D. A. Evans Classification of Functional Groups Chem 206 Common G-Functions: Symbol: (-)C-G conjugate acid Typical G-class functions are the Group l-IV metals whose reactivity patterns falls into a subset of the idealized g-FG 5 仓NCH2R oN=CHR AN=CHR ④N=CHR (-)(+)(-) H2C=CH-CH2-Li FGc(FG—C+) (- CH3-CH2-MgBr The reaction CH-R Common A-Functions: Symbol: (+)C-A E(+)9 A-functions are usually more structurally complex FGs composed of polyatomic assemblages of nitrogen, oxygen and their heavier Group V and VI relatives(P, As, S, Se) pKa- 10 0 +N-CH-R Typical A-functions, classified by inspection, are provided below -NO2=NOR=NNR2-N(OR -N2 =N mm总h SR—S(OR-S02R-SR2 -PR 2-P(O)R 2-PR a This reactivity pattern may be extended via conjugation IThese FGs are capable of conferring both(+)and (-)at point of attachment. The reaction N一CH=CHR N 一 CH2-CH-Nu X -0 X=OR, NR2 N=CH-CH-R Remarkably, the dual electronic properties of oximes were first discussed by 0()(+) Lapworth in 1924 before the modem concepts of valence bond resonance Charge affinity patterm: +N-CH=CH-R were developed Lapworth, A. Chemistry and Industry 1924, 43, 1294-1295 The Nitro Functional Group I The resonance feature which has been exploited As an example, the class designation of the nitro function is determined by an evaluation of the parent function, its nitronic acid tautomer, as well as conjugate acid and basePR3 + N CH CH R –O –O + + H2C CH CH2 Li CH3 CH2 MgBr C A C G C C C G N O O CH2R + N O –O CH2R N HO O CHR NO2 NOR SR PR2 P(O)R2 NNR2 N(O)R N2 N S(O)R SO2R SR2 R H N X: R H N X: R H N X: R H N X: N X: R H + N O –O CH CH R + N CH–R –O –O + N CH–R –O O FG C N O O CHR R H N X: FG C + N CH2 CH Nu –O O R N HO HO CHR + N CH CH R –O O + N CH2–R –O O + N –O O R El D. A. Evans Classification of Functional Groups Chem 206 Typical G-class functions are the Group I-IV metals whose reactivity patterns, falls into a subset of the idealized G-FG 5. Common G-Functions: Symbol: (–) 5 (–) (+) (–) (–) (–) (–) Common A-Functions: Symbol: A-functions are usually more structurally complex FGs composed of polyatomic assemblages of nitrogen, oxygen and their heavier Group V and VI relatives (P, As, S, Se). Typical A-functions, classified by inspection, are provided below + (±) ■ These FG's are capable of conferring both (+) and (–) at point of attachment. (+) (+) (–) (–) X = OR, NR2 Remarkably, the dual electronic properties of oximes were first discussed by Lapworth in 1924 before the modern concepts of valence bond resonance were developed. Lapworth, A. Chemistry and Industry 1924, 43, 1294-1295. ■ This reactivity pattern may be extended via conjugation: (–) The charge affinity pattern: – ● ● The Reaction: El(+) pKa ~ 10 base The Nitro Functional Group ✔✔ (–) (+) Charge affinity pattern: The Reaction: (–) (+) Nu(–) ■ The resonance feature which has been exploited: (+) (+) (–) (–) X = OR, NR2 As an example, the class designation of the nitro function is determined by an evaluation of the parent function, its nitronic acid tautomer, as well as conjugate acid and base. H-tautomer conjugate base conjugate acid (–) (+)