Steam Distillation of Essential Oils - Lab IV | CHEM 333, Lab Reports of Organic Chemistry

Download Steam Distillation of Essential Oils - Lab IV | CHEM 333 and more Lab Reports Organic Chemistry in PDF only on Docsity! CHEM–333: Experiment 4: Steam Distillation of Essential Oils; Experiments A, C, D and below. Reading: For this experiment read Chapter 10. This week you will get to use steam distillation to isolate the oils from either caraway, cinnamon, clove, or cumin (see below) and prepare a derivative of the main component of that oil. You may wish to include all four derivatization equations in your notebook, or you may wait until you come to lab to find out which spice you get. Steam distillation is not a common research laboratory procedure, but it is invaluable when it is useful, as in extraction of essential oils. I know what your thinking—didn’t we just do distillation last week? Whereas the apparatus is the same, the physics is considerably different as your compound is “distilled” as minor component of an aqueous mixture but at a much lower/ less destructive temperature than distilling the compound directly. Now you will know how to make those weird smelly extracts found in those hippie shops. You will finish this lab next week, as well as getting a tour of the chemistry library to find out about your "Literature Search" project. When assembling the setup as pictured in Figure 10.2, note that there is no need for a dropping funnel. The water initially in your round bottom flask will be sufficient for the distillation. Record the weight of your spice, and proceed as directed. Figure 10.2 does not include clamps, but they are obviously required. Boil the mixture vigorously, but watch for boil-overs! Collect about 125 mL into an Erlenmeyer flask; by the time you are done, the distillate should be clear and colorless (check for oily drops by catching some distillate in a small beaker). After you pour the distillate into the 250 mL separatory funnel, rinse the Erlenmeyer flask with 10 mL of methylene chloride using a pasteur pipette and add to the separatory funnel. Which layer is the methylene chloride? (Check the density in the back of your book.) Shake the funnel, let it settle, and collect the methylene chloride layer in a small Erlenmeyer flask. Repeat the extraction with another two 10 mL portions of methylene chloride. Add a sodium sulfate until it remains granular to the combined methylene chloride extracts, and filter it through a tiny piece of cotton into a weighed/tared 50 mL round bottom flask. Then use the rotory evaporator to remove the solvent. Use the weight of the oil to calculate the percent of oil in the ground spice. All waste solid from the steam distillation should be disposed of in the waste containers provided, not down the sink. You may not have time to complete the derivatization of your oil in one week, but there will be time next week. Use all of the oil that you have isolated. Derivatization: Why derivitize? Often the compound you isolate is too volatile or unstable to characterize itself. By making a derivative that is less volatile (and/or stable) you can better characterize your compound by meltingpoint or other technique. Caraway (Part C) Dilute the oil with 1 mL of ethanol, transfer it to a test tube, and use another 1 mL of ethanol to rinse your round-bottom flask. The DNPH solution has been prepared and is in the hood. Recrystallize your derivative from a little ethanol: add enough so that the solid dissolves when heated on a steam bath, then cool to get crystals. Be careful not to get the DNPH solution on your skin. Clove (Part D) Use all of your oil. Although clove oil is mostly eugenol, the other components interfere with crystallization of your derivative. So after you have added 1M NaOH to your water/oil mix "until the oily layer dissolves," (converting the phenolic eugenol "ArOH" into water-soluble "ArO-"), wash out the neutral compounds with two extractions of ether (add 3 ml of ether to the test tube, shake to mix, and remove the ether layer with a pipet). Dispose of ether in the waste jug (or allow it to evaporate to smell the other components of the oil). Continue with benzoyl chloride as in the text. Be sure to add this in the fume hood and keep the test tube stoppered until heating is begun. If your ester does not crystallize after following the directions in the text, add about 1 ml of petroleum ether to your mixture and cool and scratch again. Cumin (Adapted from Moore/Dalrymple/Rodig) Cuminaldehyde H2N N H NH2 O Semicarbazide + N H N O NH2 Cuminaldehyde Semicarbazone CHO The dried fruit of cumin (Cuminum cynimum L.), a small shrub cultivated in eastern Europe and India, is an important seasoning in curries, goulashes, and sausages. It is also a major component