Techniques in Organic Chemistry, Lab Reports of Organic Chemistry

Download Techniques in Organic Chemistry and more Lab Reports Organic Chemistry in PDF only on Docsity!

Chemical resistance of common types of gloves to various compounds

Glove type

Compound Neoprene Nitrile Latex

Acetone good fair good Chloroform good poor poor Dichloromethane fair poor poor Diethyl ether very good good poor Ethanol very good excellent excellent Ethyl acetate good poor fair Hexane excellent excellent poor Methanol very good fair fair Nitric acid (conc.) good poor poor Sodium hydroxide very good excellent excellent Sulfuric acid (conc.) good poor poor Toluene fair fair poor

Selected data on common acid and base solutions

Density Compound Molarity (g · ml ^1 ) % by weight

Acetic acid (glacial) 17 1.05 100 Ammonia (concentrated) 15.3 0.90 28. Hydrobromic acid (concentrated) 8.9 1.49 48 Hydrochloric acid (concentrated) 12 1.18 37 Nitric acid (concentrated) 16 1.42 71 Phosphoric acid (concentrated) 14.7 1.70 85 Sodium hydroxide 6 1.22 20 Sulfuric acid (concentrated) 18 1.84 95–

Common organic solvents

Boiling Density Dielectric Miscible Name point (°C) (g · ml ^1 ) constant with H 2 O

Acetone (2-propanone) 56.5 0.792 21 yes Dichloromethane 40 1.326 9.1 no Diethyl ether 35 0.713 4.3 no Ethanol (95% aq. azeotrope) 78 0.816 27 yes Ethanol (anhydrous) 78.5 0.789 25 yes Ethyl acetate 77 0.902 6.0 slightly Hexane 69 0.660 1.9 no Methanol 65 0.792 33 yes Pentane 36 0.626 1.8 no 2-Propanol (Isopropyl alcohol) 82.5 0.785 18 yes Toluene 111 0.866 2.4 no

