Synthesis of photoactive 1-methyl-1-R-4-(1,4-dioxo-1,4-dihydronaphthalen-2- yl)piperazinium salts

Article abstract of DOI:10.1134/S1070428011120086

Photoactive 4-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)piperazinium salts were synthesized by alkylation of 3-chloro-2-(piperazin-1-yl)- and 2-arylamino-3-(4-methylpiperazin-1-yl)-1,4-naphthoquinones. Light sensitivities of materials obtained by adsorption o

Full text of DOI:10.1134/S1070428011120086

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 12, pp. 1823–1831. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.N. Berezhnaya, V.V. Shelkovnikov, S.V. Korotaev, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 12,
pp. 1786–1793.
Synthesis of Photoactive 1-Methyl-1-R-4-(1,4-dioxo-1,4-dihydro-
naphthalen-2-yl)piperazinium Salts
V. N. Berezhnaya, V. V. Shelkovnikov, and S. V. Korotaev
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 9, Novosibirsk, 630090 Russia
e-mail: bmv@nioch.nsc.ru
Received July 13, 2010
Abstract—Photoactive 4-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)piperazinium salts were synthesized by
alkylation of 3-chloro-2-(piperazin-1-yl)- and 2-arylamino-3-(4-methylpiperazin-1-yl)-1,4-naphthoquinones.
Light sensitivities of materials obtained by adsorption of the synthesized piperazinium salts from solution onto
oxidized aluminum support were estimated.
DOI: 10.1134/S1070428011120086
2-Dialkylamino-1,4-naphthoquinone derivatives are
known to exhibit photochemical activity [1, 2], and
some compounds of this series were proposed as light-
sensitive components of non-silver photographic mate-
rials [3, 4]. With a view to extend the scope of applica-
tion of 2-dialkylamino-1,4-naphthoquinones via im-
provement of their solubility in water, arylamino
groups containing a carboxy or sulfo group were intro-
duced into the quinoid ring [5] or a sulfo group was
introduced into the aromatic ring of 1,4-naphtho-
quinone [6–8]. In the present work we tried to synthe-
size amphiphilic derivatives of dialkylamino-1,4-naph-
thoquinones by quaternization of 2-(piperazin-1-yl)-
substituted 1,4-naphthoquinones. Appearance of a pos-
itive charge on the piperazine fragment converts
neutral molecule into organic salt and enhances its
hydrophilicity, so that the piperazine fragment be-
comes hydrophilic while the naphthoquinone fragment
remains hydrophobic.
It is known [9] that in most cases quaternization of
tertiary amines with alkyl halides is not complicated
provided that the basicity of the amine is sufficiently
high and that there are no unfavorable steric factors.
The most probable site of electrophilic attack by alkyl
halide on 2-(piperazin-1-yl)-1,4-naphthoquinone mole-
cule is the nitrogen atom linked to alkyl substituent
rather than that linked to the naphthoquinone fragment.
By reactions of 3-chloro-2-(piperazin-1-yl)-1,4-naph-
thoquinone (I) with butyl bromide, benzyl chloride,
and 1,2-epoxypropane in the presence of a base we
previously obtained only monoalkylation products,
whereas the reaction with methyl iodide gave quater-
nary salt.
In the present work quaternary 4-(1,4-dioxo-1,4-di-
hydronaphthalen-2-yl)piperazinium salts were synthe-
sized by double alkylation of quinone I using an ex-
tended series of alkylating agents (alkyl halides and
1-chloro-2,3-epoxypropane). The reaction of I with
Scheme 1.
R
R
O
NH
O
N
O
N
Me
N
N
N
RX
MeI
I–
Cl
Cl
Cl
O
O
O
I
IIa–IIi
IIIa–IIIi
R = C4H9 (a), C5H11 (b), C7H15 (c), C10H21 (d), NCCH2CH2 (e), PhCH2 (f), MeCH(OH)CH2 (g), ClCH2CH(OH)CH2 (h), Me (i).
1823

BEREZHNAYA et al.
1824
Et
Me
Me
Me
Me
Me
O
O
N
O
N
O
O
N
N
N
N
Br–
I–
PF6
O
IIIj
IIIk
IIIl
alkylating agents in alcoholic medium gave the corre-
sponding monoalkylation products, N-substituted pi-
perazines IIa–IIi. We succeeded in effecting further
alkylation of piperazines IIa–IIi only by the action of
methyl iodide (Scheme 1). Piperazinium salts IIIa–IIIi
thus obtained contained one methyl group and one
bulkier substituent at the quaternized nitrogen atom. It
should be emphasized that just the above alkylation
sequence leads to formation of quaternary salt. All
attempts to introduce first a smaller substituent and
then a bulkier one, as well as successive alkylation of
2-(piperazin-1-yl)-1,4-naphthoquinone with ethyl
bromide, led to formation of the corresponding tertiary
amine salt, 4-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)-
piperazinium hydrohalide. Quaternary salt IIIj was
obtained in 28% yield by the action of ethyl bromide
on 2-(4-methylpiperazin-1-yl)-1,4-naphthoquinone.
