LAB+Report+Green+Synthesis+of+Fluorescent+Natural+Product

Green Synthesis of a Fluroescent Natural Product experiment involves the synthesis of 4-methylumbelliferone by a Pechmann condensation. A Pechmann condensation is a synthesis of coumarins via the acid-catalyzed reaction of a phenol with a b-keto ester. Coumarin are nice smelling chemical compounds found in plants. The condensation is performed under acidic conditions. Mechanism/Reaction;
 * Philip, Hailey **
 * Introduction: **

This synthesis uses Dowex 50 WX5 note that we used 5W20 as the acid catalyst. In the past less green acids have been used including H2SO4 and POCL3 (check this....I think the formula is incorrect). Dowex is preferred because it is less hazardous and does not require an additional solvent. Resorcinol is used as the phenol. The Dowex can be regenerated, however, the process of doing so requires a lagre excess of acid, thus rendering the green aspect of using the dowex more than once null.

In a 50ml Erlenmeyer flask combine ethyl aceoactate (1.0ml, 7.8 mmol), resorcinol (.08 g, 7.3mmol) and Dowex 5W20 beads (1.0 g). In two additional 50ml erlenmeyer flask add 20ml water to one and 15ml ethanol (95%) to the other. Place all three flasks on a hot plate and set to level 5 occasionally stirring and swirling the mixtures until the substance stops bubbling and becomes a solid red matter. (20- 30 min) When reaction is complete add 2ml warm ethanol (95%) to dissolve the solid. Using a Pasteur Pipette, pipette the warm ethanol solution from the dowex beads into a clean Erlenmeyer flask. If necessary, repeat warm ethanol wash two to three more times to produce a greater yield. While heating the ethanol solution add hot water until the solution becomes cloudy and then allow ethanol solution to cool slowly to room temperature. Collect white to off white preciptate by the vacuum filtration and wash with distilled water. Allow substance to dry before taking a melting point and characterizing by IR spectrum. After samples have been measured and processed dissolve a small amount (20mg) of the product into 2-3ml of ethanol (95%) into three separate test tubes. Alter the pH of two of the test tubes by adding 2 ml of a 10% HCl solution into one tube and then adding 10%Na2CO3 to the other and place under a UV Lamp. Source: Douglas M. Young, Jacob J. C. Welker, and Kenneth M. Doxsee Department of Chemistry, University of Oregon, Eugene, Oregon 97403-1253, United States J. Chem. Educ., 2011, 88 (3), pp 319–321 Publication Date (Web): December 8, 2010 Copyright © 2010 The American Chemical Society and Division of Chemical Education, Inc
 * Procedure:**
 * DOI:** 10.1021/ed1004883

Product: 1.66mmol what did you actually measure? record the measurement here, before converting to mmol. % yield=(Actual yield)/(theoretical yield) x 100% = 1.66mmol/7.3mmol x 100%= 23% yield
 * Data:**
 * Dowex || 1.00g ||
 * Resorcinol || 7.3mmol ||
 * Ethyl Acetoacetate || 7.8mmol ||
 * Water || 20.0ml ||
 * Ethanol (95%) || 6.0ml ||

Color Vs. pH Acidic: Green Basic: Blue Product: Bluish

Melting point 107.6-111.4 ºC Actual MP is 186-191 ºC IR Spectrums When comparing the IR spectrum and the melting point of the product and the actual results one can make the following assumptions that may explain why the product exhibits such different characteristics; The absence of a major peak between 1690 and 1760 on the IR spectrum indicates a lack of a pi bond between a carbon and an oxygen. This could mean that the reaction may have not have reacted to completion. This would also explain the lower melting point. The color of the product is a mixture of the acidic and basic colors, which could mean that there is a combination of the final mechanistic product and an earlier version of the product. The green coloring of the product could symbolize the sigma bond between an oxygen and a hydrogen. The presence of this bond is clear in the IR spectrum. Whereas the presence of the carbonyl bond is lacking. Speaking to the environmental factors of the lab, the Dowex catalyst is easily recoverable, however recycling the catalyst requires 3 times the amount of acid to regenerate its origional charge.
 * Conclusion:**

sources of error? how would you perform the lab differently if you were going to do it again?

This lab earned the following scores for: format (2/2) style (2/2) data (3/3) quality of result (1/1) quality of reported data (1/1) conclusion 1/2) error 0.5/1) for a total of 12.5/14.