The Laboratory Assistant
The LaboratoryBÜCHI Labortechnik AGPostfach9230 FlawilSwitzerlandTel. 41 71 394 63 63Fax 41 71 394 65 65buchi@buchi.comwww.buchi.comISBN 978-3-033-01315-5Quality in your handsThe Laboratory AssistantAssistant
The LaboratoryAssistant
ImpressumProject/ Technical editingFirst editionThird editionCaroline Portmann, Samuel Flückiger,Thomas Ziolko, Andreas Tauer,Alex Wiprächtiger, Jörg MüllerSabine Kleinhans, Cordin Arpagaus,Gerhard SchönenbergerBüchi Labortechnik AG, CH-9230 FlawilDesign byCavelti AG, Druck und Media, CH-9201 GossauCTP and Printing byCavelti AG, Druck und Media, CH-9201 GossauBound byNoch ausstehend! Noch nachliefern!Copyright 2007 by Büchi Labortechnik AG,CH-9230 FlawilFurther publications:Laboratory Chromatography Guide,ISBN 3-033-00339-7All rights reserved. No part of this book may be reprinted, or reproduced, orutilized in any form or by any electronic or mechanical means, now known orhereafter invented, including photocopying and recording, or in any informationISBN 978-3-033-01315-5 storage and retrieval system, without permission in writing from the publisher.Third editionPrinted in Switzerland
«The Laboratory Assistant» – an indispensable aide for your dailylaboratory work!The stimulus for innovation is the conversion of visions into the reality. Since decades, Buchi has supported this philosophy very successfully with new productinnovations for evaporation and separation. With the continual development ofmethods and technologies for the laboratory, we have the pleasure of presentingthe revised edition of the «Laboratory Assistant».This guide will help you acquire a broader and deeper understanding of severalof the most widely used laboratory instruments, as rotary evaporators, vacuumpumps, and instruments for melting point deter mination. The equipment shownin the illustrations are all products of Büchi Labortechnik.The chapters of the book, have been created in as general terms as possibleso that they will also apply to equipment supplied by other manu facturers.I wish all readers of this «Laboratory Assistant» an interesting time in readingthe book, and a challenging and successful work in the laboratory!Dr. Reinhardt Büchi
ContentsPart A eparation of mixtures using a rotary evaporator,Sthe glass oven and a spray dryer11.11.21.3Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Areas where rotary evaporators, drying ovens and spray dryersare utilized. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Historical development of the rotary evaporator. . . . . . . . . . . . . . . . . . . 1414 cal basis for distillationThermodynamic basis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conditions of state, phase transitions . . . . . . . . . . . . . . . . . . . . . . . . . .Boiling point, vapor pressure, and evaporation heat. . . . . . . . . . . . . . . .Vapor pressure curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Evaporation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Retarded boiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Condensation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sublimation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport of gas through the equipment . . . . . . . . . . . . . . . . . . . . . . . .Separation of mixtures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Separation by distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Separation effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ideal mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Non-ideal and azeotropic mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . .Improvement of the separation effect. . . . . . . . . . . . . . . . . . . . . . . . . . .Drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6.23.6.3Design of the rotary evaporatorSchematic design of a rotary evaporator. . . . . . . . . . . . . . . . . . . . . . . .Heat supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The heat source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Heat transfer media. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The drive and the support frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The motor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The jack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The sealing system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The glassware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The evaporation flask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The glass assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The receiving flask. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The vacuum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Description of important accessory equipment . . . . . . . . . . . . . . . . . . .The temperature probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The Combi-Clip. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Other accessory equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323333333334343434343435383839393940
44.14.24.34.3.14.3.24.3.34.3.44.44.54.64.7Rotary evaporator applicationsPossible distillations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Determining the optimum conditions for temperature and pressure. . . .The distillation process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Preparations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Starting distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ending distillation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Environmental distillation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Distillation of mixed solvents using the automatic function. . . . . . . . . . .Safety precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.55.6Design of the glass ovenSchematic design of the glass oven . . . . . . . . . . . . . . . . . . . . . . . . . . .The control section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The heater section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The drying accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The distillation accessory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The sublimation accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The bulb-tube drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The freeze drying accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515152525253545456 57575757585962626364 65666 Glass oven applications6.1 Possible applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.2 Determing the optimum conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . .6.3 Distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.3.1 Single distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.3.2 Fractional distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.4 Drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.5 Sublimation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.6 Safety precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.7 Ecological and economic considerations. . . . . . . . . . . . . . . . . . . . . . . .6.8 Table of solvents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.9 Working pressures for different vapor temperaturesof various solvents [mbar] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.10 Vapor pressure curves for various solvents . . . . . . . . . . . . . . . . . . . . . .
