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5.3: Functions and Applications of Aldehydes and Ketones

Difficulty Level: At Grade Created by: CK-12
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Methadone and Opiates

Diagram of a methadone molecule.

The ketone methadone (C21H27NO) has been used to cure addiction to opiates. Some common opiates are heroin, opium, and morphine. All of these drugs work by causing the body to release excessive amounts of the hormone dopamine. This hormone ends up in the brain, where it attaches to the dopamine receptor and creates a feeling of happiness. Opiates are extremely addictive because a person quickly develops a physiological need to have something constantly bounded to the opiate receptor. Otherwise, the addict will experience withdrawal symptoms, which include muscle aches, sweating, vomiting, agitation, abdominal cramping, and more.

This is the bulb of an opium poppy, which is used to create opium, heroin, and morphine.

To help combat opiate addiction, the oral medication methadone can be prescribed by a medical professional. Methadone works by binding to the dopamine receptor in the brain. This eliminates the user’s physical dependence on opiates because the user doesn’t need anything else to bind to the dopamine receptor. It also prevents the feelings of happiness caused by heroin because the dopamine has nowhere to attach to. This usually eliminates the user’s desire for heroin as well. Methadone is also able to suppress withdrawal symptoms for 24 – 36 hours. Although people taking methadone are now physically addicted to the drug, they are no longer controlled by their addiction. In comparison, heroin addicts tend to experience extreme emotional highs and lows and are known for their compulsive and disruptive behavior. After methadone is able to stabilize the user’s behavior, the user is able to begin the process of reducing methadone intake until the addiction is removed.

A typical dose is 5-20 milligrams of methadone in an oral solution. Patients can also receive methadone in the form of a tablet or injection. Most methadone treatment programs are outpatient programs, which means the users live at home but must come to the hospital regularly to receive treatment. One common side effect of taking methadone is drowsiness, which can make certain everyday activities more difficult. Some of the other known side effects of methadone include dehydration and excessive sweating, but these usually disappear as the user gains tolerance, allowing most methadone users to live relatively normal lives.

In 1999, about 20% of the 810,000 heroin addicts in the United States have been using methadone. Among heroin addicts treated with methadone, weekly heroin usage decreased by 69%, criminal activity decreased by 52%, and full employment increased by 24%. These statistics reflect that methadone treatment is both effective and efficient. Unfortunately, methadone is not a cure-all and can only treat opiate addictions.

Acetone in the Environment

One of the most extensively used ketones is acetone. Looking at the acetone molecule below, you may have noticed the lone oxygen atom in the middle of the compound. This oxygen atom exerts a strong pull on the electrons in the compound and makes acetone extremely polar. For this reason, acetone is used frequently in laboratories as a solvent for various chemical reactions. Acetone is also used in laboratories for rinsing glassware. It is also an ingredient in products such as nail polish removers, particle board, paint removers, and some detergents. Acetone is produced by both natural phenomena and industrial activities. It is released into the air during forest fires and volcano eruptions. It can also be released into the air from automobiles, tobacco smoke, and burning waste in landfills.

Diagram of an acetone molecule.

Because of its many uses, acetone has begun to build up in soil, water, and air, although acetone concentrations are still relatively low. The average amount of acetone in cities is 7 ppb (parts per billion), and even lower in rural areas. The average concentration in water is barely measurable and estimated at 1 ppb. The EPA limits the acetone concentration in workplaces to 750 ppm (parts per million). Acetone's first effects are noticed at 250 ppm, where it begins to affect performance on aptitude tests and can cause nose and throat irritation. Severe affects are not noticed until concentrations of 1000 ppm.

To find the acetone levels in your area, you can use this website:


Ketones and Metabolism

Ketones are also a natural byproduct of animal metabolism. Typically, the body breaks down glucose for energy. However, if the glucose level in the body is low, the body is forced to break down fatty acids or proteins for energy and produces three ketone by-products. These ketone by-products, also known as ketone bodies, are acetone, acetoacetic acid, and beta-hydroxybutyric acid. Beta-hydroxybutyric acid is technically not a ketone; it is a carboxylic acid. However, since it is produced with acetone and acetoacetic acid in metabolism, it is still classified as a ketone body. Both acetoacetic acid and beta-hydroxybutyric acid can be converted back into useful compounds that the body needs, but acetone cannot. Instead, acetone will accumulate in the bloodstream. It will exit the body when it is excreted in urine or when it is exhaled through the lungs.

While the production of a these ketone bodies is normal, the accumulation of ketone bodies can be problematic. Excess ketones may be a sign that you need to eat more carbohydrates. The body will breaks down carbohydrates into sugars, resulting in increased blood sugar level. If there is more glucose in the bloodstream, the body will not have to break down fatty acids for energy, which will reduce the amount of ketones produced.

Whole wheat bread is a good source of carbohydrates that can help prevent acetone buildup.

An excess of acetone in the bloodstream is also a common symptom of diabetes. Diabetics are either lacking in or are resistant to insulin. Insulin is a hormone that allows glucose from the bloodstream to be used in the body. If the body has no insulin or cannot use it properly, all energy must come from breaking down fatty acids. The increased activity of converting fatty acids to energy results in a much greater concentration of ketone bodies in the bloodstream.

The buildup of ketone bodies presents an especially concerning issue for diabetics. A person with diabetes is deficient in insulin, the hormone that allows sugars to enter cells. Because there is no insulin in the body, a diabetic is forced to rely on fatty acids and proteins for energy, which produces a large quantity of ketone bodies. This can be prevented by monitoring insulin levels within the body. However, if a diabetic's body is subjected to stress, such as an illness, emotional trauma, disruption to insulin treatment, or surgery, a condition called diabetic ketoacidosis (DKA) can occur. When a diabetic's body is in a stressful situation, it produces hormones such as adrenaline, which increase the rate at which fatty acids are converted to energy. This causes ketone bodies to accumulate. When so much acetone builds up in the blood, the body attempts to eliminate it all by causing excessive urination. Symptoms of diabetic ketoacidosis include dehydration, deficiencies in salts such as potassium, nausea, fatigue, confusion, abdominal cramping, excessive thirst, and decreased perspiration. DKA can be treated through undergoing insulin therapy, replenishing the body with the fluids and electrolytes, and diminishing stress.

