DOC PREVIEW
U-M CHEM 216 - Honors Cup Synthetic Proposal

This preview shows page 1-2 out of 5 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Honors Cup Synthetic Proposal Section: 270 Group Members: Jane Lee, Scott Mariouw, Neha Narula Title: Synthesis of Menthone Introduction: The target molecule menthone is the ketone form of the commonly known acid, menthol. This synthesis was done in three steps: the starting material, citronellic acid, was synthesized into citronellol, then into pulegone, and then finally, using hydrogenation, into menthone. Physical characteristics of menthone include its colorless appearance, a boiling point of 210°C, and a distinct mint/peppermint odor. Since menthone is very closely related to menthol, many of its interesting aspects are along the same line as menthol, in their wide-range commercial use. For example, menthol is found in topical pain and itching relievers, it is responsible for the tingling sensation felt after the application of after shave and suntan lotion, and it can even be used as a local anesthetic for sore throats and muscle aches. However, menthol is most heavily used as a mint flavoring agent in products like medicine, tobacco, cough drops, tooth paste, ice cream and perfumes. Overall synthetic reaction scheme: (a Chemdraw or similar drawing of all three steps) OOH OH O OStep 1 Synthetic transformation 1: (Chemdraw picture of first transformation) OHOHO1) LiAlH42)Et2O 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): A solution of citronellic acid (51.2g, 0.30 mol) in diethyl ether (200 ml) was gradually added to a magnetically stirred suspension of LiAlH4 (16.0 g, 0.30 mol) in diethyl ether (2000 mL) that was kept under N2. Then the mixture was stirred for 5 hours at room temperature. Water (100 mL) was slowly added to the mixture. The resulting mixture was filtered with suction and the filter cake was washed with ethyl acetate. After drying (using MgSO4) and evaporation of the solvent the resulting oil was distilled. Note 1: In order to achieve 40 grams of the product obtained from step one, twice the amount of citronellic acid, the dry ether (diethyl ether), LiAlH4, and water was used. Note 2: Step two was the most complex of the three, so it was kept exactly the same in amounts and procedures as the reference article’s, in order to minimize any unpredictable errors from making changes. Consequently, the other steps’ chemical amounts were altered to fit the step two’s needs. Expected yield: 90 % 42.4 g Safety, disposal and green issues 1: Water is to be added slowly to the mixture that was gradually stirred for five hours to keep LiAlH4 from reacting with water violently. LiAlH4 is an inflammable compound, especially when it is in an ether solution. Thus, adding water to a solution of LiAlH4 and ether must be done slowly and with great caution.Step 2 Synthetic transformation 2: (Chemdraw picture of second transformation) 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): To a suspension of 160g (0.8mol) of pyridinium chloromate (PCC) in 1 L of dry methylene chloride was added 40.0g (0.26 mol) of (–)-citronellol. The slurry was stirred at 25 degrees for 36 hours. The mixture was filtered through Celite and the solids were washed thoroughly with methylene chloride. The solution was evaporated to ca. 500mL and washed with 10% hydrochloric acid, 10% sodium bicarbonate, and water. The methylene chloride solution was evaporated to give a mobile oil (43g). The oil was taken up in 300mL of ethanol and treated with 600mg (!5mmol) of sodium hydroxide. The solution was heated for 1 hr, then the ethanol was evaporated under redued pressure and the residue was partitioned between 200mL of diethyl ether and 100mL of water. The diethyl ether was washed with 10% hydrochloric acid and then brine. Evaporation of the solvent and distillation of the residue gave 28g (0.184 mol, 71%) of (–)-pulegone. Expected yield: 71 % , 28 g Safety, disposal and green issues 2: PCC is toxic by inhalation and irritable to skin, so it must not be touched with bare skin. It can also have adverse effects on aquatic orgnisms or environment, so it must be disposed as hazardous wastes. Celite must not be inhaled because inhalation of it is health hazard. Diethyl ether is flammable, so no smoking is allowed and the lab must be kept well-ventilated. Step 3 ReactantOProductOHSynthetic transformation 3: 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): From the 28g of pulegone produced in step two, 1.1g was dissolved in solution containing 42mL of chloroform, 2.43g of diphenylsilane, and 0.465g of zinc chloride. Next a 0.166g sample of Pd(PPh3)4 was added and the mixture was stirred at room temperature for 3 hours. After, the solution was filtered through a silica gel column and the products were purified by distillation or flash chromatography containing an appropriate mixture of ethyl acetate and hexane. Note: In order to achieve 1 gram of the product obtained from step three, the amount of reactants used were altered from the referenced sources. 1 gram was determined as the target amount to minimize the stirring time for the sake of practicality. However, if one desires to obtain more product, the starting chemical and reagent chemical amounts need to be simply multiplied and the time increased accordingly. Expected yield: 90% 1g Safety, disposal and green issues 3: Chloroform is irritating to the skin and harmful by inhalation. Diphenylsilane is irritating to the skin. Zinc Chloride can cause burns, is toxic by inhalation, and may cause long-term adverse effects in the aquatic environmentOverall budget: Chemical Supplier Cost Amt. Needed Total Citronellic acid Aldrich $2.00/g 51.2 g $102.40 Lithium aluminum hydride (LiAlH4) Aldrich $1.59/g 16.0 g $25.44 Diethyl ether Aldrich $34.70/L 2400 mL $83.28 PCC Aldrich $0.27/g 160g $43.20 Celite Fluka $23.60/kg ~1kg $23.60 Chloroform Aldrich $0.4/ml 42 ml $16.80 Diphenylsilane Aldrich $2.93/g 2.43 g $7.12 Zinc Chloride Aldrich $4.12/g 0.465g $1.92 Total costs per synthesis: $303.76 *As you can see, all the costs are kept under the budget limit (under three dollars for the reactant, under five dollars for the reagents). *The chemicals not mentioned above were either


View Full Document

U-M CHEM 216 - Honors Cup Synthetic Proposal

Documents in this Course
Exam 2

Exam 2

12 pages

Load more
Download Honors Cup Synthetic Proposal
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Honors Cup Synthetic Proposal and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Honors Cup Synthetic Proposal 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?