Experiment 4

Experiment 4: Heating Under Reflux-Synthesis of Salicylic Acid from Wintergreen Oil

Objective:

Prepare organic salicylic acid from a sample of methyl salicylate.

Data and Results:

Mass of methyl salicylate: 0.16g (expected to use 1.525g)

Volume 6M NaOH: ~15mL

Volume 3M H2SO4: ~16mL

Final mass of crude product: .2g

Final mass of purified product: .19-.2g (range because scale used didn't tare properly)

Melting point analysis: 159˚C → Pure Salicylic Acid

Reagent Densities (g/ml) Molecular Weight MP/BP (Degrees Celsius) Amount

Methyl Salicylate 1.174 152.1 -8/223 .160g

Salicylic Acid 1.443 138.1 159 .190g

Sodium Hydroxide (6M) 2.13 40 318/1388 15ml

Sulfuric Acid (3M) 1.84 98.08 10/337 16ml

Theoretical Yield of Salicylic Acid:

.1525g of Methyl salicylate x 1mol/152.1 g x 1 mol of salicylic acid/ 1mol methyl salicylate x 138.1g /1mol = .1385g salicylic acid

.1525g M.Salicylate×(1 mol)/152.1g×(1 mol salicylic acid )/(1 mol m.salicylate)×(138.1g salicylic acid)/(1 mol salicylic acid)=.1385g salicylic acid

Percent Yield:

(mass obtained)/(mass expected)=>.190g/.1385×100 = 137.2% yield of salicylic acid

Discussion:

The objective of this experiment was to prepare salicylic acid from methyl salicylate and determine whether it differs from salicylic acid made from benzene. In this experiment, the mass of methyl salicylate used was reduced by a factor of 10, therefore the new expected yield is .1385g instead of 1.385g. In this experiment, we were successfully able to convert methyl salicylate to salicylic acid. The theoretical product yield calculated to be received from .1525g of methyl salicylate was .1385g of salicylic acid. However, 0.19g of salicylic acid was received. The product yield of 137.2% can be attributed to the fact that the final product mass weighed was not completely dried. The added water in the final product increased its mass. Relatively speaking, the product yield in this experiment was decent, considering the low yield of the product, showing that the conversion from methyl salicylate to salicylic acid was effective. The product was a flaky, white, crystalline solid.

Chemical reaction: C8H8O3(aq) +