This urine test will change color depending on the amount of ketones in the urine.

The most common way to test for an excess of ketones in the bloodstream is a urine test, although a blood test will be more accurate. Although it is not a dependable way of determining ketone buildup, ketone excess is often associated with fruity smelling breath. This is because ketones generally have a relatively high vapor pressure due to their small sizes and therefore evaporates easily. As ketones have a distinctive scent, they can be detected when they leave the body through the lungs.

Aldehydes and Ketones in Perfumes

Both ketones and aldehydes are found in a number of perfumes. Ketones are used to create acetophenone, which is responsible for creating almond, cherry, honeysuckle, jasmine, and strawberry fragrances. Compared to ketones, aldehydes are a more popular source for perfumes fragrances. The following chart shows common aldehydes used in perfumes and their scent:

Some perfumes containing aldehydes include Chanel No.5 and No.22, Lancôme Climat, Givenchy L’Interdit, Estée Lauder Estée, and D&G Sicily.

Chanel no. 5 wasn't the first perfume to include aldehydes, but it is responsible for popularizing their use in perfumes.

Aldehydes in Baked Goods and Herbs

Even the delicious scents of cookies baking in the oven come from aldehydes. Aldehydes are an important part of some sugars and are contained in many substances used in baking, such as cinnamon, vanilla, and more. They also play a crucial role in the caramelization of sugars. When sugars are cooked slowly without stirring, amino acids in the sugar begin the process of turning the aldehyde group into an unsaturated aldehyde. The substance has then become caramel, which can be used to give a product a brown color, create a crust on a baked good, or be consumed plain.

Baked goods like these cupcakes usually contain aldehydes.

Aldehydes are also contained in many herbs. The aldehyde decenal is a major component of coriander, the leaf which is often said to be the world’s most widely consumed herb. Decanal, which is responsible for the coriander leaf’s odor, is especially reactive. This causes coriander to quickly lose its scent when heated because the compound often reacts with other compounds. Another commonly encountered aldehyde is hexanal. Also known as the “leaf aldehyde,” hexanal is responsible for the “grassy” scent of fresh leaves. This scent fades, however, when the leaves are cut or crushed because the damaged cells release enzymes that are capable of breaking up the six-carbon chain.

LAB: Making Caramel

In this lab, you will chemically alter an aldehyde to create a tasty treat!


  • 1 cup white granulated cane sugar
  • water
  • a pot with a handle
  • hot pads
  • tub of ice water
  • vegetable oil
  • glass pan
  • aluminum foil


  1. Lightly oil the aluminum foil and use it to line the glass pan. Set aside.
  2. In the pot, mix the sugar with enough water to dissolve it into a thick syrup.
  3. Put the pot on the stove over low to medium heat.
  4. Use a hot pad to hold the pan by the handle and tilt the pan back and forth to dissolve all the sugar.
  5. When all the sugar has dissolved, bring the mixture to a boil. Do not stir or shake. Large bubbles should begin to form.
  6. Remove the pot from the stove once the mixture becomes golden brown.
  7. Dip the pot in the tub of ice water to stop the cooking process.
  8. Pour the mixture into the glass pan. Set aside to harden.
  9. Enjoy.


  • Take extreme caution when handling boiling substances. Use a hot pad at all times when handling the pot.
  • Do not refrigerate the caramel in an attempt to speed the cooling process. The humidity will affect the sugar.
  • If you wish to speed up the cooling process, place glass pan in the freezer for approximately five minutes.
  • The caramel will begin to harden within ten minutes. If you wish to mold the caramel or use it for cooking, work quickly.
  • Different ingredients can be added to create different flavors of caramel. For example:
    • Almond caramel: Stir in 1/2 teaspoon almond extract and 1/2 cup sliced almonds
    • Coconut caramel: Add 1/2 cup unsweetened coconut milk.
    • Coffee caramel: Add 1 tablespoon instant espresso powder to it.
    • Rum caramel: Stir in 1 tablespoon rum extract.
    • Vanilla caramel: Stir in 1 tablespoon vanilla extract.

Lab inspired by:

Formaldehyde and Glutamaldehyde as Disinfectants

Aldehydes are also used in disinfectants and antiseptics. The two types of aldehydes that are most commonly used in commercial cleaners are formaldehyde and glutamaldehyde. Formalin, the aqueous form of formaldehyde, kills bacteria by dehydration. It causes the liquid inside the cells to coagulate. Bacteria can usually flush unwanted toxins from the cell. However, when they are dehydrated, the toxins remain trapped inside the cell and cause the bacteria to die. Formalin is often used to maintain aquariums. It has also been used frequently as an embalming agent, because it helped human cells to retain their form and prevented the body from decaying before the funeral. However, formalin has been discovered to be toxic, allergenic, and even carcinogenic (cancer-causing) when inhaled. It is therefore no longer used for embalmment purposes.

Disinfectants containing aldehydes can be used to thoroughly clean your house.

Glutamaldehyde is another common cleaner. It kills bacteria, fungi, viruses, and more. Glutamate is able to attack the cell membrane and cell walls in bacteria and fungi, which prevents the cell from functioning. It also affects amino acids and causes proteins to denature. As proteins are responsible for many cell functions and make up cell DNA, this prevents the cell from functioning.

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