Petrolatum

OVERVIEW

Petrolatum (peh-tro-LAY-tum) is a mixture, not a compound. Mixtures differ from compounds in a number of important ways. The parts making up a mixture are not chemically combined with each other, as they are in a compound. Also, mixtures have no definite composition, but consist of varying amounts of the substances from which they are formed.

Petrolatum is a complex mixture of hydrocarbons derived from the distillation of petroleum. Hydrocarbons are compounds that contain only carbon and hydrogen. The hydrocarbons that make up petrolatum belong to the methane (saturated or alkane) family of hydrocarbons with the general formula C_nH_2N+2. Some members of the family include methane (CH₄), ethane (C₂H₅), propane (C₃H₈), and butane (C₄H₁₀).

KEY FACTS

OTHER NAMES:

Petroleum jelly; paraffin jelly; vasoliment; liquid paraffin; mineral oil; paraffin oil

FORMULA:

Not applicable

ELEMENTS:

Carbon, hydrogen

COMPOUND TYPE:

Not applicable

STATE:

Semi-solid or liquid

MOLECULE WEIGHT:

Not applicable

MELTING POINT:

Not applicable

BOILING POINT:

Not applicable

SOLUBILITY:

Insoluble in water and ethyl alcohol; soluble in benzene, chloroform, ether, carbon disulfide, and other organic solvents

Petrolatum occurs in a semi-solid or liquid form. The semi-solid form is also called petroleum jelly or mineral jelly and is commercially available under a number of trade names, including Kremoline, Pureline, Sherolatum, and Vaseline™. It ranges in color from white to yellowish to amber. It is practically odorless and tasteless. It melts over a wide range, from about 38°C to about 55°C (100°F to 131°F). The liquid form is also known as liquid paraffin, mineral oil, or white mineral oil. Such products are sold commercially under trade names such as Alboline, Drakeol, Frigol, Kremol, and Paroleine. It is a colorless, tasteless, and odorless oily liquid.

Oil was first discovered in the United States in the 1850s in western Pennsylvania. A chemist from Brooklyn, New York, Robert Augustus Chesebrough (1837–1938), visited the new wells and noticed a wax-like material sticking to the petroleum drilling rods. He learned that oil workers used the "rod wax" to heal burns on their skin. Chesebrough eventually extracted and purified the substance—petrolatum—from petroleum and began manufacturing it in 1870. He received several patents for his discovery and in 1878, he gave his product the trade name of Vaseline™. His product quickly became popular as an ointment for wounds and burns. Unlike the animal and vegetable oils then being used for that purpose, petrolatum did not spoil. By the late 1870s, Vaseline™ was selling at the rate of one jar every minute in the United States. In 1880, it was added to the U.S. Pharmacopoeia, a manual that lists drugs used in medical practice.

HOW IT IS MADE

Petrolatum is a product of the fractional distillation of crude oil. Crude oil is a complex mixture of hundreds or thousands of compounds. These compounds can be separated, or distilled, from each other by heating crude oil to high temperatures. As the temperature of the crude oil rises, various groups or a "fraction" of compounds boil off. The first group of compounds includes gaseous compounds dissolved in crude oil. The next group of compounds includes compounds with low boiling points. The next group of compounds includes compounds with slightly higher boiling points. And so on. Eventually, a tar-like mass of compounds with very high boiling points is left behind in the distilling tower. This residue is heated to separate liquids from solids remaining behind. Some of these liquids and solids make up the semi-solid and liquid forms of petrolatum.

COMMON USES AND POTENTIAL HAZARDS

Petrolatum has a wide variety of uses, ranging from personal care and medical applications to industrial uses. The solid form, such as Vaseline™ is used as a topical ointment for the treatment of dry, cracked skin and to reduce the risk of infection. It works as a moisturizing agent because it reduces water loss from the skin, It helps prevent infection because it creates a barrier over wounds that prevents disease-causing organisms from entering the body. Solid petrolatum is also an ingredient in many skin care and cosmetic products, such as skin lotions, body and facial cleansers, antiperspirants, lipsticks, lip balms, sunscreens, and after-sun lotions. In hair products, it helps smooth frizzy hair by allowing hair to retain its natural moisture. The formation used in most of these products remains virtually unchanged from that developed by Robert Chesebrough in the 1800s.

Interesting Facts

• Both solid and liquid petrolatum are available in three grades, known as USP (U.S. Pharmacopoeia), NF (National Formulary), and FCC (Food Chemicals Codex).
• A synthetic version of petrolatum is made from soybean oil as an alternative to petroleum-based petrolatum. It is used primarily in the manufacture of cosmetics.
• Skin care products generally contain petrolatum in a concentration of about 1 to 3 percent.

Solid petrolatum is also used in industrial applications for a variety of purposes, such as:

• As a softener in the production of rubber products;
• In the food processing industry, to coat raw fruits and vegetables and to help products retain moisture;
• As a defoaming agent in the production of beet sugar and yeasts;
• For the lubrication of firearms and machine parts;

• In the production of modeling clays;
• In the manufacture of candles, to prevent a candle from shrinking as it cools after being burned;
• In the preparation of shoe polishes; and
• As an ingredient in rust preventatives.

The primary use of liquid petrolatum is as a laxative, a product that loosens the bowels. It also has a number of other applications, such as an additive in foods such as candies, confectionary products, and baked goods; as an ingredient in personal care products, such as baby oil creams, hair conditioning lotions, and ointments; in many different kinds of pharmaceutical preparations; in the production of industrial lubricants; as a softening agent in the manufacture of rubber, textiles, fibers, adhesives, and machine parts; as dust suppressants; and as dehydrating agents for a number of industrial processes.

Words to Know

FRACTIONAL DISTILLATION

The process of extracting compounds from petroleum by heating the petroleum and collecting the individual compounds as they boil off when their boiling points are reached.

HYDROCARBON

A compound that contains hydrogen and carbon atoms.

MIXTURE

A collection of two or more elements and/or compounds with no definite composition.

FOR FURTHER INFORMATION

"Another Old-Fashioned Product Vindicates Itself." Medical Update (October 1992): 6.

Morrison, David S. "Petrolatum: A Useful Classic." Cosmetics and Toiletries (January 1996): 59-68. Also available online at http://www.penreco.com/newsevents/tradearticles/petrolatumclassic.pdf (accessed on December 22, 2005).

"Material Safety Data Sheet." Penreco. http://www.penreco.com/products/pdfs/petrolatum/pen00421technicalpetrolatum.pdf (accessed on December 22, 2005).

Penreco (Petrolatum company). http://www.penreco.com/index.asp (accessed on December 22, 2005).

Schramm, Daniel. "The North American USP Petrolatum Industry." Soap & Cosmetics (January 2002): 60-63.

See AlsoPetroleum