NutraSweet
A Case-Study Component of
ChemCases
A Case-Study General Chemistry Curriculum

Supported by the National Science Foundation

Prof. Sam Stradling

"How Sweet It Is!"

Have you ever seen TV’s The Honeymooners or The Jackie Gleason Show from the 1950s?   When Ralph Cramden said "How sweet it is!", he celebrated a victory in his ongoing battle with the vagaries of everyday life.

sweet.jpg (8415 bytes)
lab.gif (1620 bytes) In 1965, James Schlatter, of the G. D. Searle pharmaceutical company,  inadvertently tasted an experimental compound that he had synthesized in an attempt to discover a better gastric hormone inhibitor, an ulcer drug. This serendipitous event (for, as we all know, we are instructed to limit exposure to chemicals with unknown properties) led to the development, approval, marketing, and acceptance of the most widely used "artificial" sweetener in the world: aspartame, more commonly known by its trademark name, NutraSweet.

Indeed, how sweet it is!

Aspartame Concepts

This ChemCases case study introduces organic chemistry through the artificial sweetener NutraSweet.  With this dipeptide as a model, we will learn about bonding, structure, stereochemistry, and the methods for synthesizing a small but specific molecule.  We will follow the product through regulation and into commerce and deal with issues surrounding this marvelous sweetener and the consumer problems with which it has, nevertheless, presented us.

Reference to the Concept Map  suggests a mosaic of topics interrelated to NutraSweet and to each other. Although you can visually scan the individual topics of the mosaic and see their connectedness, this written narrative introduces one topic at a time, reinforcing those connections. As you read through each section, you should return to the Concept Map from time to time to refresh the connections.

Most general chemistry texts could act as a backdrop for the information presented here. This ChemCase study refers specifically, however, to the subject matter as presented in Chemistry: Molecules, Matter, and Change (3rd edition), by Peter Atkins and Loretta Jones.

The Concept Map shows the four major sections used to present information and a case for your review. The first section discusses the fundamental chemistry of the NutraSweet molecule. As important as "organic" molecules are to the world of chemistry and biology, we ignore them in many introductory chemistry courses. Courses subsequently built upon the general theories of introductory chemistry, such as organic chemistry, biochemistry, and molecular biology, are typically the vehicles that deliver the details of these important materials. Consequently, we will devote some effort to introducing those aspects of organic chemistry relevant to NutraSweet.

Once the structural aspects of NutraSweet and their relationship to physiological activity have been introduced, we will discuss the challenges of chemical synthesis, as well as some aspects of physical properties and solution chemistry.

The introduction of a synthetic chemical to the marketplace, especially one that enters as a foodstuff, justifiably requires the successful clearance of several hurdles, especially those of efficacy and safety. NutraSweet has successfully emerged from the rigorous review process, though it remains a product of considerable controversy. Patent protection has long served the entrepreneurial needs of modern society by allowing those whose commitment of time and expense in developing products to profit by that effort. Perhaps at no time in the past have the issues associated with intellectual and material property rights been more in the news. The third and fourth sections of this ChemCase explore these last two issues.

Knowledge

Comprehend Application Evaluation
Three fundamentals of organic chemistry and biochemistry are important in this case:
  • Bonding in carbon compounds;
  • Stereochemistry, as the result of carbon's bond hybridization;
  • And the determination of the biological activity of molecules by molecular shapes and charges.
In the past 125 years, three major artificial sweeteners have been discovered by a scientist accidentally tasting them.

We can understand the structure of these materials and we can see that there are few things that they have in common other than the fact that they are water-soluble, organic materials.

NutraSweet consists of two amino acids linked together.  We can apply the rules of stereochemistry to determine that four separate isomers of the diamino acid are possible.  And if we are to manufacture NutraSweet, we must find a process that makes only the correct isomer. Your new product is sweet, but not as sweet as saccharin.   If used in foods, it will degrade after a long time and no longer provide sweetness.  You can't use it in baking.

And certain people with a condition called phenylketonurea cannot use the product.

How are you going to market this sweetener? Is it wise to do so?  What should the consumer know before using NutraSweet?


Sections in this ChemCase

NutraSweet Concept Map
Biomolecular Concepts
Physical-Chemical Concepts
Food Additives
Chemical Commerce
NutraSweet Case Study Exercise

Or move on to

Next Section (Biomolecular Concepts)
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1999 Kennesaw State University.
Principal Investigator
Laurence Peterson; Project Director Matthew Hermes.
Author of this module
Sam Stradling.