The synthetic approach to 2,3-diamino-1,4-naph-
thoquinones from 2,3-dichloro-1,4-naphthoquinone,
developed previously, includes successive nucleophilic
replacement of the halogen atoms by amines. In order
to reduce donor effect of the first amino group,
2-arylamino-3-chloro-1,4-naphthoquinones were sub-
jected to acylation or nitrosation. The subsequent re-
placement of chlorine by the second amine residue and
removal of protecting group gives target 2,3-diamino-
substituted naphthoquinones [5, 11–13].
2-Arylamino-3-chloro-1,4-naphthoquinones IVa–
IVc were synthesized by heating 2,3-dichloro-1,4-
naphthoquinone with the corresponding arylamine
in boiling alcohol in the presence of N,N-diethyl-
aniline according to the procedure described in [5]
(Scheme 2). Compounds IVa–IVc were then treated
with acetic anhydride. m-Acetyl- and m-methoxy
derivatives IVb and IVc reacted with acetic anhydride
at a lower rate as compared to p-tolylamino-substituted
analog IVa which was reported previously [5]. The
acetylation of methoxy derivative IVc was complete
only after heating for 50 h at 55°C. N-Acetyl-N-(3-
methoxyphenyl)amino derivatives Vc and VIc readily
underwent hydrolysis during the isolation procedure
(treatment with water and chromatography). After
All piperazinium salts IIIa–IIIi are poorly soluble
in organic solvents. Replacement of the chlorine atom
in the naphthoquinone fragment by hydrogen (salt
IIIk) does not affect the solubility. We succeeded in
obtaining 4-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)-
piperazinium salts readily soluble in organic solvents
from 2-arylamino-3-(4-methylpiperazin-1-yl)-1,4-
naphthoquinones.
Scheme 2.
O
O
O
Ac
N
Cl
Cl
NHAr
ArNH2
Ac2O
Ar
Cl
Cl
O
O
O
IVa–IVc
Va–Vc
O
O
Ac
Me
N
N
Ar
HN
N
N
Me
VIa–VIc
Ar = 4-MeC6H4 (a), 3-MeC(O)C6H4 (b), 3-MeOC6H4 (c).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

SYNTHESIS OF PHOTOACTIVE 1-METHYL-1-R-4-(1,4-DIOXO-1,4-DIHYDRO...
1825
Scheme 3.
O
O
H
N
H
N
Ar
Ar
MeI
KOH
VIa–VIc
N
N
O
N
O
N
Me
Me
Me
VIIa–VIIc
VIIIa–VIIIc
O
O
Ac
N
C6H4COMe-3
MeI
VIb
N
N
Me
Me
VIIId
VII, VIII, Ar = 4-MeC6H4 (a), 3-MeC(O)C6H4 (b), 3-MeOC6H4 (c).
introduction of N-methylpiperazine residue into the
3-position of the 1,4-naphthoquinone fragment, com-
pounds VIa–VIc were deprotected by treatment with
alkali (KOH or NaOH) in dioxane–MeOH (1:1) [13].
minum support. After exposition through a negative,
samples were developed in solution by chemical depo-
sition of silver to enhance primary image [14]. The
light sensitivities of materials on the basis of the
synthesized piperazinium salts were determined from
the D—logH curves (see figure) and are given below.
2-Arylamino-3-(4-methylpiperazin-1-yl))-1,4-naph-
thoquinones VIIa–VIIc and VIb were subjected to
alkylation with methyl iodide in alcohol at room tem-
perature or on heating to obtain the corresponding
quaternary salts VIIIa–VIIId (Scheme 3). Piperazini-
um salts VIII having an arylamino group in position 3
of the naphthoquinone fragment were characterized by
lower melting points, better solubility in organic sol-
vents, and deeper color (Δλ ≈ 50–60 nm for the long-
wave absorption maximum) as compared to chloro-
substituted or unsubstituted analogs. Absorption max-
ima in the electronic absorption spectra of piperazini-
um salts were displaced by ~70–100 nm to shorter
wavelengths relative to those of the corresponding
bases. Replacement of the counterion in 1,1-dimethyl-
4-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)piperazinium
iodide (IIIk) by hexafluorophosphate(V) (salt IIIl)
considerably improves the solubility both in water and
in organic solvents.
