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7.3: Functions and Applications of Ethers

Difficulty Level: At Grade Created by: CK-12
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Diethyl Ether and Cocaine

Diethyl ether is one of the best known ethers. It is often referred to simply as “ether.” The formula for diethyl ether is (C2H5)2O). Originally, diethyl ether was used as an anesthetic. Now it has a variety of uses ranging from cocaine production to diesel engine fluid.

Diethyl ether is characterized by its distinctive smell, which is said to be sickly sweet. It is highly flammable and only needs a small amount of activation energy to ignite. At room temperature, even a hot radiator or a hot plate could provide the energy required for the combustion of diethyl ether. It will spontaneously ignite at only 170oC, combusting without any spark or flame. Like all ethers, it is considered to be nonpolar, or only slightly polar, and has a relatively low boiling point of 34.6oC.

In many laboratories, diethyl ether is used as a solvent. Because diethyl ether is nonpolar, it dissolves other nonpolar substances and is not miscible with polar substances like water. Therefore, diethyl ether is a great solvent for fats, waxes, oils, perfumes, alkaloids, and gums. This also makes diethyl ether perfect for the illicit production of pure cocaine, a powerful and highly addicting drug. Cocaine, which is a nonpolar organic compound, dissolves readily in diethyl ether. However, the impurities that exist in cocaine do not dissolve in diethyl ether. Dissolving cocaine in diethyl ether makes it easy to filter out these impurities, leaving behind pure cocaine and diethyl ether solution. Afterward, the solution is treated and processed to become the hydrochloride salt form of cocaine that is widely abused. This dangerous drug can cause heart attacks, stroke, paranoia, and death. It works by preventing dopamine, a neurotransmitter that is responsible for the feeling of pleasure, from being “recycled” by the cell that originally released it. This creates a buildup of dopamine, causing the euphoria that is associated with cocaine usage.

Dimethyl Ether as Fuel

Dimethyl ether is another well-known ether. Its chemical formula is CH3OCH3, and it is the simplest ether. Dimethyl ether is a hydrocarbon with two methyl groups bonded to an oxygen. It has an extremely low boiling point of −23.6oC. Dimethyl ether shares the same empirical formula as ethanol (C2H6O), but because they have different structures, these isomers have very different properties. Dimethyl ether can be formed by using either commercial feedstocks or fossil hydrocarbons. Studies have shown that it is also feasible to create dimethyl ether from industry by-products, such as paper pulp.

Dimethyl ether is a colorless gas that has a variety of uses. Currently it is being employed as an aerosol propellant, organic solvent, and extraction agent. It is also being tested as a transportation fuel because it is relatively nontoxic and has a higher cetane number than diesel. A higher cetane number means that dimethyl ether will combust more cleanly and more completely than diesel fuel, optimizing energy efficiency for the car. Dimethyl ether’s cetane number is 55-56, compared to fossil diesel’s of 42-48 and biodiesel’s of 52-55. Another benefit of dimethyl ether as a fuel source is that, unlike diesel, it does not release sulfur and aromatic compounds. These emissions are harmful to breathe in and pollute the environment.

This truck is running off of diesel fuel. The smoke that it emits contains sulfur and aromatic compounds, which are harmful to breathe in.

The combustion reaction of dimethyl ether is:

C2H6O + 3O2 -> 2CO2 + 3H2O + Energy

In real life, this reaction would be impossible because complete combustions are only theoretical. The ideal conditions that are necessary for all combustible components to be burned to completion do not exist. There will always be some left-over fuel or byproducts. This could be due to human error, insufficient mixing in the combustion chamber, lack of oxygen, or hydrogen bonding. However, dimethyl ether’s combustion is still very efficient.

Anisole and Nature

Anisoles, also known as methoxybenzenes, are ethers with the chemical formula of CH3OC6H5. It is a relatively nontoxic liquid with a surprisingly high boiling point of 155oC, or 313oF. Anisoles have a pungent, sweet odor reminiscent of the flowering plant, anise. This makes it perfect for use in perfumes and cosmetics. It is also occasionally used in pharmaceuticals. In nature, anisoles are found in insect pheromones. Madeira cockroaches, European oak bark beetles, and desert locusts use it in their chemical communication systems.

This is a black truffle of Périgord.

Because of this, many plants release anisoles to attract insects. An example of a plant that uses anisoles would be the black truffle of Périgord. Like most other fungi, it lives underground. This makes it very difficult for the truffle to spread its spores. The black truffle of Périgord gets around this problem by releasing anisoles upon reaching maturity. Insects are attracted to the anisole and inadvertently spread the spores for the truffle.

