Azeotropic or 
azeotrope-like compositions are disclosed. The azeotropic or 
azeotrope-like compositions are mixtures of E-1,1,1,4,4,5,5,5-Octafluoro-2-
pentene with 
methyl formate, n-
pentane, 2-methylbutane, 1,1,1,3,3-pentafluorobutane, trans-1,2-dichloroethylene, 1,1,1,3,3-
pentafluoropropane, 
dimethoxymethane, 
cyclopentane or Z-1,1,1,4,4,4-hexafluoro-2-
butene. Also disclosed is a process of preparing a 
thermoplastic or thermoset foam by using such azeotropic or 
azeotrope-like compositions as blowing agents. Also disclosed is a process of producing 
refrigeration by using such azeotropic or azeotrope-like compositions. Also disclosed is a process of using such azeotropic or azeotrope-like compositions as solvents. Also disclosed is a process of producing an 
aerosol product by using such azeotropic or azeotrope-like compositions as propellants. Also disclosed is a process of using such azeotropic or azeotrope-like compositions as 
heat transfer media. Also disclosed is a process of extinguishing or suppressing a fire by using such azeotropic or azeotrope-like compositions. Also disclosed is a process of using such azeotropic or azeotrope-like compositions as dielectrics. Also disclosed is a process for the separation of a 
chemical compound from a mixture of two or more chemical compounds using such azeotropic or azeotrope-like compositions.