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Synthesis of a Fruity Fragrance and Analysis by

Gas Chromatography-Mass Spectrometry

The Question of the Day:

How does temperature affect the yield of a chemical reaction?

Introduction:

After studying organic chemistry for the past semester, you have gained an understanding

of the importance of organic compounds in our daily lives. This lab is meant to increaseyour synthetic lab skills, critical thinking, and problem solving capabilities when utilizing

instrumentation techniques. Each group will synthesize banana fragrance at different

temperatures and determine the optimum temperature required to get the maximum yield.Another fruity fragrance of your choice will also be synthesized. The purity of all the

final products will be examined utilizing the GC-MS.

Pre-lab Questions: Collaborative work (type the answers.)

1. Do you expect the smell of the fruit and the skin to be the same? How can you

prove this experimentally (without smelling)?2. In general, what class of compounds is responsible for the smell of the fruits?

Give examples for the structures of these compounds in two fruits (banana and

one other fruit).3. How many peaks do you expect to see in the GC-MS after your synthesis?

(Hypothesis #1)

4. How would you synthesize the compounds you selected for question 2 in an

organic lab? Give the list of reagents needed for each one.

5. Give the chemical data table for the reagents (identified in question 4) needed, asyou have done for other experiments.

6. Write the general mechanism for the reaction you are planning to perform in thelab.

7. Do you expect variable yields for the banana-scented compound if the

temperatures maintained are different? (Hypothesis #2)

8. Give a brief description of Gas Chromatography-Mass Spectrometry (GC-MS).9. What are some applications for GC-MS?

Safety:

Remember, neverdirectly smell a chemical; instead, waft the vapors. evertaste achemical.

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1stDay of the lab:Gas Chromatography/Mass Spectrometry Lab

You will need to design an experimental procedure (macro-scale)to synthesize yourfavorite fruity fragrance. Submit a detailed procedure to your lab instructor before your

scheduled lab. You may use the following reference for GC-MS:

http://www.scientific.org/tutorials/articles/gcms.html

Each group of two students will synthesize banana fragrance at different temperatures (to

be assigned the day of the lab) and one other fruit fragrance of their choice. Copy and fillin the following table in your notebook.

Name of Ester Molecularformula

Structural formula Molar mass density BP (C) Fragrance

Apple

Banana

Cherry

GrapeOrange

Pear

Peach

Pineapple

Raspberry

Discuss the following questions with your partner and submit the answers next lab

period.

In Lab Questions: Collaborative work (type the answers.)

1. Write the structure of your fragrant compounds from both syntheses.2. How could you determine the purity of the product? Give all the methods you

know.

3. Which may be the best method among the ones you have chosen and why?

4. Suggest a procedure for purifying the products of your synthesis.5. Suggest a procedure for extracting the fruity flavor compound from your selected

fruit.

Homework: Collaborative work

Find and print the mass spectrum of each of your reactantsand expected product bysearching http://webbook.nist.gov/chemistry/name-ser.html

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2nd

Day of the lab:Gas Chromatography-Mass Spectrometry Lab

You should review the GC-MS simulation software available in the Learning ResourceCenter (see handout on the last page for instructions).

Use GC-MS to analyze the products you have synthesized. Identify peak(s) using theNIST library search, and compare mass spectra of your products to the mass spectra youobtained from the NIST website.

Discuss the following questions with your partner and submit the answers with your final

report.

Post-Lab Questions: Collaborative work (type the answers.)

1. Is your banana scented compound pure? If not, why?

2. Wasyour hypothesis #1for the number of peaks seen in the GC-MS (number of productssynthesized) correct? If not, what was the cause of the different number of peaks?

3. Is your hypothesis #2 about temperature dependence of the esterification correct? If not,why? (You will need to review the results from the other teams.)

4. Propose a method USDA can use to identify the adulteration in artificial flavors marketedin United States.

Post Lab Report: Collaborative work

Prepare your report in a format suitable for submittal to an ACS journal (such as the Journal ofOrganic Chemistry). You may find it helpful to look at some examples on the following website:http://pubs.acs.org/

AcknowledgementsThe development of this laboratory experiment was supported by a grant from the National

Science Foundation, through the Course, Curriculum, and Laboratory Improvement Grant

#0633646 to Pennsylvania State University - Altoona College.

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Instructions for using the GC-MS Software in Learning Resource Center

1. Log onto the computer that has the GC-MS Software (Savant) label on it (of the three in the

main lobby of the Learning Resource Center, it is the one on the left).

2. Click on the Fundamental of GC-MS icon on the desktop

3. Click on Click Here on the top right corner

4. Click on No Tracking

5. Click on the Table of Contents icon:

6. Click on 1. GC/MS Fundamentals

7. Click on Overview

8. Click on and review the Block Diagram tab, including the Animation.

9. Click on and review the Chromatography tab

10. Click on and review the Mass Spectrometry tab

11. Click on and review the Advantages tab

12. Return to the Table of Contents, 1. GC.MS Fundamentals, and click on Chromatography13. Click on and review the Equilibria tab

14. Click on and review the GC process tab

15. Click on and review the Retention tab

16. Click on and review the Simulator tab