Compound no.
IIIa IIIc IIId IIIh IIIk VIIIb VIIId
Light sensitivity,
S0.2 ×10–5 lx–1 s–1 2.57 1.58 3.16 1.35 5.00 1.86 1.40
It is seen that the light sensitivity of materials based
on (1,4-dioxo-1,4-dihydronaphthalen-2-yl)piperazini-
um salts in the visible region is on the average 3×
D
1.0
0.8
0.6
0.4
0.2
A practically important property of the synthesized
quaternary piperazinium salts is their ability to
undergo photochemical reduction [1, 2]. Therefore, we
estimated photosensitivity of these salts by preparing
materials in which latent image is obtained via reduc-
tive formation of catalytically active centers (materials
with physical development of latent image). Light-
sensitive materials were prepared by adsorption of
piperazinium salts from solution onto an oxidized alu-
3
4
5
logH
Characteristic curve of optical density D versus logarithm of
exposition H (lx s–1) for a photosensitive layer based on pi-
perazinium salt IIIk.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

BEREZHNAYA et al.
1826
10–5 lx–1 s–1, i.e., it exceeds the sensitivity of materials
without amplification, in particular of organic photo-
chromic compounds. These data indicate that the syn-
thesized compounds are characterized by high photo-
activity in physical development processes and are
promising from the viewpoint of practical application.
3-chloro-2-(piperazin-1-yl)-1,4-naphthoquinone in
50 ml of ethanol, and the mixture was heated for 12 h
under reflux. The mixture was filtered while hot, the
filtrate was evaporated to dryness, and the residue was
dissolved in chloroform and subjected to column chro-
matography on silica gel (50–160 µm) using in succes-
sion CCl4, CCl4–CHCl3 (1:1), and CHCl3 as eluents.
The major (chloroform) fraction was evaporated to
dryness, and the residue was recrystallized from ap-
propriate solvent.
EXPERIMENTAL
The IR spectra were recorded in KBr on a Bruker
Vector 22 spectrometer. The electronic absorption
spectra were measured on Hewlett–Packard 4853 and
Beckmann DU-8 spectrophotometers from solutions in
ethanol and water. The mass spectra were obtained on
a Finnigan MAT-8200 mass spectrometer; the molec-
ular weights and elemental compositions were deter-
mined from the precise m/z values for the molecular
3-Chloro-2-(4-pentylpiperazin-1-yl)-1,4-dihydro-
naphthalene-1,4-dione (IIb). Yield 0.56 g (41%),
mp 76–79°C (from hexane). IR spectrum, ν, cm–1:
2952, 2923, 2810 (C–H); 1671, 1655 (C=O). 1H NMR
spectrum (CDCl3), δ, ppm: 0.89 m (3H, CH3), 1.30 m
(4H, CH2), 1.51 m (2H, CH2), 2.37 m (2H, NCH2),
7.65 m (2H, 6-H, 7-H), 7.99 m and 8.10 m (1H each,
5-H, 8-H). Electronic absorption spectrum (EtOH):
λmax 447 nm (logε 2.74). Found: m/z 346.1438 [M]+.
C19H23ClN2O3. Calculated: M 346.1443.
1
ions. The H NMR spectra were recorded on Bruker
AC-200, AV-300, AM-400, and AV-400 spectrometer
using residual proton signal of deuterated solvent as
reference. The progress of reactions and the purity of
products were monitored by TLC on Silufol plates
using chloroform and benzene–acetone (4 : 1) as
eluents. Preparative chromatography was performed
using KSK silica gel.
3-Chloro-2-(4-heptylpiperazin-1-yl)-1,4-dihydro-
naphthalene-1,4-dione (IIc). Yield 0.613 g (41%),
mp 86–89°C (from hexane). IR spectrum, ν, cm–1:
1
2923, 2853, 2811 (C–H); 1671, 1652 (C=O). H NMR
spectrum (CDCl3), δ, ppm: 0.86 m (3H, CH3), 1.28 m
(6H, CH2), 1.49 m (3H, CH2), 1.74 m (1H, CH2),
2.36 m (2H, NCH2), 2.60 m (4H, NCH2), 3.62 t (4H,
NCH2), 7.65 m (2H, 6-H, 7-H), 7.98 m and 8,00 m (1H
each, 5-H, 8-H). Electronic absorption spectrum
(EtOH): λmax 493 nm (logε 3.64). Found: m/z 374.1750
[M]+. C21H27ClN2O2. Calculated: M 374.1756.
