Role of Alcohols(EtOH,MeOH) in nitro reduction used for Metal(Sn,Fe) I'm trying to reduce an aryl nitro group.
I understand that these reactions are radical reactions by the metal, but I don't understand
why alcohols are used as the solvent. Are they used as a source of protons, or just because they are good solvents?
LHM...Look at this mechanism that I posted as an answer to an earlier SE Chem question/answer relating to the reduction of nitrobenzene by metals.  



In most reactions that occur on metal surfaces, many of the mechanistic details are not fully understood (see @Martin's comments in the earlier post).  Nonetheless, this mechanistic scheme shows several steps where a proton ($\ce{H+}$) is required.  These proton transfers are necessary to complete the reduction process.  This is why these reactions are typically run in solvents, like ethanol, that have available protons that can be donated in order to complete the reaction...ron