ContentsPart BSpray Drying11.11.21.3Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .What is Spray Drying?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Particle shapes and structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6868686922.12.22.32.4Theoretical basis of the spray drying process. . . . . . . . . . . . .Feed preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Atomization and hot gas contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Evaporation, particle shape formation and drying . . . . . . . . . . . . . . . . .Separation of the dried product from the gas and discharge. . . . . . . . . 707070727333.13.23.3Design of the Mini Spray Dryer B-290. . . . . . . . . . . . . . . . . . . .Spray drying principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Open and closed mode configurations . . . . . . . . . . . . . . . . . . . . . . . . .Spray chilling accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7474757744.14.24.34.44.54.6Optimizing the spray drying process parameters. . . . . . . . . .Inlet temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Aspirator rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Feed pump rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Feed concentration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Gas spray flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Procedure to run a spray drying experiment . . . . . . . . . . . . . . . . . . . . . 787980808080815Spray drying applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 826Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 876Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Part C11.11.21.3Generation of a vacuumIntroductionOverview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . History of the development of vacuum generation. . . . . . . . . . . . . . . . . Applications for vacuums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90909222.12.22.2.12.2.22.3Theoretical basis for the generation of vacuumDefinition of a vacuum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Basic gas theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The laws of gases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Transport processes within the gas. . . . . . . . . . . . . . . . . . . . . . . . . . . .Measurement of vacuum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 949595979833.13.1.13.1.23.2Vacuum regulationChanges in pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Leakage air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Leak detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Maintaining a constant pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101102102103Survey of types of pumpsOil-sealed rotary pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oil-free displacement pumps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vapor pumps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104104106Vacuum pump technologyThe diaphragm pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Design and operation of the diaphragm pump. . . . . . . . . . . . . . . . . . . .Economic and ecological considerations. . . . . . . . . . . . . . . . . . . . . . . .The water jet pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Design and operation of the water jet pump . . . . . . . . . . . . . . . . . . . . .Economic and ecological considerations. . . . . . . . . . . . . . . . . . . . . . . . 107107109110110110 112112112112113113114 114 .26 Application of vacuum systems in the laboratory6.1 Selection of vacuum systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.1.1 Suction output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.1.2 Final vacuum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.1.3 User-friendliness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.1.4 Financial aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.1.5 Reduction of emissions into the exhaust air and waste water . . . . . . . .6.2 Comparison of the PTFE-diaphragm pump and the water injector pump. .6.3 Design of a complete vacuum system based ona PTFE-diaphragm pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.4 Instructions, parameters, and special features ofseveral laboratory applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.4.1 Vacuum for distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.4.2 Vacuum for filtration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.4.3 Vacuum for drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.5 Precautionary actions and dangers involved . . . . . . . . . . . . . . . . . . . . .
