2. Ethers
The compounds that have the R – O – R group are know as ethers. The two R groups linked to oxygen can be different or the same and they also can be aliphatic or aromatics.
The compound more well know of this family is the ethyl ether, that is frequently called ether.
CH3CH2-O-CH2CH3
Ethers are not very reactive. This is the reason for why they are not used as reactant but more as dissolvent in the reactions.

3. Nomencleture
In the IUPAC, ethers are considered hydrocarbons with RO- substitutes, that are called alkoxy groups.
ethers are named using the general formula "alkoxyalkane" for example CH3-CH2-O-CH3 is methoxyethane
In the common system the name is given to both R groups in two separate words followed by the word ether and then the name of the two groups in one word with the ending “hyl”. “For example:
CH3CH2-O-CH3
IUPAC: Methoxyethane
Common Name methyl ethyl ether

4. CH3CH2CH2CH2-O-CH2CH3
IUPAC: Ethoxybutane
Common: Ether ethylbutyl or Butyl Ethyl Ether
CH3-O-CH3
IUPAC: Methoxymethane
Common: Ether methyl or Dimethyl ether

5. Physical Properties
Ethers are substances with nice scent, lighter then water and with low boiling point due to no hydrogen bridges can be formed within its molecules.
The majority of ethers are not very soluble in water, its oxygen can form hydrogen bridges with some water molecules. They are solvent in non polar solvents. Ether is a very good dissolvent in the majority of organic compounds of intermediate polarity. Methyl ether is a gas, all other ethers are liquids at room temperature. The boiling point of ethylic ether is 34 C.

6. Syntesis of Ethers Williamson’s Reaction
With this method both symmetric and asymmetric ethers can be prepared. The reaction is made with a alkyl halide and an alcohol salt called sodium alkoxide.
Reaction:
CH3I CH3CH2CH2CH2-ONa 
methyl iodide sodium butoxid
CH3-O-CH2CH2CH2CH NaI
Methyl butyl ether (71 %)

7. Chemical Properties
Ethers are not very reactive. They do not react to alkyl metals, they are resistant to the action of alkalis and they do not easily react to oxidation agents nor reducers. The basic oxygen atom of an ether reacts with acid compounds like HI, HBr, H2SO4, etc.
Example:
R – O – R´ HI  RI R´I + H2O
(the reaction requires a temperature of 120 C)

8. Importance and Applications
Local and general anesthetics mostly used are: ethyl ether and dietyhl ether.
Eugenol is obtained from clove essence it is a soft local anesthetic used mostly by dentists that presents a ether group in its structure.
In a large quantities of organic compounds that form part of the tissue of living beings we can find ether bonds, for example carbohydrates, hormones, vitamins, etc.