Nomenclature and Structure of Alcohols

Alcohols are the family of compounds that contain one or more hydroxyl (-OH) groups. Alcohols are represented by the general formula R-OH. Alcohols are important in organic chemistry because they can be converted to and from many other types of compounds. Reactions with alcohols fall into two different categories. Reactions can cleave the R-O bond or they can cleave the O-H bond.

ethanol (ethyl alcohol, or grain alcohol) is found in alcoholic beverages, CH₃CH₂OH

Naming

Follow these rules to name alcohols the IUPAC way:

1. find the longest carbon chain containing at least one OH group, this is the parent

1. if there are multiple OH groups, look for the chain with the most of them, and the way to count as many carbons in that chain

2. name as an alcohol, alkane diol, triol, etc.

2. number the OH groups, giving each group the lowest number possible when different numbering possibilities exist

3. treat all other groups as lower priority substituents (alcohol / hydroxy groups are the highest priority group for naming)

Example alcohols

	IUPAC name	Common name
CH3CH2OH	Ethanol	Ethyl alcohol
CH3CH2CH2-OH	1-Propanol	n-Propyl alcohol
(CH3)2CH-OH	2-Propanol	Isopropyl alcohol (Note: Isopropanol would be incorrect. Cannot mix and match between systems.)

• Hydroxyl (OH) functional group

• Oxygen is sp3 hybridized

nomenclature (nomenklatura)

alcohols (alkohole)

hydroksyl group (grupa hydroksylowa)

functional group (grupa funkcyjna)

general formula (wzór ogólny)

primary alcohols (alkohole pierwszorzędowe)

secondary alcohols (alkohole drugorzędowe)

tertiary alcohols (alkohole trzeciorzędowe)

halogen derivatives (chlorowcopochodna)

bases (zasady)

Alcohols are classified into three categories: primary (1°) - pierwszorzędowy, secondary (2°) - drugorzędowy and tertiary (3°) trzeciorzędowy. This classification is based on the number of carbon-containing groups (R− for an alkyl or an aromatic group) attached to the carbon bearing the hydroxyl group.

If the carbon bearing the −OH has one R− group, the molecule is a primary alcohol. If two
R− groups are attached, it is a secondary alcohol. If three R− groups are attached, the alcohol is tertiary.

I. Physical Properties of Alcohols

The hydroxyl group present in all alcohols is a polar functional group. The polarity of this group allows alcohols to form hydrogen bonds. Small chain alcohols are able to mix with water because of the hydrogen bonding interactions that will occur between the hydroxyl functional group and the water. If the R-group of the alcohol becomes too large however, the solubility of the alcohol will decrease.

Hydrogen bonding

---