A liquid phase process is disclosed for producing halogenated alkane adducts of the formula CAR.sup.1R.sup.2CBR.sup.3R.sup.4 (where A, B, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are as defined in the specification) which involves contacting a corresponding halogenated alkane, AB, with a corresponding olefin, CR.sup.1R.sup.2.dbd.CR.sup.3R.sup.4 in a dinitrile or cyclic carbonate ester solvent which divides the reaction mixture into two liquid phases and in the presence of a catalyst system containing (i) at least one catalyst selected from monovalent and divalent copper; and optionally (ii) a promoter selected from aromatic or aliphatic heterocyclic compounds which contain at least one carbon-nitrogen double bond in the heterocyclic ring. When hydrochlorofluorocarbons are formed, the chlorine content may be reduced by reacting the hydrochlorofluorocarbons with HF.New compounds disclosed include CF.sub.3CF.sub.2CCl.sub.2CH.sub.2CCl.sub.3, CF.sub.3CCl.sub.2CH.sub.2CH.sub.2Cl and CF.sub.3CCl.sub.2CH.sub.2CHClF. These compounds are useful as intermediates for producing hydrofluorocarbons.Azeotropes of CClF.sub.2CH.sub.2CF.sub.3 with HF and azeotropes of CF.sub.3CH.sub.2CHF.sub.2 with HF are also disclosed; as are process for producing such azeotropes.A process for purification of certain hydrofluorocarbons and/or chloro-precursors thereof from mixtures of such compounds with HF is also disclosed.