Quantification of the Nucleophilicities of 3-X-Thiophenes: Highlighting the Hyperortho Correlation

Table 1

Second-order rate constants (k₁/M⁻¹·s⁻¹) and electrophilicity parameters (E) of the reactions of 3-X-thiophene 1 with the electrophiles 2a and 3a-c in acetonitrile at 20°C.

Electrophile	E^a	Nucleophile	k1 (M^−1s^−1)
	−4.58	1a	4.08 × 10^−3
		1b	1.28 × 10^−3
		1c	3.41 × 10^−4
	−4.74	1a	2.67 × 10^−3
		1b	7.18 × 10^−4
		1c	2.22 × 10^−4
	−5.06	1a	1.23 × 10^−3
		1b	3.39 × 10^−4
		1c	1.08 × 10^−4
	−6.41	1a	4.10 × 10^−5
		1b	1.35 × 10^−5
		1c	4.36 × 10^−6

^aRef [7].