Lab 1
Experiment 4: Heating Under Reflux- Synthesis of Salicylic Acid from Wintergreen Oil
Precious Ahmed
ID# 6463614
Section 07, Friday afternoon
Lab experiment performed on: Friday, January 19, 2013
Lab report submitted on: Friday, January 24, 2013
Introduction
Before the synthetic aspirin of today, salicylic acid, which is the important ingredient found in aspirin, was extracted naturally from methyl salicylate found in Wintergreen oil, which could be found in certain plants. The purpose of this lab experiment is to prepare salicylic acid from the natural starting material, methyl salicylate, and compare it with the salicylic acid produced from the artificial compound benzene (obtained through petroleum refining). Based on the two reactions of aspirin synthesis shown below, methyl salicylate and benzene share a common intermediate which is salicylic acid:
In order to prepare salicylic acid from wintergreen oil, an organic synthesis must be carried out. This is done first by separating salicylic acid from methyl salicylate, followed by its purification. The separation can be done by performing a reflux of a solution of methyl salicylate and sodium hydroxide. After the reflux is complete, sulphuric acid will be added to the refluxed solution, which will cause the salicylic acid to precipitate. This will then be filtered through suction filtration. Once the product has dried, purification must be done by recrystallization; dissolving the product in a minimum amount of hot solvent (water), and then filtering once again through suction filtration. Finally, to complete the main purpose of the experiment, which is to compare the prepared product with a standard (salicylic acid from benzene), an analysis must be done by measuring the melting point of the crystals and of the standard. This is fulfilled by using capillaries opened at one end containing a very small amount of both samples (dried product and a 1:1 mixture of the dried product with standard), and
Precious Ahmed
ID# 6463614
Section 07, Friday afternoon
Lab experiment performed on: Friday, January 19, 2013
Lab report submitted on: Friday, January 24, 2013
Introduction
Before the synthetic aspirin of today, salicylic acid, which is the important ingredient found in aspirin, was extracted naturally from methyl salicylate found in Wintergreen oil, which could be found in certain plants. The purpose of this lab experiment is to prepare salicylic acid from the natural starting material, methyl salicylate, and compare it with the salicylic acid produced from the artificial compound benzene (obtained through petroleum refining). Based on the two reactions of aspirin synthesis shown below, methyl salicylate and benzene share a common intermediate which is salicylic acid:
In order to prepare salicylic acid from wintergreen oil, an organic synthesis must be carried out. This is done first by separating salicylic acid from methyl salicylate, followed by its purification. The separation can be done by performing a reflux of a solution of methyl salicylate and sodium hydroxide. After the reflux is complete, sulphuric acid will be added to the refluxed solution, which will cause the salicylic acid to precipitate. This will then be filtered through suction filtration. Once the product has dried, purification must be done by recrystallization; dissolving the product in a minimum amount of hot solvent (water), and then filtering once again through suction filtration. Finally, to complete the main purpose of the experiment, which is to compare the prepared product with a standard (salicylic acid from benzene), an analysis must be done by measuring the melting point of the crystals and of the standard. This is fulfilled by using capillaries opened at one end containing a very small amount of both samples (dried product and a 1:1 mixture of the dried product with standard), and
References: Lehman, John W. Operational Organic Chemistry, 4th ed.; Prentice Hall, 2008. p. 61-68 Lehman, John W. Operational Organic Chemistry, 4th ed.; Prentice Hall, 2008. p.843-846 Fleming, Steven A.; Jones, Maitland Jr. Organic Chemistry, 4th ed.; New York, 2010. Smith, Michael B.; March, Jerry. Organic Chemistry, 6th ed.; New Jersey, 2007. Laurence M. Harwood, Christopher J. Moody, Jonathan M. Percy. Experimental organic chemistry: standard and microscaling.; 1998.