Artificial Sweeteners

Kimberley M. Armstrong

Organic Chemistry Paper

December 5, 2006

In this paper I intend to show how artificial sweeteners are made, why they are used, what they are made of, and what, if any, health effects they cause. I will give a brief history of three common artificial sweeteners—Aspartame, Saccharin, Sucralose, and Acesulfame-K—along with the history of sugar to contrast with the artificial sugars. I will also give the uses, chemical compositions, possible health effects of each, and any other information that is important in understanding the compound.

(Sucrose, C12H22O11)

Sugar is used in almost every food that people consume today. It has been thought that is was first discovered in Polynesia sometime before 510 BC when it spread to India and China. Sugar remained in that area until 1099, when it was introduced to Europe and the Western world of that time, because of the Crusades. (A Brief History of Sugar) Since then sugar has become rampant and has grown into a huge and profitable industry. The USA alone produces 6.5 million tons in a year, without exporting any of it. (How Sugar is Made) Sugar is the most simple of all carbohydrates and is made up of the simple sugars fructose and glucose. The three compositions of sugar include the monosaccharides, the disaccharides, and the polyols. (A Brief History of Sugar)

Sugar is formed by some plants in a process known as photosynthesis. The plants then use the sugar is then used as energy, storing the left over energy as sugar. This is where people get sugar from—from the inside of the stalks of either sugar cane or sugar beet. (How Sugar is Made) The reaction of photosynthesis is as follows:

12 CO2 + 11 H2 O

C12 H22 O11 + 12 O2

carbon dioxide + water

sucrose + oxygen

The leaves of the plant take in the carbon dioxide while the roots absorb water to form the disaccharide sucrose. Glucose (C6H12O6), the monosaccharide, takes on an extra oxygen molecule. (How Sugar is Made)

In contrast to today’s artificial sweeteners, real sugar seems almost docile, but it has a history of destruction. Sugar is said to cause tooth decay, abdominal obesity, diabetes, high cholesterol, hypertension, and heart disease—to name a few. It is because of these problems that artificial sweeteners were introduced in the first place. Especially as dieting and obesity rates have increased. (A Brief History of Sugar)

(Aspartame, C13H18O5N2)

In 1964 a team of scientists, Dr. Robert Mazer, James Schlatter, Arthur Goldkemp, and Imperial Chemical, at the International Pharmaceutical Company were researching and working to hopefully find a drug to help those with “gastrointestinal secretory hormone gastrin.” (Preapproval) By 1965 they had synthesized the chemical “L-aspartyl-L-phenylalanine-methyl-ester”--aspartame. It wasn’t until December of that year the Schlatter recrystallized the aspartame compound from ethanol and mistakenly licked his fingers after coming into contact with it, and noticed its intense sweetness. After that he tasted more upon deciding that it was probably non-toxic. Then between 1969-1970, extensive research and testing was done on animals, unfortunately many of the animals died. After hundreds more studies, hopeful results were established and Aspartame was declared approved for limited use in July of 1974. Aspartame was not to be used for baking or in any carbonated drink. (Preapproval) Already the controversy over aspartame was unbending. Many people were very wary of aspartame because of the effects and eventual death it produced in the animals it was tested on—mice were found to have holes burned in their brains from the aspartic acid in aspartame.

Aspartame is now one of the most popular artificial sweeteners and goes under the brand names “Equal” and “NutraSweet.” (Paajanen) Aspartame has a molecular mass of 294.301 g/mol, a melting point of 246-247 degrees Celsius, and decomposes at its boiling point. It is about 180 to 200 times sweeter than sugar, does not contain enough calories to note, and does not cause tooth decay. Today it is used very frequently in all kinds of beverages, carbonated included, but it still isn’t for cooking as Aspartame breaks down under heat and would not produce the sweet taste anymore. It is most stable in its dry form—“80 of the aspartame decomposes after 4 hours at a temperature of about 150 degrees Celsius. At a temperature of 25 degrees Celsius, dry aspartame will not decompose.” (Wahlen) Even so, it has been found that health related concerns about aspartame are unfounded--save for a very small population of humans. For this small population Aspartame causes headaches, gas, confusion, and possibly brain tumors, and those people simply should not consume aspartame. (Wahlen)

Aspartame is a dipeptide made of two different amino acids—L-phenylalanine, a methyl ester, and L-aspartic acid. (Wahlen) There are two different methods one can use when making Aspartame. One way is to break down and then hydrolyze the ester bond in methanol. Through this aspartylphenylalanine, a dipeptide, and methanol are made. The second way produces aspartylphenylalanine, but no methanol, and is made by “the cyclization of aspartame into diketopiperazine.” (Wahlen)

Since Aspartame breaks down into phenylalanine and aspartic acid, it operates like a protein, and renders an energy value of 4 kcal/g, which is the same as sugar. (Wahlen) Since Aspartame is 180-200 times sweeter than sugar, one needs only use the slightest amount to make something sweet--therefore, Aspartame contains no significant calories.

People who can be severely harmed by Aspartame are those who have the genetic disease “phenylketonuria” or “PKU.” (Wahlen) A person who is afflicted with PKU cannot metabolize phenylalanine, which constitutes for 50 of the weight of aspartame. Since they cannot metabolize this amino acid, dangerous amounts of it build up in the blood—this causes severe mental retardation. Nevertheless, those with PKU become mentally retarded within the first few months of life or are immediately diagnosed, and simply will not consume aspartame. Studies have shown that even those with PKU can consume small amounts of aspartame with no consequence, as long as it has time to depart the body before more builds up. As a whole, Aspartame seems quite safe for most humans to consume.

