EPR Properties of Cyclic Phosphinylhydrazyl Radicals
J . Org. Chem., Vol. 65, No. 9, 2000 2727
This determination was carried out by adding a known
amount of the diamagnetic compound A to water solu-
tions containing CD and the hydrazyl radical 2b. Under
addition, the temperature was allowed to reach room temper-
ature, and the solution was stirred for an additional 1 h. A
white precipitate was formed. The mixture was washed twice
with 50 mL of water and twice with a 10% solution of K CO .
2 3
The organic layer was separated and dried under sodium
sulfate, and the solvent was removed in a vacuum. A total of
these conditions (eq 3), the affinity constant of A, K
be calculated from eq 5 by using the [CD] value obtained
by introducing in eq 2 the known value of K and the
4
, can
2
7
9.7 g of a white powder was recovered in 93% yield. The
compound was recrystallized from diisopropyl ether: mp 101-
experimental ratio [RCD‚]/[R‚] measured in the solution
containing A.
+
1
103 °C; MS (EI) m/z 238 (M , 5); H NMR (CDCl
3
) δ 3.92
(
s, 1H), 4.09 (m, 4H), 3.69 (m, 4H), 2.71 (m, 4H), 1.30 (td,
J
3
4
13
H-H ) 7.0 Hz, J P-H ) 0.9 Hz, 6H); C NMR (CDCl
3
) δ 66.53
2
3
(
(
s), 62.93 (d, J P-C ) 5.7 Hz), 58.73 (d, J P-C ) 6.9 Hz), 16.15
3
8 19 2 4
d, J P-C ) 6.9 Hz). Anal. Calcd for C H N O P: C, 40.34;
H,7.98; N, 11.76. Found: C, 40.20; H, 8.01; N, 11.58.
2,2,6,6-Tetr am eth ylpiper idin -1-yl)ph osph or am idic Acid
Dieth yl Ester (2a ). (A) Syn th esis of 2,2,6,6-Tetr a m eth yl-
(
1
2
3
-n itr osop ip er id in e. To a solution of 23.5 g (0.167 mol) of
,2,6,6-tetramethylpiperidine in 200 mL of water. HCl (10 mL,
7%) was added. The solution was heated at 75 °C, and a
Actually, when adding diclofenac to the solution, the
spectral lines due to the included radical showed a
marked decrease proportional to the quantity of drug
solution of 63 g (0.9 mol) of sodium nitrite in 200 mL of water
was slowly added. The solution was allowed to react for 3 h at
7
5 °C and for an additional 10 h at 100 °C. The reaction
-
1
mixture was cooled at room temperature and treated twice
with 300 mL of diethyl ether. The organic layer was then
washed with 100 mL of a water solution of 2 N HCl and with
4
from which a binding constant K of 470 M could be
calculated. Since this value is close to that reported in
the literature for diclofenac, it is concluded that the
competition method here described can be usefully em-
ployed to determine binding constants of drugs for
cyclodextrins in those cases where traditional methods
such as NMR and UV-vis spectroscopy cannot be ap-
plied.
1
2 3
00 mL of a saturated water solution of Na CO . The organic
phase was then dried under anhydrous sodium sulfate, and
the solvent was removed under vacuum. An orange oil was
+
1
recovered in 98% yield: MS (EI) m/z 170 (M , 25); H NMR
1
3
(CDCl
CDCl
3
) δ 1.60 (broad s, 12H), 1.40 (broad m, 6H); C NMR
) δ 62.08, 60.66, 41.58, 38.89, 31.90, 26.11, 16.24. (B)
(
3
Syn th esis of 2,2,6,6-Tetr a m eth ylp ip er id in -1-yla m in e. To
a solution of 15 g of LiAlH in 250 mL of anhydrous dibutyl
4
Exp er im en ta l Section
ether cooled at 0 °C was slowly added 30 g of the compound
from part A dissolved in 75 mL of dibutyl ether. The temper-
ature was increased to 95 °C (reflux temperature), and the
mixture was allowed to react for 3 h. The mixture was cooled
at about 0 °C, and 50 mL of water was slowly added. The
organic layer was recovered and dried under sodium sulfate.