3-Chloro-2-(piperazin-1-yl)-1,4-naphthoquinone (I)
[10] and 2-(piperazin-1-yl)-1,4-naphthoquinone [15]
were synthesized by reactions of 2,3-dichloro-1,4-
naphthoquinone and 1,4-naphthoquinone, respectively,
with a large excess of piperazine. 3-Chloro-2-(4-
methylpiperazin-1-yl)-1,4-naphthoquinone (IIe) and
3-[4-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-
piperazin-1-yl]propanenitrile (IIi) were prepared by
reactions of 2,3-dichloro-1,4-naphthoquinone with the
corresponding N-substituted piperazines. 2-(4-Butyl-
piperazin-1-yl)-3-chloro-1,4-naphthoquinone (IIa),
2-(4-benzylpiperazin-1-yl)-3-chloro-1,4-naphthoqui-
none (IIg), and 3-chloro-2-[4-(2-hydroxypropyl)piper-
azin-1-yl]-1,4-naphthoquinone (IIh) were obtained by
alkylation of 3-chloro-2-(piperazin-1-yl)-1,4-naphtho-
quinone (I) with butyl iodide, benzyl chloride, and
1,2-epoxypropane, respectively, according to the pro-
cedure described in [10]. 3-Chloro-2-(4-methylphenyl-
amino)-1,4-naphthoquinone (IVa) and 2-[acetyl(4-
methylphenyl)amino]-3-chloro-1,4-naphthoquinone
(Va) were synthesized as reported in [5].
3-Chloro-2-(4-decylpiperazin-1-yl)-1,4-dihydro-
naphthalene-1,4-dione (IId). A suspension of 1.40 g
(5 mmol) of 3-chloro-2-(piperazin-1-yl)-1,4-naphtho-
quinone, 2.7 ml (2 mmol) of triethylamine, and 4 ml
(40 mmol) of decyl chloride in 40 ml of acetonitrile
was heated for 70 h under reflux. The mixture was
filtered while hot, the filtrate was evaporated to dry-
ness, and the residue was dissolved in chloroform and
subjected to column chromatography on silica gel (50–
160 µm) using in succession CCl4, CCl4–CHCl3 (1:1),
and CHCl3 as eluents. The major (chloroform) fraction
was evaporated to dryness, and the residue was
crystallized from ethanol. Yield 0.997 g (47%), mp 67–
69°C. IR spectrum, ν, cm–1: 2953, 2869 (C–H); 1671,
1
Alkylation of 3-chloro-2-(piperazin-1-yl)-1,4-
naphthoquinone with alkyl bromides (general pro-
cedure). Triethylamine, 0.6 ml (4 mmol), and the
corresponding alkyl bromide, 0.5 ml (4 mmol), were
added to a warm solution of 1.10 g (4 mmol) of
1652 (C=O). H NMR spectrum (CDCl3), δ, ppm:
0.86 m (3H, CH3), 1.40–1.65 m (16H, CH2), 2.38 m
(2H, NCH2), 2.61 m (4H, NCH2), 3.63 t (4H, NCH2),
7.66 m (2H, 6-H, 7-H), 7.99 m and 8.10 m (1H each,
5-H, 8-H). Electronic absorption spectrum (EtOH):
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

SYNTHESIS OF PHOTOACTIVE 1-METHYL-1-R-4-(1,4-DIOXO-1,4-DIHYDRO...
1827
λmax 493 nm (logε 3.68). Found: m/z 416.2225 [M]+.
C24H33ClN2O2. Calculated: M 416.2230.
using CCl4, CCl4–CHCl3, and CHCl3 as eluents. The
product was isolated from the second yellow fraction
(chloroform). Yield 29%, mp 121–124°C. IR spectrum,
3-Chloro-2-[4-(3-chloro-2-hydroxypropyl)piper-
azin-1-yl]-1,4-dihydronaphthalene-1,4-dione (IIh).
1-Chloro-2,3-epoxypropane, 1.6 ml (20 mmol), was
added dropwise under stirring at room temperature to
a suspension of 1.10 g (4 mmol) of 3-chloro-2-(piper-
azin-1-yl)-1,4-naphthoquinone in 50 ml of ethanol.