ContentsPart D11.11.21.31.4Melting pointIntroductionWhat is a melting point? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Why measure melting points?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Who measures melting points?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .The boiling point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1201201211222 Theoretical basis for the measurement of boiling pointsand melting points2.1 Physical states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 Phase transitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2.1 Phase diagrams for 1-material systems (state diagrams). . . . . . . . . . . .2.3 What happens during melting? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4 The boiling point, or «What happens during evaporation»? . . . . . . . . . .2.5 The range between the boiling point and the melting point . . . . . . . . . .2.6 Melting point depression and the mixed melting point. . . . . . . . . . . . . .2.6.1 Melting point depression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.6.2 Mixed melting point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.6.3 The eutectic point. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123124124126127129129129130130 131131132134134134136 136137137 1381381401401411411411421431441451461473 Principles and methods of melting point determination3.1 Methods of melting point determination. . . . . . . . . . . . . . . . . . . . . . . . .3.1.1 Determining the melting point in the capillary tube. . . . . . . . . . . . . . . . .3.1.2 Immediate melting point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.2 Principles of melting point determination. . . . . . . . . . . . . . . . . . . . . . . .3.2.1 Melting point determination according to the pharmacopoeia. . . . . . . .3.2.2 Thermodynamic determination of melting points. . . . . . . . . . . . . . . . . .3.3 Melting point determination yesterday and today – an overview. . . . . . .3.3.1 Instruments for melting point determinationover the course of the years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.3.2 From silicone oil to the metal block. . . . . . . . . . . . . . . . . . . . . . . . . . . .3.3.3 Data Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54.6Melting point determination using the Büchi B-545Operating Principle of the Büchi B-545. . . . . . . . . . . . . . . . . . . . . . . . .Automatic Determination of the melting points. . . . . . . . . . . . . . . . . . . .Metal heating block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Structure of the Büchi Melting Point B-545. . . . . . . . . . . . . . . . . . . . . .Melting point determination procedure with the Büchi B-545. . . . . . . . .Preparation of the samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Temperature settings and rate of heat rise. . . . . . . . . . . . . . . . . . . . . . .Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Flow charts for a melting point determination with the Büchi B-545. . . .Substances with a known melting point or range. . . . . . . . . . . . . . . . . .Substances with an unknown melting point or range. . . . . . . . . . . . . . .Boiling point determination with the Büchi Melting Point B-545. . . . . . .Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55.15.25.35.46Data quality – accuracy controlPharmacopoeia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Avoiding errors in melting point determination. . . . . . . . . . . . . . . . . . . .GLP (Good Laboratory Practice) regulations . . . . . . . . . . . . . . . . . . . . .GMP (Good Manufacturing Practice) regulations. . . . . . . . . . . . . . . . . . 148148149150Technical terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151AppendixBibliography Part A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bibliography Part B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bibliography Part C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bibliography Part D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153154155156
ABCDSeparation of mixturesusing a rotary evaporator, aglass oven and a spray dryerSpray DryingGeneration of a vacuumMelting point
Separation of mixturesusing a rotary evaporator,a glass oven and a spray dryerA
14Part A Separation of mixtures using a rotary evaporator, a glass oven and a spray dryer1Introduction1.1OverviewThis chapter describes the equipment used for thermal separation of mixturesof materials. The name given to the process differs according to the condition inwhich the materials being separated are present. Whenever two liquids are beingseparated, one speaks of distillation. Whenever a liquid is being separated froma solid, one speaks of drying. Sublimation is a separation of solids by evaporating them, bypassing their liquid phase, and then re-solidifying them. Spray dryinginvolves the drying of a solution or a suspension of a compound by spraying itinto a hot air stream. Nevertheless, most of these procedures are based on thesame principle. This being that different materials have different vapor pressures.The mixture is heated until it evaporates and then is re-condensed. The substancewith the lower vapor pressure accumulates in the vapor and in the condensate.There are a great number of devices available to carry out distillation, drying, andsublimation. This chapter restricts itself to the rotary