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Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include
higher alkanes Higher alkanes are alkanes having nine or more carbon atoms. Nonane is the lightest alkane to have a flash point above 25 °C, and is not classified as dangerously flammable. The term ''higher alkanes'' is sometimes used literally as "alkanes ...
and lipids, typically with melting points above about 40 °C (104 °F), melting to give low viscosity liquids. Waxes are insoluble in water but soluble in nonpolar organic solvents such as hexane, benzene and
chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to ...
. Natural waxes of different types are produced by plants and animals and occur in petroleum.


Chemistry

Waxes are organic compounds that characteristically consist of long aliphatic alkyl chains, although aromatic compounds may also be present. Natural waxes may contain unsaturated bonds and include various functional groups such as fatty acids,
primary Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...
and secondary alcohols,
ketones In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...
, aldehydes and fatty acid esters. Synthetic waxes often consist of
homologous series In organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched, or differ by molecular formula of and molecu ...
of long-chain aliphatic hydrocarbons (
alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...
s or paraffins) that lack functional groups.


Plant and animal waxes

Waxes are synthesized by many plants and animals. Those of animal origin typically consist of wax esters derived from a variety of fatty acids and carboxylic alcohols. In waxes of plant origin, characteristic mixtures of unesterified hydrocarbons may predominate over esters. The composition depends not only on species, but also on geographic location of the organism.


Animal waxes

The best-known animal wax is beeswax used in constructing the honeycombs of beehives, but other insects also secrete waxes. A major component of beeswax is myricyl palmitate which is an ester of triacontanol and palmitic acid. Its melting point is 62-65 °C.
Spermaceti Spermaceti is a waxy substance found in the head cavities of the sperm whale (and, in smaller quantities, in the oils of other whales). Spermaceti is created in the spermaceti organ inside the whale's head. This organ may contain as much as of ...
occurs in large amounts in the head oil of the
sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...
. One of its main constituents is
cetyl palmitate Hexadecyl hexadecanoate, also known as Cetyl palmitate, is the ester derived from hexadecanoic acid and hexadecanol. This white waxy solid is the primary constituent of spermaceti, the once highly prized wax found in the skull of sperm whales.Wi ...
, another ester of a fatty acid and a
fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies ...
. Lanolin is a wax obtained from wool, consisting of esters of
sterol Sterol is an organic compound with formula , whose molecule is derived from that of gonane by replacement of a hydrogen atom in position 3 by a hydroxyl group. It is therefore an alcohol of gonane. More generally, any compounds that contain the go ...
s.Wilhelm Riemenschneider1 and Hermann M. Bolt "Esters, Organic" Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim.


Plant waxes

Plants secrete waxes into and on the surface of their cuticles as a way to control evaporation, wettability and hydration. The epicuticular waxes of plants are mixtures of substituted long-chain aliphatic hydrocarbons, containing alkanes, alkyl esters, fatty acids, primary and secondary alcohols,
diol A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. The most common industrial diol is e ...
s, ketones and aldehydes.EA Baker (1982) Chemistry and morphology of plant epicuticular waxes. In The Plant Cuticle. Ed. DF Cutler, KL Alvin, CE Price. Academic Press. From the commercial perspective, the most important plant wax is carnauba wax, a hard wax obtained from the Brazilian palm ''
Copernicia prunifera ''Copernicia prunifera'' or the carnaúba palm or carnaubeira palm () is a species of palm tree native to northeastern Brazil (mainly the states of Ceará, Piauí, Maranhão, Rio Grande do Norte and Bahia). Known by many as 'tree of life' becaus ...
''. Containing the ester myricyl cerotate, it has many applications, such as confectionery and other food coatings, car and furniture polish, floss coating, and
surfboard wax Surfboard wax (also known as surfwax) is a formulation of natural and/or synthetic wax for application to the deck of a surfboard, bodyboard, or skimboard, to keep the surfer from slipping off the board when paddling out or riding a wave. It is al ...
. Other more specialized vegetable waxes include jojoba oil,
candelilla wax Candelilla wax is a wax derived from the leaves of the small Candelilla shrub native to northern Mexico and the southwestern United States, '' Euphorbia antisyphilitica'', from the family ''Euphorbiaceae''. It is yellowish-brown, hard, brittle, a ...
and ouricury wax.


