Caffeine is an alkaloid stimulant via a cyclic backbone framework analogous to the purine structures of DNA, providing it the capability to impact biochemical pathways in the body1. In commercial application, caffeine supplements pharmaceuticals and particular beverages such as coffee or tea. Standard tea bags contain 2.00 +/- 0.05 g of tea leaves in addition to about 55 mg of caffeine<1>. Using the proper extraction approaches, the caffeine within a tea bag can potentially be isolated to yield a pure solid; the mass of this solid would reflect the actual yield of caffeine in the tea. To do so, caffeine have to be introduced to a solvent that is both volatile and also insoluble to water; a perfect example is methylene chloride<2>. Caffeine has a better affinity for methylene chloride and will conveniently disfix in this solvent over water; yet caffeine is not the just organic substance found in tea that is qualified of reacting via methylene chloride. Alengthy through caffeine, tea bags contain organic substances referred to as tannins, or gallic acid1. Both caffeine and also gallic acid are qualified of disaddressing in water; but, caffeine has actually a stronger attraction to water as a result of the dipole-dipole interaction that results from the higher polarity of caffeine and the hydrogen bonds that form in between caffeine and also water1. Theoretically, the intermolecular pressures of gallic acid deserve to be manipulated to induce a stronger dipole-ion interactivity. If a widespread salt favor sodium carbonate was introduced to the solution, gallic acid might revert ago right into phenol salt: a polar, not natural molecule that is insoluble in methylene chloride<3>.
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In methylene chloride, caffeine will have a better attraction for the organic solvent and the hydrogen bonds between caffeine and also water will be damaged. Using a separatory apparatus, two insoluble solutions deserve to be separated, isolating caffeine and also the brand-new phenol anion from one one more. The denser methylene chloride layer deserve to then be released from the funnel to render a pure solution of caffeine and methylene chloride. To encertain that no water interferes with the interactivity of caffeine and also methylene chloride, sodium sulfate might be supplied to absorb any kind of excess water that might have escaped from the tea solution1. If heated, the solvent would easily evapoprice because of low boiling point of methylene chloride2. The staying solid would certainly then be pure caffeine.
Materials and Methods:
To begin, a 150 mL beaker containing 50 mL deionized water and also 2 boiling stones was ready to dissolve 2.0 grams of sodium carbonate to react with the gallic acid in tea. The beaker was enabled to warm till the water started to boil, at which allude the temperature was lowered and also 2 tea bags were put right into the water. The solution was heated for 10 to 12 minutes to achieve the highest possible concentration of tea. At the exact same time, the insoluble cellushed components of tea separated from the solution rendering the tea concentprice, caffeine, and also the new phenol anion product. The final saturated solution was poured right into a 100 mL beaker while the fluids trapped within the tea bags were all at once rinsed through a secondary 10 mL of deionized water. Once cooled, the solution was moved into a 125 mL separatory apparatus, a glass funnel supplied to sepaprice unmixable remedies. From the peak of the funnel, methylene chloride was poured into the solution in increments of 5 mL. Following eextremely enhancement of methylene chloride, the funnel was inverted to release the built-up press from the reaction. The reactivity rendered brvery own optimal layer of tea and a clear bottom layer of dense methylene chloride. The bottom layer was released from the stopcock and also accumulated right into a 100 mL beaker leaving behind a thin layer of methylene chloride to proccasion contamicountry.
Methylene chloride was included 2 even more times to assure that every one of the caffeine was reacted via. Sodium sulfate was included to the extractivity to absorb any water that escaped from the tea and also the remaining liquid was decanted and rinsed right into a pre-weighed 50 mL beaker with boiling stones making use of an additional 2.0 mL of methylene chloride. When boiled, the volatile methylene chloride evaporated, rendering pure, solid caffeine.<1>,<2>,<3>
Experiment 1: Isolation of Caffeine from Tea Leaves
|Density of H2O|
|Density of CH2Cl2|
|Weight of Tea Bags|
|Weight of 50 mL beaker and also boiling stones|
|Weight of 50 mL beaker, boiling stones, and caffeine|
|Weight of Caffeine|
|Theoretical Yield of Caffeine|
|Actual Yield of Caffeine|
Figure 3: Obtained IR Spectrum Graph of Caffeine
The prefigured out masses offered by the Lipton Tea manufacturers are welcomed as the experimental measurements of both tea and also caffeine. The approximate weight of an individual Lipton tea bag is 2.00 ± 0.05 g, containing 55 mg of caffeine per bag. In an experiment utilizing 2 tea bags, 110 mg is the supposed yield of caffeine to attain. A 50 mL beaker, together with 2 boiling stones, was weighed in breakthrough with a total mass of 27.56 g during the extraction procedure. To extract caffeine, the heated tea solution, together with 5 mL of methylene chloride, was poured right into an isolated separatory funnel and inverted to mix the solution totally. Due to the reactivity, push gathered inside the funnel, requiring the stopcock to be opened to release excess gas adhering to each invariation. Once settled, the solution separated right into 2 layers: the polar, brvery own tea solution on the peak and also the nonpolar, clear methylene chloride on the bottom. The tea separated over the methylene chloride because while the density of water is 0.997 g/mL, the thickness of methylene chloride is 1.32 g/mL. Between the two layers sat small bubbles or feasible emulsions that restricted the amount of methylene chloride that can be extracted. Despite this, the methylene chloride/ caffeine layer was efficiently drained right into the pre-weighed 50 mL beaker and also the procedure was repeated 2 additional times to encertain that every one of the caffeine was reacted via. In doing so, the volatile methylene chloride began to evaporate right into the surroundings because of the raised room temperature. The remaining solution was heated briefly until the volatile solvent evaporated, leaving behind solid caffeine. When weighed, the beaker, stones, and caffeine rendered a full mass of 27.58 g. The difference in mass between the initial weight of the beaker and also the final product was then the actual yield of caffeine, 0.02 g. In compariboy to the theoretical mass, the experiment gave 18.18% yield of caffeine.
