The hydrogen bonding associated with the hydroxyl groups of alcohols cause them to be higher boiling than alkanes of similar structure and molecular weight. With the additional degree of intermolecular force corresponding to hydrogen bonding, alcohols also have higher boiling points than similar alkyl halides. Hydrogen bonding is stronger than dipole-dipole interaction. The boiling points of ethers are comparable to alkanes, but their solubility is comparable to alcohols. Pure ether does not undergo hydrogen bonding but in solution ethers can participate in hydrogen bonding with water. Alcohols are amphiprotic. They can serve as either a very weak acid or a very weak base, being able either to donate a proton (in the presence of a strong base) forming an alkoxide anion, or to receive a proton (in the presence of a strong acid) to form an alkyloxonium cation.