Microscale Organic Laboratory

Dana W. Mayo holds the Charles Weston Pickard Research Professor of Chemistry Chair at Bowdoin College.During the summers of 1960-1971 he co-directed with Professor R.C. Lord one-week Summer Courses on the Technique and Applications of Infrared Spectroscopy at MIT. From 1972-81 he continued to co-direct these programs at Bowdoin College and became Director in 1982. Ronald M. Pike is the author of Microscale Organic Laboratory with Multistep and Multiscale Syntheses, Binder Ready Version, 6th Edition, published by Wiley. David C. Forbes is the author of Microscale Organic Laboratory with Multistep and Multiscale Syntheses, Binder Ready Version, 6th Edition, published by Wiley.

Chapter 1 INTRODUCTION 1 General Rules for the Microscale Laboratory 3 The Organic Chemistry Laboratory 4

Chapter 2 SAFETY 5

Making the Laboratory a Safer Place 5

Nature of Hazards 5

Reduction of Risks 6

Precautionary Measures 7

Thinking About the Risks In Using Chemicals 8

Disposal of Chemicals 8

Material Safety Data Sheets 9

Alternate Sources of Information 12

Estimating Risks from Vapors 13

Microwave Safety 14

Concluding Thoughts 15

General Safety References 16

Chapter 3 INTRODUCTION TO MICROSCALE ORGANIC LABORATORY EQUIPMENT AND TECHNIQUES 18

Microglassware Equipment 19

Standard Taper Joints 19

Conical Vials 20

Condensers 20

Distillation Heads 20

Recrystallization Tubes 20

Miscellaneous Items 20

Gas Chromatographic Fraction Collection Items 21

Standard Experimental Apparatus 21

Heating and Stirring Arrangements 21

Sand Bath Technique—Hot Plate Calibration 21

Metal Heat-Transfer Devices 22

Stirring 22

Reflux Apparatus 23

Distillation Apparatus 24

Moisture-Protected Reaction Apparatus 25

Specialized Pieces of Equipment 26

Microwave Heating as a Tool for Organic Chemistry 27

Introduction 27

Applications 32

Equipment Available 34

Experimental Protocols 35

Microscale Laws 35

Rules of the Trade for Handling Organic Materials at the Microscale Level 35

Rules for Working with Liquids at the Microscale Level 36

Rules for Working with Solids at the Microscale Level 39

The Laboratory Notebook 40

Example of a Laboratory Notebook Entry 41

Calculating Yields 42

Chapter 4 DETERMINATION OF PHYSICAL PROPERTIES 45

Liquids 46

Ultramicro Boiling Point 46

Density 50

Solids 51

Melting Points 51

Chapter 5 MICROSCALE LABORATORY TECHNIQUES 55

TECHNIQUE 1 Gas Chromatography 55

GC Instrumentation 56

TECHNIQUE 2 Simple Distillation 61

TECHNIQUE 3 Fractional Distillation 64

TECHNIQUE 4 Solvent Extraction 67

Intermolecular Properties: Solubility 67

Partition (or Distribution) Coefficient 70

Extraction 72

Solid–Liquid Extraction 79

Drying Agents 80

Solid-Phase Extraction 83

TECHNIQUE 5 Crystallization 85

General Crystallization Procedure 85

Simple Crystallization 87

Filtration Techniques 88

TECHNIQUE 6 Chromatography 92

Column, Flash, High-Performance Liquid, and Thin-Layer Chromatography 92

Column Chromatography 92

Flash Chromatography 95

Thin-Layer Chromatography 97

Paper Chromatography 99

High-Performance Liquid Chromatography 100

TECHNIQUE 6B Concentration of Solutions 101

Distillation 102

Evaporation with Nitrogen Gas 102

Removal of Solvent Under Reduced Pressure 102

TECHNIQUE 7 Collection or Control of Gaseous Products 105

Water-Insoluble Gases 105

Trapping Byproduct Gases 106

TECHNIQUE 8 Measurement of Specific Rotation 108

Theory 108

The Polarimeter 109

TECHNIQUE 9 Sublimation 111

Sublimation Theory 112

Experimental Setup 113

Precautions 113

Chapter 6 MICROSCALE ORGANIC LABORATORY EXPERIMENTS 115

EXPERIMENT 1 Getting to Know You: Measurement of Physical Properties 116

Discussion 117

Experimental Procedure 118

Melting Point 118

EXPERIMENT 2 The Separation of a 25-L Mixture of Heptanal (bp 153 C) and Cyclohexanol (bp 160 C) by Gas Chromatography 123

