Physical and chemical properties of alcohols
The lower and middle members of the series of saturated monohydric alcohols are liquids whose boiling points rise as the composition becomes more complex.
The lower representatives have a characteristic alcoholic odor and a burning taste the middle representatives, an unpleasant odor, and the higher ones are odorless.
The density of alcohols is less than unity, and only that of some aromatic alcohols is higher than unity.
The first three members mix with water in all proportions, but solubility diminishes as the radical becomes more complex.
Higher alcohols, like hydrocarbons are practically water-insoluble.
The molecules of alcohols in solid and liquid states, like water molecules, are associated.
The hydrogen bond is a special type of bond which originates at the expense of the hydrogen atom of such functional group as –OH, -COOH and NH2 and of electronegative atoms (O, N, F) which posses free electron pains.
The atomic size is important in the formation of the hydrogen bond.
The hydrogen atom is closer to one of the oxygen atoms with which it is linked by a covalent bond.
When alcohols dissolve in water, they form new hydrogen bonds with water molecules.
Association is interrupted as alcohols pass over to a vapor state.
Association is caused by hydrogen bonds which originate between molecules.
The functional group of alcohols the hydroxyl determines the main chemical properties of these compound.
Alcohols are characterized by great chemical activity.
Alcohols are practically neutral substances.
However, in certain reactions, alcohols exhibit properties of very weak acids and bases.
When alkali metals act on alcohols in an anhydrous medium, hydroxyl hydrogen is forced out and alkoxides are formed.
Ethers are obtained when alkoxides react with alkyl halides.
The action of hydrogen halides on alcohols is an important nucleophilic substitution reaction.
Alcohols are capable of losing water under definite conditions.
Alcohols are oxidized more readily than hydrocarbons and the first to be oxidized is the carbon to which the hydroxyl group is attached.
Different products can be formed.
Primary alcohols yield at first aldehydes, and then acids.
Ketones are formed from secondary alcohols too.
Alcohols can be converted into aldehydes and ketones also by dehydrogenation.