Table 4. Hammett σ⁺ Values.

substituent	σ+	comment
ortho-OH	–0.92	based on σ+(para)
meta-OH	+0.13	based on σ(meta)
ortho-NH2	–1.30	based on σ+(para)
ortho-O–	–2.30	based on σ+(para)
meta-Cl	+0.37	based on σ(meta)
meta-Me	–0.06	based on σ (meta)
meta-CO·CH=CHPh	+0.36	based on σ(meta) COPh
meta-OCH2CH2OH	+0.10	based on σ(meta) OEt
ortho-OMe	–0.81	based on σ+(para) OEt
meta-OMe	+0.12	based on σ(meta) OEt
ring N in pyridines, meta	+0.73	based on σ(meta)
ring N in pyridines, para	+0.83	based on σ(para)
meta-Ph	+0.05	based on σ(meta)
ortho-Ph	–0.18	based on σ+(para)