After 24 h, the red precipitate was filtered off, washed
with ethanol, and dried. Yield 1.13 g (76%), mp 130–
132°C (from benzene–petroleum ether, 1:1). IR spec-
trum, ν, cm–1: 3425 (O–H); 2952–2821 (C–H); 1673,
1
ν, cm–1: 1695, 1674 (C=O). H NMR spectrum
(CDCl3), δ, ppm: 2.18 s (3H, COCH3), 3.84 s (3H,
OCH3), 6.86 m (1H, 6′-H), 6.98 m (1H, 2′-H), 7.03 m
(1H, 4′-H), 7.29 m (1H, 5′-H), 7.75 m (2H, 6-H, 7-H),
8.13 m (2H, 5-H, 8-H). Found; m/z 355.04 [M]+
(Irel 4.31%). C19H14ClNO4. Calculated: M 355.78.
N-Aryl-N-[3-(4-methylpiperazin-1-yl)-1,4-dioxo-
1,4-dihydronaphthalen-2-yl)acetamides VIa–VIc
(general procedure). N-Methylpiperazine, 5 mmol,
was added under stirring at room temperature to
a suspension of 1 mmol of naphthoquinone Va–Vc in
7.5 ml of ethanol, and the mixture was stirred until the
initial quinone disappeared. The mixture was poured
into water, acidified with 4% hydrochloric acid, and
extracted with chloroform. The extract was dried over
sodium sulfate and evaporated, and the residue was
subjected to column chromatography on silica gel (50–
160 µm–160–315 µm, ~1:1) using CCl4, CCl4–
CH2Cl2, CH2Cl2, and C6H6–acetone (4:1) as eluents (in
succession). The major red fraction (C6H6–acetone,
4:1) was evaporated to dryness, and the residue was
recrystallized from appropriate solvent.
1
1641 (C=O). H NMR spectrum (CDCl3), δ, ppm:
2.55 m (2H, CH2Cl), 2.63 m (2H, NCH2), 2.81 m (2H,
NCH2), 3.39 br.s (1H, OH), 3.60 m (6H, NCH2),
3.97 m (1H, CHOH), 7.67 m (2H, 6-H, 7-H), 7.98 m
and 8.08 m (1H each, 5-H, 8-H). Electronic absorption
spectrum: λmax 491 nm (logε 3.36). Found: m/z 368.0668
[M]+. C17H18ClN2O3. Calculated: M 368.0689.
3-Chloro-2-(3-methoxyphenylamino)-1,4-dihy-
dronaphthalene-1,4-dione (IVc). A suspension of
5.68 g (25 mmol) of 2,3-dichloro-1,4-naphthoquinone,
5.6 ml (50 mmol) of 3-methoxyaniline, and 1 ml of
N,N-diethylaniline in 50 ml of alcohol was heated
under reflux with stirring until the initial quinone
disappeared according to the TLC data. After 5 h, the
mixture cooled, and the precipitate was filtered off,
washed with ethanol and petroleum ether, and dried.
Yield 85%, mp 150–152°C (from EtOH). IR spectrum,
ν, cm–1: 3223 (NH); 1674, 1644 (C=O). 1H NMR spec-
trum (DMSO-d6), δ, ppm: 3.73 s (3H, OCH3), 6.72 m
(3H, Harom), 7.19 m (1H, 5′-H), 7.84 m (2H, 6-H, 7-H),
8.04 m (2H, 5-H, 8-H), 9.25 br.s (1H, NH). Found: m/z
313.7421 [M]+. C17H12ClNO3. Calculated: M 313.7437.
N-(4-Methylphenyl)-N-[3-(4-methylpiperazin-1-
yl)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)acetamide
(VIa). Reaction time 3.5 h. Yield 50%, mp 168–170°C
(from ethanol). IR spectrum, ν, cm–1: 1645, 1673
1
(C=O). H NMR spectrum (DMSO-d6), δ, ppm: 2.06 s
(3H, NCH3), 2.17 s (3H, CH3), 2.26 m (5H, CH3,
NCH2), 2.43 m (2H, NCH2), 3.09 m (2H, NCH2),
3.48 m (2H, NCH2), 7.11 m (2H), 7.18 m (2H), 7.83 m
(2H, 6-H, 7-H), 7.97 m (2H, 5-H, 8-H). Electronic
absorption spectrum: λmax 487 nm (logε 3.61). Found:
m/z 403.1893 [M]+. C24H25N3O3. Calculated:
M 403.1890.
Acylation of 2-arylamino-3-chloro-1,4-naphthoqui-
nones with acetic anhydride was performed according
to the procedure reported in [5].
N-(3-Acetylphenyl)-N-(3-chloro-1,4-dioxo-1,4-di-
hydronaphthalen-2-yl)acetamide (Vb). Reaction
time 3 days. Yield 66%, mp 166–168°C (from EtOH).
