Lab 6

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CHEM 282 Experiment #6: Isolation of Cinnamaldehyde from Cinnamon Sophie Wolkoff (20107258) & Kaelen Partridge (20127197) TA: Bily Deng March 5, 2020 Experimental:

The first step of the procedure involved a simple distillation, performed by each partner, using 0.5 to 0.8 g of sodium chloride, approximately 3 g of ground cinnamon, and 50 to 60 mL of water in a 250-mL round-bottom flask. Approximately 10 to 15 mL of water-cinnamaldehyde distillate was collected by each partner and combined. The distillates were then extracted in a separatory funnel with three successive 5-mL portions of dichloromethane, transferring the dichloromethane layer to an Erlenmeyer flask each time. These layers were dried over sodium sulfate and separated by gravity filtration into a pre-weighed beaker. The solvent was evaporated over a steam bath until an oil remained, then it was cooled and reweighed to calculate the actual weight of cinnamaldehyde. Subsequently, 2 mL of ethyl alcohol was dissolved into the substance. Step two involved the formation of semicarbazone or 2,4-dinitrophenylhydrazone by first adding 1 mL of the cinnamaldehyde-alcohol solution to 0.5 mL of 2M semicarbazide hydrochloride solution in a test tube. Then, 0.5 mL of a base, 2M aqueous sodium acetate solution, was added to the mixture and the test tube was shaken, warmed over a steam bath and left to stand for 15 minutes. The test tube was cooled in an ice bath and the crystals formed were collected by vacuum filtration. Using the dried crystals, the melting point of the substance was determined in order to identify the solid. This step was repeated using 3 to 5 drops of HPLC-grade acetone instead of cinnamaldehyde-alcohol solution, excluding the vacuum filtration and identification step. In the third step, the Tollens’ test was conducted. Approximately 1 mL of 5% silver nitrate solution and 1 drop of 20% sodium hydroxide solution were mixed in a test tube to form the Tollens’ reagent. Between 3 to 6 drops of 15% ammonia solution was added and swirled until precipitate nearly dissolved, then 1 mL of the alcohol solution of

cinnamaldehyde was added to the reagent. The test tube was briefly heated on the steam bath and left to stand for 5 minutes, and any observed changes were recorded. This test was performed again, instead with 2 to 3 drops of HLPC-grade acetone in the place of cinnamaldehyde solution, and observations were recorded and interpreted. Results: Table 1: Cinnamaldehyde Product Mass of cinnamon 3.0 g + 3.0 g = 6.0 g between partners Mass of beaker 51.393 g Mass of beaker with cinnamaldehyde oil 51.464 g Mass of cinnamaldehyde oil 0.071 g Mass of cinnamaldehyde in cinnamon 0.0639 g Percent by weight of cinnamaldehyde in cinnamon 1.065% Mass of cinnamaldehyde oil = Mass of beaker with oil (g) - Mass of beaker (g) = 51.464 g - 51.393 g = 0.071 g Mass of cinnamaldehyde in cinnamon In theory, cinnamon essential oil contains about 90% cinnamaldehyde.¹ = (Mass of cinnamaldehyde oil (g) x 0.9) = 0.071 g x 0.9

= 0.0639 g Percent by weight of cinnamaldehyde in cinnamon = (Mass of cinnamaldehyde (g) / Mass of cinnamon (g)) x 100% = (0.0639 g / 6.0 g) x 100% = 1.065% Table 2: Melting point analysis Observed melting point Literature melting point of cinnamaldehyde (semicarbazone derivative) Identification of the product 203-210°C 215°C Cinnamaldehyde semicarbazide Table 3: Test Results Test Results Semicarbazide test with cinnamaldehyde - Clumps of white, solid, opaque precipitate formed in a murky white solution within the test tube - A very small yield of white,

opaque, solid flakes were collected after vacuum filtration Semicarbazide test with acetone - White, solid precipitate formed - Produced white crystals in the test tube and white film - Opaque, granulated solid Tollens test with cinnamaldehyde - Immediately after heating, the solution was brown and seemed grainy with precipitate. Some precipitate stuck to the walls - The brown precipitate separated a bit, with the solution around becoming light/more transparent - Dark brown, grainy precipitate sunk to the bottom, with the solution on top being murky brown - Precipitate finally became slightly silvery/black, after about 5 minutes Tollens test with acetone - Solid brown precipitate formed - After heating, the solid separated from within the liquid and moved to the bottom of the tube - A thin black film formed on the surface layer of the liquid - The liquid was transparent and tinted black - Black specks were present in film on the sides of the tube Discussion: Part A Steam distillation is a separation process used to isolate heat-sensitive components within a mixture.³ This method involves separating substances through evaporation and condensation as each component has a different boiling point. Water is a crucial element of the distillation as it forms a mixture with the organic compounds,

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