Fatty alcohol
Encyclopedia
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s consisting of a chain of 8 to 22 carbon atoms. Fatty alcohols usually have even number of carbon atoms and a single alcohol group (-OH) attached to the terminal carbon. Some are unsaturated and some are branched. They are widely used in industrial chemistry.
Production and occurrence
Most fatty alcohols in nature are found as waxWax
thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...
es which are ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s with fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s and fatty alcohols. They are produced by bacteria, plants and animals for purposes of buoyancy, as source of metabolic water and energy, biosonoar lenses (marine mammals) and for thermal insulation in the form of waxes (in plants and insects) . Fatty alcohols were unavailable until the early 1900s. They were originally obtained by reduction of wax esters with sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
by the Bouveault–Blanc reduction process. In the 1930s catalytic hydrogenation was commercialized, which allowed the conversion of fatty acid esters, typically tallow
Tallow
Tallow is a rendered form of beef or mutton fat, processed from suet. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.In industry,...
, to the alcohols. In the 1940s and 1950s, petrochemicals became an important source of chemicals, and Karl Ziegler
Karl Ziegler
Karl Waldemar Ziegler was a German chemist who won the Nobel Prize in Chemistry in 1963, with Giulio Natta, for work on polymers. The Nobel Committee recognized his "excellent work on organometallic compounds [which]...led to new polymerization reactions and ... paved the way for new and highly...
had discovered the polymerization
Polymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
of ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
. These two developments opened the way to synthetic fatty alcohols.
From natural sources
The traditional and still important source of fatty alcohols are fatty acid esters. Wax esters were formerly extracted from sperm oil, obtained from whaleWhale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s. An alternative plant source is jojoba
Jojoba
Jojoba, pronounced , is a shrub native to the Sonoran and Mojave deserts of Arizona, California, and Mexico. It is the sole species of the family Simmondsiaceae, placed in the order Caryophyllales. It is also known as goat nut, deer nut, pignut, wild hazel, quinine nut, coffeeberry, and gray box...
. Fatty acid triesters, known as triglyceride
Triglyceride
A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
s, are obtained from plant and animal sources. These triesters are subjected to transesterification
Transesterification
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R′ of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst...
to give methyl esters, which in turn are hydrogenated to the alcohols. Although tallow is typically C16-C18, the chain length from plant sources are more variable. Higher alcohols (C20–C22) can be obtained from rapeseed
Rapeseed
Rapeseed , also known as rape, oilseed rape, rapa, rappi, rapaseed is a bright yellow flowering member of the family Brassicaceae...
. Shorter alcohols (C12-C14) are obtained from coconut oil.
From petrochemical sources
Fatty alcohols are also prepared from petrochemical sources. In the Ziegler process, ethyleneEthylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
is oligomer
Oligomer
In chemistry, an oligomer is a molecule that consists of a few monomer units , in contrast to a polymer that, at least in principle, consists of an unlimited number of monomers. Dimers, trimers, and tetramers are oligomers. Many oils are oligomeric, such as liquid paraffin...
ized using triethylaluminium
Triethylaluminium
Triethylaluminium is an organoaluminium compound. This volatile, colorless liquid is highly pyrophoric, igniting immediately upon exposure to air. It is normally stored in stainless steel containers either as a pure liquid or as a solution in hydrocarbon solvents such as hexane, heptane, or ...
followed by air oxidation. This process affords even-numbered alcohols:
- Al(C2H5)3 + 18 C2H4 → Al(C14H29)3
- Al(C14H29)3 + 1.5 O2 + 1.5 H2O → 3 HOC14H29 + 0.5 Al2O3
Alternatively ethylene can be oligomerized to give mixtures of alkenes, which are subjected to hydroformylation
Hydroformylation
Hydroformylation, also known as oxo synthesis or oxo process, is an important industrial process for the production of aldehydes from alkenes. This chemical reaction entails the addition of a formyl group and a hydrogen atom to a carbon-carbon double bond...
, this process affording odd-numbered aldehyde, which is subsequently hydrogenated. For example, from 1-decene, hydroformylation gives the C11 alcohol:
- C8H17CH=CH2 + H2 + CO → C8H17CH2CH2CHO
- C8H17CH2CH2CHO + H2 → C8H17CH2CH2CH2OH
In the Shell higher olefin process
Shell higher olefin process
The Shell higher olefin process is a chemical process for the production of linear alpha olefins via ethylene oligomerization and olefin metathesis invented and exploited by Royal Dutch Shell. The olefin products are converted to fatty aldehydes and then to fatty alcohols, which are precursors...
