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Propyl Group

carbon propane atoms acid

Propyl group is the name given to the portion of an organic molecule that is derived from propane and has the molecular structure -CH2CH3. A propyl group can be abbreviated -Pr. The propyl group is one of the alkyl groups defined by dropping the -ane ending from their parent compound and replacing it with -yl. The propyl group is derived from propane (HCH2CH2CH3) by removing one of the end hydrogens. The parent compound consists of three carbon atoms connected by single bonds, each of which is connected to hydrogen atoms, resulting in each of the three carbon atoms having four bonds each. Propane is derived form the very old acid, propionic acid. Propionic acid (CH3CH2CO2H) is the simplest organic acid which has a soapy or fat-like feel and was named from the Greek words proto for first and pion for fat. A very similar group to a propyl group is the isopropyl group, -CH(CH3)2, which derived by removing either of the hydrogen atoms attached to the central carbon atom of propane (CH3CH2CH3).

Propane is a gas produced primarily from various refinery processes. It is often mixed with butane, a four carbon atomalkane, and sold as bottled gas or liquefied petroleum gas, LPG. The bottled gas is used as an inexpensive fuel for cooking and heating homes not located near natural gas lines. Since liquefied petroleum gas burns very cleanly, it is being used as an alternate fuel for cars, trucks, and buses. Many buses are using bottled gas for fuel in order to avoid polluting the air and propane gas filling stations are being established in many cities. Propane is a gaseous active ingredient used for the dispersion of various products, such as deodorants or "fix-a-flat" rubbers from aerosol cans.

Propane is a simple organic compound that is used industrially to make ethylene (H2C=CH2) and propylene (CH3CH=CH2). Ethylene and propylene are produced by heating a mixture of propane and steam to a very high temperature. Ethylene is used to make many compounds that contain two carbon atoms or have a two carbon atom branch attached to a chain of carbon atoms. Propylene is polymerized to make polypropylene, a plastic, which is used for car battery cases, toys, kitchen utensils, and containers. It can be used in chemical reactions to attach a chain of three carbon atoms to benzene rings and other chemicals. Propylene is used to make other chemicals that contain three carbon atoms, such as, the specialty solvent acrylonitrile and propylene oxide used in the manufacture of rubber. Isopropyl alcohol or rubbing alcohol is manufactured by reacting propylene with water. It is a good solvent and is found in many industrial and consumer products. Isopropyl alcohol is a primary ingredient of nail polish, after shave lotion, deodorant, and skin lotion. It is used to kill microorganisms that grow in hospitals as well as around the home with tincture of iodine and mercurophen being home medicinals which contain the active ingredient isopropyl alcohol.

When a propyl group or a chain of three carbon atoms is added to a molecule's structure, their addition gives the compound various properties that make it commercially important. The mosquito and fly repellents dipropyl isocinchomeronate and propyl N,N-diethylsuccinamate both contain the three carbon propyl chain. Valeric acid or pentanoic acid is a five carbon acid that is commercially used as a food flavor. When a propyl group is attached to the second carbon atom of this acid, 2-propylpentanoic acid or valproic acid is produced. Valproic acid is prescribed for the treatment of seizures and various types of epilepsy. The manufacturers of herbicides have known for years that the presence of a isopropyl group in a molecule results in an increase in the efficiency of that compounds weed killing properties. Propham or isopropyl carbanilate has been used for this purpose since 1945.

Resources

Books

Kirk-Othmer Encyclopedia of Chemical Technology. Vols. 13 and 19. New York: John Wiley and Sons, 1991.

Loudon,G. Mark. Organic Chemistry. Oxford: Oxford University Press, 2002.


Andrew Poss

KEY TERMS

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Isopropyl group

—Has the molecular structure of —CH(CH3)2, and is derived from propane by removing either of the hydrogen atoms attached to the central carbon atom (CH3CH2CH3).

Propane

—Has the molecular formula, CH3CH2CH3, and consists of three carbon atoms connected by single bonds, each of which is connected to enough hydrogen atoms to have four bonds each.

Propyl group

—The portion of an organic molecule that is derived from propane and has the molecular structure -CH2CH3.

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