Experiment 1: Extraction of Caffeine from Tea The primary objective of the experiment is to separate the caffeine from tea leaves. The mixture of tea and the calcium carbonate is separated from tea leaves by vacuum filtration. The solvent used in extraction of caffeine is dichloromethane. Anhydrous magnesium sulfate is added to the dichloromethane solution to dehydrate the mixture. The dichloromethane is then separated from the mixture in the rotary evaporator.
After the effervescence, (15mL) of concentrated HCl was added drop wise to the solution. The mixture was then heated for 15 minutes in a boiling water bath. In two separate small beakers (20mL) of distilled water was placed in one and (20mL) of 6M HCl in the other. Both beakers were placed into an ice bath. After heating, the mixture was cooled to room temperature and filtered by vacuum filtration into a fritted funnel to yield a purple product.
Isolation of Caffeine from Tea CHEM243A 2-23-11 Abstract: The purpose of this experiment was to isolate caffeine from a tea bag. Once isolated, the caffeine was purified using sublimation. The percent recovery was calculated to be 83.3%. The melting point of the original substance was 51ºC-139ºC. Since it was inaccurate, the melting point of another group’s sample was recorded.
The third test will utilize thin layer chromatography to evaluate the purity of the aspirin as well as testing for the presence of leftover salicylic acid or other by products of the reactions. Experimental: Week 1: For the synthesis of the aspirin, 250 mL of water was boiled. 1.5 g. of salicylic acid were poured on a test tube. Then, 3.5 mL of acetic anhydride and four drops of 85% phosphoric acid were added. A cotton ball was placed to prevent vapor escape.
Gently stir the resulting mixture for 30-60 seconds. * Step 4 –Place a suitable filter (cloth, filter paper or a fine sieve) over an empty glass, and secure it with the rubber band. Pour the mixture into the filter. If the mixture is too thick, stir in more of the extraction solution. Leave to filter for about 10 minutes.
Wash and add Gram’s iodine (mordant) - 1 min. 4. Drain off iodine, add alcohol (decolorizer) -15 seconds 5. Wash and add Basic fuchsin or Safranin (secondary stain)- 1 min. 6.
Introduction Caffeine is a molecule that is similar to the purine base xanthine. The only recognizable difference is that caffeine has a methyl group. The goal of this experiment is to isolate caffeine from tea leaves, and then purify it by using sublimation. This experiment will use three techniques, extraction, recrystallization and melting point determination. A sequence of extractions has to be done to take out the other components from tea.
PROCEDURE: A. 2,4-Diphenylhydrazones 0.05 g Unknown 0.05 g Unknown 5 ml 5 ml ----Warm for a few mins in water bath ----Crystallization ----Collect product Figure 1. Hirsch funnel filtration apparatus. ----Wash crystals w/ large amt of H2O ----Press a pc. of moist litmus paper onto crystals ----Wash with more H2O if acidic ----Press between sheets of filter paper until dry ----Recrystallize from EtOH If unknown is a ketone If unknown is a ketone Clean up: Filtrate Dilute w/ water, neutralize w/ Na2CO3, flush down the drain Mother liquor from recrystallization Dilute w/ water and flush down the drain SolidSuction filter: FiltrateFlush down the drain Filter paperPhenylhydrazone waste B. Semicarbazones 1 mmol Unknown 1 mmol Unknown 0.5 ml 0.5 ml (Draw test tube here) 1ml CH3OH (show extended structure) 1ml CH3OH (show extended structure) 10 drops 10 drops ----Warm the solution gently on steam bath for a few mins ----Cool slowly to room temp; scratch inside of tube ----Cool tube in ice If unknown is a ketone If unknown is a ketone ----Suction filter the product (See Figure 1 for apparatus) ----Wash w/ H2O, then cold CH3OH ----Recrystallize from CH2-CH3-OH Clean up: Filtrate + mother liquorDilute w/ water, + dil.
The watch glass was removed with the beaker tongs. Using a rubber bulb and a stirring rod to stir the solution continuously, 15.00mL of .25M BaCl2 solution was added to the solution in the beaker. The watch glass is replaced and the solution is keep hot but not boiling for 15 minutes. The precipitate was allowed to settle. When the liquid above the precipitate was clear, the solution was tested for completeness of precipitation when a few drops of BaCl2 solution were added from a pipette.
Abstract: The ability to isolate caffeine from tea leaves was questioned and was found to be successful in this experiment. This was achieved by extracting caffeine, separating other natural substances and sublimating the existing caffeine. The weight of the caffeine isolated from the tea leaves was .0186g; which is a 33.8% recovery of the original material of caffeinated tea leaves. Introduction: This experiment’s purpose is to extract the caffeine that consists in a small portion of tea leaves. The theory of extraction is a technique used to separate organic compounds from a mixture or a solution of compounds.