Chlorofluorocarbon (CFC) based chemicals have been widely used in industry in a variety of different applications including as refrigerants, aerosol propellants, blowing agents and solvents, among others. However, certain CFCs are suspected of depleting the Earth's ozone layer. Accordingly, more environmentally friendly substitutes have been introduced as replacements for CFCs. For example, 1,1,1,3,3-pentafluoropropane (HFC-245fa) is recognized as having favorable physical properties for certain industrial applications, such as foam blowing agents and solvents, and therefore is consider to be a good substitute for the CFCs previously used for these applications. Unfortunately, the use of certain hydrofluorocarbons, including HFC-245fa, in industrial applications is now believed to contribute to the global warming. Accordingly, more environmentally friendly substitutes for hydrofluorocarbons are now being sought.
The compound 1-chloro-3,3,3-trifluoropropene, also known as HCFO-1233zd or simply 1233zd, is a candidate for replacing HFC-245fa in some applications, including uses as blowing agents and solvents. 1233zd has two isomers with different physical properties. As one example of the different properties between the two isomers, 1233zd(Z) has a boiling point of approximately 38° C., whereas 1233zd(E) has a boiling point of approximately 19° C. In some applications, it is desirable to use either pure 1233zd(E), pure 1233zd(Z), a particular blend of the (Z) and (E) isomers, or a particular blend of one or both of the 1233zd isomers and another compound in order to control the properties of the solution. For example, in some solvent applications, it is desirable to have a relatively high boiling point. In some such applications, pure 1233zd(Z) may have more desirable physical properties (e.g., a higher boiling point) than either pure 1233zd(E) or mixtures of the two 1233zd isomers.
Processes for synthesizing 1233zd are known. For example, PCT Publication No. WO 97/24307 discloses a process for preparing 1233zd via the gas-phase reaction of 1,1,1,3,3-penta-chloropropane (HCC-240fa) with hydrogen fluoride (HF). However, this process produces relatively low yields of 1233zd.
U.S. Pat. No. 6,844,475 describes a catalytic liquid phase reaction of HCC-240fa with HF to produce 1233zd in higher yields. However the presence of the fluorination catalyst promotes the formation of heavy by-products, oligomers, and tars which can build up in the reactor over time and lead to catalyst dilution and catalyst deactivation, resulting in loss of productivity due to excessive downtime to remove these by-products from the reactor on a periodic basis.
U.S. Pat. No. 8,704,017 discloses a non-catalytic liquid phase reaction of HCC-240fa with HF to reduce the formation of heavy by-products. However, one drawback of not using a catalyst is the problem of slower reaction rates, resulting in the formation of significant amounts of stable underfluorinated intermediates comprising tetrachlorofluoropropanes including 1,1,3,3-tetrachloro-1-fluoropropane (HCFC-241fa), trichlorodifluoropropanes including 1,3,3-trichloro-1,1-difluoropropane (HCFC-242fa) and 1,1,3-trichloro-1,3-difluoropropane (HCFC-242fb) and dichlorotrifluoropropanes including 1,1-dichloro-3,3,3-trifluoropropane (HCFC-243fa) and 1,3-dichloro-1,1,3-trifluoro-propane (HCFC-243fb) can be formed, which significantly decreases the single pass productivity of HCFC-1233zd.
U.S. Pat. No. 9,045,386 describes a process to produce trans-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)) at high purity on a commercial scale. This patent publication is hereby incorporated herein by reference.
Based on the above, there remains a need for means by which partially fluorinated intermediates can be converted into the target product, namely, HCFO-1233zd. This invention satisfies that need.