Functional groups The structural features that make it possible to classify compounds by reactivity are called functional groups. A functional group is a part of a larger molecule and is composed of an atom or a group of atoms that have a characteristic chemical behavior. The Chemistry of every organic molecules

Substitution reactions occur when two reactants exchange parts to give two new products. In a substitution, one replaces another

Quinones are an interesting and valuable class of compounds because of their oxidation-reduction, or redox, properties. The redox properties of quinones are important to the functioning of living cells, where compounds called ubiquinones(泛醌) act as biochemical oxidizing agents to mediate the electro-transfer processes involved in energy production

17.7 Lithium Enolates 17.8 α-Selenation: A Synthesis of α,β-Unsaturated Carbonyl Compounds 17.9 Additions to α,β-Unsaturated Aldehydes and Ketones

17.1 The Acidity of the α Hydrogens of Carbonyl Compounds: Enolate Anions 17.2 Keto and Enol Tautomers 17.3 Reactions via Enols and Enolate Anions

The most characteristic reaction of aldehydes and ketones is nucleophilic addition to the carbon-oxygen double bond

More reactive than benzene toward electrophilic substitution NO2 An deactivating group Less reactive than benzene toward electrophilic substitution Ortho-para director Meta director

The most characteristic reactions of benzenoid arenes are the substitution reactions that occur when they react with electrophilic reagents. The electrophiles are either a positive ion (E+) or some other electron-deficient species with a large partial positive charge

No addition of bromine No oxidation No hydroation Slow addition at high temperature and pressure

A UV-Vis spectrophotometer measures the amount of light absorbed at each wavelength of the UV and visible regions of the electromagnetic spectrum. λmax— the wavelength of maximum absorption