This page intentionally left blank

Techniques

in Organic Chemistry

This page intentionally left blank

Techniques

in Organic Chemistry

Miniscale, Standard Taper Microscale,

and Williamson Microscale

Third Edition

JERRY R. MOHRIG Carleton College

CHRISTINA NORING HAMMOND Vassar College

PAUL F. SCHATZ University of Wisconsin, Madison

W. H. Freeman and Company

New York

• ESSAY— The Role of the Laboratory PART 1 INTRODUCTION TO THE ORGANIC LABORATORY
• 1 Safety in the Laboratory
  • 1.1 Causes of Laboratory Accidents /
  • 1.2 Safety Features in the Laboratory /
  • 1.3 Preventing Accidents /
  • 1.4 What to Do if an Accident Occurs /
  • 1.5 Chemical Toxicology /
  • 1.6 Where to Find Chemical Safety Information /
• 2 Protecting the Environment
  • 2.1 Green Chemistry /
  • 2.2 How Can a Laboratory Procedure Be Made Greener? /
  • 2.3 Fewer Reaction By-Products /
  • 2.4 Handling Laboratory Waste /
• 3 Laboratory Notebooks and Prelaboratory Information
  • 3.1 The Laboratory Notebook /
  • 3.2 Calculation of the Percent Yield /
  • 3.3 Sources of Prelaboratory Information /
  • ESSAY— Learning to Do Organic Chemistry PART 2 CARRYING OUT CHEMICAL REACTIONS
• 4 Laboratory Glassware
  • 4.1 Desk Equipment /
  • 4.2 Standard Taper Miniscale Glassware /
  • 4.3 Microscale Glassware /
  • 4.4 Cleaning and Drying Laboratory Glassware /
• 5 Measurements and Transferring Reagents viii Contents
  • 5.1 Using Electronic Balances /
  • 5.2 Transferring Solids to a Reaction Vessel /
  • 5.3 Measuring Volume and Transferring Liquids /
  • 5.4 Measuring Temperature /
• 6 Heating and Cooling Methods
  • 6.1 Preventing Bumping of Liquids /
  • 6.2 Heating Devices /
  • 6.3 Cooling Methods /
  • 6.4 Laboratory Jacks /
• 7 Assembling a Reaction Apparatus
  • 7.1 Refluxing a Reaction Mixture /
  • 7.2 Anhydrous Reaction Conditions /
  • 7.3 Addition of Reagents During a Reaction /
  • 7.4 Removal of Noxious Vapors /
• 8 Computational Chemistry
  • 8.1 Picturing Molecules on the Computer /
  • 8.2 Molecular Mechanics Method /
    • and DFT Methods / 8.3 Quantum Mechanics Methods: Ab Initio, Semiempirical,
  • 8.4 Which Computational Method Is Best? /
  • 8.5 Sources of Confusion /
• 9 Designing a Chemical Reaction
  • 9.1 Importance of the Library /
  • 9.2 Modifying the Scale of a Reaction and Carrying It Out /
  • 9.3 Case Study: Synthesis of a Solvatochromic Dye /
    • Using NaOCl Bleach / 9.4 Case Study: Oxidation of a Secondary Alcohol to a Ketone
  • 9.5 The Literature of Organic Chemistry /
  • ESSAY— Intermolecular Forces in Organic Chemistry PART 3 SEPARATION AND PURIFICATION TECHNIQUES
• 10 Filtration
  • 10.1 Filtering Media /
  • 10.2 Miniscale Gravity Filtration /
  • 10.3 Microscale Gravity Filtration /
  • 10.4 Vacuum Filtration /
  • 10.5 Other Liquid-Solid and Liquid-Liquid Separation Techniques /
  • 10.6 Sources of Confusion /
• 11 Extraction Contents ix
  • 11.1 Understanding How Extraction Works /
  • 11.2 Practical Advice on Extractions /
  • 11.3 Miniscale Extractions /
  • 11.4 Summary of the Miniscale Extraction Procedure /
  • 11.5 Microscale Extractions /
    • 11.5A EQUIPMENT AND TECHNIQUES COMMON TO MICROSCALE EXTRACTIONS /
    • 11.5B MICROSCALE EXTRACTIONS WITH AN ORGANIC PHASE LESS DENSE THAN WATER /
    • 11.5C MICROSCALE EXTRACTIONS WITH AN ORGANIC PHASE DENSER THAN WATER /
  • 11.6 Sources of Confusion in Extractions /
• 12 Drying Organic Liquids and Recovering Reaction Products
  • 12.1 Drying Agents /
  • 12.2 Methods for Separating Drying Agents from Organic Liquids /
  • 12.3 Recovery of an Organic Product from a Dried Extraction Solution /
  • 12.4 Sources of Confusion in Drying Liquids /
• 13 Boiling Points and Distillation
  • 13.1 Determination of Boiling Points /
  • 13.2 Distillation and Separation of Mixtures /
  • 13.3 Simple Distillation /
    • 13.3A MINISCALE DISTILLATION /
    • 13.3B MINISCALE SHORT-PATH DISTILLATION /
    • 13.3C MICROSCALE DISTILLATION USING STANDARD TAPER 14/10 APPARATUS /
    • 13.3D MICROSCALE DISTILLATION USING WILLIAMSON A PPARATUS /
  • 13.4 Fractional Distillation /
  • 13.5 Azeotropic Distillation /
  • 13.6 Steam Distillation /
  • 13.7 Vacuum Distillation /
  • 13.8 Sources of Confusion /
• 14 Melting Points and Melting Ranges
  • 14.1 Melting-Point Theory /
  • 14.2 Apparatus for Determining Melting Ranges /
  • 14.3 Determining Melting Ranges /
