Fatty alcohol

Source: Wikipedia, the free encyclopedia.
An example of a fatty alcohol

Fatty alcohols (or long-chain

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 dodecanol
.

Production and occurrence

Fatty alcohols became commercially available in the early 1900s. They were originally obtained by reduction of

catalytic hydrogenation was commercialized, which allowed the conversion of fatty acid esters, typically tallow, to the alcohols. In the 1940s and 1950s, petrochemicals became an important source of chemicals, and Karl Ziegler had discovered the polymerization of ethylene
. These two developments opened the way to synthetic fatty alcohols.

From natural sources

Most fatty alcohols in nature are found as waxes, which are esters of 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] The traditional sources of fatty alcohols have largely been various

mustard seed oil. Midcut alcohols are obtained from coconut oil (C12–C14) or palm kernel oil
(C16–C18).

From petrochemical sources

Fatty alcohols are also prepared from petrochemical sources. In the Ziegler process, ethylene is oligomerized using triethylaluminium followed by air oxidation. This process affords even-numbered alcohols:

Al(C2H5)3 + 18 C2H4 → Al(C14H29)3
Al(C14H29)3 + 3⁄2 O2 + 3⁄2 H2O → 3 HOC14H29 + 1⁄2 Al2O3

Alternatively ethylene can be oligomerized to give mixtures of alkenes, which are subjected to hydroformylation, 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 alkene oligomers is adjusted so as to more closely match market demand. Shell does this by means of an intermediate metathesis reaction.[5] 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

thickeners in cosmetics and food industry. About 50% of fatty alcohols used commercially are of natural origin, the remainder being synthetic.[1]

Nutrition

Very long-chain fatty alcohols (VLCFA), obtained from plant waxes and

peroxisomal disorders, including adrenoleukodystrophy and Sjögren–Larsson syndrome.[6]

Safety

Human health

Fatty alcohols are relatively benign materials, with

LD50 (oral, rat) ranging from 3.1–4 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 (smaller than C12). Short-chain fatty alcohols are considered eye irritants, while long chain alcohols are not.[7] Fatty alcohols exhibit no skin sensitization.[8]

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

NOAEL) ranges from 200 mg/kg/day to 1000 mg/kg/day by ingestion. There has been no evidence that fatty alcohols are mutagenic or cause reproductive toxicity or infertility. Fatty alcohols are effectively eliminated from the body when exposed, limiting possibility of retention or bioaccumulation.[8]

Margins of exposure resulting from consumer uses of these chemicals are adequate for the protection of human health as determined by the

Organisation for Economic Co-operation and Development (OECD) high production volume chemicals program.[7][9]

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 wastewater treatment plants have shown that 99% of fatty alcohols lengths C12–C18 are removed.[8]

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.[8]

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.[8]

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 — 0.01 mg/L
>C16 – –

This category of chemicals was evaluated under the

Organisation for Economic Co-operation and Development (OECD) high production volume chemicals program. No unacceptable environmental risks were identified.[9]

Table with common names

This table lists some alkyl alcohols. Note that in general the alcohols with even numbers of carbon atoms have common names, since they are found in nature, whereas those with odd numbers of carbon atoms generally do not have a common name.

Name Carbon atoms Branches/saturation Formula
tert-Butyl alcohol 4 carbon atoms branched C4H10O
tert-Amyl alcohol 5 carbon atoms branched C5H12O
3-Methyl-3-pentanol 6 carbon atoms branched C6H14O
1-Heptanol (enanthic alcohol) 7 carbon atoms C7H16O
1-Octanol (capryl alcohol) 8 carbon atoms C8H18O
Pelargonic alcohol
(1-nonanol)		 9 carbon atoms C9H20O
1-Decanol (decyl alcohol, capric alcohol) 10 carbon atoms C10H22O
Undecyl alcohol
(1-undecanol, undecanol, Hendecanol)		 11 carbon atoms C11H24O
Lauryl alcohol
(dodecanol, 1-dodecanol)		 12 carbon atoms C12H26O
Tridecyl alcohol
(1-tridecanol, tridecanol, isotridecanol)		 13 carbon atoms C13H28O
Myristyl alcohol
(1-tetradecanol)		 14 carbon atoms C14H30O
Pentadecyl alcohol
(1-pentadecanol, pentadecanol)		 15 carbon atoms C15H32O
Cetyl alcohol (1-hexadecanol) 16 carbon atoms C16H34O
Palmitoleyl alcohol (cis-9-hexadecen-1-ol) 16 carbon atoms unsaturated C16H32O
Heptadecyl alcohol
(1-n-heptadecanol, heptadecanol)		 17 carbon atoms C17H36O
Stearyl alcohol (1-octadecanol) 18 carbon atoms C18H38O
Oleyl alcohol (1-octadecenol) 18 carbon atoms unsaturated C18H36O
Nonadecyl alcohol
(1-nonadecanol)		 19 carbon atoms C19H40O
Arachidyl alcohol (1-eicosanol) 20 carbon atoms C20H42O
Heneicosyl alcohol (1-heneicosanol) 21 carbon atoms C21H44O
Behenyl alcohol
(1-docosanol)		 22 carbon atoms C22H46O
Erucyl alcohol (cis-13-docosen-1-ol) 22 carbon atoms unsaturated C22H44O
Lignoceryl alcohol
(1-tetracosanol)		 24 carbon atoms C24H50O
Ceryl alcohol
(1-hexacosanol)		 26 carbon atoms C26H54O
1-Heptacosanol 27 carbon atoms C27H56O
Montanyl alcohol
, cluytyl alcohol, or 1-octacosanol		 28 carbon atoms C28H58O
1-Nonacosanol 29 carbon atoms C29H60O
Myricyl alcohol
, melissyl alcohol, or 1-triacontanol		 30 carbon atoms C30H62O
1-Dotriacontanol (Lacceryl alcohol) 32 carbon atoms C32H66O
Geddyl alcohol
(1-tetratriacontanol)		 34 carbon atoms C34H70O

References

  1. ^
    ISBN 978-3527306732
    .
  2. doi:10.1351/goldbook.F02330
  3. PMID 20820625
    .
  4. S2CID 84849226
    .
  5. ^ Ashford's Dictionary of Industrial Chemicals (3rd ed.). 2011. pp. 6706–6711.[ISBN missing]
  6. S2CID 38905297
    .
  7. ^
    PMID 19237197
    .
  8. ^ a b c d e UK/ICCA (2006). "SIDS Initial Assessment Profile". OECD Existing Chemicals Database.
  9. ^
    PMID 19038453
    .

External links
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