evaporator, glass oven andthe spray dryer.The first section presents the theoretical fundamentals for an understandingof thermal separation processes. The sections that follow deal with the designand applications of the rotary evaporator, the glass oven, the spray dryer andimportant accessory equipment.1.2Areas where rotary evaporators, drying ovens and spray dryersare utilizedRotary evaporators carry out single distillations and drying quickly and sparingly.The rotation increases the surface area of the mixture, thereby improving theheat transfer. This makes vaporization easier and avoids local overheating and incrustation. It also reduces retarded boiling and foaming. The vacuum lowers theboiling point, making low-temperature distillation possible. In addition, the use ofspecial glass attachments enables carrying out extractions, (re-)crystallizations,and reflux reactions as well as distillation and drying.Glass ovens are suitable for separating small amounts of mixed substances.They can be used in all separation processes. The possibility of connecting drying ovens to a rotary motor and their vacuum strength make them similar to smallrotary evaporators. In addition, they can use bulb-tube distillation to separatemulti-component mixtures. Glass ovens are ideal for work being performed ona micro-scale. During the spray drying process a solution or suspension is dispersed into millions of individual droplets with the help of a spray nozzle. Thesurface area is strongly increased and the solvent, usually water, evaporates in astream of hot air. Within few seconds the product is present as either a powder,granulate or agglomerate. Spray drying technology is commonly utilized for thereduction of weight and volume in the chemical and foodstuffs industries, as wellfor the preservation of food.1.3Historical development of the rotary evaporatorDistillation, or «drop-by-drop separation», is an art that has been in practice fora long time. The Persians are thought to have invented it in about 3,500 B.C.in order to produce rose water. From Persia, it spread very quickly across thewhole of Europe, North Africa, and Asia. In addition to being used for produc-
Part A Introduction 15Figure 1:Historical distillation equipment (2nd century).ing essences, distillation was also used by mariners for desalinating sea water.Alchemists also practiced distillation. The teachings of alchemy, which arose inEgypt during the 2nd centrury, represented a combination of religious aspectsand chemistry. This was the first «science» that concerned itself in a practicalway with material. Aristotelian natural philosophy had postulated the existenceof a fundamental material with no qualities, the «prima materia». The alchemistsFigure 2:An air-cooled and awater-cooled distillationdevice for laboratory use(16th century).sought to transform natural materials chemically into this basic material, andthento impart to it the new qualities desired, e.g., those of gold (transmutation). Intheir search they discovered a large number of chemical compounds, improvedexisting processes and equipment, and discovered new processes that havelater been adopted and used in modern chemistry. They also developed distillation apparatus that, from a design-related stand-point, is still being used today.Four classical components of the design include: the heating bath, the bubbleflask, the head, and the condenser.During the 17th and 18th centuries, the focus was on the impro vement of ex isting equipment. The equip ment was insulated, the process of con tinuous distillation was introduced, and water was used as a cool ant. The vapor distillationpro cess was also discovered during this time. In selecting the materials for theirapparatus, scientists departed more and more from metal and concentrated onglass.At the end of the 17th century, the Irish physicist Robert Boyle (1627–1691)who had involved himself intensively with vacuums, performed the first vacuumdistillations. Finally, during the 19th century, there came the first rectifying columns that made multi-stage distillation possible. A innovative explosion occurredin the mid-19th century with the arrival of organic chemistry. New equipment
16Part A IntroductionFigure 3:Büchi’s first rotaryevaporator.was specially designed for the needs of the laboratory. Financial involvementby the alcohol industry in France brought about a rapid development on a largeindustrial scale as well.The use of a vacuum in distillation processes has played a decisive role eversince Boyle’s first experiments. Invention of the pressure regulator and improvement of pumps also enabled a more directed use of the vacuum. In the beginning, only bubble equipment was used for vacuum distillations. Articles by C.C.Draig (1950) and M.E. Volk (1955) published the operating principle behind therotary evaporator. This process has a far better heat transfer rate than the flaskprocess, which spares the product and increases output. Only two years afterVolk’s article appeared in early 1957, Büchi Labortechnik in Flawil brought thefirst rotary evaporator to the market.For more detailed information on this topic:– E. Krell: Handbuch der Laboratoriumsdestillation This book provides an interesting history of distillation. Unfortunately, its presentation concentrates mainly on the development of the equipment andless on the individuals who took part in it.