(C7H5O3NS)

Saccharin (C7H5O3NS) or (C7H4NNaO3S · 2H2O when it is in its sodium salt form), the first artificial sweetener, was discovered in 1879 by Constantin Fahlberg and Ira Remsen of John Hopkins University. By 1901 it was being produced in the United States. In 1911 it was banned though, because of possible cancerous side effects, but with World War I approaching, the ban was lifted during the sugar rationing. (Shea) Even now Saccharin shows to cause bladder cancer, and people who drink two cans of Saccharin-sweetened soda a day are at a higher risk. (Shea) At the same time, other studies show that regular amounts of saccharin in rats does not cause bladder cancer, and to most humans, excluding those who drink extreme amounts, it should be relatively safe. (Comments on Saccharin)

Unlike Aspartame, Saccharin is stable enough to be heated, very easy to make, does not react chemically with other food ingredients, and is about 300-500 times sweeter than sucrose (C12H22O11). Saccharin is not very soluble in water, but its sodium salt derivative (C7H4NNaO3S · 2H2O) is sold commercially and is soluble in water. (Artificial Sweeteners) Unfortunately Saccharin has an unpleasant bitter, metallic taste—especially at high concentrations. (Saccharin) Like aspartame, it has been followed with an expanse of disputation; studies in the 1960s and 70s showed that Saccharin caused bladder cancer in rats, and a study in 1977 showed it to be a causative agent. (Whitworth) Many people wanted Saccharin to be banned, but it is still widely on the market. For diabetics, Saccharin is very operative. Not only does Saccharin contain no calories, it does not affect insulin levels. (Saccharin)

Saccharin is produced with dextrose under the patronymic “Sweet n’ Low.” (Paajanen) Dextrose is a natural carbohydrate that is used to dilute the Saccharin. Unlike Aspartame, which contains fractions of calories, Saccharin really does contain none because it is not digested by the body. Saccharin is a “coal-tar derivative” (Toluene), and has a very complex structure. (Artificial Sweetener) It was accidentally discovered when Remsen and Fahlberg forgot to wash their hands before eating when they had just been working with derivatives of Toluene. (Saccharin)

Though originally made with Toluene, it is now often made by reacting anthranilic acid with nitrous acid, sulfur dioxide, chlorine, and then ammonia. Another common way is made from o-chlorotoluene. (Saccharin)

Sucralose (C11H19O8Cl3)

Sucralose (C11H19O8Cl3) was discovered by Leslie Hough and Shashikant Phadnis from Tate & Lyle who were working at Queen Elizabeth College in London in 1976. They were chlorinating sugar and then testing them as “chemical intermediates.” (Sucralose) Through a misunderstanding, Phadnis ended up tasting the compound and found it so incredibly sweet. After working with Tate & Lyle for another year, they finally agreed on the final formula.

Sucralose has a molecular mass of 397.63 g/mol, an unknown density, and a melting point of 130 degrees Celsius. It was found to be approximately 600 times sweeter than Sucrose, and has to be diluted with 600 parts filler to make it taste natural. (Selim)

Sucralose is actually made from Sucrose and has been deemed the “most natural” artificial sweetener by its manufacturing company—“Splenda.” The composition of Sucralose is Sucrose with three chlorine molecules added to it. This chlorine molecule makes the sweetener unusable to the body which is how it is free of calories. Sucralose goes through the body untouched. (Paajanen)

Sucralose is made by covalently bonding chlorine molecules to carbon atoms, forming a “chlorocarbon.” (Sucralose) Most of the chlorocarbons are toxic, but since Sucralose does not break down in the body, nor dechlorinate, it is not toxic—in this condition anyway.

Sucralose is now considered by many to be the safest of the artificial sweeteners, but much disputation has come of the possible harmful effects to the thymus gland, which is an important part of the immune system. Extreme doses of Sucralose in rats caused a decrease in the weight of the thymus gland, and feasibly would do the same to humans. But in proportion, the amount need to see any immunological effects in humans is 60 Splenda packets a day for an entire month—and 240 packets a day to get the same amount of trauma the rats had. So unless someone was consuming enormous amounts of this artificial sweetener a day, nothing harmful should come about through Sucralose.

Acesulfame-K (C4H4KNO4S)

Acesulfame-K, or Acesulfame Potassium, as it is commonly called, has been on the market since 1983. It has been tested, and has shown to be safe as long as the consumer is taking in only an acceptable daily value. Many scientists feel that Acesulfame-K still isn’t understood as well as it should be and feel that it could potentially be unsafe for consumption. They also claim that the testing hasn’t focused on any long-term effects of this artificial sweetener. Still others say that Acesulfame-K is not harmful at all. (Acesulfame Potassium)

Acesulfame-K was discovered in 1967 by Karl Clauß, a German chemist who was working at Hoechst AG. Acesulfame-K’s chemical composition is 6-methyl-1,2,3- oxathiazine-4(3H)-one 2,2-dioxide, and its molecular weight is 201.24. (Acesulfame Potassium) It is 180-200 times sweeter than sucrose, and, like Saccharin, has a bitter aftertaste. Acesulfame-K is able to withstand a long shelf life, is stable under heat, which makes it useable in baking. It is now sold under the brand names “Sunette,” “Sweet ‘n Safe,” and “Sweet One,” and is used in many famous products such as Coca-Cola Zero, Fresca, Powerade, Hershey’s Lite Syrup, and Trident Gum. Acesulfame-K is rarely used by itself and is commonly combined with either Aspartame or Sucralose. (Acesulfame Potassium) Structurally, Acesulfame-K is very similar to Saccharin.

Artificial sweeteners remain one of the most tested compounds ever, and continue to be tested all the time. Though we still do not understand them completely, we have benefited from their low caloric-values, and have possibly been harmed by side-effects that remain to be unseen right now. As science continues to advance and gain new knowledge we will certainly take steps in making artificial sweeteners safer and better.