Modified plant and animal waxes

Plant and animal based waxes or oils can undergo selective chemical modifications to produce waxes with more desirable properties than are available in the unmodified starting material. This approach has relied on green chemistry approaches including olefin metathesis and enzymatic reactions and can be used to produce waxes from inexpensive starting materials like vegetable oils.


Petroleum derived waxes

Although many natural waxes contain esters, paraffin waxes are hydrocarbons, mixtures of alkanes usually in a
homologous series In organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched, or differ by molecular formula of and molecu ...
of chain lengths. These materials represent a significant fraction of petroleum. They are refined by vacuum distillation. Paraffin waxes are mixtures of saturated n- and iso- alkanes, naphthenes, and alkyl- and naphthene-substituted aromatic compounds. A typical alkane paraffin wax chemical composition comprises hydrocarbons with the general formula C''n''H2''n''+2, such as hentriacontane, C31H64. The degree of branching has an important influence on the properties. Microcrystalline wax is a lesser produced petroleum based wax that contains higher percentage of isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons. Millions of tons of paraffin waxes are produced annually. They are used in foods (such as chewing gum and cheese wrapping), in candles and cosmetics, as non-stick and waterproofing coatings and in polishes.


Montan wax

Montan wax is a fossilized wax extracted from coal and
lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...
. It is very hard, reflecting the high concentration of saturated fatty acids and alcohols. Although dark brown and odorous, they can be purified and bleached to give commercially useful products.


Polyethylene and related derivatives

, about 200 million kilograms of polyethylene waxes were consumed annually. Polyethylene waxes are manufactured by one of three methods: # The direct polymerization of ethylene, potentially including co-monomers also; # The thermal degradation of high molecular weight polyethylene resin; # The recovery of low molecular weight fractions from high molecular weight resin production. Each production technique generates products with slightly different properties. Key properties of low molecular weight polyethylene waxes are viscosity, density and melt point. Polyethylene waxes produced by means of degradation or recovery from polyethylene resin streams contain very low molecular weight materials that must be removed to prevent volatilization and potential fire hazards during use. Polyethylene waxes manufactured by this method are usually stripped of low molecular weight fractions to yield a flash point >500°F (>260°C). Many polyethylene resin plants produce a low molecular weight stream often referred to as Low Polymer Wax (LPW). LPW is unrefined and contains volatile oligomers, corrosive catalyst and may contain other foreign material and water. Refining of LPW to produce a polyethylene wax involves removal of oligomers and hazardous catalyst. Proper refining of LPW to produce polyethylene wax is especially important when being used in applications requiring FDA or other regulatory certification.


Uses

Waxes are mainly consumed industrially as components of complex formulations, often for coatings. The main use of polyethylene and polypropylene waxes is in the formulation of colourants for plastics. Waxes confer matting effects (i.e., to confer non-glossy finishes) and wear resistance to paints. Polyethylene waxes are incorporated into inks in the form of dispersions to decrease friction. They are employed as release agents, find use as slip agents in furniture, and confer corrosion resistance.Uwe Wolfmeier, Mr. Hans Schmidt, Franz-Leo Heinrichs, Georg Michalczyk, Wolfgang Payer, Wolfram Dietsche, Klaus Boehlke, Gerd Hohner, Josef Wildgruber "Waxes" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. .


Candles

Waxes such as paraffin wax or beeswax, and hard fats such as tallow are used to make candles, used for lighting and decoration. Another fuel type used in candle manufacturing includes soy. Soy wax is made by the hydrogenation process using soybean oil.


Wax products

Waxes are used as finishes and coatings for wood products. Beeswax is frequently used as a lubricant on drawer slides where wood to wood contact occurs.


