ethanol

ethanol , or ethyl alcohol, is the second simplest compound in the family of hydrocarbons known as alcohols, which are defined by the suffix OH. An ethyl group attached to a hydroxyl group, ethanol is written chemically as C2H5OH. As the most commonly used alcohol, ethanol is commonly known simply as “alcohol.” Ethanol can be produced through several methods, but the most common is fermentation, which is the metabolization by yeast of sugars, usually sucrose and fructose, into ethanol and carbon dioxide. The only method of ethanol production that occurs naturally, fermentation is the source of all ingested ethanol, though further concentration of ethanol in water occurs through fortification or distillation. In addition to its use as an intoxicant due to its psychoactive effects, ethanol has other domestic and industrial uses, most notably as a solvent, an antiseptic, and engine fuel. At room temperature it is a colorless liquid.

The intoxicating properties of ethanol, or at least of compounds where it is present, have been known for at least nine thousand years, and the fermentation of alcoholic beverages out of grains and fruits is generally considered to be the first controlled chemical reaction of any ancient civilization. Evidence of the concentration of ethanol through distillation goes back at least 2,500 years, to India. See distillation, history. Due to the azeotropic nature of the bond it forms with water, pure ethanol cannot be isolated by distillation without chemical adjuncts and it was only first isolated by Raymond Lull in the thirteenth century. The composition and formula for ethanol were determined, respectively, by the French chemists Antoine Lavoisier and Nicolas-Theodore de Saussure, in 1781 and 1808. See azeotrope.

The human body responds to the effects of ethanol progressively, as increased consumption leads to displays of excitement, followed by loss of inhibitions and decreased coordination—the expression of these being to a significant degree affected by societal norms surrounding alcohol consumption—and ultimately stupor, which is universal. Ethanol behaves as a depressant, as the compound is transferred from the blood to the brain, where alcohol inhibits the proper functioning of neurotransmitters, the chemical messengers that bridge the synapse between nerve endings. Normal communication between neurons depends on a natural equilibrium of excitatory and inhibitory neurotransmitters. Although these interactions are complex, it appears in the short term primarily that ethanol increases inhibitory neurotransmission and decreases excitatory neurotransmission. The body’s attempt to compensate for these actions over time lead to some of the effects of long-term alcohol consumption, such as tolerance, withdrawal symptoms, and possibly addiction. See health and spirits.

Ethanol is metabolized in the liver by the enzyme alcohol dehydrogenase. Pharmacological sensitivity to ethanol is not limited to humans or even vertebrates as a whole; sensitivity to ethanol, made evident by impaired motor control, has been observed and studied in insects. Indeed, the study of alcoholic sensitivity in the fruit fly, Drosophila melanogaster, has led to the creation of several mutations known (among others) as barfly, tipsy, and cheapdate. These gene sequences are evolutionarily related to genes that code for neurological pathways in vertebrates.

In addition to its intoxicating effects, several other properties of the ethanol compound are significant within the context of spirits and cocktails. Its complete miscibility (ability to dissolve completely with water in any proportion) to form a homogenous and transparent solution permits its storage at any concentration. This property, which holds true with alcohol and many organic substances in addition to water, as well as its related ability to dissolve both polar and non-polar substances, such as ionic salts, essential oils, flavoring, and coloring agents, allows for the integration of complex flavors into potable spirits. Put simply, the diverse and complex flavors attainable in alcoholic beverages are a function of ethanol’s ability to dissolve and hold other molecules easily in suspension at any temperature over a wide range of alcoholic concentrations.

Ethanol’s boiling point of 78° C allows for the relatively simple distillation from water solutions. And because ethanol has a freezing point of −114° C, alcoholic beverages can be produced, stored, and served below the freezing point of water. As an antiseptic it can be used to preserve organic material and be used for infusions. Ethanol is flammable, and a 40 percent alcohol to water solution will ignite at 26° C when a flame is put to it.

Heberlein, Ulrike. Genetics of Alcohol-Induced Behaviors in Drosophila. Alcohol Health and Research 24 (November 2000): 185–188.

Morrison, Robert Thornton, and Robert Neilson Boyd. Organic Chemistry. Boston: Allyn & Bacon, 1987.

Valenzuela, C. Fernando. “Alcohol and Neurotransmitter Interactions.” Alcohol Health and Research 21 (November 1997): 144–148.

By: Eben Klemm