Octanol

Octanol is a straight chain fatty alcohol with eight carbon atoms and the molecular formula CH₃(CH₂)₇OH. Although the term octanol usually refers exclusively to the primary alcohol 1-octanol, there are other less common isomers of octanol such as the secondary alcohols 2-octanol, 3-octanol and 4-octanol.

Additional recommended knowledge

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Octanol occurs naturally in the form of esters in some essential oils. The primary use of octanol is in the manufacture of various esters (both synthetic and naturally occurring), such as octyl acetate, which are used in perfumery and flavors. Other uses include experimental medical applications utilizing octanol to control Essential Tremor and other types of involuntary neurological tremors.^[1]

Preparation

Octanol is produced industrially by the oligomerization of ethylene using triethylaluminium followed by oxidation of the alkylaluminium products.^[2] An idealized synthesis is shown:

Al(C₂H₅)₃ + 9 C₂H₄ → Al(C₈H₁₇)₃

Al(C₈H₁₇)₃ + 3 O + 3 H₂O → 3 HOC₈H₁₇ + Al(OH)₃

The process generates a range of alcohols that are separated by distillation.

Water/ octanol partitioning

Octanol and water are immiscible. The distribution of a compound between water and octanol is used to calculate the partition coefficient 'P' of that molecule (often expressed as its logarithm to the base 10, log P). Water/ octanol partitioning is a good approximation of the partitioning between the cytosol and lipid membranes of living systems.^{[citation needed]}

Many dermal absorption models consider the stratum corneum/ water partition coefficient to be well approximated by a function of the water/ octanol partition coefficient of the form ^[3]:

log(K_{sc / w}) = a + blog(K_{w / o})

Where a and b are constants,K_{sc / w} is the stratum corneum/ water partition coefficient, andK_{o / w} is the water/ octanol partition coefficient. The values of a and b vary between papers, but Cleek & Bunge ^[4] have reported the values a=0, b=0.74.

References

1. ^ ClinicalTrials.gov NCT00102596
2. ^ Jürgen Falbe, Helmut Bahrmann, Wolfgang Lipps, Dieter Mayer "Alcohols, Aliphatic" in Ullmann's Encyclopedia of Chemical Technology Wiley-VCH Verlag; Weinheim, 2002. DOI: 10.1002/14356007.a01_279
3. ^ McCarley KD, Bunge AL (2001). "Pharmacokinetic Models of Dermal Absorption". Journal of Pharmaceutical Sciences 90 (11): 1699-1719. PMID 11745728.
4. ^ Cleek RL, Bunge AL (1993). "A new method for estimating dermal absorption from chemical exposure. 1. General approach.". Pharmaceutical Research 10 (4): 497-506. PMID 8483831.