The solvent was removed under vacuum. A yellow oil was
Gen er a l Meth od s. NMR spectra were recorded on a
Bruker AMX 300 MHz spectrometer. Elemental analyses were
carried out on a Perkin-Elmer 2400 CHN in the Ciba Specialty
Chemical laboratory. Mass spectra were carried out on a
Hewlett-Packard HP 5973 spectrometer. EPR spectra were
obtained using a Bruker ESP 300 spectrometer equipped with
an NMR gaussmeter for field calibration and a Hewlett-
Packard 5350B microwave frequency counter for the determi-
nation of the g-factors, which were referenced to that of the
+
1
recovered at 73% yield: MS (EI) m/z 156 (M , 12); H NMR
1
3
(
(
(
CDCl
CDCl
3
) δ 1.40 (broad s, 6H), 0.95 (broad m, 12H); C NMR
3
) δ 57.02, 40.52, 25.52, 17.60. (C). To a solution of 6 g
38.5 mmol) of the compound from part B in 60 mL of
2 4
perylene radical cation in concentrated H SO (g ) 2.002 58).
anhydrous THF cooled at -78 °C was slowly added 15.2 mL
of a solution of butyllithium 2.5 N in n-hexane. After the
addition, the temperature was increased to room temperature
and the mixture allowed to react for 30 h. The mixture was
then cooled again at -78 °C, and 6.6 g (38 mmol) of diethyl
chlorophosphate was slowly added. After 30 h, the solution
was heated at room temperature. The solvent was removed
under vacuum and the residue dissolved in methylene chloride,
washed with water, and dried with sodium sulfate. A white
powder recovered with 40% yield was then crystallized by
The sample temperature was controlled with a standard
variable-temperature accessory and was monitored before and
after each run using a copper-constantan thermocouple.
Digitized EPR spectra were transferred to a personal computer
and were analyzed using digital simulations carried out with
a program developed in our laboratory and based on a Monte
1
6
Carlo procedure. Radicals 1b and 2b were generated in
organic solvents by reacting the corresponding hydrazine with
photolytically produced tert-butoxyl radicals. CD-included
radical 2b was generated by a flash of intense UV irradiation
of a sample containing hydrazine 2a in benzene/di-tert-butyl
peroxide (10:1 (v/v)). The solvent was removed under reduced
pressure, and the residue was dissolved in water containing
variable amounts of cyclodextrin. Samples were then trans-
ferred in capillary tubes (1 mm i.d.), and EPR spectra were
recorded.
+
1
n-hexane: mp 136-138 °C; MS (EI) m/z 292 (M , 15); H NMR
2
(
CDCl
3
) δ 4.06 (m, 4H), 3.67 (d, J P-H ) 32 Hz, 1H), 1.50 (broad
3
s, 6H), 1.26 (td,
(
5
1
J
H-H ) 7.0 Hz, 4
broad m, 12H); 13C NMR (CDCl
) δ 63.24 (d, J P-C ) 6.0 Hz),
9.10 (s), 40.48(s), 33.61 (broad s), 18.42 (broad s), 17.63 (s),
6.58 (d, J P-C ) 7.2 Hz). Anal. Calcd for C13
H, 9.93; N, 9.59. Found: C, 53.3; H, 10.10; N, 8.93.
J P-H ) 0.9 Hz, 6H), 1.00
2
3
3
29 2 3
H N O P: C, 53.4;
Mor p h olin -4-yl-p h osp h or a m id ic Acid Dieth yl Ester
(
1a ). To a solution of 39.7 g (0.389 mol) of N-aminomorpholine
Ack n ow led gm en t. Financial support from CNR
Rome), from the University of Bologna, and from
MURST (Research project “Free Radicals and Radical
Ions in Chemical and Biological Processes”) is gratefully
acknowledged by M.L. and G.F.P.
and 39.3 g (0.389 mol) of triethylamine in 1000 mL of
methylene dichloride under nitrogen, cooled to 0 °C, was slowly
added 172.6 g (0.398 mol) of diethyl chlorophosphate. The
temperature was kept during the addition at 0 °C. After the
(
(16) Kirste, B. J . Magn. Reson. 1987, 73, 213.
J O9918293