Polyethylene Glycol (PEG) and Its Many Uses

Polyethylene glycol (PEG for short) is a long-chained, organic compound with the chemical structure of C2n+2H4n+6On+2. It can come in many different lengths; hence the variable n is included in the molecular formula.

PEG can come as either a clear liquid, waxy substance, or an opaque solid, depending on the size of its chain. Small PEG chains with a molecular weight less than 200 tend to come as clear liquids. At a molecular weight of 200-2000, the PEG chain is a waxy substance. Any chain with a molecular weight heavier than 2000 comes as an opaque solid. Unlike most ethers, PEG is soluble in both organic compounds and water. This is because it is a “polyether,” or a compound that contains more than one ether group. Because the oxygen-carbon bond in the ether group is polar, multiple ether groups on PEG will increase the polarity of the overall molecule, making it soluble in other polar compounds. PEG, being non-toxic and water soluble, is often used in pharmaceuticals and food additives.

The uses for PEGs vary with the size of the PEG chain. Low molecule PEG chains can be used as laxatives, skin creams, lubricants, dispersants in toothpastes, thickening agents, and binding agents in tablets and molds, among others. Larger molecule PEG chains are used as packing materials for foods, binding agents and thickeners for paints, and polar stationary phases for gas chromatography.

PEGs are widely used in toothpaste.

Many of these functions depend on the ability of PEG to bind with both water and organic solvents. For example, in toothpaste, PEG binds water to xanthan gum, thus keeping the gum uniform throughout the toothpaste. The water solubility of PEG also plays a huge role in its uses. It is used as a mold release agent and a lubricant for creating natural and synthetic rubbers. Because of their solubility in water, PEGs can be easily applied and removed in these processes.

For a full list of items that use polyethylene glycol, you can view:


LAB: Solubility

Polyethylene’s miscibility in both non-polar and polar compounds is important for its functions.

Let’s take a closer look at how polarity affects solubility. In this lab, you will test the miscibility of a polar substance (soap) in a mixture containing nonpolar components (milk with fat).


  • Plate
  • Food Coloring
  • Toothpick
  • Soap


  1. Fill the plate with milk, just enough so that the base is all covered.
  2. Put a drop of food coloring into different areas of the milk. Try to use different colors of food coloring
  3. Take the toothpick and dip it in the soap.
  4. Then poke the drop of food coloring with your soapy toothpick.
  5. Repeat steps 3-4 to your liking and observe.

Test Your Understanding

  1. Would this have happened if water were used instead of milk?
  1. Why would fat free milk not have worked in this lab?


  • Answers available upon request. Please send an email to teachers-requests@ck12.org to request solutions.

Ethylene Oxide as a Disinfectant

Ethylene oxide is a gas with the chemical formula C2H4O. It has an extremely low boiling point of 10.73oC (51.314oF) at atmospheric pressure. This means that at normal room temperature, intermolecular forces are too weak to hold ethylene oxide as a liquid. Therefore, it is usually found in its gas phase. This makes ethylene useful as a disinfectant for medical and pharmaceutical products. Many of these products contain plastics and would melt if they went through conventional, high-temperature sterilization processes. This is where ethylene oxide comes in handy. At room temperature, it can be pumped into packages containing the medical and pharmaceutical products to kill the bacteria that have grown on them. This cleans the packages and the products.

The disinfecting abilities of ethylene oxide stem from the fact that it is a strong alkylating agent. This is a compound that can transfer an alkyl group onto another compound. By doing this, ethylene oxide can bind directly to the bacteria’s nucleic acids. Once there, it changes the bacteria’s DNA structure slightly in one of three ways. The first method is for ethylene oxide to attach an alkyl group to the DNA bases. When repair enzymes attempt to replace the alkylated bases, the enzymes will actually fragment the DNA strand. Another way that ethylene oxide changes DNA structure is by linking together two DNA bases. This prevents the DNA strand from being separated for synthesis or transcription. Lastly, ethylene oxide can also cause bases to be mispaired. All of these mechanisms work to kill bacteria. Although extremely effective, the use of ethylene oxide as a disinfectant has some major drawbacks. Ethylene oxide is extremely explosive and is harmful to humans. The alkylating properties of ethylene oxide do not just affect bacteria; this property affects the DNA structures of any cells, including human cells. Long-term exposure to ethylene oxide has been associated with cancer, reproductive effects, mutagenic changes, neurotoxicity, and sensitization.

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