Organic compounds with the same functional group often have similar properties. The simplest carbon compounds consist only of hydrogen and carbon. The first molecule shown in the animation is an example of one, propane, which is widely used as “bottled gas: for home heating and cooking and in industrial torches. If one of the hydrogen atoms is replaced by an OH group, the result is an alcohol. The second compound is isopropyl alcohol, also known as rubbing alcohol. If the carbon atom forms a double bond with the oxygen atom, eliminating the hydrogen atom attached to the oxygen atom, a ketone is formed. The third molecule, is the ketone, acetone. If the double-bonded oxygen atom is attached to one of the two ends of the carbon chain, then compound is an aldehyde. The new molecule formed by the rearrangement of acetone is propaldehyde. .On the other hand, if the oxygen atom is a part of the chain, an ether is formed. Ethers are very unreactive compounds, and the next compound is called methyl ethyl ether. Two other common types of functional groups require two oxygen atom attachments. If a double-bonded oxygen atom is attached to a carbon atoms that also forms a single bond with a second oxygen, an ester is formed. Many of the fruit flavors, such as banana flavor, are esters. The ester shown in the animation is ethyl acetate. If a carbon atom forms a double bond with an oxygen and is also bonded to an OH group, a carboxylic acid is formed. Like aldehydes, carboxylic acids must be terminal groups. The last molecule shown in the animation is acetic acid, which is the key ingredient in vinegar.

Questions

1. At first glance, alcohols like ethanol and carboxylic acids like acetic acid appear to have similar structures. And yet, consider the different effects of consuming ethanol, a key ingredient in alcoholic beverages, and acetic acid, a key ingredient in vinegar. What do these differences show about the importance of functional groups?
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2. Spearmint is a man-made flavoring agent. Based on the information given in the animation, what type of organic compound would you predict spearmint is?
3. Why are small alcohol molecules like ethanol and small ether molecules like diethyl ether (regular ‘ether’) are soluble in water? Why are very large alcohols and ethers composed of long carbon chains are not soluable in water? (Hint: consider the polarity of long carbon chains and oxygen-containing functional groups.)