Water straight-chain alcohols

Studies on non-ionic surfactants as effective drag-reducing additives have been submitted by Zakin (1972). He studied various effects on three non-ionic surfactants formed from straight-chain alcohols and ethyleneoxide. These surfactants have an upper and a lower temperature limit for solubility in water and prove effective drag reducers near their upper critical solubility temperature or clouding point. The clouding point is the point at which a solution of a non-ionic agent in water becomes turbid as the temperature is raised. 

Most studies of the solution gas interface have involved organic compounds, for example, organic alcohols and acids. These dissolve in water to some extent as a result of the polar group. However, the alkyl group in the molecule is hydro-phobic, so that the solute molecules are always found in excess at the solution air interface. The accumulation of the organic molecule means that its surface excess is positive so that the interfacial tension of the solution decreases as the concentration of the organic molecule increases. An example of data for the straight chain alcohols in the series n-butanol to n-octanol is shown in fig. 8.8. The results are presented in terms of the surface pressure H, which is defined as the interfacial tension, with respect to that for the pure solvent, that is,... 

Keywords Water-hexane interface-straight chain alcohols - anesthetics -computer simulations... 

In this paper, we discuss the behavior of eight solutes at the interface between two immiscible liquids - water and hexane. Four of the solutes, methanol, ethanol, butanol and hexanol, are amphiphilic, straight chain alcohols. This choice allows us to examine systematically the interfacial activity of amphiphiles as a function of the hydrophobic chain length. The remaining four molecules, nitrous oxide, cyclopropane, isoflurane and desflurane are not amphiphilic. Even though nitrous oxide, cyclopropane and the two halogenated ethers are structurally unrelated, they, nonetheless, share an important property - all of them are clinical anesthetics. 

The changing polarity across water-membrane systems may influence not only the distribution of solute molecules in the membrane but also their orientations and conformations. The effect on orientations is particularly evident for amphiphilic solutes, such as straight chain alcohols [43]. These solutes exhibit a strong tendency to concentrate at the interface because in this environment their polar OH groups can be immersed in water while their nonpolar alkyl chains can extend towards the nonpolar phase. It should be stressed, however, that although amphiphilicity of a solute is sufficient to ensure its interfacial activity, it is not a necessary condition. In fact, several other polar, interfacially active, solutes, discussed above, are not amphiphilic. Furthermore, orientational preferences of solutes are not entirely due to electrostatic effects. The non-uniform distribution of the free volume in the membrane (the cavity formation term) may also influence solutes by favoring orientations in which the long axis of an asymmetric... 

The behavior of insoluble monolayers at the hydrocarbon-water interface has been studied to some extent. In general, a values for straight-chain acids and alcohols are greater at a given film pressure than if spread at the water-air interface. This is perhaps to be expected since the nonpolar phase should tend to reduce the cohesion between the hydrocarbon tails. See Ref. 91 for early reviews. Takenaka [92] has reported polarized resonance Raman spectra for an azo dye monolayer at the CCl4-water interface some conclusions as to orientation were possible. A mean-held theory based on Lennard-Jones potentials has been used to model an amphiphile at an oil-water interface one conclusion was that the depth of the interfacial region can be relatively large [93]. 

Urea has the remarkable property of forming crystalline complexes or adducts with straight-chain organic compounds. These crystalline complexes consist of a hoUow channel, formed by the crystallized urea molecules, in which the hydrocarbon is completely occluded. Such compounds are known as clathrates. The type of hydrocarbon occluded, on the basis of its chain length, is determined by the temperature at which the clathrate is formed. This property of urea clathrates is widely used in the petroleum-refining industry for the production of jet aviation fuels (see Aviation and other gas-TURBINE fuels) and for dewaxing of lubricant oils (see also Petroleum, refinery processes). The clathrates are broken down by simply dissolving urea in water or in alcohol. 

The mixture of carbon monoxide and hydrogen is enriched with hydrogen from the water gas catalytic (Bosch) process, ie, water gas shift reaction, and passed over a cobalt—thoria catalyst to form straight-chain, ie, linear, paraffins, olefins, and alcohols in what is known as the Fisher-Tropsch synthesis. 

Condensations Highly atom economical since small molecules of water or alcohol are liberated Atom economy increases as the molecular weights of the combining fragments increases For cyclization reactions such as the Dieckmann condensation and the synthesis of cyclic ethers from straight chain diols the atom economy increases with increasing ring size... 

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