Small-chain alcohols

How can this experiment help explain why small-chain alcohols have a warning label indicating that they are flammable ... 

Silica is heated with alcohols containing from two to eighteen carbon atoms to 190° (with primary alcohols) or 275° (with secondary alcohols). For small-chain alcohols an autoclave is used. Esterification with higher-boiling alcohols is achieved simply by refluxing while the water formed in the reaction is removed by azeotropic distillation. A small... 

On the shelves of drugstores you can find bottles of ethanol labeled denatured alcohol. Denatured alcohol is ethanol to which small amounts of noxious materials such as aviation gasoline or other organic solvents have been added. Ethanol is denatured in order to make it unfit to drink. Because of their polar hydroxyl groups, alcohols make good solvents for other polar organic substances. For example, methanol, the smallest alcohol, is a common industrial solvent found in some paint strippers, and 2-butanol is found in some stains and varnishes, as shown in Figure 23-5. Perform the CHEMLAB at the end of this chapter to learn about some other properties of small-chain alcohols. 

FIGURE 6.7 Alcoholysis of polyurethane (PU) waste. By the action of small-chain alcohols (e.g., diol), PU is decomposed yielding homogeneous, liquid, and mixed polyols. 

In HPLC, alcohols and especially acetonitrile are often added to the biological samples to remove (serum) proteins. In CE, in addition to the removal of proteins, the presence of acetonitrile and small-chain alcohols in the sample leads to stacking, as discussed earlier. Protein removal can also be accomplished by alcohols such as ethanol and by acids such as trichloroacetic acid. In CE, precipitation with acids is less desirable than the precipitation with organic solvents, as it increases the salt load. Following precipitation, proteins can also be dissolved in the appropriate buffers and assayed by CE. 

Environmental Considerations. Environmental problems in Ziegler chemistry alcohol processes are not severe. A small quantity of aluminum alkyl wastes is usually produced and represents the most significant disposal problem. It can be handled by controlled hydrolysis and separate disposal of the aqueous and organic streams. Organic by-products produced in chain growth and hydrolysis can be cleanly burned. Wastewater streams must be monitored for dissolved carbon, such as short-chain alcohols, and treated conventionally when necessary. 

Mini-emulsion processes have been developed where the monomer is emulsified under high energy with either a long-chain alcohol or a polymer producing very small droplets. The long-chain alcohol retards the diffusion of the monomer out of the droplets (65). Polymerization takes place primarily... 

This precipitation process can be carried out rather cleverly on the surface of a reverse phase. If the protein solution is brought into contact with a reversed phase, and the protein has dispersive groups that allow dispersive interactions with the bonded phase, a layer of protein will be adsorbed onto the surface. This is similar to the adsorption of a long chain alcohol on the surface of a reverse phase according to the Langmuir Adsorption Isotherm which has been discussed in an earlier chapter. Now the surface will be covered by a relatively small amount of protein. If, however, the salt concentration is now increased, then the protein already on the surface acts as deposition or seeding sites for the rest of the protein. Removal of the reverse phase will separate the protein from the bulk matrix and the original protein can be recovered from the reverse phase by a separate procedure. 

Hydroformylation of higher olefins provide long chain alcohols which find use mainly as plasticizers. No aqueous/organic biphasic process is operated yet for this reaction, for several reasons. First, solubility of higher olefins is too small to achieve reasonable reaction rates without applying special additives (co-solvents, detergents, etc.) or other means (e.g. 

A microemulsion is defined as a thermodynamically stable and clear isotropic mixture of water-oil-surfactant-cosurfactant (in most systems, it is a mixture of short-chain alcohols). The cosurfactant is the fourth component, which effects the formation of very small aggregates or drops that make the microemulsion almost clear. 

Above a plane surface, the resistance J i of the gas phase may be quite large, of the order 100 sec. cm., if there is a stagnant film (e.g., of air) overlying the water. Compared with such a value of Ri, the resistance Rj is rather small, even if a monolayer of a long-chain alcohol or acid is present. But if the air pressure is reduced below atmospheric, or if the air is stirred (e.g., by wind or by a fan), Ri can be reduced to only a few sec. cm. S and the resistance Ri (up to 20 sec. cm. with suitable films) may become controlling. 

From Eq. (5) it is clear that for very small droplets (a small) the rate of evaporation will become extremely great unless Rj is appreciable. Conversely, a small amount of surface impurity may have a large effect on the rate of evaporation of very small drops. Thus, a monolayer of a long-chain alcohol or acid, which at room temperature can increase Ri (from 0.002 sec. cm. for the clean water surface) to 10 sec. cm. , should be able to reduce the rate of evaporation of a very small drop by 5000 times. The life-times in dry air of water drops of 1 /.i radius are correspondingly increased from a few milliseconds to about a minute by... 

Naturally occurring fats contain small amounts of soluble minor consituents pigments (carotenoids, chlorophyll, etc.), sterols (phytosterols in plant fats, cholesterol in animal fats), vitamin A (from carotenes), vitamin D (calciferol), waxes (esters of long-chain alcohols and fatty acids), ethers, and degradation products of fatty acids, proteins, and carbohydrates. Most of these minor compounds are removed in processing, and some are valuable by-products. 

The influence of solubilization on solution properties may vary from no appreciable effects to very marked ones. We may take solutions of CTAB as an illustrative example of the manifold of possibilities. Here solubilization of cyclohexane has a very small influence on a variety of rheological and spectroscopic properties while addition of aromatic compounds and long-chain alcohols may cause extensive changes. 

Long chain alcohols, known as fatty alcohols, are present only in very small amounts in vegetable oil but are found in greater quantities in some marine oils (Sonntag, 1979). Fatty alcohols also exist in small amounts in vegetable... 

The phenomenon, that a little excess amount of short-chain alcohols inactivates immobilized C. antarctica lipase but their overly excessive amounts do not, has not yet been clarified. However, because it is well known that lipase is active and very stable in water-immiscible organic solvents (Zaks and Klibanov, 1984), this fact may be explained the enzyme has bound water which it needs for the expression of its activity and which affects the maintenance of its structure. The structure is not maintained in the mixture including a small excessive amount of EtOH, but is strengthened in the mixture including large excessive amounts of EtOH owing to removal of bound water which does not participate in the expression of the activity. 

Coal below 0.5 mm in size, classified as fine coal, typically makes up 5-20 percent of the feed to the cleaning plant. It is generally processed by methods such as froth flotation, which depend on surface properties. In froth flotation, the fine coal slurry, to which a small amount of flotation agent (usually fuel oil and a short-chain alcohol, such as methyl isobutyl carbinol) is added, is processed through a flotation cell. In the cell, fine bubbles are generated by using either forced air or suction. 

---