Methanol vs Ethanol – The Chemistry of a Poison

Most biology textbooks have opening chapters that review chemistry. I often tell my students that we need to learn a little bit of chemistry because really, organisms are just bags of chemicals. Advanced classes will need to understand some basics of chemistry: molecular bonds, pH scale, and water chemistry.

This article with questions compares two organic molecules, ethanol and methanol. Ethanol is the main ingredient in alcohol beverages, created from the fermentation of grains and fruits. Methanol has a very similar chemical structure, with only one carbon in its backbone rather than the two found in ethanol. Both have an alcohol (OH) group attached.

During Prohibition, bootleggers often created a version of “spirits” from methanol by burning wood. Methanol is a poison! The result was that people drinking methanol would die or become blind as methanol was converted into a more toxic compound: formic acid. This process is known as toxification.

Students read the article that describes the compounds and their effects while answering related questions. A final section describes another type of poisoning from Lindol. Alcohol spiked with this compound could lead to paralysis, a condition called “Jake Leg” after the name of the alcohol that was toxic (Ginger Jake.)

Methanol as a Poison

Metabolic products: Methanol is toxic because of its metabolic products, which cause an accumulation of acid in the blood (metabolic acidosis), blindness, and death. When methanol is metabolized, it is converted into formaldehyde and then into formic acid, which is responsible for the toxic effects