Fatty From Wikipedia, the free encyclopedia

Fatty alcohol

Fatty (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 with the source.[1][2] Some commercially important fatty alcohols are lauryl, stearyl, and oleyl alcohols. They are colourless oily liquids (for smaller carbon numbers) or waxy solids, although impure samples may appear yellow. Fatty alcohols usually have an 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 industry. As with fatty acids, they are often referred to generically by the number of carbon atoms in the molecule, such as "a C12 alcohol", that is an alcohol having 12 carbons, for example .

Contents [hide]

 1 Production and occurrence

o 1.1 From natural sources

o 1.2 From petrochemical sources

 2 Applications

o 2.1 Nutrition

 3 Safety

o 3.1 Human Health

o 3.2 Environment

o 3.3 Aquatic Organisms

 4 Common names and related compounds

 5 References

 6 External links

Production and occurrence[edit] Most fatty alcohols in nature are found as which are with fatty acids and fatty alcohols.[1] They are produced by bacteria, plants and animals for purposes of buoyancy, as source of metabolic water and energy, biosonar lenses (marine mammals) and for thermal insulation in the form of waxes (in plants and insects).[3]Fatty alcohols were unavailable until the early 1900s. They were originally obtained by reduction of esters with sodium by the Bouveault–Blanc reduction process. In the 1930s catalytic was commercialized, which allowed the conversion of esters, typically , to the alcohols. In the 1940s and 1950s, petrochemicals became an important source of chemicals, and had discovered the of . These two developments opened the way to synthetic fatty alcohols. From natural sources[edit] The traditional and still important source of fatty alcohols is fatty acid esters. Wax esters were formerly extracted from , obtained from whales. An alternative plant source is jojoba. Fatty acid triesters, known as , are obtained from plant and animal sources. These triesters are subjected to to give methyl esters, which in turn are hydrogenated to the alcohols. Although tallow is predominantly C16-C18, the chain lengths from plant sources are more variable (C6-C24). Higher alcohols (C20–C22) can be obtained from rapeseed or mustard seed. Midcut alcohols (C12-C14) are obtained from coconut or palm oil. From petrochemical sources[edit] Fatty alcohols are also prepared from petrochemical sources. In the , ethylene is oligomerized using 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 , which are subjected to , 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, the chain-length distribution in the initial mixture of oligomers is adjusted so as to more closely match market demand. Shell does this by means of an intermediate metathesis reaction.[4] The resultant mixture is fractionated and hydroformylated/hydrogenated in a subsequent step.

Applications[edit] Fatty alcohols are mainly used in the production of detergents and surfactants. They are components also of , foods, and as industrial . Due to theiramphipathic nature, fatty alcohols behave as nonionic surfactants. They find use as emulsifiers, emollients and thickeners in cosmetics and food industry. About 50% of fatty alcohols used commercially are of natural origin, the remainder being synthetic.[1] Nutrition[edit] Very long chain fatty alcohols (VLCFA), obtained from plant waxes and have been reported to lower plasma 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 andtriacontanol, lower low-density lipoprotein (LDL) cholesterol by 21%–29% and raise high-density lipoprotein cholesterol by 8%– 15%.[citation needed] Wax esters arehydrolyzed by a bile salt– dependent pancreatic carboxyl esterase, releasing long chain alcohols and fatty acids that are absorbed in the . Studies of 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 and Sjögren- Larsson syndrome.[5]

Safety[edit] Human Health[edit] Fatty alcohols are relatively benign materials, with LD50s (oral, rat) ranging from 3.1-r g/kg for hexanol to 6 -8 g/kg for octadecanol.[1] For a 50 kg person, these values translate to more than 100 g. 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 fewer health effects than short chain (< C12). Short chain fatty alcohols are considered eye irritants, while long chain alcohols are not.[6] Fatty alcohols exhibit no skin sensitization.[7] 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 dosages of 1-hexanol and 1- 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.[7] 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.[6][8] Environment[edit] 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.[7] Fate prediction using fugacity 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.[7] Aquatic Organisms[edit] 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.[7] Chain Size Acute Toxicity for fish Chronic Toxicity for fish

< 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.[8]

Common names and related compounds[edit]

Name Carbon atoms Branches/saturated? Formula

tert -Butyl alcohol 4 carbon atoms C4H10O

tert - 5 carbon atoms C5H12O

3-Methyl-3-pentanol 6 carbon atoms C6H14O

Ethchlorvynol 7 carbon atoms C7H9ClO

1-Octanol (capryl alcohol) 8 carbon atoms C8H18O

2-ethyl hexanol 8 carbon atoms branched pelargonic alcohol (1-nonanol) 9 carbon atoms

10 carbon 1-Decanol (decyl alcohol, capric alcohol) atoms Undecyl alcohol (1-, undecanol, 11 carbon Hendecanol) atoms

12 carbon Lauryl alcohol (Dodecanol, 1-dodecanol) atoms

Tridecyl alcohol (1-tridecanol, tridecanol, 13 carbon isotridecanol) atoms

14 carbon Myristyl alcohol (1-tetradecanol) atoms

Pentadecyl alcohol (1-pentadecanol, 15 carbon pentadecanol) atoms

16 carbon (1-hexadecanol) atoms

16 carbon palmitoleyl alcohol (cis-9-hexadecen-1-ol) unsaturated atoms

Heptadecyl alcohol (1-n-heptadecanol, 17 carbon heptadecanol) atoms

18 carbon (1-octadecanol) atoms

19 carbon Nonadecyl alcohol (1-nonadecanol) atoms

20 carbon (1-eicosanol) atoms

21 carbon Heneicosyl alcohol (1-heneicosanol) atoms behenyl alcohol (1-docosanol) 22 carbon atoms

22 carbon erucyl alcohol (cis-13-docosen-1-ol) unsaturated atoms

24 carbon lignoceryl alcohol (1-tetracosanol) atoms

26 carbon ceryl alcohol (1-hexacosanol) atoms

27 carbon 1-heptacosanol atoms montanyl alcohol, cluytyl alcohol, or 1- 28 carbon octacosanol atoms

29 carbon 1-nonacosanol atoms myricyl alcohol, melissyl alcohol, or 1- 30 carbon triacontanol atoms

32 carbon 1-dotriacontanol C32H66O atoms

34 carbon geddyl alcohol (1-tetratriacontanol) atoms

Cetearyl alcohol