazin-6-one 1 with vapor of N, N-dimethylamine. The anisotropic behaviour of the reaction process is rationalized by atom-atom potential energy calculations.

Dans le cadre de l'hypothèse selon laquelle la formation de noyaux (nucléation) est l'étape préliminaire des transitions de phase, nous avons envisagé un réarrangement local concerté de molécules pour la transition de phase α-β du cristal de p-dichloro-benzène. La valeur (13 kcal. mole -1) de la barrière de potentiel nécessaire à cette nucléation, calculée selon une méthode potentiel atome-atome, permet d'envisager comme possible un tel processus de nucléation.

Langmuir-Blodgett (LB) monolayers of p-octadecylbis homooxacalix[4]arene 1 were formed at the air-water interface, in the presence of sodium hydroxide, with a solid state packing. The structure of the solid state was investigated by X ray diffraction techniques and the molecular packing was modeled by minimum energy calculations.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheoretical determination of relative stabilities of various polymorphs of organic substances: application on para-substituted phenolsJ. Royer, C. Decoret, B. Tinland, M. Perrin, and R. PerrinCite this: J. Phys. Chem. 1989, 93, 9, 3393–3396Publication Date (Print):May 1, 1989Publication History Published online1 May 2002Published inissue 1 May 1989https://pubs.acs.org/doi/10.1021/j100346a006https://doi.org/10.1021/j100346a006research-articleACS PublicationsRequest reuse permissionsArticle Views49Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

Single crystals of 2-phenyl-4H-3,1-benzoxazin-4-one,1,(a = 13.315 Å, b = 3.912 A, c = 20.465 Å, β = 94.93°, Z = 4, P21/n, R = 0.047) have been found to undergo hydrolysis at room temperature. Reacting single crystals were observed to react first at needle ends of crystals with the reaction proceeding along the b axis of the needle. The chemical mechanism and the reaction pathway in the solid is rationalized by chemical results (analysis of mass spectra resulting from 180 water experiments) and theoretical calculations based on the X-ray data. Evaluation of occupied and free-space in crystal 1 is obtained by the method of Gavezzotti.

AbstractA possible reaction path for the polymorphic transformation of trans‐trans solid diacetamide into its trans‐cis from is envisaged. A description of the two crystalline forms in the same crystallographic system is adopted, and the energy profile of the crystallographic reaction path is calculated by using an empirical 6‐exp. atom‐atom potential method and a 6‐13G ab initio procedure for the inter‐ and intramolecular contributions, respectively. Two barriers appear along the reaction path. The first corresponds to the destruction of the trans‐trans chains and the second to the formation of the trans‐cis dimers. These barriers, being lower than the acetyl rotation barier, are in agreement with the ability to isomerize diacetamide in solid state. The presence of a small energy minimum between these barriers would suggest the existence of an intermediate crystallographic form.

Abstract This communication reports the study of the reactivity of single crystals of benzoxazinones 1 and 2 and naphtoxazinones 3 and 4. Single crystals 1, 2 and 4 react anisotropicly while single crystal 3 reacts randomly. The crystalline structures of 3 and 4 have been determined. The experimental results are rationalized by the use of the program of Gavezzotti and the program of Caillet and Claverie.

Using as hypothesis a second order transition and a pure cooperative mechanism, energy calculations were performed for the polymorphic transformation of Z,Z solid diacetamide into its E,Z form along a possible pathway. The low calculated barriers are in agreement with the ability of diacetamide to isomerize.

Dans cette communication, nous montrons comment les différentes réactivités observées pour une réaction cristal gaz dans une même série de composés peuvent être interprétées par les différences dans leur arrangement cristallin et dans leur force de cohésion. Ces interprétations permettent une meilleure approche du mécanisme réactionnel. L’hydrolyse gazeuse de monocristaux de benzoxazinones 1 se fait d’une façon anisotrope, alors que celle de naphtoxazinones 2 se fait d’une façon isotrope. Le modèle théorique montre que les cristaux 1 contiennent des canaux parallèles à la direction de la réaction. Au contraire les cristaux 2 ne présentent pas de canaux. Des calculs évaluant la force de cohésion à la surface des cristaux 1 et 2 sont présentés.

Chemischer InformationsdienstVolume 17, Issue 7 Physical Organic Chemistry ChemInform Abstract: Substituent Effects on Aromatic Ring: Theoretical Studies of Molecular Geometries of Alkylphenols (Vergleich nach MM2 berechneter Daten für 3-Methyl-2-, -4-, -5-, -6-isopropyl-phenol, 2,3-, 2,5-, 2,6-, 3,4-Dimethyl-phenol sowie o-, m- und p-Kresol mit kristallographischen Daten). C. DECORET, C. DECORETSearch for more papers by this authorB. TINLAND, B. TINLANDSearch for more papers by this authorG. BERTHOLON, G. BERTHOLONSearch for more papers by this author C. DECORET, C. DECORETSearch for more papers by this authorB. TINLAND, B. TINLANDSearch for more papers by this authorG. BERTHOLON, G. BERTHOLONSearch for more papers by this author First published: February 18, 1986 https://doi.org/10.1002/chin.198607064AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume17, Issue7February 18, 1986 RelatedInformation

Three of our recent attempts to study the mechanism of organic reactions in the solid phase are presented. The stability of organic crystals of monotropic polymorphic substances is studied. Also described are the rearrangement of orthocyclohexadienone into paracyclohexadienone and the solid state hydrolysis of acetylanthranyl. In all cases it is shown that organic single crystals are useful for the study of reaction mechanisms.

AbstractKinetic studies of hydrolysis and deuteriolysis of microcrystalline 2‐methyl‐4H‐benzoaxazin‐4‐one 1 into N‐acetylanthranilic acid 2 are presented. Hydrolysis of mixtures of microcyrstalline 1 and 2 are given. The results are interpreted and a mechanism is proposed for the solid gas reaction. A theoretical approach of the crystal packing of 1 permits an evaluation of the mode of diffusion of water molecules in the crystal. Both experimental and theoretical results lead to a proposal of the mechanism of water propagation and the hydrolysis process in the solid phase.