  • 14.4 Summary of Mel-Temp Melting-Point Determinations /
  • 14.5 Using Melting Points to Identify Compounds /
  • 14.6 Sources of Confusion /
• 15 Recrystallization
  • 15.1 Introduction to Recrystallization /
  • 15.2 Carrying Out Successful Recrystallizations /
  • 15.3 How to Select a Recrystallization Solvent /
  • 15.4 Miniscale Procedure for Recrystallizing a Solid /
  • 15.5 Summary of the Miniscale Recrystallization Procedure /
  • 15.6 Microscale Recrystallization /
  • 15.7 Summary of Microscale Recrystallization Procedure / x Contents
  • 15.8 Sources of Confusion /
• 16 Specialized Techniques
  • Sublimation /
  • 16.1 Assembling the Apparatus for a Sublimation /
  • 16.2 Carrying Out a Sublimation /
  • Refractometry /
  • 16.3 The Refractometer /
  • 16.4 Determining a Refractive Index /
  • Optical Activity and Enantiomeric Analysis /
  • 16.5 Mixtures of Optical Isomers: Separation/Resolution /
  • 16.6 Polarimetric Techniques /
  • 16.7 Analyzing Polarimetric Readings /
  • 16.8 Modern Methods of Enantiomeric Analysis /
  • Inert Atmosphere Reaction Conditions /
  • 16.9 Reaction Apparatus /
  • 16.10 Transfer of Reagents Using Syringe Techniques /
  • ESSAY— Modern Chromatographic Separations PART 4 CHROMATOGRAPHY
• 17 Thin-Layer Chromatography
  • 17.1 Plates for Thin-Layer Chromatography /
  • 17.2 Sample Application /
  • 17.3 Development of a TLC Plate /
  • 17.4 Visualization Techniques /
  • 17.5 Analysis of a Thin-Layer Chromatogram /
  • 17.6 Summary of TLC Procedure /
  • 17.7 How to Choose a Developing Solvent When None Is Specified /
  • 17.8 Using TLC Analysis in Synthetic Organic Chemistry /
  • 17.9 Sources of Confusion /
• 18 Liquid Chromatography
  • 18.1 Adsorbents /
  • 18.2 Elution Solvents /
  • 18.3 Determining the Column Size /
  • 18.4 Miniscale Liquid Chromatography /
  • 18.5 Microscale Liquid Chromatography /
    • 18.5A PREPARATION AND ELUTION OF A MICROSCALE C OLUMN /
    • 18.5B PREPARATION AND ELUTION OF A WILLIAMSON MICROSCALE C OLUMN /
  • 18.6 Summary of Column Chromatography Procedures /
  • 18.7 Flash Chromatography /
  • 18.8 Sources of Confusion /
  • 18.9 High-Performance Liquid Chromatography /
• 19 Gas Chromatography Contents xi
  • 19.1 Instrumentation for GC /
  • 19.2 Types of Columns and Liquid Stationary Phases /
  • 19.3 Detectors /
  • 19.4 Recorders and Data Stations /
  • 19.5 Practical GC Operating Procedures /
  • 19.6 Sources of Confusion /
  • 19.7 Identification of Components Shown on a Chromatogram /
  • 19.8 Quantitative Analysis /
  • ESSAY— The Spectroscopic Revolution PART 5 SPECTROSCOPIC METHODS
• 20 Infrared Spectroscopy
  • 20.1 IR Spectra /
  • 20.2 Molecular Vibrations /
  • 20.3 IR Instrumentation /
  • 20.4 Operating an FTIR Spectrometer /
  • 20.5 Sample Preparation for Transmittance IR Spectra /
  • 20.6 Sample Preparation for Attenuated Total Reflectance (ATR) Spectra /
  • 20.7 Interpreting IR Spectra /
  • 20.8 Procedure for Interpreting an IR Spectrum /
  • 20.9 Case Study /
  • 20.10 Sources of Confusion /
• 21 Nuclear Magnetic Resonance Spectroscopy
  • 21.1 NMR Instrumentation /
  • 21.2 Preparing Samples for NMR Analysis /
  • 21.3 Summary of Steps for Preparing an NMR Sample /
  • 21.4 Interpreting 1 H NMR Spectra /
  • 21.5 How Many Types of Protons Are Present? /
  • 21.6 Counting Protons (Integration) /
  • 21.7 Chemical Shift /
  • 21.8 Quantitative Estimation of Chemical Shifts /
  • 21.9 Spin-Spin Coupling (Splitting) /
  • 21.10 Sources of Confusion /
  • 21.11 Two Case Studies /
  • 21.12 Advanced Topics in 1 H NMR /
• 22 13 C and Two-Dimensional NMR Spectroscopy
  • 22.1 13 C NMR Spectra /
  • 22.2 13 C Chemical Shifts /
  • 22.3 Quantitative Estimation of 13 C Chemical Shifts /
  • 22.4 Determining Numbers of Protons on Carbon Atoms /
  • 22.5 Case Study /
  • 22.6 Two-Dimensional Correlated Spectroscopy (2D COSY) /
• 23 Mass Spectrometry
  • 23.1 Mass Spectrometers /
  • 23.2 Mass Spectra and the Molecular Ion /
  • 23.3 High-Resolution Mass Spectrometry /
  • 23.4 Mass Spectral Libraries /
  • 23.5 Fragmentation of the Molecule /
  • 23.6 Case Study /
  • 23.7 Sources of Confusion /
• 24 Ultraviolet and Visible Spectroscopy
  • 24.1 UV/VIS Spectra and Electronic Excitation /
  • 24.2 UV/VIS Instrumentation /
  • 24.3 Preparing Samples and Operating the Spectrometer /
  • 24.4 Sources of Confusion /
• 25 Integrated Spectroscopy Problems
• Index

