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Extraction of Caffeine from Coffee

Performed by: James Forst, Sibora Peca Performed on 10/3/2019 Submitted on 10/17/2019

Abstract Within this experiment the separation of caffeine from coffee will be performed. Caffeine is the byproduct of the decaffeinating process of coffee. To perform the separation of caffeine and coffee we must add a solution to our coffee in order to remove tannins from the coffee. The solution we added was Na2CO3. This allowed the tannins to react and solidify and turning them into a salt. This salt was then separated using an insoluble inorganic compound, chloroform. The addition of chloroform created inorganic and organic layers in which we separated in order to dry and determine our final yield of caffeine. In the experiment we collected 0.15g of caffeine from our coffee grounds. In later testing our caffeine product melted completely at 230 degrees Celsius under observation of a Mel-temp apparatus. Objective The main objective is to separate caffeine from coffee. To accomplish this the tannins that give coffee its dark color must be removed in order to isolate the caffeine. This will be performed by adding Na2CO3. Since the separated tannins are partially soluble they separate into organic and inorganic compounds. To further perform the separation of caffeine Chloroform will be added to separate the inorganic and organic compounds leaving a final caffeine product to be dried. Introduction Worldwide caffeine is one of the most widely used legal drugs. Caffeine is a nervous system stimulant that has a pharmacological effect on humans and animals. Caffeine is contained within several natural sources such as coffee beans and tea leaves. It is estimated that nearly 90% of Americans consume some form of caffeine daily. Caffeine is classified as an alkaloid meaning it is an organic compound containing nitrogen. Within in this experiment several separations must be performed in order to isolate the caffeine from coffee by use of organic and inorganic compounds that will create a solubility difference allowing for separation of caffeine from coffee. Extraction is a method of separation used to remove or isolate a compound from another compound. In this experiment coffee contains dissolved caffeine that will be separated. This extraction will be performed by adding a solvent to the coffee. The key to extraction is creating a solubility difference in order to separate the desired compound. By adding a solvent in a separation experiment the goal is to have the more soluble substance caffeine, separate from the remaining liquid. We began the experiment by measuring 5 grams of coffee grounds and 30ml of distilled water along with 2g of Na2CO3. The first separation that must be performed in this experiment is separating tannins from the coffee. Tannins contained in coffee and are what give the coffee it’s dark color. When isolated using Na2CO3 solution, the tannins will become a salt. To remove the tannins from the coffee an experimenter must add specific quantities of Na2CO3 and water. The salt formed is soluble in water but insoluble in chloroform. Therefore, by adding chloroform, we will be able to extract the tannin salt from the mixture. Chloroform is an inorganic solvent

therefore it’s addition will create two layers within our apparatus. By adding chloroform to the aqueous mixture the salts will be left behind in a separate layer that is easily visible. After the initial separation is performed and chloroform is added the caffeine will remain and be considered a crude solid. A seperatory funnel will be the apparatus used to further separate the caffeine from the coffee. The seperatory funnel used contains a valve that allows for slow separation into a separate beaker. The product collected within this separate beaker will then transferred to a 25ml round bottom flask that will be heated over a sand bath allowing any remaining liquid to evaporate. After this drying process takes place the reaming product is pure caffeine. By weighting the round bottom flask empty and the final product and round bottom flask it can be determined how much caffeine has been collected from the coffee grounds. To verify the results other experiments must be taken into account along with a melting point test for the final product. Materials · Filter Paper (To Separate Compounds) · Stem-less Funnel (Holds Filter Paper to catch the product) · 5.0 Grams Ground Coffee · 30 ml Distilled Water · 2.0 GRAMS NA2CO3 · Buchner/Hirsch Funnel (Used on the filter flask to vacuum) · Vacuum (Used to remove excess water/products) · 125ml Seperatory funnel · Hot Plate (Heated water and glassware) · 100ml Beakers (Used for compounds) · 8ml of Chloroform · 25ml Erlenmeyer Flask · Aspirator Tube (Attaches to hood vacuum and creates vacuum seal) · Hot Sand Bath (Provided more even heating) · Filter Flask (Shape allows vacuum effect and allows rapid filtration of compounds through hood) · Scale (Used to weight the filter paper and compounds)

Table of Physical Constants Compound

Name

Molecular Weight (g) 194.11

Density

Caffeine

Melting Point (c ) 230-238

Chloroform

61.2

119.37

1.49g/cm3

Sodium Carbonate

851

105.98

2.54g/cm3

Water

100

18.01

997kg/m3

1.23g/ml

Apparatus

Seperatory Funnel

Procedure and Observations Procedure 1. Prepare 5g of Coffee Grounds 2. Place in a 100ml beaker, add 30ml of H2O and 2g of Na2CO3 3. Heat and stir, Allow boiling for 10 Minutes 4. Heat a separate 50ml of water 5. Prepare the Vacuum under and filter flask

