Question

Q-why ethers have less dipole moment than alcohols?

Q-why ethers can't be cleaved by bases?

Answer 1

Part : I
Ethers have less dipole moment than alcohol.

Reason :
Structure of ether contain two alkyl groups attached with oxygen atom. The difference in electronegativity of alkyl group with oxygen is less as compare to the H-O electronegativity difference in alcohol. The tendency of difference in Electronegativity introduce a partial delta + charge on Hydrogen atom of alcohol and partial delta - charge on O. Since the partial charge on alcoholic group is higher than that of ether. The ethers have less dipole moment than alcohol.

Ether : R-O-R
Alcohol : R-O-H

Part : II
Ethers can't be cleaved by bases
Reason : 1
This is can be explained on the basis of nucleophilic nature of oxygen atom in R-O-R molecule. The base rather that abstracting hydrogen or breaking the bond it is added on the electron rich oxygen atom as electrophile and undergo addition reaction.
Reason : 2
Presence of alkyl group and their inductive effect increases the bond strength of R-O bond and do not allow the bond to cleave by even a strong base.