The present disclosure relates to compositions comprising E-1,1,1,4,4,4-hexafluoro-2-butene and additional compounds that may be useful as refrigerants, heat transfer compositions, aerosol propellants, foaming agents, blowing agents, solvents, cleaning agents, carrier fluids, displacement drying agents, buffing abrasion agents, polymerization media, expansion agents for polyolefins and polyurethane, gaseous dielectrics, power cycle working fluids, extinguishing agents, and fire suppression agents in liquid or vapor form, and in methods for detecting leaks.