I found this problem en Minimals (last version) and on TexLive 2013.
\setupbodyfont[11pt]
\usemodule[chemic]
\starttext
\startchemical[width=fit,scale=small,size=big]
\bottext{á-Glycerophosphate}
\chemical[ONE,SB1357,Z0357][\TL{á}{C},\SL{OPO\lohi{3}{2-}},H,H]
\chemical[MOV1,SB137,Z037][C,\SL{OH},H]
\chemical[MOV1,SB137,Z0137][C,H,\SL{OH},H]
\stopchemical
\definechemical[desoxyribose]
{\chemical[FIVE,FRONT,BB125,+SB3,-SB4,Z4][O]
\chemical[FIVE,FRONT,+R1235,+RZ1235][H,H,\SR{HOH_2C},OH]
\chemical[FIVE,FRONT,-R1235,-RZ1235][H,OH,H,H]}
\startchemical[height=6500,top=2000,bottom=2500,width=4500]
\chemical[desoxyribose]
\bottext{Desoxiribosa (dR)}
\stopchemical
\startchemical[height=4500,bottom=2500]
\bottext{$\alpha$-D-Fructofuranose}
\chemical
[FIVE,FRONT,BB125,+SB3,-SB4,Z4][O]
\chemical
[FIVE,FRONT,+R1235,+RZ1235][\SR{HO},H,\SR{HOH_2C},CH_2OH]
\chemical
[FIVE,FRONT,-R1235,-RZ1235][OH,H,\SR{HO},H,CH_2OH]
\stopchemical
\startchemical[height=4500,bottom=2500]
\chemical [FIVE,FRONT,B,R]
\chemical [+RZ1..5] [1,2,3,4,5]
\chemical [-RZ1..5] [a,b,c,d,e]
\stopchemical
\stoptext