| http://www.w3.org/ns/prov#value | - Methods for the preparation of urethanes described in the patent literature include the reaction of nitro compounds with carbon monoxide and alcohols in the presence of selenium or selenium compounds (German Offenlegungsschriften No. 2,343,826 (U.S. Pat. No. 3,895,054): 2,614,101 and 2,623,694 (U.S. Pat. No. 4,080,365) or of noble metals, in particular palladium, in the presence of Lewis acids (Ge
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