2.2: Functional Groups and Basic Chemical Tests

• Organic chemistry is the study of organic compounds and their structure, properties, and reactions.
• Each carbon in the compound is bonded in the exact same way to both of its neighbors.
• Organic compounds are chemicals that are based on the element carbon, and most often they would also contain bonds between carbon and hydrogen.
• Methane, a hydrocarbon, is one of the simplest organic compounds.
• Many organic compounds contain elements other than carbon and hydrogen, typically oxygen and nitrogen, but it can also be other groups such as phosphorus or halogens.
• Some carbon compounds are not considered to be organic, e.g

  carbonates and carbon oxides like carbon monoxide and carbon dioxide.
• Functional groups are the parts of a molecule responsible for its reactivity.
• Different functional groups give rise to different reaction types in organic chemistry.
• Functional groups can be a specific arrangement of carbon and hydrogen, e.g

  a double bond, or can also include other elements.
• The most common elements in organic compounds besides carbon and hydrogen are oxygen and nitrogen.
• Other examples of elements are phosphorus and halogens.
• The ceric ammonium nitrate test is a way to examine a solution for the presence of either alcohols or phenols.
• In solution, the orange-yellow ceric ammonium nitrate makes a complex with the alcohol or phenol, which results in a color change.
• Alcohols cause a red color change, whereas phenols induce a more dark-red to dark-brown color change, depending on the phenol involved.
• Benzene can react with bromine in the presence of a catalyst, but not without a catalyst since it is not reactive enough.
• Benzene is one of the simplest aromatic compounds.
• Bromine will also react with aromatic compounds, such as phenol, but it can't react with alkanes as they contain only single bonds, and therefore there is no color change when these are mixed.
• The bromine test is used to test for an unsaturated carbon carbon bond, such as an alkene or alkyne.
• Bromine causes eye and skin burns, as well as digestive and respiratory tract burns.
• Alcohols are a functional group where a hydroxy (-OH) group is bound to a saturated carbon.
• Phenol is both the name of the functional group, and the simplest compound within this group.
• Bromine is corrosive, toxic, and an environmental hazard.
• The bromine test uses a type of chemical reaction called addition, where a reactant, here bromine, is added to an organic compound to break a double or triple bond.
• Hexane mixed with water forms two phases, a hydrocarbon phase and a water phase, which can be used for extracting organic compounds from a water sample into hexane.
• Contact with other material may cause a fire.
• Chloroform is harmful.
• Phenol is more reactive than benzene so can react with bromine without a catalyst.
• Bromine has an orange-brownish color when in solution, so the color of the solution is lost when an alkene or alkyne is present for bromine to react with.
• Bromine may be fatal if inhaled and is a strong oxidizer.
• Aromatic rings are a common group in organic chemistry.
• Carbon tetrachloride is toxic.
• The alcohol group in phenol donates electron density into the delocalized benzene ring, which is why phenol can react with bromine without a catalyst.
• Aromatic rings are planar ring systems, where a series of double bonds make the molecule conjugated, which means that the p orbitals used for the π bonds overlap with p orbitals on both sides of each carbon atom.
• Bromine is corrosive to metal.
• Sodium hydrogen carbonate, also known as sodium bicarbonate, reacts with acidic solutions to form carbon dioxide, which is released as gas from the solution, resulting in so-called brisk effervescence.
• Sodium hydrogen carbonate can be used to test for carboxylic acids.
• If effervescence occurs, then an acid group is present.
• The reaction of a negatively charged bicarbonate ion with a positively charged hydrogen to form water and carbon dioxide is the first reaction in the reaction of sodium hydrogen carbonate.
• The second reaction in the reaction of sodium hydrogen carbonate is the reaction of a carboxylic acid, R C O O H, with sodium hydrogen carbonate to form a sodium carbonate salt, R C O O N a, water, and carbon dioxide.
• Phenol is a weak acid meaning it dissolves in sodium hydroxide solution but does not dissolve in sodium hydrogen carbonate solution.