Discussion 123

Collection Yield 124

Collection Yield 125

Components 126

Experimental Procedure 126

EXPERIMENT 3 Distillation 129

Experiment 3A Simple Distillation at the Semimicroscale

Level: Separation of Ethyl Acetate from trans-1,2-Dibenzoylethylene 130

Discussion 130

Components 130

Experimental Procedure 131

Experiment 3B Fractional Semimicroscale Distillation: Separation of Hexane and Toluene 132

Discussion 133

Components 133

Experimental Procedure 133

Experiment 3C Fractional Semimicroscale Distillation: Separation of 2-Methylpentane and Cyclohexane Using a Spinning-Band Column 135

Discussion 135

Components 136

Experimental Procedure 136

Experiment 3D Fractional Semimicroscale Distillation: The Separation of 2-Methylpentane and Cyclohexane Using a Spinning Band in a Hickman–Hinkle Still 138

Discussion 139

Components 139

Experimental Procedure 139

EXPERIMENT 4 Solvent Extraction 141

Experiment 4A Determination of Partition Coefficient for the System Benzoic Acid, Methylene Chloride, and Water 141

Discussion 141

Components 144

Experimental Procedure 144

Experiment 4B Solvent Extraction I: The System; Benzoic Acid, Methylene Chloride, and 10% Sodium Bicarbonate Solution; An Example of Acid–Base Extraction Techniques 146

Reaction 146

Discussion 146

Experimental Procedure 146

Experiment 4C Solvent Extraction II: A Three-Component Mixture; An Example of the Separation of an Acid, a Base, and a Neutral Substance 147

Discussion 147

Components 148

Experimental Procedure 148

EXPERIMENT 5 Reduction of Ketones Using a Metal Hydride Reagent: Cyclohexanol and cis- and trans-4-tert-Butylcyclohexanol 151

Reaction (Experiment [5A]) 151

Discussion 152

Experiment 5A Cyclohexanol 153

Experimental Procedure 153

Experiment 5B cis- and trans-4-tert-Butylcyclohexanol 158

Reaction 158

Experimental Procedure 158

EXPERIMENT 6 Photochemical Isomerization of an Alkene: cis-1,2-Dibenzoylethylene 163

Biologically Important Photochemical Reactions 164

Reaction 165

Discussion 166

Experiment 6A Purification of trans-1,2-Dibenzoylethylene 166

Experimental Procedure 166

Experiment 6B Isomerization of an Alkene: Thin-Layer Chromatographic Analysis 167

Experimental Procedure 167

Experiment 6C Isomerization of an Alkene: Nuclear Magnetic Resonance Analysis 173

Experimental Procedure 173

EXPERIMENT 7 The Cannizzaro Reaction with 4-Chlorobenzaldehyde: 4-Chlorobenzoic Acid and 4-Chlorobenzyl Alcohol 174

Reaction 176

Discussion 176

Experimental Procedure 177

Experiment 7-1 4-Chlorobenzoic Acid and 4-Chlorobenzyl Alcohol: Preparation Using a Monomode Microwave Apparatus 184

Experimental Procedure 184

Experiment 7-2 4-Chlorobenzoic Acid and

4-Chlorobenzyl Alcohol: Preparation Using a Multimode Microwave Apparatus 185

Experimental Procedure 185

EXPERIMENT 8 The Esterification Reaction: Ethyl Laurate, Isopentyl Acetate, and the Use of Acidic Resins 188

Reaction 188

Discussion 189

Lipids 190

Experiment 8A Ethyl Laurate 199

Reaction 199

Experimental Procedure 199

Experiment 8B Isopentyl Acetate: Semimicroscale Preparation 201

Reaction 201

Experimental Procedure 201

Experiment 8B-1 Isopentyl Acetate: Preparation Using a Monomode Microwave Apparatus 203

Experimental Procedure 203

Experiment 8B-2 Isopentyl Acetate: Preparation Using a Multimode Microwave Apparatus 205

