Alcohols I

Overview:

Alcohols I is the first of a two part study of compounds containing the OH functional group. It includes structure and naming of alcohols, common alcohols and their usage, physical properties and preparations of alcohols. A section addressing thiols is included. A separate unit on reactions and analysis of alcohols is addressed in Alcohols II.

The structure surrounding the functional group of alcohols is compared to that of water so students may better understand the role alcohols will play in formation of hydrogen bonding. The boiling points of alcohols are compared to boiling points of alkanes of similar molecular weight to again reinforce the impact of hydrogen bonding on molecular behavior.

Nomenclature of alcohols is addressed from both the systematic (predominately IUPAC) and common approach. A section using the old carbinol method of alcohol nomenclature is also included.

Some common alcohols, their properties, and uses within the world of the layman are introduced: methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, and glycerol. The terms used by the layman such as wood alcohol, grain alcohol, and the like are explained. Hazards of these five alcohols which find significant common application are discussed and described.

Preparations of alcohols treated in this unit include hydrolysis of alkenes, oxymercuration/demercuration, hydroboration/oxidation, hydroxylation, hydrolysis of alkyl halides, reduction of carbonyls, and the Grignard. The student is reminded that preparations of one functional group are often reactions of another functional group so that the orderliness of organic chemistry is stressed. This becomes particularly apparent in this unit on Alcohols I.
Hydroxylation using permanganate followed by sodium hydrogen sulfate is used to prepare a diol from an olefin, but the fact that the reaction also works well using oxmium tetroxide is noted. In both cases, the syn, rather than the anti addition is shown to occur.

Prior to discussing reduction of carbonyls as a method of preparing alcohols, the order of oxidation and reduction for organic compounds is developed. The idea is that organic students presented with the logical progression of oxidation and reduction will find the numerous oxidation and reduction reactions they study much easier to grasp. The problems of which oxidizing agent and which reducing agent to use are also addressed, with particular emphasis placed on the three classic reducing agents: sodium borohydride, lithium aluminum hydride, and hydrogen with a catalyst.

The structure, physical properties, and nomenclature of thiols are introduced in a section at the end of this unit. Both systematic and common names are discussed as is oxidation and reduction regarding thiols.