Crystallization Experiment

Crystallization Experiment - Experiment 2 O CH3 CH3 CH2O NH...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Experiment 2 CRYSTALLIZATION NH CH 3 CH 2 O Phenacetin Benzoic Acid O OH CH 3 O Phenacetin was a common ingredient of pain-relieving medications until recently, when tests showed carcinogenicity in laboratory animals. The analgesic properties of phenacetin are due to its degradation in the body to acetaminophen, which is the active ingredient of such medications as Tylenol. In this experiment, you will identify a solvent that could be used to purify phenacetin by the technique of crystallization. You will then purify benzoic acid by the technique of crystallization as classically done on a large scale. The technique is effective in removing both soluble and insoluble impurities. Therefore, you should have no trouble removing the small percent of impurities that is present in your sample of crude benzoic acid. Background Reading Read Chapter 7 about the crystallization technique, Chapter 8 about melting point, and the Appendix about percent recovery. Also review “steam bath” in section 3.3. Webpage Demonstration View the PowerPoint demonstration about hot filtration and vacuum filtration. Properties of New Materials Name Appearance Properties Comments Phenacetin Benzoic acid White solid White solid Melting point 135 o C Melting point 121 o C Mutagen and cancer suspect agent Irritant Ligroin Colorless liquid Boiling point 30-60 o C Flammable Ethyl acetate Colorless liquid Boiling point 77 o C Flammable and mildly toxic
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Safety Precautions Organic solvents are generally volatile. It is important to minimize escape of vapors for two reasons: flammability and toxicity. Therefore, store the solvents in a beaker covered with a watch glass or in an Erlenmeyer flask and work in the hood whenever it is practical. Because the solvents and materials dissolved in them can be absorbed through skin, try to avoid contact. You may choose to wear gloves. To avoid the inhalation of solvent vapor escaping from the test tube, do not point the test tube toward anybody. Never add a boiling stone to a hot solution – it could cause violent bumping. The test tube holder is not designed to hold an Erlenmeyer flask firmly. If it is too hot to hold the Erlenmeyer flask with your fingers, use a clamp. Experimental Procedure Part A Solvent Trials Step in procedure Comments 1) In the following steps, test the solubility of phenacetin in ligroin, ethyl acetate, and 95% ethanol. Pure phenacetin, instead of the impure sample, is used for the solvent trial so that any undissolved phenacetin will not be confused with insoluble impurities. Solvents are listed in order of increasing polarity. A solid tends to dissolve more readily in a solvent whose polarity is similar to its own. To appreciate this relationship, compare the structures of phenacetin and the three solvents. For recording data from multiple trials in your notebook, it
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

Crystallization Experiment - Experiment 2 O CH3 CH3 CH2O NH...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online