Honors Cup Synthetic Proposal

Transcription

1 onors up Synthetic Proposal Section: 221 Group Members: Shahid Ali, Jamuna Kesavan, harles Weidle, Pooja Desai, Suellen Yin Title: Synthesis of Vanillin: Mmmm What s that Aroma? Introduction: Vanillin is the main chemical that gives vanilla its distinctive flavor and aroma. It was first synthesized in as far back as urrently less than 1% of vanillin productions come from vanilla extractions from pods. The low cost and ease at which vanillin is synthesized has caused it to become an important chemical intermediate in many fields. Less than half of vanillin produced is actually used for food products. verall synthetic reaction scheme: (a hemdraw or similar drawing of all three steps) Mn K N

2 Step 1 Synthetic transformation 1: (hemdraw picture of first transformation) Experimental 1 (notes if this transformation is not exactly the one reported in literature (e.g. on a different scale) and how it was modified): Dissolve 8 g of isoeugenol in 20 ml of acetic anhydride in a round-bottomed flask. Add 0.40 ml of concentrated sulfuric acid as a catalyst to the mixture. eat the mixture for 30 minutes on a sand bath at 100 º. ool the mixture for 30 minutes in an ice bath. Add 30 ml of water to the mixture, swirl, and scratch the mixture until the oil crystallizes. ollect the solid and wash well with water. Purify the solid by slurrying the solid in methanol using the conversion of 35 ml per every 10 grams for 5 minutes in an ice bath. ollect the solid by vacuum filtration. Expected yield: 37 % 4.00 g Safety, disposal and green issues 1: Safety: Gloves and goggles must be worn at all times. Wearing an apron is highly recommended, as sulfuric acid and acetic anhydride are corrosive reagents. Isoeugenol is a harmful irritant to both the respiratory system and to the eyes; therefore all work must be done under a hood. Inhalation of fumes and any contact with skin should be avoided. ontact between Isoeugenol and water or acid releases toxic gas; therefore care should be taken to keep the sulfuric acid and aqueous reagents separate from this chemical. When heating, use caution; Isoeugenol can be highly flammable in use. Never add water to this chemical. Methanol is toxic and therefore its container should remain tightly closed when not in use. Disposal: Isoeugenol, sulfuric acid, acetic anhydride, and methanol should not be emptied into the drains; they should be disposed of in a waste container. Green Issues: There are no major green issues for this step.

3 Step 2 Synthetic transformation 2: (hemdraw picture of second transformation) Mn K N Experimental 2 (notes if this transformation is not exactly the one reported in literature (e.g. on a different scale) and how it was modified): The second step involves two layers (dimethyl chloride and aqueous layer). The PT allows the organic reagent and the KMN 4 to react even when they are in separate layers. *Scale this step appropriately, depending on your yield from Experimental 1. urrent scale is based on isolating 2.00 g of isoeugenol acetate. The procedure reported in literature requires little modification and is of the same scale that could be performed in the laboratory. Following is an outline of the procedure presented in literature: Mix 100 ml of water, 80 ml of dichloromethane, 3.84 g of potassium permanganate, 3.84 g of magnesium sulfate hydrate, 0.10 g of tricaprylmethylammonium chloride (Aliquat-336, a phase transfer catalyst) into a Erlenmeyer flask (at least 500 ml). Dissolve 2.00 g of isoeugenol acetate in 20 ml of dichloromethane and add drop wise for 15 minutes. ontinue to let the mixture stir for an addition 15 minutes. The following steps must be completed rapidly. Use vacuum filtration and a elite pad with a medium fritted funnel. Separate the aqueous from the organic layer by washing the mixture twice with 50 ml of dichloromethane. Re-extract the aqueous layer once more using 40 ml of dichloromethane. ombine the organic layers and remove extra solvent by Rotovap technique. Expected yield: See below % See below g The expected yield would be impractical to obtain at this stage of synthesis because it would require re-crystallization. Also, the product of this step must undergo reaction (step 3) quickly in order to produce the final product. Safety, disposal and green issues 2: Safety:

