Table 2.

Driving Forces, Rate Constants, and Kinetic Isotope Effects for Nitroxyl plus Hydroxylamine Reactions.^a

Reaction	Solvent	ΔG°b	kH (M−1 s−1)a	kD (M−1 s−1)a,c	kH/kDa,c	Ref.
4-oxo-TEMPO• + TEMPO-Hd	MeCN	−0.9 ± 0.2	10 ± 1	0.44 ± 0.05	23 ± 3	e
4-oxo-TEMPO• + TEMPO-H	CH2Cl2	−1.2 ± 0.2	48 ± 4	2.1 ± 0.3	23 ± 4	e
4-oxo-TEMPO• + TEMPO-H	CCl4	–	300 ± 30	17 ± 4	18 ± 5	e
4-oxo-TEMPO• + 4-MeO-TEMPO-H	MeCN	−0.6 ± 0.2	7.8 ± 0.7	0.37 ± 0.05	21 ± 3	e
tBu2NO• + TEMPO-H	MeCN	1.3 ± 0.2	1.9 ± 0.2	0.12 ± 0.02	16 ± 3	e
tBu2NO• + TEMPO-H	CH2Cl2	1.4 ± 0.2	4.6 ± 0.4	0.35 ± 0.04	13 ± 2	e
PINO• + 4Me-NHPIf	AcOH(D)	−0.4 ± 0.1	677 ± 24	61.3 ± 2.1	11.0 ± 0.5	18
4-Me-PINO• + NHPIf	AcOH(D)	0.4 ± 0.1	354 ± 23	31.8 ± 2.0	11.1 ± 1.0	18
tBu2NO• + tBu2NOH	CCl4	0	320 ± 40	–	–	13
tBu2NO• + tBu2NOH	C6H5Cl	0	240 ± 60	–	–	13
tBu(Ar)NO• + tBu(Ar)NOHg	CCl4	0	(2.0 ± 0.4) × 103	(1.3 ± 0.2) × 103	1.5 ± 0.4	13
tBu(Ar)NO• + tBu(Ar)NOHg	C6H5Cl	0	(5.2 ± 0.4) × 102	–	–	13
tBu(Ar)NO• + tBu(Ar)NOHg	CH2Cl2	0	< 20	–	–	13
Ph2NO• + Ph2NOH	CCl4	0	> 107	–	–	13
	hexane	−0.2 ± 0.1	(4.3 ± 0.2) × 104	(2.5 ± 0.1) × 104	1.7 ± 0.1	14
	hexane	2.0 ± 0.1	(4.5 ± 0.2) × 103	(2.9 ± 0.2) × 103	1.6 ± 0.1	14
B + A (R = CPh3)	hexane	0.9 ± 0.1	(1.4 ± 0.1) × 104	(7.3 ± 0.4) × 103	1.9 ± 0.2	14
B (R = Ph) + A	hexane	1.6 ± 0.1	(8.6 ± 0.4) × 103	(5.7 ± 0.3) × 103	1.5 ± 0.1	14
TEMPO• + A	hexane	−0.6 ± 0.1	(7.6 ± 0.4) × 104	–	–	14
TEMPO• + A (R = CPh3)	hexane	−1.4 ± 0.1	(1.5 ± 0.1) × 105	–	–	14
4-oxo-TEMPO• + A	hexane	−1.3 ± 0.1	(6.4 ± 0.3) × 104	–	–	14

^aT = 298 (this work and ref.18), 300 (ref. ¹³), and 293 K (ref. ¹⁴); – means not determined.

^bkcal mol⁻¹.

^cNot corrected for the incomplete (98±1%) deuterium enrichment; the true k_H/k_D values are roughly a factor of two higher; see text.

^dRef. ²⁰.

^eThis work.

^fPINO^• = phthalimide N-oxyl radical, NHPI = N-hydroxyphthalimide.

^gAr = 2,6-dimethoxyphenyl.