Paolo Cardillo

The N⋯I Intermolecular Interaction as a General Protocol for the Formation of Perfluorocarbon–Hydrocarbon Supramolecular Architectures 1

Abstract The formation of infinite 1D networks where diiodoperfluorocarbons are halogen bonded to di-nitrogen substituted hydrocarbons is described. The N⋯I non-covalent interaction is specific, directional, and strong enough to effectively overcome the low affinity between perfluorocarbon and hydrocarbon modules and to drive their self-assembly in the solid and liquid phase. Several analytical techniques are used to identify and characterise the electron donation from nitrogen to iodine atoms. The effectiveness of the interaction is largely independent from the overall structure of the involved modules. Indeed, supramolecular architectures have been obtained starting from diiodoperfluoroalkanes and -arenes (electron poor motifs) as well as from pyridine derivatives and di- or trialkylamines (electron rich motifs). The halogen bonding can thus begin to be considered as a first choice intermolecular interaction in crystal engineering.

Perfluorocarbon—hydrocarbon self assembling. Thermal and vibrational analyses of one-dimensional networks formed by α,ω-diiodoperfluoroalkanes with K.2.2. and K.2.2.2.

Abstract When perfluorocarbon diiodides 1 and hydrocarbon diamines 2,3 are co-crystallised from chloroform a donor-acceptor interaction between the nitrogen atoms of 1 and the iodine atoms of 2, 3 lead to the formation of infinite one-dimensional coordination networks 4 and 5 . Thermal and infrared analyses of these adducts are reported. Nitrogen-iodine interaction is proposed as a non-covalent bonding strong enough to drive the formation of co-crystals between fluorocarbon and hydrocarbon derivatives.

Theoretical and calorimetric evaluation of thermal stability of glycidol

Abstract Several thermoanalytical and calorimetric techniques, such as differential scanning calorimetry, accelerating rate calorimetry and heat flow calorimetry, were used to check the thermal stability of glycidol and glycidolisopropanol mixtures. The influence of some impurities on polymerization were also evaluated. Chemical thermodynamic and energy release evaluation were first assessed by the CHETAH computer program developed by ASTM.

The Seveso case and the safety problem in the production of 2,4,5-trichlorophenol

Abstract Extensive investigations of the “Seveso mixture” by advanced thermoanalytical techniques and engineering experiments allow an explanation of the Seveso accident and a definition of the criteria for conduction of the process for the production of 2,4,5-trichlorophenol. A critical comparison of the process in methanol and in ethylene glycol as reaction medium points to the latter as being more controllable and consequently safer.

Reactivity limits of aluminium and halohydrocarbon mixtures: determination by the ASTM CHETAH program

Abstract The CHETAH program has been successfully used to assess potential hazards of binary mixtures of aluminium with several halogenated compounds. From this thermochemical evaluation, conducted on more than 2000 mixtures, it was possible to distinguish mixtures with very low reactivity from mixtures with high reactivity delimited by two well defined concentrations of Al. These two concentration limits,analogous to flammability limits, can be considered as upper and lower reactivity limits. The CHETAH evaluation,carried out on mixtures with the highest reactivity values, in the presence of different amounts of an ‘inert’ compound (heptane), gives a triangular reactivity diagram similar to that frequently used in flammability characterization of combustible gases and vapours.

Thermal hazard assessment using Closed-Cell Adiabatic Calorimetry

Adiabatic Calorimetry is a suitable technique for characterising highly exothermic processes, such as decomposition reactions. Closed-Cell Adiabatic Calorimetry (CCAC) has been used for years as a reference technique for thermal hazard assessment of pure chemicals and mixtures. In this paper some of the results of a comparison study involving two of the most popular adiabatic calorimeters, ARC and PHI-TEC II, are presented. This project was carried out during 1994 and 1995 at the Stazione Sperimentale per i Combustibili (Italy) and at the Chemical Engineering Department of the Institut Quimic de Sarria (Spain).

Calorimetric data for hazard process assessment: alkene epoxidation with peracids

Abstract Reaction calorimetry is a very efficient tool to obtain quantitative data under realistic process conditions for the development and optimization of chemical processes. In this paper, a new example of the application of reaction calorimetry in process development is presented. The process under investigation was an epoxidation reaction with peracid.

Hazardous N-containing system: thermochemical and computational evaluation of the intrinsic molecular reactivity of some aryl azides and diazides

The exothermic decompositions of the tosyl azide 1, five substituted aryl monoazides 2––6 and two diazides: 1-azido-4-(4-azidophenoxy)benzene 7 and 1-azido-4-[(4-azidophenyl)sulfanyl]benzene 8 were studied experimentally using DSC, weight loss TGA-FTIR and C80-FTIR techniques, and theoretically using the CHETAH software. Numerical modelling and electron impact mass spectrometry (EI-MS) were also performed to investigate the nature of the intrinsic molecular reactivity of azides 1––8, and the possible early stage rate-controlling of an oxidative self-heating process. Significant data were obtained in the instances of 4-methylbenzenesulfonyl azide 1, 4-azido-1,1′-biphenyl-2,2-azido-1,1′-biphenyl 3 and 1-azido-2-(trifluoromethyl)benzene 6. The most likely decomposition pathways of the azides are proposed to explain the observed thermal behavior.

Some historical accidental explosions

Abstract In the pioneering period, at least until half way through the 19th century, the modern figure of the ‘chemist’ did not exist. The researchers were mostly philosophers, doctors and pharmacists, who were interested in that part of science known as ‘chemistry’ or described by the word ‘chemistry’. Some became chemists for passion and others vocation, urged on by a deep desire to challenge very often the dangers connected with their manipulations and to work in environmental conditions that today would be unthinkable. By reading old books of chemistry and the history of chemistry we learn that some of the greatest chemists of the past, the fathers of chemistry, have sometimes been involved in accidental explosions, some of which were serious. In this paper there is a short collection of historical accidental explosions where the protagonists were some of our great predecessors.

Application of d.s.c. with atmospheric control in thermal hazard evaluation : a discussion of the sources of error

Abstract Since differential scanning calorimetry is a dynamic temperature technique, there are several factors which can affect the resulting experimental curves. For example, it is well known that changing from nitrogen to air atmosphere can create additional exothermic peaks. However, during routine determinations into closed pans, the influence of static air remaining in the crucible is often forgotten. The aim of this paper is to emphasize the importance of performing such tests in a completely inert atmosphere; even minimal traces of air can cause misinterpretations and consequently the use of unnecessary safety measures that could penalize the process. A simple device that allows crucibles to be closed directly in an inert atmosphere, is described.