1,1,1,3,3-pentachloropropane process purge stream concentration using a secondary refluxed evaporator and secondary product recovery

A method for generating 1,1,1,3,3-pentachloropropane comprising

• (a) reacting carbon tetrachloride with vinyl chloride in the presence of a catalyst comprising elemental iron, ferric chloride, and tributylphosphate, producing a reactor effluent, and
• (b) distilling the reactor effluent, separating 1,1,1,3,3-pentachloropropane and lower boiling components from high boiling components at a temperature and pressure which do not substantially inactivate the catalyst, and producing a bottom fraction containing the catalyst components and less than 50% of the 1,1,1,3,3-pentachloropropane contained in the reactor affluent from step (a), and
• (c) distilling the bottom fraction from step (b) to recover overhead at least 70% of the 1,1,1,3,3-pentachloropropane remaining in the bottom fraction from step (b), and producing a new bottom fraction suitable for recycle to the reactor, and
• (d) combining the distillate fractions of steps (b) and (c) for further purification of the 1,1,1,3,3-pentachloropropane product.

A method for producing a purified halohydrocarbon and a catalyst recycle stream comprising

• (a) reacting carbon tetrachloride and an olefin in the presence of a catalyst to prepare a mixture of a desired halohydrocarbon and catalyst,
• (b) processing the desired halohydrocarbon and catalyst in a first refluxed evaporator employing a partial vacuum and moderate temperature effective to prevent excessive catalyst degradation, recovering a substantial fraction of the desired halohydrocarbon overhead, and producing a bottom fraction containing the catalyst components,
• (c) processing the bottom fraction from step (b) in a second refluxed evaporator employing a partial vacuum, moderate temperature, and shortened liquid residence time effective to prevent excessive catalyst degradation, recovering a substantial fraction of the remaining desired halohydrocarbon overhead, and producing a bottom fraction containing the catalyst components in a state suitable for substantial recycle to the reactor, and
• (d) further processing the combined overhead fractions from the first and second refluxed evaporators of steps (b) and (c) to produce a purified halohydrocarbon stream.

A process for preparing a desired haloalkane product comprising:

• (a) contacting a haloalkene and a haloalkane feedstock in the presence of effective amounts of catalyst components ferrous chloride, ferric chloride, and a trialkylphosphate compound, under conditions effective to promote an addition reaction and to form a reactor effluent containing said haloalkane product, higher boiling haloalkane byproducts, unreacted feedstocks, and catalyst components, and
• (b) separating the desired haloalkane product from the high-boiling undesired haloalkane byproducts and the catalyst components using a two-stage catalyst recovery unit, wherein
• (i) the bottom fraction from the first stage flows into the second stage, and
• (ii) the first stage of the CRU recovers, in the distillate, between 50 and 90% of the desired haloalkane product contained in the reactor effluent, leaving more than 98% of the high-boiling undesired haloalkane byproducts in the bottom fraction, and
• (iii) the second stage of the CRU recovers, in the distillate, more than 70% of the remaining desired haloalkane product, leaving more than 33% of the high-boiling undesired haloalkane byproducts in the bottom fraction, together with the catalyst components, and
• (iv) further distilling the overhead fraction from step iii. to produce a new overhead fraction containing the desired haloalkane product and less than 1 wt. % of the high-boiling undesired haloalkane products and a new bottom fraction containing the undesired haloalkane product, and
• (v) disposing or otherwise using the bottom fraction of step iv., and
• (c) combining the overhead fraction of step iv. with the overhead frction of step ii. for further purification, and
• (d) recycling most of the bottom fraction from step iii. to the reactor, and purging a small fraction of it from the system to control byproduct concentrations in the reactor and to avoid excessive catalyst degradation.