A Cocktail of Compounds Trivia Quiz

Answer:

Whilst the everyday usage of the word 'alcohol' pertains to ethanol-containing drinks such as beer, wine and spirits (mine is an old fashioned please), its usage in chemistry has a far greater scope; very broadly put, the class of compounds known as the alcohols has its foundations in oxygen infiltrating chains of hydrogen and carbon (hydrocarbons).

The most basic hydrocarbons are the alkanes (only single bonds between carbon atoms, C-C) and the alkenes (one or more carbon-carbon double bonds, C=C). As alkanes such as methane, butane and octane are exclusively formed of single bonds (to the point of saturation) there is very little else that can be achieved with them beyond processes such as cracking (creating shorter alkanes from larger ones) and combustion: alkane + oxygen --> carbon dioxide + water (and heat). If combustion is incomplete then other undesirable compounds are also created.

Alkenes contain a double bond and this makes them more interesting than the alkanes, particularly with respect to what can happen when the double bond is broken and other elements introduced. Breaking the double bond of an alkene provides a mechanism by which an alcohol can be created. For the purposes of this introduction it would suffice to say that alcohols are distinguished by the presence of a hydroxyl group (-OH) which is formed of one atom of oxygen and one atom of hydrogen (a more complete treatment involves evaluating the nature of the hydrocarbon skeleton that the hydroxyl group has bonded to as well as identifying other functional groups present in the compound).

An alcohol can be formed in many ways but the hydration of an alkene is a straightforward example. The first step is to break the double C=C bond to create a C-C bond and in so doing create a vacancy for another atom or compound to occupy. Hydration is the addition of water (H2O) and given that H2O contains both oxygen and hydrogen, you have a solid basis for a mechanism whereby an -OH group can be formed and occupy the vacancy left by the destruction of the double C=C bond. This process is slow, so more efficient processes that involve catalysis are prevalent in industry.

The simplest alcohol is methanol (CH3OH - note the OH ending) which contains just the one atom of carbon; it is commonly used in reactions to create formaldehyde and for downstream uses in plastics and adhesives. It is rather famously a toxic contaminant of poorly made alcoholic beverages. For a quality alcoholic drink, it is ethanol (C2H5OH) we are after!

Ethylene glycol, glycerol, xylitol and sorbitol are but just four examples of sugar alcohols that are sometimes referred to as polyols due to the presence of multiple -OH groups. The sugar alcohols have a wide range of uses including sweeteners (xylitol, glycerol and sorbitol) and antifreeze (ethylene glycol).

Propan-2-ol (an alcohol containing three carbons with the -OH group bonded to the middle or second carbon, hence the 2 in the name) which is used in solvents and cleaning agents. Isobutyl alcohol (isobutanol) finds an application in the creation of varnishes whilst 1-pentanol is useful in the creation of solvents. Cyclohexanol (with the cyclo- prefix indicating that the carbon chain has formed a ring) is handy when it comes to synthesising nylon.

It is no coincidence that the correct answers end in the "-ol" suffix as this is very much a feature of the standardised nature of naming chemical compounds. Recognising that pattern - and avoiding the main red herrings of aerosol and petrol - was the key to unlocking this quiz. Classifying compounds solely using this naming convention starts to become less reliable as the chemistry becomes more complex. Distinguishing phenols (with their aromatic benzene-like rings and the impact that has on the saturation of the carbon atoms within its structure) from alcohols is one such example that is best explored another time!