Survey of implementations to see which treat ' as a delimiter that terminates a symbol:
I tested (list 'a'b) on the usual suite of Schemes.
Returned (a b): Racket, Gauche, MIT, Gambit, Chicken, Scheme48/scsh,
Kawa, Chibi, Chez, Vicare, NexJ, JScheme, STklos, KSi, SigScheme, Scheme 9, RScheme, BDC,
XLisp, Rep, Oaklisp, Spark, Llava, FemtoLisp, Foment, Owl Lisp, Sagittarius
Returned (a'b): Bigloo, Guile, SISC, SCM, Shoe, TinyScheme, Dream,
S7, Schemik, Elk, UMB, VX, Sizzle, Dfsch, Inlab
Syntax error: Ikarus, Larceny, Ypsilon, Mosh, IronScheme, SXM, MScheme
I suspect that a lot of implementations think it's simplest to just gobble up what they see until they get to an unquestioned delimiter.