Other uses

Sealing wax was used to close important documents in the Middle Ages.
Wax tablet A wax tablet is a tablet made of wood and covered with a layer of wax, often linked loosely to a cover tablet, as a "double-leaved" diptych. It was used as a reusable and portable writing surface in Antiquity and throughout the Middle Ages. C ...
s were used as writing surfaces. There were different types of wax in the Middle Ages, namely four kinds of wax (
Ragusan Ragusan may refer to: * citizen of the Republic of Ragusa hr, Sloboda se ne prodaje za sve zlato svijeta it, La libertà non si vende nemmeno per tutto l'oro del mondo"Liberty is not sold for all the gold in the world" , population_estimate ...
, Montenegro, Byzantine, and Bulgarian), "ordinary" waxes from Spain, Poland, and
Riga Riga (; lv, Rīga , liv, Rīgõ) is the capital and largest city of Latvia and is home to 605,802 inhabitants which is a third of Latvia's population. The city lies on the Gulf of Riga at the mouth of the Daugava river where it meets the Ba ...
, unrefined waxes and colored waxes (red, white, and green). Waxes are used to make wax paper, impregnating and coating paper and card to waterproof it or make it resistant to staining, or to modify its surface properties. Waxes are also used in
shoe polish Shoe polish (or boot polish) is a waxy paste, cream, or liquid that is used to polish, shine, and waterproof leather shoes or boots to extend the footwear's life and restore its appearance. Shoe polishes are distinguished by their textures, ...
es,
wood polish Wood finishing refers to the process of refining or protecting a wooden surface, especially in the production of furniture where typically it represents between 5 and 30% of manufacturing costs. Finishing is the final step of the manufacturing ...
es, and automotive polishes, as mold release agents in
mold making Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have ...
, as a coating for many
cheese Cheese is a dairy product produced in wide ranges of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. During production, ...
s, and to waterproof leather and fabric. Wax has been used since antiquity as a temporary, removable model in
lost-wax casting Lost-wax casting (also called "investment casting", "precision casting", or ''cire perdue'' which has been adopted into English from the French, ) is the process by which a duplicate metal sculpture (often silver, gold, brass, or bronze) is ...
of gold, silver and other materials. Wax with colorful pigments added has been used as a medium in encaustic painting, and is used today in the manufacture of crayons, china markers and colored pencils. Carbon paper, used for making duplicate
typewritten A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectively ...
documents was coated with carbon black suspended in wax, typically montan wax, but has largely been superseded by photocopiers and
computer printer In computing, a printer is a peripheral machine which makes a persistent representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. Differ ...
s. In another context,
lipstick Lipstick is a cosmetic product used to apply coloration and texture to lips, often made of wax and oil. Different pigments are used to produce color, and minerals such as silica may be used to provide texture. The use of lipstick dates back to ...
and mascara are blends of various fats and waxes colored with pigments, and both beeswax and lanolin are used in other cosmetics. Ski wax is used in skiing and
snowboarding Snowboarding is a recreational and competitive activity that involves descending a snow-covered surface while standing on a snowboard that is almost always attached to a rider's feet. It features in the Winter Olympic Games and Winter Paralympi ...
. Also, the sports of surfing and
skateboarding Skateboarding is an extreme sport, action sport originating in the United States that involves riding and performing tricks using a skateboard, as well as a recreational activity, an art form, an entertainment industry Profession, job, and a ...
often use wax to enhance the performance. Some waxes are considered food-safe and are used to coat wooden cutting boards and other items that come into contact with food. Beeswax or coloured synthetic wax is used to decorate Easter eggs in Romania, Ukraine, Poland,
Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...
and the Czech Republic. Paraffin wax is used in making chocolate covered sweets. Wax is also used in wax bullets, which are used as simulation aids.


Specific examples


Animal waxes

* Beeswax - produced by honey bees *
Chinese wax Chinese wax is a white to yellowish-white, gelatinous, crystalline water-insoluble substance obtained from the wax secreted by certain insects. It resembles spermaceti but is harder, more friable, and with a higher melting point. Two scale insects ...
- produced by the
scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the ...
''Ceroplastes ceriferus'' * Lanolin (wool wax) - from the sebaceous glands of sheep * Shellac wax - from the lac insect '' Kerria lacca'' *
Spermaceti Spermaceti is a waxy substance found in the head cavities of the sperm whale (and, in smaller quantities, in the oils of other whales). Spermaceti is created in the spermaceti organ inside the whale's head. This organ may contain as much as of ...
- from the head cavities and blubber of the
sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...