Experimental Procedure 205

Experiment 8C Esterification by Use of Acidic Resins: Semimicroscale Preparations 206

Reaction 207

Experimental Procedure 207

EXPERIMENT 9 The E1 Elimination Reaction: Dehydration of 2-Butanol to Yield 1-Butene, trans-2-Butene, and cis-2-Butene 209

The Development of Carbocation Theory 210

Reaction 211

Discussion 212

Experimental Procedure 215

EXPERIMENT 10 The E2 Elimination Reaction: Dehydrohalogenation of 2-Bromobutane to Yield 1-Butene, trans-2-Butene, and cis-2-Butene 217

Reaction 218

Discussion 218

Experimental Procedure 220

EXPERIMENT 11 The Isolation of Natural Products 224

Experiment 11A Isolation and Characterization of an Optically Active Natural Product: Usnic Acid 224

Lichens and Natural Products 225

Discussion 227

Experimental Procedure 227

Experiment 11B Isolation and Characterization of a Natural Product: Caffeine and Caffeine 5-Nitrosalicylate 229

Alkaloids 230

The Classification of Alkaloids 230

Discussion 231

Experimental Procedure 233

Derivative: Caffeine 5-Nitrosalicylate 235

Experimental Procedure 236

Experiment 11C Isolation of a Natural Product by Steam Distillation: Cinnamaldehyde from Cinnamon 238

Essential Oils 239

Discussion 241

Component 242

Experimental Procedure 242

EXPERIMENT 12 Reductive Catalytic Hydrogenation of an Alkene: Octane 244

Reaction 245

Discussion 245

Experimental Procedure 247

EXPERIMENT 13 Hydroboration–Oxidation of an Alkene: Octanol 250

Reaction 251

Discussion 251

Experimental Procedure 254

EXPERIMENT 14 Diels–Alder Reaction: 4-Cyclohexenecis-1,2-dicarboxylic Acid Anhydride 257

Reaction 258

Discussion 259

Experimental Procedure 261

Optional Semimicroscale Preparation 266

EXPERIMENT 15 Diels–Alder Reaction: 9,10-Dihydroanthracene-9,10-,-succinic Acid Anhydride 269

Reaction 269

Discussion 270

Experimental Procedure 271

Optional Semimicroscale Preparations 272

Experiment 15-1 9,10-Dihydroanthracene-9,10-,-succinic Acid Anhydride: Preparation Using a Monomode Microwave Apparatus 273

Experimental Procedure 273

Experiment 15-2 9,10-Dihydroanthracene-9,10-,-succinic Acid Anhydride: Preparation Using a Multimode Microwave Apparatus 274

Experimental Procedure 274

EXPERIMENT 16 Grignard Reaction with a Ketone: Triphenylmethanol 275

Reaction 276

Discussion 277

Experimental Procedure 279

EXPERIMENT 17 Grignard Reaction with an Aldehyde: 4-Methyl-3-heptanol 284

Reaction 284

Discussion 284

Experimental Procedure 285

EXPERIMENT 18 The Perkin Reaction: Condensation of Rhodanine with an Aromatic Aldehyde to Yield o-Chlorobenzylidene Rhodanine 289

Reaction 290

Discussion 291

Experimental Procedure 292

Optional Semimicroscale Preparation 293

EXPERIMENT 19 Alkene Preparation by the

Wittig Reaction: (E)-Stilbene; Methylene-4-tertbutylcyclohexane; and trans-9-(2-Phenylethenyl) anthracene 294

Reaction 296

Discussion 296

Experiment 19A (E)-Stilbene by the “Instant Ylide” Method 299

Reaction 299

Experimental Procedure 300

Experiment 19B (E)-Stilbene by the Horner–Wadsworth–Emmons Reaction 302

Reaction 302

Experimental Procedure 302

Experiment 19C Methylene-4-tert-butylcyclohexane 303

Reaction 303

Experimental Procedure 304

Experiment 19D trans-9-(2-Phenylethenyl) anthracene 306

Reaction 306

Experimental Procedure 306

EXPERIMENT 20 Aldol Reaction: Dibenzalacetone 309

Reaction 309

Discussion 310

Experimental Procedure 311

Optional Semimicroscale Preparation 316

EXPERIMENT 21 Quantitative Analysis of Grignard Reagents: 1-Methylbutylmagnesium Bromide and Phenylmagnesium Bromide 317