xiv Preface

chemistry laboratory. The book is written to provide effective support for guided- inquiry and design-based experiments and projects. It can also serve as a useful ref- erence for laboratory practitioners and instructors.

Flexibility

Techniques in Organic Chemistry offers a great deal of flexibility. It can be used in any organic laboratory with any glassware. The basic techniques for using standard taper miniscale glassware as well as 14/10 standard taper microscale and Williamson mi- croscale glassware are all covered. The miniscale glassware that is described is appropriate with virtually any 14/20 or 19/22 standard taper glassware kit.

Modern Instrumentation

Modern instrumental methods play a crucial role in supporting guided-inquiry ex- periments, which provide the active learning opportunities many instructors seek for their students. We feature instrumental methods that offer quick, reliable, quantita- tive data. NMR spectroscopy and gas chromatography are particularly important. Our emphasis is on how to acquire good data and how to read spectra efficiently and with real understanding. Chapters on 1 H and 13 C NMR, IR, and mass spectrometry stress the practical interpretation of spectra and how they can be used to answer questions posed in an experimental context. They describe how to deal with real lab- oratory samples and include case studies of analyzed spectra.

Organization

The book is divided into five parts:

• Part 1 has chapters on safety, green chemistry, and the lab notebook.
• Part 2 discusses glassware, measurements, heating methods, computational chemistry, and planning a chemical reaction.
• Part 3 introduces filtration, extraction, drying organic liquids, distillation, melting points, recrystallization, and a chapter on specialized techniques—sublimation, refractometry, measurement of optical activity, and inert atmosphere techniques.
• Part 4 presents the three chromatographic techniques widely used in the organic laboratory—thin-layer, liquid, and gas chromatography.
• Part 5 discusses IR, 1 H and 13 C NMR, MS, and UV-visible spectra in some detail.

Traditional organic qualitative analysis is available on our Web site: www.whfreeman.com/mohrig.

Modern Projects and Experiments in Organic Chemistry

The accompanying laboratory manual, Modern Projects and Experiments in Organic Chemistry, comes in two complete versions:

• Modern Projects and Experiments in Organic Chemistry: Miniscale and Standard Taper Microscale (ISBN 0-7167-9779-8)
• Modern Projects and Experiments in Organic Chemistry: Miniscale and Williamson Microscale (ISBN 0-7167-3921-6)

Preface xv

Modern Projects and Experiments is a combination of inquiry-based and traditional ex- periments, plus multiweek inquiry-based projects. It is designed to provide quality content, student accessibility, and instructor flexibility. This laboratory manual intro- duces students to the way the contemporary organic lab actually functions and al- lows them to experience the process of science.

