Structural Biochemistry/Lipids/Fatty Wax

Fatty Wax

A wax is a simple lipid that is an ester of a long-chain alcohol and a fatty acid. The alcohol may be made up of 12-32 carbon atoms.

These waxes can be found in nature as coatings on leaves and stems of plants, and prevents the plant from losing excessive amounts of water. Carnuba wax is found on the leaves of Brazilian palm trees and is used in floor and automobile waxes. Lanolin coats lamb's wool. Beeswax is secreted by bees to make cells for honey and eggs. Spermaceti wax is found in the head cavities and blubber of the sperm whale. Many of these waxes are used in ointments, hand creams, and cosmetics, which can be seen in the ingredients lists.

Paraffin wax which is used in some candles, is not based upon the ester functional group, but instead is a mixture of high molecular weight alkanes. Ear wax, on the other hand, is a mixture of phospholipids and esters of cholesterol.

The waxes with their component alcohols and fatty acids are listed below:

Carnuba:

Alcohol- CH₃(CH₂)₂₈CH₂-OH, Fatty Acid- CH₃(CH₂)₂₄COOH

Beeswax:

Alcohol- CH₃(CH₂)₂₈CH₂-OH, Fatty Acid- CH₃(CH₂)₁₄COOH

Spermacetic:

Alcohol- CH₃(CH₂)₁₄CH₂-OH, Fatty Acid- CH₃(CH₂)₁₄COOH

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Ester Synthesis:

Simple esters contain an organic acid and an alcohol. The ester functional group is of significance in the biochemical group of compounds called waxes, triglycerides, and phospholipids. The simplified reaction reveals the process of breaking some bonds and forming the ester and the by product, water. It is as follows: First, the -OH bond of the acid is broken as well as the -H bond of the alcohol. Both join to make HOH, a water molecule. Secondly, the oxygen of the alcohol forms a bond to the acid at the carbon with the double bond oxygen. This forms the ester functional group. Note that the long carbon chains do not participate in the reaction, but are just part of the final molecule.

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Lipstick:

Lipstick is a common form of fatty wax. It consists of a suspension of coloring agents in high molecular weight hydrocarbons, waxes, and/or fats. The color usually comes from a dye precipitated by a metal ion such as Fe (III), Ni(II), or Co(II) ions. An ingredients list on the lipstick might contain: dye (4-8%); castor oil, paraffin, or fats to dissolve dye (50%); lanolin (25%); carnauba and/or beeswax as a stiffening agent (36%); perfume (1.5%). The lipstick is made by first dispersing the dye in the castor oil. Then, the other waxes and lanolin are added as the mixture is heated and stirred. The molten waxes are then cast in a suitable form to harden.

Eye Makeup:

Eye makeup is also another form of fatty wax. Eyebrow pencils are similar to lipstick but contain lamp black (carbon soot) as a black coloring agent. A different mixture of waxes may be used to give the desired melting point. Brown pencils are made by adding iron oxide (rust) as a pigment. A water-resistant mascara has a mixture of waxes, fats, oils, and soap. Other coloring agents in addition to blacks and browns may be chromic oxide (dark green) and ultramarine (blue pigment of sodium and aluminum silicate).

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Reference: Ophardt, Charles E. Elmhurst College, Virtual Chembook 2003. http://www.elmhurst.edu/~chm/vchembook/554wax.html