Reaction 318

Discussion 318

Experimental Procedure 319

EXPERIMENT 22 Williamson Synthesis of Ethers 321

Reaction 321

Discussion 322

Experiment 22A Propyl p-Tolyl Ether 323

Experimental Procedure 323

Optional Macroscale Preparation 324

Experiment 22B Methyl p-Ethylphenyl Ether 327

Reaction 327

Experimental Procedure 327

Optional Semimicroscale and Macroscale

Preparations 329

Experiment 22C Butyl p-Nitrophenyl Ether: Preparation Using a Monomode Microwave Apparatus 332

Reaction 332

Experimental Procedure 332

Experiment 22D Butyl p-Nitrophenyl Ether: Preparation Using a Multimode Microwave Apparatus 334

Reaction 334

Experimental Procedure 334

EXPERIMENT 23 Amide Synthesis: Acetanilide and N,N’-Diacetyl-1,4-phenylenediamine 338

Reaction 338

Discussion 339

Experiment 23A Acetanilide 341

Experimental Procedure 341

Optional Semimicroscale Preparation 342

Experiment 23B N,N’-Diacetyl-1,4-phenylenediamine 343

Reaction 343

Experimental Procedure 343

EXPERIMENT 24 Imide Synthesis: N-Phenylmaleimide 346

Reaction 346

Discussion 347

Experiment 24A Maleanilic Acid 348

Experimental Procedure 348

Reaction 348

Experiment 24B N-Phenylmaleimide 349

Reaction 349

Experimental Procedure 350

EXPERIMENT 25 Synthesis of Cyclic Carboxylic Acid Anhydrides: Succinic Anhydride and Phthalic Anhydride 352

Reaction 352

Discussion 352

Experiment 25A Succinic Anhydride 354

Experimental Procedure 354

Experiment 25B Phthalic Anhydride 355

Reaction 355

Experimental Procedure 355

EXPERIMENT 26 Diazonium Coupling Reaction: Methyl Red 356

Reaction 357

Discussion 357

Experimental Procedure 359

EXPERIMENT 27 Friedel–Crafts Acylation: Acetylferrocene and Diacetylferrocene 361

Reaction 362

Discussion 362

Experimental Procedure 364

EXPERIMENT 28 Halogenation: Electrophilic Aromatic Substitution to Yield 4-Bromoacetanilide 368

Reaction 368

Discussion 369

Experimental Procedure 369

EXPERIMENT 29 Nitration: 2,5-Dichloronitrobenzene; N,N’-Diacetyl-2,3-dinitro-1,4-phenylenediamine; 5-Nitrosalicylic Acid; and 2- and 4-Nitrophenol 373

General Reaction 374

Discussion 374

Semimicroscale Preparation of Anhydrous Nitric Acid 375

Experimental Procedure 376

Experiment 29A 2,5-Dichloronitrobenzene 376

Reaction 376

Experimental Procedure 377

Experiment 29B N,N-Diacetyl-2,3-dinitro-1,4-phenylenediamine 378

Reaction 378

Experimental Procedure 378

Experiment 29C 5-Nitrosalicylic Acid 379

Reaction 379

Experimental Procedure 380

Experiment 29D 2- and 4-Nitrophenol 381

Reaction 381

Experimental Procedure 381

EXPERIMENT 30 Nucleophilic Aromatic Substitution: 2,4-Dinitrophenylthiocyanate 384

Reaction 385

Discussion 385

Experimental Procedure 386

Experiment 30-1 2,4-Dinitrophenylthiocyanate: Preparation Using a Monomode Microwave Apparatus 387

Experimental Procedure 387

Experiment 30-2 2,4-Dinitrophenylthiocyanate: Preparation Using a Multimode Microwave Apparatus 388

Experimental Procedure 388

EXPERIMENT 31 Halogenation Using

N-Bromosuccinimide: 9-Bromoanthracene 390

Reaction 390

Discussion 391

Initiation Step 391

Propagation Step 391

Experimental Procedure 392

EXPERIMENT 32 Hypochlorite Oxidation of an Alcohol: Cyclohexanone 394

Reaction 394

Discussion 394

Experimental Procedure 395

EXPERIMENT 33 Chromium Trioxide–Resin or Hypochlorite Oxidation of an Alcohol: 9-Fluorenone 398