IR spectrum, ν, cm–1: 1698, 1681, 1671 (C=O).
1H NMR spectrum (CDCl3), δ, ppm: 2.11 s (3H, CH3),
2.58 s (3H, CH3), 7.57 m (3H, 4′-H, 5′-H, 6′-H),
7.94 m (3H, 2′-H, 6-H, 7-H), 8.12 m (2H, 5-H, 8-H).
Found: m/z 367.0601 [M]+. C20H14ClNO4. Calculated:
M 367.0606.
N-(3-Acetylphenyl)-N-[3-(4-methylpiperazin-1-
yl)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)acetamide
(VIb). Reaction time 2.5 h. The tarry residue obtained
after chromatography was washed with petroleum
ether (40–70°C), and the residual solvent was removed
under reduced pressure (water-jet pump). Yield 39%,
solid substance, mp 144–146°C (from ethanol). IR
1
spectrum, ν, cm–1: 1640, 1671 (C=O). H NMR spec-
trum (CDCl3), δ, ppm: 2.17 s (3H, CH3), 2.31 s (3H,
NCH3), 2.45 m (2H, NCH2), 2.56 s (3H, CH3), 2.63 m
(2H, NCH2), 3.30 m (2H, NCH2), 3.71 m (2H, NCH2),
7.44 m (1H, 5′-H), 7.52 m (1H, 6′-H), 7.66 m (2H,
6-H, 7-H), 7.72 m (1H, 4′-H), 7.80 m (1H, 2′-H),
N-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-2-
yl)-N-(3-methoxyphenyl)acetamide (Vc). Reaction
time 50 h (~55°C). The precipitate was subjected to
column chromatography on silica gel (50–160 µm)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

BEREZHNAYA et al.
1828
7.86 m and 8.00 m (1H each, 5-H, 8-H). Electronic
absorption spectrum: λmax 479 nm (logε 3.53). Found:
m/z 431.1846 [M]+. C25H25N3O4. Calculated:
M 431.18396.
5′-H), 7.40 m (1H, 2′-H), 7.53 m (1H, 4′-H), 7.64 m
(2H, 6-H, 7-H), 8.01 m (2H, 5-H, 8-H). Electronic
absorption spectrum: λmax 556 nm (logε 3.31). Found:
m/z 389.1737 [M]+. C23H23N3O3. Calculated:
M 389.1734.
N-(3-Methoxyphenyl)-N-[3-(4-methylpiperazin-
1-yl)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)acet-
amide (VIc). Reaction time 20 h. Yield 71%, mp 141–
144°C (from benzene–petroleum ether). IR spectrum,
2-(3-Methoxyphenylamino)-3-(4-methylpipera-
zin-1-yl)-1,4-dihydronaphthalene-1,4-dione (VIIc).
Reaction time 10 h. Yield 62%, mp 96–97°C (from
petroleum ether, bp 40–70°C). IR spectrum, ν, cm–1:
1
ν, cm–1: 1635, 1671 (C=O). H NMR spectrum
1
3300 (NH), 1644 (C=O). H NMR spectrum (CDCl3),
(CDCl3), δ, ppm: 2.16 s (3H, COCH3), 2.30 s (3H,
NCH3), 2.45 m (2H, NCH2), 2.64 m (2H, NCH2),
3.27 m (2H, NCH2), 3.74 m (5H, NCH2, OCH3),
6.76 m (1H, 6′-H), 6.82 m (1H, 2′-H), 6.86 m (1H,
4′-H), 7.20 m (1H, 5′-H), 7.64 m (2H, 6-H, 7-H), 7.96 m
and 8.00 m (1H each, 5-H, 8-H). Electronic absorption
spectrum: λmax 481 nm (log ε 3.53). Found: m/z
419.1841 [M]+. C24H25N3O4. Calculated: M 419.1400.
δ, ppm: 2.12 s (3H, NCH3), 2.16 (4H, NCH2), 3.25 m
(4H, NCH2), 3.76 s (3H, OCH3), 6.36 s (1H, NH),
6.52 m (2H, 4′-H, 6′-H), 7.07 s (1H, 2′-H), 7.14 m (1H,
5′-H), 7.61 m (2H, 6-H, 7-H), 7.98 m (2H, 5-H, 8-H).
Electronic absorption spectrum: λmax 571 nm (logε
3.34). Found: m/z 377.1730 [M]+. C22H23N3O3. Calcu-
lated: M 377.1734.
