How would you prepare the following ethers? Use whichever method you think is more appropriate, Williamson synthesis or the alkoxymercuration reaction.
(a) Butyl cyclohexyl ether
(b) Benzyl ethyl ether (C₆H₅CH₂OCH₂CH₃)
(c) sec-Butyl tert-butyl ether
(d) Tetrahydrofuran