Experiment 33A 9-Fluorenone: CrO3 Oxidation of 9-Fluorenol 398

Reaction 398

Discussion 398

Experimental Procedure 399

Experiment 33B 9-Fluorenone: NaOCl Oxidation of 9-Fluorenol 401

Reaction 401

Discussion 401

Experimental Procedure 401

EXPERIMENT 34 Hypochlorite Oxidation of Methyl Ketones by the Haloform Reaction: Benzoic Acid and p-Methoxybenzoic Acid 403

Reaction 404

Discussion 404

Experiment 34A Benzoic Acid 405

Experimental Procedure 405

Experiment 34B p-Methoxybenzoic Acid 406

Reaction 406

Experimental Procedure 406

Optional Semimicroscale Preparation 407

EXPERIMENT 35 Conversion of Cyclohexyl Bromide to Cyclohexene–An E2 Elimination Reaction: Factors Affecting the Rate of a Chemical

Reaction 409

Reaction 409

Discussion 409

Experimental Procedure 414

Data Analysis 416

Variation of Parameters 416

EXPERIMENT 36 Aqueous Suzuki Synthesis of 4-Phenylphenol 421

Reaction 421

Discussion 421

Experimental Procedure 424

Chapter 7 SEQUENTIAL SYNTHESES: THE TRANSITION FROM MACRO TO MICRO 428

SEQUENCE A The Synthesis of Hexaphenylbenzene 431

EXPERIMENTS A1a, A2a, A3a, A1b, A2b, A3b, and A4ab The Synthesis of Hexaphenylbenzene from Benzaldehyde: 434