, the chain-length distribution in the initial mixture of alkene oligomers is adjusted so as to more closely match market demand. Shell does this by means of an intermediate metathesis
Olefin metathesis
Olefin metathesis or transalkylidenation is an organic reaction that entails redistribution of alkylene fragments by the scission of carbon - carbon double bonds in olefins . Its advantages include the creation of fewer sideproducts and hazardous wastes. Yves Chauvin, Robert H. Grubbs, and Richard R...
reaction. The resultant mixture is fractionated and hydroformylated/hydrogenated in a subsequent step.
Applications
Fatty alcohols are mainly used in the production of detergents and surfactants. They are components also of cosmeticsCosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
, foods, and as industrial solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
s. Due to their amphipathic nature, fatty alcohols behave as nonionic surfactant
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
s. They find use as emulsifiers, emollients and thickeners in cosmetics
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
and food industry
Food industry
The food production is a complex, global collective of diverse businesses that together supply much of the food energy consumed by the world population...
.
Nutrition
Very long chain fatty alcohols (VLCFA), obtained from plant waxes and beeswaxBeeswax
Beeswax is a natural wax produced in the bee hive of honey bees of the genus Apis. It is mainly esters of fatty acids and various long chain alcohols...
have been reported to lower plasma cholesterol
Cholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
in humans. They can be found in unrefined cereal grains, beeswax, and many plant-derived foods. Reports suggest that 5–20 mg per day of mixed C24–C34 alcohols, including octacosanol and triacontanol
Triacontanol
1-Triacontanol is a fatty alcohol of the general formula C30H62O, also known as melissyl alcohol or myricyl alcohol. It is found in plant cuticle waxes and in beeswax. Triacontanol is a growth stimulant for many plants, most notably roses, in which it rapidly increases the number of basal breaks....
, lower low-density lipoprotein (LDL) cholesterol by 21%–29% and raise high-density lipoprotein cholesterol by 8%–15%. Wax esters are hydrolyzed by a bile
Bile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
salt–dependent pancreatic carboxyl esterase, releasing long chain alcohols and fatty acids that are absorbed in the gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
. Studies of fatty alcohol metabolism in fibroblasts suggest that very long chain fatty alcohols, fatty aldehydes, and fatty acids are reversibly inter-converted in a fatty alcohol cycle. The metabolism of these compounds is impaired in several inherited human peroxisomal disorders, including adrenoleukodystrophy
Adrenoleukodystrophy
Adrenoleukodystrophy is a rare, inherited disorder that leads to progressive brain damage, failure of the adrenal glands and eventually death. ALD is a disease in a group of genetic disorders called leukodystrophies, whose chief feature is damage to myelin...
and Sjögren-Larsson syndrome
Sjögren-Larsson syndrome
Sjögren–Larsson syndrome is an autosomal recessive form of ichthyosis apparent at birth.-Causes:It is associated with a deficiency of the enzyme "fatty aldehyde dehydrogenase"...
.
Exposure
Exposure could occur with commercial application in the manufacturing (such as in production and formulation) or with use of the final product. Hazards are mitigated in industry by following information found in material safety data sheets.Human Health
Tests of acute and repeated exposures have revealed a low level of toxicity from inhalation, oral or dermal exposure of fatty alcohols. Fatty alcohols are not very volatile and the acute lethal concentration is greater than the saturated vapor pressure. Longer chain (C12-C16) fatty alcohols produce less health effects than short chain (< C12). Short chain fatty alcohols are considered eye irritants, while long chain alcohols are not. There is no skin sensitization potential from fatty alcohols.Repeated exposure to fatty alcohols produce low level toxicity and certain compounds in this category can cause local irritation on contact or low-grade liver effects (essentially linear alcohols have a slightly higher rate of occurrence of these effects). No effects on the central nervous system have been seen with inhalation and oral exposure. Tests of repeated bolus
Bolus
-Medicine:* Bolus , the administration of a drug, medication or other substance in the form of a single, large dose* Bolus , a tissue equivalent substance used in radiation therapy...
dosages of 1-hexanol and 1-octanol showed potential for CNS depression and induced respiratory distress. No potential for peripheral neuropathy has been found. In rats, the no observable adverse effect level (NOAEL) ranges from 200 mg/kg/day to 1000 mg/kg/day by ingestion. There has been no evidence that fatty alcohols are carcinogenic, mutagenic, or cause reproductive toxicity or infertility.Fatty alcohols are effectively eliminated from the body when exposed, limiting possibility of retention or bioaccumulation .
Margins of exposure resulting from consumer uses of these chemicals are adequate for the protection of human health as determined by the Organization for Economic Co-operation and Development (OECD) high production volume chemicals program .