Part A Theoretical basis for distillation 22.12.1.117Theoretical basis for distillationThermodynamic basisConditions of state, phase transitionsDepending on pressure and temperature, any material may be present in threedifferent phases: solid, liquid, and gaseous. In the solid phase the smallest particles behave as a solid showing only small degrees of motion due to a highbinding energy. They swing in a fixed position in their molecular lattices and usually rotate around their axes. The higher the temperature, the more violently theyswing or rotate and the distance between the particles usually increases. Whenheat is applied to a solid material, its kinetic energy increases steadily until, atthe melting point, the kinetic energy becomes strong enough to overcome theforces of attraction. The material liquefies. The individual molecules are now ableto move about more or less freely within the substance, but the attracting energybetween them is still too strong for them to separate from the other molecules.Additional heating of the material removes that energy barrier up to the boilingpoint. The molecules then have sufficient kinetic energy to enable them to movefreely within space without being held back by the forces of attraction. The material is now a gas.Figure 4:Particle model of the3 phases: solid, liquid,and gas.These phase transitions are revers ible. When a gas turns into a liquid, peopletalk of condensation. When a liquid turns into a solid, it freezes or solidifies. Ifthe right conditions are selected, a solid can also be transformed directly intoits gaseous phase, bypassing the liquid state. This process, in either direction,is called sublimation. The existing phase is influenced both by the temperatureand by the pressure. The lower the pressure, the weaker the forces of attractionbetween the molecules. This means that both the melting point and the boilingpoint are lower at low pressures.A given material may have several solid phases that differ in their crystallinelattice structure but, with the exception of helium, it can have only one liquid andone gaseous phase.Fig. 5 shows the relationships between temperature, pressure, and volume.This diagram shows various possible paths for going from the solid into the gaseous phase.– Path from A to F: A solid is being heated under constant atmospheric pressure.When it reaches the melting point, there is a sudden increase in volume: thematerial liquefies. With further heating, its volume increases steadily until the
18Part A Theoretical basis for distillationFigure 5:p-V-T surface of a pure material. V has beengraphed logari
methods and technologies for the laboratory, we have the pleasure of presenting the revised edition of the «Laboratory Assistant». This guide will help you acquire a broader and deeper understanding of several of the most widely used laboratory instruments, as rotary evaporators, vacuu
May 02, 2018 · D. Program Evaluation ͟The organization has provided a description of the framework for how each program will be evaluated. The framework should include all the elements below: ͟The evaluation methods are cost-effective for the organization ͟Quantitative and qualitative data is being collected (at Basics tier, data collection must have begun)
Silat is a combative art of self-defense and survival rooted from Matay archipelago. It was traced at thé early of Langkasuka Kingdom (2nd century CE) till thé reign of Melaka (Malaysia) Sultanate era (13th century). Silat has now evolved to become part of social culture and tradition with thé appearance of a fine physical and spiritual .
On an exceptional basis, Member States may request UNESCO to provide thé candidates with access to thé platform so they can complète thé form by themselves. Thèse requests must be addressed to esd rize unesco. or by 15 A ril 2021 UNESCO will provide thé nomineewith accessto thé platform via their émail address.
̶The leading indicator of employee engagement is based on the quality of the relationship between employee and supervisor Empower your managers! ̶Help them understand the impact on the organization ̶Share important changes, plan options, tasks, and deadlines ̶Provide key messages and talking points ̶Prepare them to answer employee questions
Dr. Sunita Bharatwal** Dr. Pawan Garga*** Abstract Customer satisfaction is derived from thè functionalities and values, a product or Service can provide. The current study aims to segregate thè dimensions of ordine Service quality and gather insights on its impact on web shopping. The trends of purchases have
Chính Văn.- Còn đức Thế tôn thì tuệ giác cực kỳ trong sạch 8: hiện hành bất nhị 9, đạt đến vô tướng 10, đứng vào chỗ đứng của các đức Thế tôn 11, thể hiện tính bình đẳng của các Ngài, đến chỗ không còn chướng ngại 12, giáo pháp không thể khuynh đảo, tâm thức không bị cản trở, cái được
Le genou de Lucy. Odile Jacob. 1999. Coppens Y. Pré-textes. L’homme préhistorique en morceaux. Eds Odile Jacob. 2011. Costentin J., Delaveau P. Café, thé, chocolat, les bons effets sur le cerveau et pour le corps. Editions Odile Jacob. 2010. Crawford M., Marsh D. The driving force : food in human evolution and the future.
Le genou de Lucy. Odile Jacob. 1999. Coppens Y. Pré-textes. L’homme préhistorique en morceaux. Eds Odile Jacob. 2011. Costentin J., Delaveau P. Café, thé, chocolat, les bons effets sur le cerveau et pour le corps. Editions Odile Jacob. 2010. 3 Crawford M., Marsh D. The driving force : food in human evolution and the future.
