Alcohol, absolute denaturants

Most alcohol is sold as 95% ethanol-5 % water since it forms an azeotrope at that temperature. To obtain absolute alcohol, a third component, such as benzene, must be added during the distillation. This tertiary azeotrope carries over the water and leaves the pure alcohol behind. Common industrial alcohol is denatured, and additives are purposely included to make it nondrinkable and therefore not subject to the high taxes of the alcoholic beverage industry. 

Properties and handling. Ethyl alcohol is a colorless, flammable liquid (good for flam be ) having a characteristic odor nearly universally recognizable. It is soluble in water (and club soda) in all proportions. Its commercially available as 190 proof (the 95% ethyl alcohol-water azeotrope) and absolute (200 proof). It is frequently denatured to avoid the high tax associated with 190 and 200 proof grades. Methanol and/or sometimes formaldehyde are common denaturants used to prevent consumption as an alcoholic beverage. 

The strength of alcohol commonly used in the US is 95% (190 proof), while 96% is used in Europe. For prepn of perfumes the 70% alcobol is used. TTie so-called absolute alcobol (200 proof) is at least 99% and its use is restricted. to analytical purposes or research. The so-called industrial alcohol is unfit to drink because it contains up to 5% methanol (wood alcohol) or benzene. Such alcohol is known as denatured and it is briefly described in Vol 3 of Encycl, p D63-R. Denatured alcohol is used as a solvent for expls, rocket fuels, rubbers, detergents, etc. Mixture of 1 part alcobol with 2 parts eth (described in Vol 5 of Encycl as Diethyl Ether) used as a solvent in dehydration of Pyrocellulose in manuf of single-base propint, such as described in Davis (Ref 2) and also on p C399 of Vol 3 of Encycl, under "Colloiding Agents and Colloidal Propellants ... 

Denatured alcohol (Formula 3A) containing 10% absolute methanol is a satisfactory solvent for recrystallization. 

Grade USP (95% by volume), absolute, pure, completely denatured, specially denatured, industrial, various proofs (one-half the proof number is the percentage of alcohol by volume). 

Since the use of absolute ethanol may present a problem in large scale use, one of the first such survey involved the comparison of absolute EtOH with some denatured alcohols. The two chosen were EtOH-3C (denatured by 0.5% toluene) and EtOH-2B (denatured by 0.5% i-PrOH). These solvents were used in the hydrogenations of methyl 2-acetamidocinnamate (1) over Rh(DiPamp)PTA/Al203 with the results listed in Table 1. 

As obtained synthetically, ethanol contains 4 wt.-% of water, as well as acetaldehyde and acetone. Alcohol obtained by fermentation contains also higher alcohols. Further impurities are the denaturing agents that are usually added (methanol, pyridine bases, petroleum). Absolute alcohol obtained commercially by azeotropic distillation may contain also traces of benzene or trichloroethylene. 

Protein coagulation has also been reported occurring in microorganisms at alcohol concentrations of 60-70%. In the absence of water, proteins are not denaturated as readily as when water is present. This is likely why absolute ethanol is less bactericidal than are mixtures of alcohol and water. Coagulation of cellular proteins leads to loss of cellular functions. 

Absolute alcohol n. Ethyl alcohol that has been refined by azeotropic distillation to 99.9% purity (200 proof). Other commercial ethanols contain about 5% water and may contain denaturants that make the alcohol undrinkable. Pure anhydrous ethyl alcohol (ethanol). The term is used to distinguish it from the several varieties of alcohol which are available, and which contain varying amounts of water and/or other impurities. 

Ethyl alcohol (1869) (alcohol, ethanol, and grain alcohol) n. An alcohol used, in denatured form, as a solvent for ethyl cellulose, polyvinyl acetate, and polyvinyl butyrate. The industrial grade of undenatured alcohol usually contains 5 wt% water. Properties bp, 78°C Sp gr. 0.7938/15°C refractive index, 1.367. The pure compound is called absolute alcohol. 

Packaging Rectified spirit (96% ethanol by volume) is marketed directly for the manufacture of chemicals such as acetic acid, acetone, oxalic acid and absolute alcohol. Denatured ethanol for industrial and laboratory use typically contains 60-95% ethanol as well as between 1% and 5% each of methanol, isopropanol, methyl isobutyl ketone (MIBK), ethyl acetate and so forth. For beverages, the alcohol is matured and blended with malt alcohol (for manufacture of whisky) and diluted to requisite strength to obtain the desired type of liquor. This is bottled appropriately in a bottling plant. Anhydrous ethanol for fuelblending applications (power alcohol) requires concentration of the ethanol to 99.5 wt% purity. The ethanol dehydration is typically done using molecular sieves. 

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