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The n-octanol-water partition coefficient, K ow is a partition coefficient for the two-phase system consisting of n-octanol and water. [1] K ow is also frequently referred to by the symbol P, especially in the English literature. It is also called n-octanol-water partition ratio. [2] [3] [4]
Conversely, hydrophilic drugs (low octanol/water partition coefficients) are found primarily in aqueous regions such as blood serum. [4] If one of the solvents is a gas and the other a liquid, a gas/liquid partition coefficient can be determined.
Octane is a hydrocarbon and also an alkane with the chemical formula C 8 H 18, and the condensed structural formula CH 3 (CH 2) 6 CH 3. Octane has many structural isomers that differ by the location of branching in the carbon chain .
Another type of octane rating, called Motor Octane Number (MON), is determined at 900 rpm engine speed instead of the 600 rpm for RON. [2] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance.
Octane rating is measured relative to a mixture of 2,2,4-trimethylpentane (an isomer of octane) and n-heptane. There are different conventions for expressing octane ratings, so the same physical fuel may have several different octane ratings based on the measure used. One of the best known is the research octane number (RON).
Scientific evidence reveals that water is an inhibitor for corrosion by ethanol. [6] The experiments are done with E50, which is more aggressive and speeds up the corrosion effect. It is very clear that by increasing the amount of water in fuel ethanol one can reduce corrosion. At 2% or 20,000 ppm water in the ethanol fuel the corrosion stopped.
Catalytic reforming is a chemical process used to convert naphthas from crude oil into liquid products called reformates, which are premium "blending stocks" for high-octane gasoline. The process converts low-octane linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic naphthenes , which are then partially ...
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 relatively good approximation of the partitioning between the cytosol and lipid membranes of living systems.