Alcohol

This is an article about the chemical functional group. For the beverage, see alcoholic drinks

Alcohols are a group of organic compounds consisting of a hydrocarbon or group with an -OH group; C_nH₂₊₁OH.

Commonly, the word alcohol refers to ethanol (C₂H₅OH), which is the alcohol found in alcoholic drinks. Ethanol is produced by yeast during the anaerobic metabolism, comparable to the production of lactic acid in mammals.

Methanol

Methanol consists of a single carbon atom, with three hydrogen atoms and a hydroxyl group (-OH). Traditionally, methanol was produced by the fermentation of wood, leading to the term 'wood alcohol'. Industrially, methanol can be produced by the reaction of carbon monoxide and hydrogen (CO + 2 H₂ = CHO₃OH). For this industrial process, copper, zinc oxide and aluminum oxide may be used as catalysts at 250°C and a pressure of 50-100 atm.

The primary use of methanol is its addition to ethanol to make it undrinkable. It has also been used as a biofuel.

Methanol is highly toxic to humans. This toxicity is largely indirect, as alcohol dehydrogense metabolises methanol to form formaldehyde, which causes blindness and death. Small amounts of methanol may be present in alcohol drinks are can cause a burning sensation of the eyes.

Ethanol

Ethanol (C₂H₅OH) is a major industrial spirit widely used in laboratories and household applications. It is also the type used in all alcoholic beverages.

Oxidation of Alcohols

By heating a primary alcohol with an oxidising agent, such as acidified potassium dichromate, an aldehyde is formed. If the oxidation is down under reflux, the aldehyde will then itself oxidise to a carboxylic acid.

Secondary alcohols also oxidise, forming a ketone. Ketones, unlike aldehydes, cannot be oxidised further.