Vegetable waxes

*
Bayberry wax Bayberry wax is an aromatic green vegetable wax. It is removed from the surface of the fruit of the bayberry (wax-myrtle) shrub (ex. ''Myrica cerifera'') by boiling the fruits in water and skimming the wax from the surface of the water. It is made ...
- from the surface wax of the
fruits In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particula ...
of the bayberry shrub, '' Myrica faya'' *
Candelilla wax Candelilla wax is a wax derived from the leaves of the small Candelilla shrub native to northern Mexico and the southwestern United States, '' Euphorbia antisyphilitica'', from the family ''Euphorbiaceae''. It is yellowish-brown, hard, brittle, a ...
- from the Mexican shrubs '' Euphorbia cerifera'' and ''
Euphorbia antisyphilitica ''Euphorbia antisyphilitica'' is a species of flowering plant in the spurge family Euphorbiaceae. It is native to the Trans-Pecos of Texas and southern New Mexico in the United States as well as Chihuahua, Coahuila, Hidalgo, and Querétaro in Me ...
'' * Carnauba wax - from the leaves of the Carnauba palm, ''
Copernicia cerifera ''Copernicia prunifera'' or the carnaúba palm or carnaubeira palm () is a species of palm tree native to northeastern Brazil (mainly the states of Ceará, Piauí, Maranhão, Rio Grande do Norte and Bahia). Known by many as 'tree of life' becaus ...
'' * Castor wax - catalytically hydrogenated castor oil * Esparto wax - a byproduct of making paper from esparto grass, (''Macrochloa tenacissima'') * Japan wax - a vegetable triglyceride (not a true wax), from the berries of ''Rhus'' and ''Toxicodendron'' species * Jojoba oil - a liquid wax ester, from the seed of ''Simmondsia chinensis''. * Ouricury wax - from the Brazilian feather palm, ''
Syagrus coronata ''Syagrus coronata'', commonly known as the ouricury palm, aricuri palm, or licuri palm, is a species of palm tree that is native to eastern Brazil, ranging from the southern part of the state of Pernambuco, into the state of Bahia, south to the ...
''. *
Rice bran wax Rice bran wax is the vegetable wax extracted from the bran oil of rice (''Oryza sativa''). Chemical Composition The main components of rice bran wax are aliphatic acids (wax acids) and higher alcohol esters. The aliphatic acids consist of palmit ...
- obtained from rice bran (''Oryza sativa'') *
Soy wax Soy candles are candles made from soy wax, which is a processed form of soybean oil. They are usually container candles, because soy wax typically has a lower melting point than traditional waxes, but can also be made into pillar candles if ce ...
- from soybean oil * Tallow Tree wax - from the seeds of the tallow tree ''Triadica sebifera''.


Mineral waxes

* Ceresin waxes * Montan wax - extracted from
lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...
and brown coal *
Ozocerite Ozokerite or ozocerite, archaically referred to as earthwax or earth wax, is a naturally occurring odoriferous mineral wax or paraffin found in many localities. Lacking a definite composition and crystalline structure, it is not considered a min ...
- found in lignite beds *
Peat wax Peat Wax is a dark waxy substance extracted from peat using organic solvents. It is very similar to the coal derived Montan wax Montan wax, also known as lignite wax or OP wax, is a hard wax obtained by solvent extraction of certain types of ...
es


Petroleum waxes

* Paraffin wax - made of long-chain
alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...
hydrocarbons * Microcrystalline wax - with very fine crystalline structure


See also

*
Slip melting point The Slip melting point (SMP) or "slip point" is one conventional definition of the melting point of a waxy solid. It is determined by casting a 10 mm column of the solid in a glass tube with an internal diameter of about 1 mm and a length of a ...
* Wax acid * Wax argument or the "ball of wax example", is a thought experiment originally articulated by Renė Descartes.


References


External links


Waxes
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