US 12,365,702 B2
Process for the production of alkyltin halides
Peter Frenkel, Danbury, CT (US); Joseph Salsbury, Southbury, CT (US); and Steven McKeown, Southbury, CT (US)
Assigned to GALATA CHEMICALS LLC, Southbury, CT (US)
Filed by GALATA CHEMICALS LLC, Southbury, CT (US)
Filed on Sep. 4, 2020, as Appl. No. 17/012,090.
Application 17/012,090 is a continuation of application No. PCT/US2019/020560, filed on Mar. 4, 2019.
Claims priority of provisional application 62/639,015, filed on Mar. 6, 2018.
Prior Publication US 2020/0399294 A1, Dec. 24, 2020
Int. Cl. C07F 7/22 (2006.01); B01D 3/40 (2006.01)
CPC C07F 7/2208 (2013.01) [B01D 3/40 (2013.01); C07F 7/2296 (2013.01)] 21 Claims
 
1. A process for producing mono-alkyltin and di-alkyltin bis(thioglycolate ester) streams comprising:
(a) contacting a feed stream comprising a di-alkyltin dihalide distillate with an alkylation agent, thereby forming an alkylated mixture comprising R4Sn and optionally R3SnX, R2SnX2, or mixtures thereof, where R is a linear, branched or cyclic C1-C20 alkyl, and X is a halide;
(b) contacting the alkylated mixture with SnX4, thereby forming an alkyltin halide mixture comprising RSnX3, R2SnX2, and chromophoric impurities, R3SnX or mixtures thereof;
(c) separating by distillation the alkyltin halide mixture to form a mono-alkyltin halide-rich distillate stream having a boiling point of 150-250° C. at less than 10 mm Hg and a liquid di-alkyltin halide-rich bottoms stream comprising 70.0 to 97.0 wt % R2SnX2, 3.0 to 30.0 wt % RSnX3, chromophoric impurities, and optionally R3SnX;
(d) separating by distillation the liquid di-alkyltin halide-rich bottoms stream at a temperature of 200-220° C. at less than 5 mm Hg vacuum, thereby forming a separated liquid di-alkyltin dihalide distillate comprising 90.0 to 100.0 wt % R2SnX2, and at most 10.0 wt % RSnX3, having a Gardner color value of 2 or less, and an impurities-rich bottoms stream comprising chromophoric impurities;
(e) recycling a part, Xrecycle, of the separated liquid di-alkyltin dihalide distillate to step (a), thereby forming a recycled dihalide distillate stream and a non-recycled dihalide distillate stream, where Xrecycle ranges from greater than 10.0% to 90.0% of the separated liquid di-alkyltin dihalide distillate;
(f) reacting the non-recycled liquid di-alkyltin dihalide distillate with iso-octylmercaptoacetate, 2-ethylhexylmercaptoacetate, or n-octylmercaptoacetate, to form the corresponding di-alkyltin bis(thioglycolate ester)-containing stabilizer, wherein the di-alkyltin bis(thioglycolate ester)-containing stabilizer has a Gardner color value of at most 3.