Mammoth Uncensored Word List:
13 words ending with ne, 18 letters long

diethylcarbamazine dihydronaphthalene dimethyltryptamine electrocardiophone methylcholanthrene methylcyclopentane methylcyclopentene methylcyclopropane methylcyclopropene methylprednisolone paraliageosyncline polychlorocamphene triphenylphosphine