The solid caffeine product was run through an Infrared Spectrometer that supplies bond energies to identify chemical compounds. The spectrometer created a graph based upon measurements of photon power within a frequency range between 400 and also 4000 Hz. Individual spikes on the graph suggest the distinct bond energies of particular useful teams. For instance, the photon power spike visible roughly the 3000 Hz frequency represents amine and amide team noticeable in caffeine. The various other necessary spike shows up about 1600 Hz and 1750 Hz. This spike represents the alkene percentage of the caffeine molecule. Using these individual spikes in photon energy, the infrared spectrometer predicts the composition of the compound current. The spectrometer predicted the probability that the sample produced was caffeine to be 869 out of 1000. This worth has actually no relation to the purity of caffeine.
As is expected, the percent yield of caffeine was not 100%; yet, achieving this goal is impossible. The mass of caffeine from 2 Lipton tea bags was just 18.18% of the theoretical yield but in consideration of all the determinants responsible for error, 18.18% is an acceptable value. The error in yield results from a number of unpreventable experimental flaws. The initially flegislation originates from the reaction between gallic acid and also sodium carbonate. Although the convariation of gallic acid is important for the reaction of caffeine and also methylene chloride to occur, the phenol anion byproduct of this reactivity is responsible for important error<1>. When phenolic acids are went back ago into salts, anionic surfactants are produced4. These surfactants are responsible for emulsifying water insoluble products like methylene chloride. As a result, large soapy bubbles dubbed emulsions are developed by the polar and also nonpolar remedies. During the extraction phase of this experiment, these bubbles minimal the amount of caffeine released from the separatory funnel leading to a lesser yield. Anvarious other resource of lesser yield originated from techniques supplied to prevent the contamination of the methylene chloride solution. While extracting the caffeine, a little layer of methylene chloride required to be left behind to stop tainting the final product<2>. By discarding component of the methylene chloride solution, a section of the caffeine was left behind that influenced the overall yield of the product. The final source of error originates from unavoidable environmental problems. As an outcome of the hot plates offered before the caffeine extraction phase, the temperature of the laboratory was boosted. Methylene chloride does not generally evaporate at room temperature yet being out in the open up at an increased temperature triggered the solution to react early on leaving less methylene chloride to react via the caffeine. This would certainly lead to a lesser amount of caffeine extracted from the solution and also a lesser yield.
Questions:Look up the framework of caffeine and determine the strongest intermolecular pressure current.
The strongest intermolecular force in caffeine is the dipole-dipole interaction bereason of the polarity of the molecule. The dipole minute of the molecule outweighs the weak van der waals pressures making it the strongest intermolecular force in caffeine.
Caffeine is more soluble in methylene chloride than water bereason both caffeine and methylene chloride are organic substances while water is inorganic. Although caffeine is qualified of disresolving in water by forming hydrogen bonds, the higher affinity that caffeine has actually for methylene chloride breaks these bonds.
3. Describe the function of including sodium carbonate to the reactivity mixture?
The objective of adding sodium carbonate to the mixture wregarding transform the chemical framework of gallic acid. Initially, gallic acid has actually a slight affinity for methylene chloride that would certainly conflict through the reactivity between caffeine and also the methylene solvent. By presenting of a simple sat prefer sodium carbonate to the solution, gallic acid will certainly be converted right into an not natural, phenol salt that is insoluble in methylene chloride however extremely soluble in water. As an outcome, methylene chloride extract will contain the highest possible yield of caffeine alone.
Work CitedBettelheim, F. and Landsberg, J. Laboratory experiments for organic and also biochemisattempt. Saunders College Publishing, 107-111, 1995.
Experiment 6: Isolation of caffeine from tea leaves. (n.d.). SUNY Oneonta. Retrieved February 2, 2014, from http://employees.oneonta.edu/knauerbr/ch
Gensler, W.J., Griffing, S.F., and Mohr, S.C. Fundamentals of Organic and Biological Chemistry; Laboratory Manual. Prentice Hall Publishing, 249-254, 1994.
Landgrebe, J.A., Theory and also Practice in the Organic Laboratory. 3rd edition, D.C. Health and Company, 452-255, 1982.
Stoker, H. S. (2013). Organic and Biological Chemistry. Belmont: Mary Finch.
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Swartz, D. (2014, January). Experiment 1: Isolation of caffeine from tea leaves. BioOrganic Lab. Lecture carried out from Daeguys College, Amherst, NY.
College of Coloraperform, Boulder, Chemistry and Biochemistry Department. (2011). IR: carboxylic acids. Retrieved from IR Spectroscopy Tutorial: