麻省理工学院：《有机化学基本实验操作技巧》教学资源（讲义）How do you Recrystallize a Mothball

WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofafety training special facilities and equip meat, and supervision by appropr priate individual You bear the sole responsiblity, liability, and risk for the implementation of such safcty procedures and measures. MT shall have no responsibility, liability, or rsk for the content or implemcutation of ay ofthe material presented. Legal Notices 2. Purification of Solids by recrystallization 2.1. Competent Chemist Rating: "How do you recrystallize a Mothball? Techniques Checklist Solubility tests Choosing a good solvent system 口口口 Inducing crystallization Filtration Pre-Lab Discussion and Required reading: Theory of recrystallization: Zubrick Ch 13, LLP Ch. 11.2 Digital Lab Techniques Manual: 9. Recrystallize Equipment: Test tubes(five 13x100 mm Erlenmeyer flasks(2x 50-mL, 1x125-mL) nne Filter Buchner funnel and filter paper Magnetic stirring/hot plate Filter flask(250-mL) Rubber filter adapter Test tube rack Large crystallizing dish 19

2. Purification of Solids by Recrystallization 2.1. Competent Chemist Rating: “How do you recrystallize a Mothball?” Techniques Checklist: • Solubility tests ❑ • Choosing a good solvent system ❑ • Inducing crystallization ❑ • Filtration ❑ Pre-Lab Discussion and Required Reading: • Theory of recrystallization : Zubrick Ch. 13, LLP Ch. 11.2 Digital Lab Techniques Manual: • 9. Recrystallization Equipment: • Test tubes (five 13x100 mm) • Erlenmeyer flasks (2x50-mL, 1x125-mL) • Small magnetic stir bar • Funnel • Filter paper • Büchner funnel and filter paper • Magnetic stirring/hot plate • Filter flask (250-mL) • Rubber filter adapter • Large vial with white cap • Test tube rack • Large crystallizing dish • Desiccator 19 WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. WARNING NOTICE: The experiments described in these materials are potentially hazardous and require a high level ofsafety training, special facilities and equipment, and supervision by appropriate individuals. You bear the sole responsibility, liability, and risk for the implementation of such safety procedures and measures. MIT shall have no responsibility, liability, or risk for the content or implementation of any of the material presented. Legal Notices

Goal You will be given 2.00 g of impure naphthalene (mothballs! ) Your job is to purify the naphthalene by recrystallization without losing a significant amount of your Experiment Outline: Solubility Tests Determine an appropriate solvent system for the recrystallization of naphthale For your tests try: water, methanol, acetone, hexane, and toluene. understand how to find the appropriate solvent or solvent mixture for recrystallization, see pages 104-105 in Zubrick. I. Recrystallization of Naphthalene Transfer the material to a 50-mL Erlenmeyer flask equipped with a stir bar. Add about 20 mL of the solvent(determined in Part Dand heat to boiling on a stir/ho Remove any insoluble impurities by filtration, and recrystallize your product-see Two-Solvent Recrystallization guide Collect your crystals on a small Buchner funnel by vacuum filtration, and rinse with the cold solvent mixture Your crystals should be colorless. If some orange or yellow your material with cold hexane.( Be careful: What is the solubility of naphthalene Dry your compound well-see Two-Solvent Recrystallization Guide for tips Determine the yield and obtain a melting point Results: To obtain your CC Rating "in Purification of Solids by Crystallization, you must obtain colorless, well dried crystals weighing at least 1. 30 g(no traces of ellow! ) The purified material must melt over no more than three degrees with the lower range beginning no lower than 77C and the upper range ending no higher than 83C. This material must also be submitted to the ta for possible weight and melting point verification IAdapted from Fieser, L F. Williamson, K. L. Organic Experiments; 7th ed. D. C. Heath and Company Lexington, MA, 1992; p. 40

Goal: You will be given 2.00 g of impure naphthalene (mothballs!). Your job is to purify the naphthalene by recrystallization without losing a significant amount of your Naphthalene sample!1 Experiment Outline: I. Solubility Tests • Determine an appropriate solvent system for the recrystallization of naphthalene. For your tests try: water, methanol, acetone, hexane, and toluene. To understand how to find the appropriate solvent or solvent mixture for recrystallization, see pages 104–105 in Zubrick. II. Recrystallization of Naphthalene • Transfer the material to a 50-mL Erlenmeyer flask equipped with a stir bar. Add about 20 mL of the solvent (determined in Part I) and heat to boiling on a stir/hot plate. • Remove any insoluble impurities by filtration, and recrystallize your product - see Two-Solvent Recrystallization Guide. • Collect your crystals on a small Büchner funnel by vacuum filtration, and rinse with the cold solvent mixture. • Your crystals should be colorless. If some orange or yellow color persists, wash your material with cold hexane. (Be careful: What is the solubility of naphthalene in hexane?). • Dry your compound well - see Two-Solvent Recrystallization Guide for tips. • Determine the yield, and obtain a melting point. Results: • To obtain your "CC Rating" in Purification of Solids by Crystallization, you must obtain colorless, well dried crystals weighing at least 1.30 g (no traces of yellow!). The purified material must melt over no more than three degrees with the lower range beginning no lower than 77 °C and the upper range ending no higher than 83 °C. This material must also be submitted to the TA for possible weight and melting point verification. 1Adapted from Fieser, L. F.; Williamson, K. L. Organic Experiments; 7th ed.; D. C. Heath and Company: Lexington, MA, 1992; p. 40. 20