Observation 5.0g Prepared 2.0g of Na2CO3 prepared The solution was boiled for 8 minutes as it appeared to dry. We were able to heat the H2O Simultaneously

6. Filter the mixture using the vacuum apparatus 7. Add the separate 50ml of water to the now filtered mixture (Wash) 8. Allow the solution to cool to room temperature 9. Add 8ml of Chloroform and gently swirl the solution in a Seperatory funnel. Be sure to release the pressure using the valve. 10. Collect the suspended solution in a separate beaker (Organic and inorganic layers) 11. Add an additional 5ml of Chloroform to the Seperatory funnel, Collect more of the separated solution. 12. The solution was transferred to a round bottom flask. Allow the liquid to evaporate, Weight the final product. 13. Transfer Dried Prodcut to capillary tube to test for melting point

The apparatus filtered slower than expected. We suspected an issue but were able to filter the mixture This water was used to make sure all of the mixture was transferred after it cooled. We waited until the solution was cool to the touch. We released pressure from the seperatory funnel 2x. A lot of pressure was built up on the first release The solution was slowly collected into a separate 100ml beaker to prevent mixing the layers The additional 5ml helped to further separate the layers. This potentially provided a better yield. 22.43g Round Bottom Flask 22.58g Round bottom Flask + Caffeine product Caffeine Weight = 0.15g 220C melting began in Mel-temp apparatus 230C The product completely melted

Flow Chart

Prepare 5g of Coffee Grounds

Transfer to Beaker with 2g Na2CO3 and 30ml H2O

Add heat and stir soluton

Boil for minutes

Boil an Additonal 50ml of H2O

Prepare Vaccumn Appartus

Filter and Seperate solution, transfer to a beaker and allow cooling

Add Chloroform

Use a sepratory funnel to seperate the organic layer

Dry the remaing prodcut in a round bottom beaker in a sand bath

Calculate the mass of the caffiene and the round bottom beaker

Waste Disposal and Safety Precautions In terms of waste disposal and safety precautions in this experiment we used the proper lab wear. This lab wear includes closed toe shoes, a closed lab coat, eye wear, and rubber gloves. All of these lab wear items work together in order to protect the experimenter from the chemicals and apparatus they are working with. In terms of protection eye wear is the most important as many chemicals can irritate or damage the eyes. Gloves protect the experimenter from hot surfaces and direct skin reactions from chemicals. The lab coat and closed toe shoes protect experimenters from spills and damaging their clothes. Waste disposal is almost as important as the experiment itself. Not only is proper waste disposal safer as it prevents reactions and environmental damage it helps to prevent lab accidents. In our experiment all items went into their appropriate bins solids with solids, liquids with liquids and non-reactive chemicals went down the drain or into a marked trash bin. Results and Discussion Based on our procedure and results we separated 0.15 grams of caffeine from our 5-gram sample of coffee grounds. We calculated this by taking initial weights of all our materials. The round bottom flask our final product contained in was weighted before use as 22.43g and with the product it weighted 22.58g. After the final weight was subtracted from the original weight the conclusion of 0.15 grams of caffeine was made. The result seems low and can be contributed to a variety of factors. For instance, we learned the boiling time of the initial mixture of water, sodium carbonate and coffee dissolved quickly over heat. This may have led to lost product. Another experimenter error could have occurred as loss of material through transfer of beakers. Precautions were taken to prevent loss of material through transfer and filtration however there was obvious visual loss of some material during our experiment. In a 7oz brewed coffee there is approximately 0.08g to 0.135g of caffeine. In our experiment we used coffee grounds rather than brewed coffee. On average according to the USDA, there is 157mg (0.157g) per 5 grams of coffee. This makes our observation of 0.15 grams seem appropriate however we are not aware of the brand or caffeine content of our coffee, therefore our figure is up to debate based on the type of coffee we used. The caffeine end product was found in a Mel-temp apparatus to start melting around 220C and completely melt at 230C. Conclusion To summarize extraction is an effective laboratory method used to separate two compounds from one another. In this experiment extraction was used to separate caffeine from ground coffee. By adding solvents to separate caffeine from coffee such as sodium carbonate and chloroform our final prodcut of 0.15g of caffeine was collected. This final product of caffeine collected was compared to data from the USDA to determine if our results were comparable or probable based on their average observation of caffeine in coffee grounds. Based on this data and testing the melting point using Mel-temp apparatus at a later date we determined that our final product extracted was caffeine as our melting point matched the range we researched for caffeine and our caffeine content in grams was close to the USDA average for ground coffee.

References I. II. III.

Williamson, Kenneth L. Organic Experiments. Vol. 9, Cengage Learning, 2011. Morrison, Robert Thornton., et al. Organic Chemistry. Pearson, 2011. USDA, Food Composition Database. https://ndb.nal.usda.gov/ndb/search/list? qlookup=14214...