2. Ethers are quite stable chemical compounds which do not
react with bases, active metals, dilute acids, oxidising agents
and reducing agents. Generally, they are of low chemical
reactivity, but they are more reactive than alkanes (epoxides,
ketals, and acetals are unrepresentative classes of ethers and
are discussed in separate articles). Important reactions are
listed after.
3. Acidic Cleavage
Ethers are generally unreactive
Strong acid will cleave an ether at elevated temperature
HI, HBr produce an alkyl halide from less hindered
component by SN2 (tertiary ethers undergo SN1)
ROCH3 + HBr → CH3Br + ROH
3
4. Claisen Rearrangement
Specific to allyl aryl ethers, ArOCH2CH=CH2
Heating to 200–250°C leads to an o-allylphenol
Result is alkylation of the phenol in an ortho position
5. Peroxide Formation
When stored in the presence of air or oxygen, ethers tend to form
explosive peroxides, such as diethyl ether peroxide. The reaction is
accelerated by light, metal catalysts, and aldehydes. In addition to
avoiding storage conditions likely to form peroxides, it is recommended,
when an ether is used as a solvent, not to distill it to dryness, as any
peroxides that may have formed, being less volatile than the original ether,
will become concentrated in the last few drops of liquid.
6. Lewis Bases
Ethers serve as Lewis bases and Bronsted bases. Strong acids protonate the
oxygen to give "onium ions." For instance, diethyl ether forms a complex
with boron trifluoride, i.e. diethyl etherate (BF3.OEt2). Ethers also
coordinate to Mg(II) center in Grignard reagents. Polyethers, including
many antibiotics, cryptands, and crown ethers, bind alkali metal cations
stron.
Alpha-halogenation
This reactivity is akin to the tendency of ethers with alpha hydrogen atoms to form
peroxides. Chlorine gives alpha-chloroethers.
