how to separate gamma-butyrolactone from N-methyl-2-pyrrolidone Since these two chemicals have different freezing temps (pyrrolidone is $-11~\mathrm{^\circ F}$ [$-24~\mathrm{^\circ C}$] and $\unicode[Times]{x3b3}$-butyrolactone freezes (also called melting) at $-46~\mathrm{^\circ F}$ [$-43~\mathrm{^\circ C}$]), could a person wanting to separate these just immerse them in liquid nitrogen (or something else?) to get the desired chemical to freeze, then filter off the unfrozen butyrolactone? Other routes seem quite difficult for a non chemist. Any objections or other routes? Anything you can add? Even a step by process will be much appreciated.
Cud [sic] a person wanting to separate these just emerse [sic] them into liquid nitro [sic] or any [sic] to get the desired chemical to freeze then filter off the unfrozen butyrolacton [sic]?


With liquid nitrogen this would not be possible because liquid nitrogen condenses/boils at -195 &deg;C.  It would freeze both the pyrrolidone and the lactone.