Chem 51A 10/14/09 Ch. 3. Hydrocarbons, Alcohols, Amines

This paragraph introduces alkenes and alkynes, hydrocarbons containing carbon-carbon double and triple bonds, respectively. It explains the difference between trivial and systematic names, using ethylene (trivial) and ethene (systematic) as examples. The paragraph also highlights the greater reactivity of alkenes and alkynes compared to alkanes, which are relatively inert.

Here, the reactivity of alkenes with bromine is demonstrated using 1-butene as an example. When bromine, a red liquid, is added to an alkene in an inert solvent, the color disappears, indicating a chemical reaction. In contrast, alkanes like hexane do not react with bromine under ordinary conditions unless an energy source, like UV light, is present. The paragraph concludes with a brief mention of aromatic hydrocarbons, like benzene, which are also unreactive with bromine without a catalyst.

This paragraph discusses the beauty of crystallization, using naphthalene as an example, and describes the physical properties of benzene. Benzene, a liquid boiling at 80°C, was once widely used as a solvent until its carcinogenic properties were discovered. The paragraph also introduces phenyl groups (derived from benzene) in organic molecules and their prevalence in scientific literature. Aromatic compounds like benzene are less reactive than alkenes and alkynes unless a catalyst is used.

The discussion shifts to alcohols, noting that small alcohols like ethanol and methanol are miscible in water, while larger ones like 1-butanol are only partially soluble. Hydrocarbons, including alkanes, alkenes, and alkynes, are hydrophobic and do not dissolve in water. The paragraph emphasizes the importance of solubility in water for medicinal compounds and introduces the concept of hydrophobicity.

This paragraph explains the importance of solvents in facilitating chemical reactions by dissolving reactants and dissipating heat. It lists typical organic solvents, such as diethyl ether and hexane, and discusses their properties and uses. The paragraph also touches on the hazards associated with flammable solvents and the preference for non-flammable alternatives like dichloromethane in industrial processes.

Ethers, compounds with an R-O-R' structure, are introduced as analogs to alcohols. The paragraph explains the structure and naming conventions for ethers and compares them to alcohols and thiols (R-SH). An example of a thiol, 1-butanethiol, is given, and its strong odor is mentioned. The text highlights the importance of recognizing functional groups in organic chemistry.

Amines, nitrogen-containing compounds related to ammonia, are discussed. The paragraph explains primary, secondary, and tertiary amines based on the number of alkyl groups attached to the nitrogen. Examples like methylamine and triethylamine are provided. The significance of amines in natural products, such as alkaloids and medicines, is also highlighted.

This paragraph draws and analyzes the structure of morphine, a complex molecule with multiple functional groups. The analysis includes identifying benzene rings, hydroxy groups, an ether, and a tertiary amine. Morphine's medical use as a pain reliever and its relation to heroin is mentioned. The paragraph serves to illustrate the complexity and interrelation of functional groups in biologically active molecules.

Continuing from the previous paragraph, this section further breaks down the functional groups in morphine, including alkenes and aromatic rings. The reactivity of these groups, such as the alkene's reaction with bromine, is discussed. The paragraph underscores the importance of recognizing various functional groups within a single molecule.

Alkyl halides, compounds containing a halogen, are introduced. Examples like bromomethane (methyl bromide) and chloromethane (methyl chloride) are provided, along with their uses and environmental impact. The paragraph notes the shift from harmful CFCs to less destructive HFCs in air conditioning systems and concludes with a brief mention of iodomethane.