tailieunhanh - THE VAPRO PRESSURE OF ENVIRONMENTALLY SIGNIFICANT ORGANIC CHEMICALS: AREVIEW OF METHODS AND DATA AT AMBIENT TEPERATURE

Much attention has increasingly been paid on safety, health and environmental issues, not only in industry but also in the university. Small scale experiments are safer in lowering the risk of chemical contact, more environmentally friendly, produce less waste and gain many other benefits. Although several universities are familiar with small scale chemistry and some universities have operated small scale chemistry laboratories successfully, several other universities have not yet adopted these practices, particularly for organic chemistry laboratory. Due to the nature of the organic chemistry laboratory which is more complicated than the general chemistry laboratory, many kinds of special. | The Vapor Pressure of Environmentally Significant Organic Chemicals A Review of Methods and Data at Ambient Temperature Alessandro Delle Site ENEA Environmental Department AMB-TEIN Via Anguillarese 301 00060 Rome Italy Received 19 May 1996 revised manuscript received 10 September 1996 The experimental techniques and the prediction procedures for the determination or evaluation of the vapor pressure of environmentally relevant organic compounds are described with 259 references examined. For each of them the characteristics of precision and accuracy are given when available from the literature. The experimental methods are classified as direct and indirect. The first class includes all those which can measure directly the vapor pressure while the second concerns those which need known vapor pressures of reference compounds for the calibration. Prediction methods are based on the application of the Clapeyron-Clausius equation or on the quantitative structure-property relationships. Also correlation methods require a suitable calibration. The vapor pressures at ambient temperature for several polycyclic aromatic hydrocarbons polychlorinated biphenyls polychlorinated dibenzo-p-dioxins and furans selected pesticides and some reference compounds are tabulated together with the vapor pressure equations and the enthalpy values in the temperature range of measurement. A critical comparison based on a statistical analysis of the data obtained with different methods and derived from 152 references is also carried out. 1996 American Institute of Physics and American Chemical Society. S0047-2689 96 00206-1 Key words chlorinated biphenyls chlorinated dioxins critically reviewed data critically reviewed methods pesticides polynuclear aromatics vapor pressure. Contents 1. Introduction. 157 2. Experimental methods. 158 . Direct experimental methods. 158 . Manometric methods. 158 . Boiling point at reduced pressures. 159 . Effusion. 160 . Gas saturation. 161 .