WARNING NOTICE: The e periments descnbed in these materials are potentially hazardous and require a lovel facilities and equip cat, and supervision by app opriate individuals. You bear the sole and risk for the implamentation of such safcty procedures and measu res MrT shall bave Do or risk for the content or implementation of ay of the material presented. Legal Notice 7.9. Flash Column Chromatography guide Overview: Flash column chromatography is a quick and (usually) easy way to separate complex mixtures of compounds. We will be performing relatively large scale separations in 5.301, around 1.0 g of compound. Columns are often smaller in scale than this and some of you will experience these once you move into the research lab. Column chromatography uses the same principles discussed in the TLC Handout, but it can be used on a preparative scale. We will be running flash columns since we will use compressed air to push the solvent through the column. This not only helps provide better separation, but it also cuts down on the amount of time required to run a column Reading: For an excellent description, see LLP pages 205-214 Preparing and Running a Flash Column: I)Determine the dry, solvent-free weight of the mixture that you want to separate 2) Determine the solvent system for the column by using TLC. You should aim for Rf values between 0. 2 and 0.3. If your mixture is complicated, this may not be possible. In complex cases, you will probably have to resort to gradient elution. This simply means that you increase the polarity of the solvent running through the column(eluent) throughout the course of the purification. This technique will be described in more detail later in the handout, but for the tlC analysis you should determine which solvent systems put each of the different spots in the 0. 2 to 0.3 Rf range 3)Determine the method of application to the column. You have three choices: neat, in solution, or deposited on silica. Neat: If your compound is a non-viscous oil, it is sometimes easiest to apply it neat. You can use a long Pasteur pipet to apply the liquid to the column and then rinse a traces of it into the column using the predetermined solvent system In Solution: Neat application can sometimes lead to column cracking, so a more common method for liquids, as well as solids, is to dissolve the sample in a solvent and apply it to the column in solution. In the best case, all of the components of your mixture should have an Rf of zero in this solvent-usually pentane or hexane. In many situations7.9. Flash Column Chromatography Guide Overview: Flash column chromatography is a quick and (usually) easy way to separate complex mixtures of compounds. We will be performing relatively large scale separations in 5.301, around 1.0 g of compound. Columns are often smaller in scale than this and some of you will experience these once you move into the research lab. Column chromatography uses the same principles discussed in the TLC Handout, but it can be used on a preparative scale. We will be running flash columns since we will use compressed air to push the solvent through the column. This not only helps provide better separation, but it also cuts down on the amount of time required to run a column. Reading: For an excellent description, see LLP pages 205–214. Preparing and Running a Flash Column: 1) Determine the dry, solvent-free weight of the mixture that you want to separate. 2) Determine the solvent system for the column by using TLC. You should aim for Rf values between 0.2 and 0.3. If your mixture is complicated, this may not be possible. In complex cases, you will probably have to resort to gradient elution. This simply means that you increase the polarity of the solvent running through the column (eluent) throughout the course of the purification. This technique will be described in more detail later in the handout, but for the TLC analysis you should determine which solvent systems put each of the different spots in the 0.2 to 0.3 Rf range. 3) Determine the method of application to the column. You have three choices: neat, in solution, or deposited on silica. Neat: If your compound is a non-viscous oil, it is sometimes easiest to apply it neat. You can use a long Pasteur pipet to apply the liquid to the column and then rinse any traces of it into the column using the predetermined solvent system. In Solution: Neat application can sometimes lead to column cracking, so a more common method for liquids, as well as solids, is to dissolve the sample in a solvent and apply it to the column in solution. In the best case, all of the components of your mixture should have an Rf of zero in this solvent - usually pentane or hexane. In many situations 63 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