Custom Publishing

All experiments and projects are available through LabPartner for Chemistry, Freeman Custom Publishing’s newest offering. LabPartner provides instructors with a diverse database of experiments, selected from the extensive array published by W. H. Freeman and Hayden-McNeil Publishing. Instructors can use LabPartner to create their own customized lab manual by selecting specific experiments from Modern Projects and Experiments, adding experiments from other WHF or H-M titles, and incorporating their own original material so that the manual is organized to suit their course. Visit http://www.whfreeman.com/labpartner to learn more.

ACKNOWLEDGMENTS

We have benefited greatly from the insights and thoughtful critiques of the review- ers for this edition:

Scott Allen, University of Tampa Bal Barot, Lake Michigan College Peter T. Bell, Tarleton State University Haishi Cao, University of Nebraska, Kearney J. Derek Elgin, Coastal Carolina University George Griffin, Bunker Hill Community College Jason A. Morrill, William Jewel College Judith Moroz, Bradley University Kimberly A. O. Pacheco, University of Northern Colorado David Schedler, Birmingham Southern College Levi Simpson, University of Texas, Southwestern Medical Center Patricia Somers, Colorado State University Bernhard Vogler, University of Alabama, Huntsville Denyce K. Wicht, Suffolk University Kurt Wiegel, University of Wisconsin, Eau Claire Jane E. Wissinger, University of Minnesota Linfeng Xie, University of Wisconsin, Oshkosh

We especially thank Jane Wissinger and George Griffin, who provided many helpful suggestions regarding specific techniques for this edition, as well as thought- ful critiques of the entire book. We wish to thank Kathryn Treadwell, our editor at W. H. Freeman and Company, for her direction in planning this revision, arranging for such an outstanding group of reviewers, and overseeing most of the manuscript preparation. We also thank Kristina Treadwell, our editor during the last stages of publication, Leigh Renhard, Project Editor, for her proficient direction of the production stages, and Penny Hull

Introduction to the

Organic Laboratory

Essay — The Role of the Laboratory

Organic chemistry is an experimental science, and the laboratory is where you learn about “how we know what we know about it.” The laboratory deals with the processes of scientific inquiry that organic chemists use. It demonstrates the experi- mental basis of what your textbook presents as fact. The primary goal of the labora- tory is to help you understand how organic chemistry is done by actually doing it. Learning how to obtain and interpret experimental results and draw reasonable con- clusions from them is at the heart of doing science. Your laboratory work will give you the opportunity to exercise your critical thinking abilities, to join in the process of science—to observe, to think, and to act.

To learn to do experimental organic chemistry, you need to master an array of tech- niques for carrying out and interpreting chemical reactions, separating products from their reaction mixtures, purifying products, and analyzing the results. Techniques in Organic Chemistry is designed to provide you with a sound fundamental understand- ing of the techniques that organic chemists use and the chemical principles they are based on. Mastering these techniques involves attention to detail and careful observa- tions that will enable you to obtain accurate results and reach reasonable conclusions in your investigations of chemical phenomena.

While you are in the laboratory, you will have a variety of experiences—from learn- ing basic techniques to running chemical reactions. Interpretation of your experimen- tal results will involve consideration of the relationship between theory and experiment and provide reinforcement of what you are learning in the classroom. You may have the opportunity to do guided-inquiry experiments that ask you to answer a question or solve a problem by drawing conclusions from your experiments. You may also have the opportunity to synthesize an interesting organic compound by adapting a generic experimental procedure from the chemical literature.

PART

PART

Science is often done by teams of people working together on problems, and your experiments may involve teamwork with other students in your lab section. Some of your lab work may involve multiweek related experiments, which have a flexibility that may allow you to repeat a reaction procedure successfully if it didn’t work well the first time. In fact, virtually all experimental results that are reported in chemical journals have been repeated many times before they are published.

Part of learning how to do organic chemistry in the laboratory includes learn- ing how to do it safely. Technique 1 discusses laboratory safety and safe handling practices for the chemicals you will use. We urge you to read it carefully before you begin laboratory work.

2 Part 1 • Introduction to the Organic Laboratory