The Types of Ethanol
By Adrian Dingle
Alcohol. A ubiquitous word that can take on several different meanings depending on the context. In pure chemistry terms, the word refers to a family – or homologous series – of organic compounds that contain the hydroxyl (-OH) group, connected to some kind of carbon chain.
| Methanol | Ethanol | Propanol | Butanol |
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Cheers!
Perhaps the most common use of the word “alcohol” in everyday life is simply with reference to alcoholic drinks. When that’s the case then we’re talking about solutions of ethanol, the alcohol composed of a simple, saturated (singly bonded) two carbon hydrocarbon chain, and a single -OH group. Ethanol is found in all alcoholic drinks. Beer typically contains anywhere from 3 to 10% alcohol by volume, wine might have an ethanol content of around 12 to 15%, and liquor of various types will have the highest percent ethanol by volume, usually in the region of 40%.
Ethanol’s other uses
Other than its role in alcoholic drinks, ethanol is an important compound used in all kinds of industrial and commercial processes and products. It can also be found in the home where it is primarily used as a solvent for cleaning paint brushes, and where it can also be used as a fuel. In those situations the ethanol is found in purities that are much higher than those in alcoholic drinks; in fact it can be up to 100%, but more normally between and 60 and 90%.
Denatured and undenatured ethanol
Consumption of such ethanol-containing products is incredibly dangerous, not only due to elevated levels of ethanol, but more so due to the presence of denaturants – toxic compounds that are added specifically to deter ingestion. Denatured alcohol is not subject to the taxation of potable ethanol, but is still appropriate for cleaning and fuel purposes, since the actual chemistry of the ethanol molecule is unaltered.
Denatured and undenatured ethanol
The denaturing process is designed to make consuming the ethanol undesirable by making it taste unpleasant, including the addition of bitterants or coloring agents. For example, denatonium is a compound that is added as a bittering agent to create a bad taste in the ethanol mixture. Denatured alcohol may also be colored – typically light purple – to distinguish it from clear liquors such as vodka or gin, to make it more obvious that it is not intended for consumption.
Deadly poisonous methanol
Many different additives may be used in the process of denaturing ethanol, the most common being methanol. This accounts for the name methylated spirits which is given to denatured alcohol in many parts of the world. Methanol is an acutely poisonous substance, and the addition of relatively small amounts make the ethanol completely unsafe for drinking. Undenatured alcohol is simply ethanol that has not undergone the process of denaturing, and will in most cases simply be a solution of ethanol and water of various percentages.
Prohibition and poisonous ethanol
When prohibition was introduced in the United States in 1920 the first few years were largely uneventful in terms of alcohol poisoning. At the beginning of the decade there was still a significant supply of liquor left over from the pre-prohibition years. As time went by that changed dramatically. People’s desire to obtain alcohol drove them to distill alcohol from almost any organic material that they could get their hands on. This included sawdust and their wooden furniture! The distillation of wood doesn’t produce ethanol though, rather it produces a substance known as wood alcohol, which is essentially methanol. Unlike ethanol that can be processed by the body, methanol is oxidized to formaldehyde and ultimately formic acid, and can cause blindness, a comatose state, and ultimately death. It’s an extremely dangerous poison.
Battling the bootleggers
As the demand for alcohol grew, bootleggers started to take the ethanol intended for industrial use, and convert it to alcohol that could be drunk. As soon as it became apparent that this trend was gaining pace, the US Government began to denature the ethanol. At first the denaturing process involved the introduction of only relatively small amounts of poisons, but that still didn’t deter some people from consuming it. The denatured ethanol was known as ‘smoke’ in dive bars, and it was served neat. Bootleggers had success in re-distilling the denatured ethanol to ‘purify’ it somewhat, but some poisonous remnants were always left over, and even this treated product posed a significant danger to the drinker. As the problem got worse the government went to extraordinary lengths to further poison the ethanol supply, introducing a myriad of extra chemical substances in an attempt to further deter illicit alcohol consumption. At the mid-point of the 1920s, the number of deaths caused by the consumption of an especially dangerous concoction of what was described by the government as, “4 parts methanol (wood alcohol), 2.25 parts pyridine bases, 0.5 parts benzene to 100 parts ethyl alcohol” had reached epidemic proportions. It was killing thousands of people. New York City’s first Chief Medical Examiner Charles Norris, together with his colleague the toxicologist Alexander Gettler became advocates for safer public health in relation to denatured alcohol. Eventually the true folly of prohibition was finally acknowledged, and the huge rise in the number of deaths caused by people drinking denatured ethanol ultimately brought about the repeal of the American experiment known as prohibition.
Special denaturing and complete denaturing and taxation
In modern times the denaturing of ethanol falls broadly into two categories: Specially Denatured Alcohol (SDA) and Complete Denatured Alcohol (CDA), and is regulated by the Alcohol and Tobacco Tax and Trade Bureau (TTB), a subset (bureau) of the US Department of the Treasury. SDA refers to several different combinations of chemicals that are added to ethanol in various quantities depending on the intended final use. Many of those uses are in cosmetics, but also in pharmaceuticals, and in the general chemical industry as solvents or reagents. TTB permits are required for purchasing SDA. CDA refers to alcohol that has been so thoroughly denatured that it would be impossible for it to be practically used for any type of consumption. Again, the specific combinations of chemical components in CDAs are highly variable but CDA has been denatured in such a comprehensive manner that it does not require a TTB permit for purchase. In many countries ethanol designed for consumption in drinks is subject to heavy taxation by the government. By denaturing the ethanol, it becomes unusable in alcoholic drink manufacture and so also becomes ineligible for taxation. Were it not denatured, then it could be used in drinks and would attract some level of governmental tax. After the denaturing process no tax is applied.
