Vacuum filtration - UCLA Chemistry and Biochemistry
Synthesis of Salicylic Acid from Methyl Salicylate Gualtheria procumbens Vacuum Filtration
Synthesis and Characterization of Aspirin - Odinity
Ryu, their Teacher Assistants: Anke, Bri, Greg, Joe Nailah, and Glyftawlbnz (Casey)
Synthesize aspirin from a non- petroleum source
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Background of IR Spectroscopy
Used to determine purity of compound by analyzing to which degree bonds absorb IR radiation
Quantization of energy allows for absorption of specific energy levels of bonds
Wavenumbers are representative of the energy levels
% transmittance measures to what degree the absorption occurs
Vibrational energy turns into bending and stretching
The Alkali Metals
Synthesis of Aspirin
Common Medical Applications
Negative Side Effects
Synthesis of Salicylic Acid
Extraction of Caffeine
Extraction procedure from Coke
Extraction procedure from Coffee
UV analysis of caffeine
Synthesis of Salicylic Acid from Methyl Salicylate
Add 6 M NaOH into a boiling flask that contains methyl salicylate.
With H2O flowing in
heat reaction mixture under reflux for 30 minutes.
Transfer to beaker, add H2SO4
Cool mixture and collect salicylic acid via
A vacuum filtration is usually faster than a simple gravity filtration using a simple conical funnel. However, there are several points that have to be considered when performing a vacuum filtration. Due to the fact that reduced pressure is used in this procedure, special attention has to be paid to the equipment used in this procedure. The glassware (i.e. filter flask) should not have any cracks on the sides or the bottom. It is also imperative that the filter flask and the vacuum trap are clamped securely, so that they do not move during the filtration. The thick-walled tubing tends to act like a whip sometimes, and slams the filter flask into the hotplate or other metal objects resulting in an implosion (or tips the flask over and the product is found afterwards on the bench or even worse on the dirty floor!).
The clean filter flask and the vacuum trap consist of heavy-walled glassware. Thick-walled tubing should be used as well. Normal tubings that are used as water hoses will collapse when a vacuum is applied!
Never perform a vacuum filtration without a vacuum trap. It is also a good idea to keep the trap clean, just in case something gets sucked in there. It is easier to recover it from a clean trap then from a dirty trap.
Vacuum filtrations can only be performed with funnels that have a flat surface e.g. Hirsch or Büchner funnel, which are both made from procelain! The filter paper has to cover all holes in the bottom of the funnel and does not extend up the sides. This means that the small pieces (~1.3 cm) of filter paper are used for the Hirsch funnel, and not a bigger circle hanging in the funnel. If the filter paper has the wrong size or not properly placed in the funnel, a significant part of the solid will "run through" the filter paper.
If the filter paper is too big for the Büchner funnel, it has to be cut to size with scissors. (From this point of view, it might be a good idea to generate a cardboard blank from an existing filter paper). The filter paper is moistened with the solvent that makes up the solution. This prevents the formation of multi-layer systems in the filter flask. It should adhere well to the bottom before the vacuum is applied. Then the solution is slowly poured slowly into the funnel.
December « 2017 « New Drug Approvals
Taken from the University of Minnesota
Alkali Metal's IR results for salicylic acid
Difference between Salicylic Acid and Methyl Salicylate
Background of Nuclear Magnetic Resonance (NMR)
Nuclei have spin and all nuclei are electrically charged.
When an external magnetic field is applied, energy transfer is possible between the base energy & higher energy level.
Energy transfer takes place at a wavelength that corresponds to radio frequencies.
When spin returns to base level, energy is emitted at same frequency.
Protons in different electronic environments will absorb different frequencies of this radiation.
Calculations: Synthesis of Salicylic Acid from Methyl Salicylate
Mass: 1.0002 grams
Percent Yield: 70% Yield
Accepted Melting point: 159 degrees Celsius
Measured Melting point: 152 degrees Celsius
Synthesis of Aspirin from Salicylic Acid
Add acetic anhydride to salicylic acid with a few drops of sulfuric acid.
Heat, allow for recrystallization, separate by vacuum filtration.
Repeat and add ethanol and water.
Test for purity by adding 1 drop of ferric chloride
NMR spectrometers employ strong magnetic fields and the frequency of radiation typically required for nuclear resonance falls in the radio wave region of the electromagnetic spectrum.
Difference between Salicylic Acid and Aspirin
Experimentally-Obtained NMR of Aspirin
Left: Crude aspirin
Middle: Aspirin after purification
Right: Pure salicylic acid
IR Spectra of Salicylic Acid
Lab technique used to learn about the composition of a substance.
Measures absorption of visible & UV light by bonds of organic compounds
Different atom conformations absorb different wavelengths of light
Determines molecular structure by which wavelengths are absorbed
Used to identify molecules & test for purity
Experimentally-Obtained IR Spectra
Experimental Comparison of Aspirin and Salicylic Acid
Comparison of Aspirin and Salicylic Acid
Used to test for purity of synthesized aspirin sample
Sent wavelength absorbed well by salicylic acid but not well by aspirin
Compared absorption by pure salicylic standards to absorption of aspirin sample
Plotted best fit absorption line based off of salicylic acid samples
Used the line’s equation to calculate amount of salicylic acid in aspirin sample
Results indicate our aspirin had .89% salicylic acid mixed in
Experimentally-Obtained IR Spectra of Aspirin
UV/vis in Aspirin Synthesis
Alkali Metal's IR results for Aspirin
"Institute for Protein Research, Osaka University." Institute for Protein Research, Osaka University.
When a funnel is placed on top of the filter flask, a neoprene adapter (the black or gray "rubbery thing") or rubber stopper is used to ensure a good seal between the filter flask and the funnel.
When the filtration is finished, the tubing from the filter flask should be removed before the vacuum is turned off. This is less important when the house vacuum line is used like in the instruction lab, but it will be when an aspirator is used. The low pressure in the filter flask sucks the water back into the mother liquor, and if this is the part of interest, the experimenter is in big trouble.
Also, a vacuum filtration is not suitable for solvents with low boiling points e.g. diethyl ether, dichloromethane or other low boiling solvents. The solvent evaporates under the vacuum and the dissolved solids precipitate, clogging up the pores of the filter paper and get stuck on the insides of the funnel i.e. stem, etc. The same applies to hot solutions, since the solvent is close to its boiling point as well. In those cases, gravity filtration is used.
If a very fine precipitate has to be filtered, it is advisable to use some filter aid like diatomaceous earth or Celite. This will prevent that the holes of the filter paper will get clogged up too fast. This technique is obviously not very useful if the solid is the interesting part, because it will be very time consuming to separate the product from the filter aid.
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Make sure the mouse is hot enough.
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