Quaternary piperazinium salts (general proce-
dure). a. A suspension of 0.5 mmol of 2-(4-alkylpiper-
azin-1-yl)-3-chloro-1,4-naphthoquinone II in 15 ml
of methanol was heated until complete dissolution,
0.13 ml of methyl iodide was added at ~35°C, and the
mixture was kept at that temperature, additional
0.13-ml portions of methyl iodide being added every
8 h. The precipitate was filtered off, washed with
diethyl ether, and dried.
Hydrolysis of N-aryl-N-[3-(4-methylpiperazin-
1-yl)-1,4-dioxo-1,4-dihydronaphthalen-2-yl)acet-
amides VIa–VIc (general procedure). The reaction
was carried out according to the procedure described in
[13]. The mixture was then poured into water, acidified
with 4% hydrochloric acid, and extracted with chloro-
form. The extract was dried over Na2SO4 and evapo-
rated, and the residue was subjected to column chro-
matography on silica gel (50–160 µm–160–315 µm ≈
1:2) using CCl4, CH2Cl2, and C6H6–acetone (4:1) as
eluents (in succession). The black–blue fraction
(C6H6–acetone, 4:1) was evaporated to dryness, and
the residue was crystallized from appropriate solvent.
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-2-
yl)-1,1-dimethylpiperazinium iodide was synthesized
as described in [10]. Electronic absorption spectrum
(H2O): λmax 475 nm (logε 3.54).
2-(4-Methylphenylamino)-3-(4-methylpiperazin-
1-yl)-1,4-dihydronaphthalene-1,4-dione (VIIa).
Reaction time 12 h. Yield 79%, mp 60–63°C (from
petroleum ether). IR spectrum, ν, cm–1: 3297 (NH),
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-
2-yl)-1-(2-cyanoethyl)-1-methylpiperazinium iodide
(IIIe). Reaction time 32 h. Yield 40%, mp 187–189°C.
1
IR spectrum, ν, cm–1: 1650, 1673 (C=O). H NMR
1
1640 (C=O). H NMR spectrum (CDCl3), δ, ppm:
spectrum (CD3CN), δ, ppm: 3.06 m (1H), 3.20 s (3H,
NCH3), 3.48–3.62 m (5H), 3.76–3.90 m (6H), 7.81 m
(2H), 8.05 m (2H). Electronic absorption spectrum
(H2O): λmax 477 nm. Found, %: C 45.48; H 4.52;
I 26.29; N 8.27. C18H19ClIN3O2. Calculated, %:
C 45.81; H 4.30; I 26.94; N 8.91.
2.10 m (7H, NCH2, NCH3), 2.29 (3H, CH3), 3.17 t
3
(4H, NCH2), 6.75 d (2H, 2′-H, 6′-H, J = 8.0 Hz),
3
7.02 d (2H, 3′-H, 5′-H, J = 8.0 Hz), 7.11 br.s (1H,
NH), 7.59 m (2H, 6-H, 7-H), 7.98 m (2H, 5-H, 8-H).
Electronic absorption spectrum: λmax 570 nm (logε
3.47). Found: m/z 361.1792 [M]+. C22H23N3O2. Cal-
culated: M 361.1785.
1-Benzyl-4-(3-chloro-1,4-dioxo-1,4-dihydronaph-
thalen-2-yl)-1-methylpiperazinium iodide (IIIg).
Reaction time 38 h. Yield 83%, mp 213–215°C.
1H NMR spectrum (CD3CN), δ, ppm: 3.09 s (3H,
NCH3), 3.38–3.51 m (2H), 3.58–3.73 m (2H), 3.82–
3.93 m (4H), 4.65 s (2H), 7.56 m (5H), 7.80 m (2H),
8.05 m (2H). Electronic absorption spectrum (H2O):
λmax 476 nm. Found, %: C 51.84; H 4.20; I 25.01;
N 5.20. C22H 22ClIN2O2. Calculated, %: C 51.92;
H 4.33; I 24.96; N 5.51.
2-(3-Acetylphenylamino)-3-(4-methylpiperazin-
1-yl)-1,4-dihydronaphthalene-1,4-dione (VIIb).
Reaction time 12.5 h. Yield 21%, mp 157–159°C
(from C6H6–petroleum ether). IR spectrum, ν, cm–1:
1
3345 (NH); 1680, 1652, 1640 (C=O). H NMR spec-
trum (CDCl3), δ, ppm: 2.12 s (3H, NCH3), 2.16 m (4H,
NCH2), 2.57 s (3H, CH3), 3.22 m (4H, NCH2), 7.06 d
3
(1H, 6′-H, J = 8.0 Hz), 7.16 s (1H, NH), 7.33 m (1H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

SYNTHESIS OF PHOTOACTIVE 1-METHYL-1-R-4-(1,4-DIOXO-1,4-DIHYDRO...
