preferred_name: chloroethene + AH2 <=> ethene + chloride + A + H(+)
preferred_name_lc: chloroethene + ah2 <=> ethene + chloride + a + h(+)
label: chloroethene + AH2 <=> ethene + chloride + A + H(+)
label_lc: chloroethene + ah2 <=> ethene + chloride + a + h(+)