4 Gloves and goggles must be worn at all times. Dichloromethane releases toxic fumes; all work must be done under a hood. Potassium permanganate and magnesium sulfate hydrate react with water; care must be taken in handling these reagents and water in the same step. Disposal: Aliquat-336 should be disposed of as hazardous waste. Dichloromethane, potassium permanganate, and magnesium sulfate hydrate should not be emptied into the drains; they should be disposed of in a waste container. Green Issues: Aliquat-336 is dangerous for the environment. Specifically, it is toxic to aquatic organisms. Potassium permanganate is very toxic to aquatic organisms and if released into an ecosystem, it may cause long-term adverse effects in the aquatic environment. Step 3 Synthetic transformation 3: (hemdraw picture of third transformation) Experimental 3 (notes if this transformation is not exactly the one reported in literature (e.g. on a different scale) and how it was modified): *Scale this step appropriately, depending on your yield from Experimental 1. urrent scale is based on isolating 2.00 g of isoeugenol acetate. Add 40 ml of 6 M hydrochloric acid to the oil (organic layer) and heat mixture for 30 min while stirring. After cooling, extract the mixture with three 50 ml portions of diethyl ether. Make 20% aqueous sodium bisulfate by adding 20g of sodium bisulfate to 80 ml of distilled water. Extract the ether layers with four 20 ml portions of the 20% aqueous sodium bisulfite to remove the vanillin as the vanillin bisulfite compound. Shake mixture for 1.5 min for each extraction. Add 12 ml of 85% sulfuric acid to the aqueous layer with bisulfite compound in a drop wise manner over 40 min at 50-60º, in a hood, while bubbling air through the mixture. Extract cooled aqueous phase with three 50 ml portions of diethyl ether. ombine the organic washes, dry with

5 MgS 4 to remove water, and evaporate the ether by rotovapping. A yellow-green oil should be obtained which is 95% vanillin. Expected yield: 45 % 1.4 g (if you isolate 4 g of isoeugenol acetate in Experimental 1) Safety, disposal and green issues 3: Safety: Gloves and goggles must be worn at all times. Dichloromethane releases toxic fumes and work with diethyl ether must be kept well ventilated; all work must be done under a hood. Wearing an apron is highly recommended, as l is a corrosive reagent. Diethyl ether is extremely flammable and should be kept away from any open flames. Disposal: Dichloromethane, l, Diethyl ether, and Sodium bisulfate should not be emptied into the drains; they should be disposed of in a waste container Green Issues: There are no major issues associated with this step. verall budget: hemical Supplier ost Amt. Total Needed I17206 Isoeugenol Sigma $0.28/g 4.00 g $ Acetic anhydride Fluka $0.07/mL 10 ml $ Sulfuric acid Sigma-Aldrich $0.08/mL 12.2 ml $0.98 (concentrated) Potassium permanganate Sigma-Aldrich $0.08/g 3.84 g $ Tricaprylylmethylammon Aldrich $0.15/mL 0.10 g $0.02 ium chloride ($0.17/g) Magnesium sulfate Fluka $0.75/g 3.84 g $0.29 hydrate ydrochloric acid Sigma-Aldrich $0.07/mL 20 ml $ Diethyl ether Aldrich $0.02/mL 150 ml $3.17 D65100 Dichloromethane Sigma-Aldrich $0.02/mL 80 ml $ Methanol Sigma-Aldrich $0.04/ml 12 ml $ Sodium Bisulfate Fluka $0.02/g 20 g $0.40 Total costs per synthesis: $10.72 References (include at least two different sources for your experiments): Step 1: Lampman G. M.; Steven D. S. J. hem. Educ. 1983, 60, Vitor Sobrinho, E.; ardaso, D.; Souza-Aguiar, E.F.; J. Braz. hem. Soc., 1998, 9,

6 Step 2: Lampman G. M.; Steven D. S. J. hem. Educ. 1983, 60, Weber W. P.; Gokel G. W. J. hem. Educ. 1978, 55, Step 3: Lampman G. M.; Steven D. S. J. hem. Educ. 1983, 60, Vitor Sobrinho, E.; ardaso, D.; Souza-Aguiar, E.F.; J. Braz. hem. Soc., 1998, 9,