Experiment A1a The Benzoin Condensation of Benzaldehyde: Benzoin 436

Reaction 436

Discussion 437

Semimicroscale Experimental Procedure 438

Optional Scales 439

Microscale Reaction Procedure 439

Experiment A2a Copper(II) Ion Oxidation of Benzoin: Benzil 440

Reaction 441

Discussion 441

Semimicroscale Experimental Procedure 442

Optional Microscale Preparation 444

Experiment A3a Tetraphenylcyclopentadienone 445

Reaction 445

Discussion 446

Microscale Reaction Procedure (1) 446

Microscale Reaction Procedure (2) 447

Experiment A1b (E)-Stilbene 448

Reaction 449

Discussion 449

Experimental Procedure 450

Experiment A2b Bromination of (E)-Stilbene: meso-Stilbene Dibromide 451

Reaction 452

Discussion 452

Semimicroscale Experimental Procedure 454

Experiment A3b Dehydrohalogenation of

meso-Stilbene Dibromide: Diphenylacetylene 457

Reaction 457

Discussion 457

Semimicroscale Experimental Procedure 458

Optional Macroscale and Microscale

Preparations 459

Experiment A4ab Hexaphenylbenzene 460

Reaction 461

Discussion 461

Experimental Procedure 462

SEQUENCE B The Stepwise Synthesis of Nylon-6,6 464

Experiment B1 Oxidation of Cyclohexanol: Adipic Acid 465

Reaction 465

Discussion 465

Experimental Procedure 467

Experiment B2 Preparation of an Acid Chloride: Adipoyl Chloride 468

Reaction 468

Discussion 469

Experimental Procedure 469

Experiment B3 Preparation of a Polyamide: Nylon-6,6 471

Reaction 471

Discussion 471

Experimental Procedure 472

SEQUENCE C The Synthesis of Sulfanilamide 473

The Sulfa Drugs 473

Experiment C1 Acetylation of Aniline: 2,2,2-Trifluoroacetanilide 474

Reaction 475

Discussion 475

Experimental Procedure 476

Experiment C2 Chlorosulfonation of 2,2,2-

Trifluoroacetanilide: p-(Trifluoroacetamido) benzenesulfonyl Chloride 477

Reaction 478

Discussion 478

Experimental Procedure 479

Experiment C3 Preparation of an Arene Sulfonamide: Sulfanilamide 480

Discussion 481

Experimental Procedure 481

Chapter 8 SPECTROSCOPIC IDENTIFICATION OF ORGANIC COMPOUNDS 484

Infrared Spectroscopy 484

Introduction to Group Frequencies: Interpretation of Infrared Spectra 485

A Survey of Group Frequencies Identified in Organic Molecules 488

Group Frequencies of the Hydrocarbons 489

Group Frequencies of Carbonyl

Groups: C O 490

Group Frequencies of the Heteroatom Functional Groups 492

Esters 493

Infrared Spectroscopy Instrumentation and Sample Handling 496

Instrumentation 496

Sample Handling in the Infrared 497

Nuclear Magnetic Resonance Spectroscopy 504

Nuclear spin 504

Instrumentation 505

Chemical Shift 508

Spin–Spin Coupling 509

Intensities 512

Second-Order Effects 513

Interpretation of 1H NMR Spectra 514

1H Chemical Shifts 517

Spin–Spin Coupling 518

Geminal Coupling 518

Vicinal Coupling 518

Long-Range Coupling 520

Examples of Complex, Yet First-Order, Coupling 520

Ethyl Vinyl Ether 520

Allyl Acetate 522

13C NMR Spectroscopy 525

Two-Dimensional NMR Spectroscopy 531

Nuclear Magnetic Resonance Sampling 532

Ultraviolet–Visible Spectroscopy: Introduction to Absorption Spectroscopy 537

UV–VIS Spectroscopy 539

Application to Organic Molecules 540

Instrumentation 547

The Source of Radiation 548

The Monochromator 549

Sample Compartment 550

The Detector 550

The Electronics: The Amplifier and Recorder 550

Sample Preparation 551

Criteria for Choosing a Solvent 552

Mass Spectrometry 553

Instrumentation 555

Ion Source 556

Mass Analyzer 557

Detector 559

Tuning the Mass Spectrometer 559

Sample Introduction 560

Gas Chromatography/Mass Spectrometry (GC/MS) 560

Capillary Columns 560

Split Injection 561

Split/Splitless Injection 561

Features of the Mass Spectrum 562

Terms 563

Isotope Peaks 563

Recognizing the Molecular Ion 565

Mass Spectral Interpretation 566

Case Study: Synthesis of Methyl Benzoate 567

Chapter 9 QUALITATIVE IDENTIFICATION OF ORGANIC COMPOUNDS 573

Organic Qualitative Analysis 573

Preliminary Tests 575

Nonchemical Tests 575

Ignition Test 576

Separation of Impurities 577

Detection of Elements Other Than Carbon, Hydrogen, or Oxygen 578

Sodium Fusion 578

Sulfur 579

Nitrogen 580

The Halogens (Except Fluorine) 580

Solubility Characteristics 582

The Classification Tests 584

Alcohols 584

Periodic Acid: Vicinal Diols 586

Aldehydes and Ketones 586

Alkanes and Cycloalkanes: Saturated Hydrocarbons 588

Alkenes and Alkynes: Unsaturated Hydrocarbons 589

Alkyl Halides 589

Amides, Ammonium Salts, and Nitriles 591

Amines 592

Aromatic Hydrocarbons with no Functional Groups 593

Carboxylic Acids 594

Esters 594

Ethers 595

Methyl Ketones and Methyl Carbinols 595

Nitro Compounds 596

Phenols and Enols 597

Preparation of Derivatives 598

Carboxylic Acids 599

Preparation of Acid Chlorides 599

Amides 599

Anilides 600

Toluidides 600

Alcohols 600

Phenyl- and -Naphthylurethanes (Phenyl- and -Naphthylcarbamates) 600

3,5-Dinitrobenzoates 601

Aldehydes and Ketones 602

2,4-Dinitrophenylhydrazones 602

Semicarbazones 602

Amines 602

Primary and Secondary Amines: Acetamides 602

Primary and Secondary Amines: Benzamides 603

Primary, Secondary, and Tertiary Amines: Picrates 603

Acid Chlorides and Anhydrides 604

Amides 604

Aromatic Hydrocarbons 604

Picrates 604

Nitriles 604

Hydrolysis to Amides 604

Phenols 605

-Naphthylurethanes (-Naphthylcarbamates) 605

Bromo Derivatives 605

Aliphatic Hydrocarbons, Halogenated Hydrocarbons, Amides, Nitro Compounds, Ethers, and Esters 606

Glossary 609

Index 612