Practically – and I say this to you, undergraduate student of chemistry – from a synthetic perspective – it’s not a very general synthesis of ethers. First of all, it’s limited to symmetrical ethers,. Secondly, the temperature has to be carefully optimized, because there are lots of side reactions possible. For example the optimal temperature for the formation of diethyl ether is about 130-140 degrees C. Once the temperature gets to 150 degrees and above, elimination starts to compete, leading to the formation of ethylene gas. And this is for primary alcohols, which don’t form carbocations very easily. Once you get into the category of using this process for secondary and tertiary alcohols, carbocations are much easier to form and elimination becomes an even more significant destructive pathway.
Wow, I had no idea it’d ever been used on that scale in a synthesis! Unfortunately for those guys the Upjohn catalytic procedure wasn’t reported until 20 years later. I seem to remember that Kumamoto’s synthesis of methyl-kinamycin C and Corey’s neotripterifordin also use it stoichiometrically, although not on anywhere near that scale. I once saw the selective dihydroxylation of one bond in a 1,4-cyclohexadiene reported in a very old Tet. Lett. using stoichiometric OsO4. When I tried it with NMO as the terminal oxidant aromatisation was a major problem so I changed my route. I never had the courage to try with the equiv. reported so I’ll always wonder if it would have worked. If nothing else, OsO4 is also damned expensive (~300$/g from Aldrich).
Benzoic acid occurs naturally as do its esters in many plant and animal species. Appreciable amounts have been found in most berries (around %). Ripe fruits of several Vaccinium species (., cranberry , V. vitis macrocarpon ; bilberry , V. myrtillus ) contain as much as –% free benzoic acid. Benzoic acid is also formed in apples after infection with the fungus Nectria galligena . Among animals, benzoic acid has been identified primarily in omnivorous or phytophageous species, ., in viscera and muscles of the rock ptarmigan ( Lagopus muta ) as well as in gland secretions of male muskoxen ( Ovibos moschatus ) or Asian bull elephants ( Elephas maximus ).