Environment
Fatty alcohols up to chain length C18 are biodegradable, with length up to C16 biodegrading within 10 days completely. Chains C16 to C18 were found to biodegrade from 62% to 76% in 10 days. Chains greater than C18 were found to degrade by 37% in 10 days. Field studies at waste-water treatment plants have shown that 99% of fatty alcohols lengths C12-C18 are removed .Fate prediction using Fugacity
Fugacity
In chemical thermodynamics, the fugacity of a real gas is an effective pressure which replaces the true mechanical pressure in accurate chemical equilibrium calculations. It is equal to the pressure of an ideal gas which has the same chemical potential as the real gas. For example, nitrogen gas ...
modeling has shown that fatty alcohols with chain lengths of C10 and greater in water partition into sediment. Lengths C14 and above are predicted to stay in the air upon release. Modeling shows that each type of fatty alcohol will respond independently upon environmental release.
Aquatic Organisms
Fish, invertebrates and algae experience similar levels of toxicity with fatty alcohols although it is dependent on chain length with the shorter chain having greater toxicity potential. Longer chain lengths show no toxicity to aquatic organisms .| Chain Size | Acute Toxicity | Chronic Toxicity |
|---|---|---|
| < C11 | 1-100 mg/l | 0.1-1.0 mg/l |
| C11-C13 | 0.1-1.0 mg/l | 0.1 - <1.0 mg/l |
| C14-C15 | NA | 0.01 mg/l |
| >C16 | NA | NA |
This category of chemicals was evaluated under the Organization for Economic Co-operation and Development (OECD) high production volume chemicals program. No unacceptable environmental risks were identified.
Common names and related compounds
| Name | Carbon atoms | Branches/saturated? | Formula >- | capryl alcohol (1-octanol) |
8 carbon atoms | >- | 8 carbon atoms | branched | >- | 9 carbon atoms | >- | 10 carbon atoms | >- | 11 carbon atoms | >- | 12 carbon atoms | >- | 13 carbon atoms | >- | 14 carbon atoms | >- | 15 carbon atoms | >- | 16 carbon atoms | >- | 16 carbon atoms | unsaturated | 3(CH2)5CH=CH(CH2)8OH >- | Heptadecyl alcohol (1-n-heptadecanol, heptadecanol) |
17 carbon atoms | >- | 18 carbon atoms | >- | 18 carbon atoms | branched | 3)2CH-(CH2)15OH >- | elaidyl alcohol (9E-octadecen-1-ol) |
18 carbon atoms | unsaturated | 3(CH2)7CH=CH(CH2)8OH >- | oleyl alcohol Oleyl alcohol Oleyl alcohol, octadecenol, or cis-9-octadecen-1-ol, is a fatty alcohol coming from inedible beef fat. It is also found in fish oil.Its chemical formula is 1836 or CH37-CH=CH-8OH.It is a non-ionic, unsaturated fatty alcohol.... (cis-9-octadecen-1-ol) |
18 carbon atoms | unsaturated | >- | 18 carbon atoms | polyunsaturated, a hydrolyzation of linoleic acid Linoleic acid Linoleic acid is an unsaturated n-6 fatty acid. It is a colorless liquid at room temperature. In physiological literature, it has a lipid number of 18:2... , an omega 6 fatty acid |
>- | 18 carbon atoms | polyunsaturated | >- | 18 carbon atoms | polyunsaturated | >- | 18 carbon atoms | polyunsaturated | >- | 18 carbon atoms | unsaturated, diol | 3(CH2)5CH(OH)CH2CH=CH(CH2)8OH >- | Nonadecyl alcohol (1-nonadecanol) |
19 carbon atoms | >- | 20 carbon atoms | >- | 21 carbon atoms | >- | 22 carbon atoms | >- | 22 carbon atoms | unsaturated | 3(CH2)7CH=CH(CH2)12OH >- | lignoceryl alcohol (1-tetracosanol) |
24 carbon atoms | >- | 26 carbon atoms | >- | 28 carbon atoms | >- | 30 carbon atoms | >- | 34 carbon atoms | >- |
Behenyl alcohol, lignoceryl alcohol, ceryl alcohol, 1-heptacosanol
1-Heptacosanol
1-Heptacosanol is a fatty alcohol....
, montanyl alcohol, 1-nonacosanol
1-Nonacosanol
1-Nonacosanol is a fatty alcohol....
, myricyl alcohol, 1-dotriacontanol
1-Dotriacontanol
1-Dotriacontanol is an alcohol....
, and geddyl alcohol are together classified as policosanol
Policosanol
Policosanol is the generic term for a natural extract of plant waxes. It is used as a nutritional supplement intended to lower LDL cholesterol and increase HDL cholesterol and to help prevent atherosclerosis, though some studies have raised questions about the effectiveness of policosanol.-...
, with montanyl alcohol and myricyl alcohol being the most abundant.