1829
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-
2-yl)-1-(2-hydroxypropyl)-1-methylpiperazinium
iodide (IIIh). Reaction time 25 h. Yield 68%, mp 237–
239°C. IR spectrum, ν, cm–1: 1632, 1680 (C=O).
1H NMR spectrum (CD3CN), δ, ppm: 1.23 d (3H,
CH3), 3.25 s (3H, NCH3), 3.32–3.89 m (11H), 4.40 br.s
(1H), 7.80 m (2H), 8.05 m (2H). Electronic absorption
spectrum (H2O): λmax 474 nm. Found, %: C 45.23;
H 4.56; I 26.98; N 5.57. C18H22ClIN2O3. Calculated,
%: C 45.33; H 4.62; I 26.65; N 5.88.
H 5.72; Cl 6.77; I 26.00; N 5.99. C20H26ClIN2O2. Cal-
culated, %: C 51.11; H 5.81; Cl 6.86; I 24.59; N 5.42.
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-2-
yl)-1-decylpiperazinium iodide (IIId). Reaction time
10 days. Yield 77%, mp 160–164°C. IR spectrum, ν,
1
cm–1: 2928, 2857 (C–H); 1673, 1647 (C=O). H NMR
spectrum (CD3CN), δ, ppm: 0.86 t (3H, CH3), 1.32 m
(14H, CH2), 1.75 m (2H, CH2), 3.15 s (3H, NCH3),
3.42 m (2H, NCH2), 3.53 m (4H, NCH2), 3.83 m (4H,
NCH2), 7.78 m (2H, 6-H, 7-H), 8.03 m (2H, 5-H, 8-H).
Electronic absorption spectrum (EtOH): λmax 462 nm
(logε 3.49). Found, %: C 53.48; H 6.97; Cl 6.62;
I 22.68; N 4.98. C25H36ClIN2O2. Calculated, %:
C 53.72; H 6.45; Cl 6.36; I 22.74; N 5.01.
b. Methyl iodide, 2 ml (32 mmol), was added to
a warm solution of 1.4 mmol of 2-(4-alkylpiperazin-1-
yl)-3-chloro-1,4-naphthoquinone in 15 ml of methanol,
and the mixture was kept in a closed vessel in the dark
at room temperature until the initial quinone disap-
peared. The precipitate was filtered off, washed with
methanol, and dried.
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-
2-yl)-1-(3-chloro-2-hydroxypropyl)-1-methylpiper-
azinium iodide (IIIi). Reaction time 30 days. Yield
79%, mp 218–220°C (decomp.). IR spectrum, ν, cm–1:
1-Butyl-4-(3-chloro-1,4-dioxo-1,4-dihydronaph-
thalen-2-yl)-1-methylpiperazinium iodide (IIIa).
Reaction time 7 days. Yield 75%, mp 226–228°C. IR
1
3442 (OH); 2999 (C–H); 1678, 1641 (C=O). H NMR
spectrum (CD3CN), δ, ppm: 3.30 s (3H, NCH3), 3.50–
3.90 m (12H, CH2, OH), 4.35 m (1H, NCH2), 4.50 m
(1H, CHOH), 7.81 m (2H, 6-H, 7-H), 8.08 m (2H,
5-H, 8-H). Electronic absorption spectrum (EtOH):
λmax 467 nm (logε 3.33). Found, %: C 42.18; H 4.28;
Cl 13.74; I 25.28; N 5.36. C17H18ClIN2O3. Calculated,
%: C 42.27; H 4.11; Cl 13.87; I 24.85; N 5.48.
1
spectrum, ν, cm–1: 1650, 1674 (C=O). H NMR spec-
trum (CD3CN), δ, ppm: 1.00 t (3H, CH3), 1.40 m (2H),
1.75 m (3H), 3.12 s (3H, NCH3), 3.41 m (2H), 3.50 m
(4H), 3.83 m (4H), 7.81 m (2H), 8.06 m (2H). Elec-
tronic absorption spectrum (H2O): λmax 475 nm
(logε 3.57). Found, %: C 47.97; H 5.07; I 26.89;
N 5.81. C19H24ClIN2O2. Calculated, %: C 48.05;
H 5.06; I 26.77; N 5.90.
4-(1,4-Dioxo-1,4-dihydronaphthalen-2-yl)-1-
ethyl-1-methylpiperazinium bromide (IIIj). Ethyl
bromide, 3.3 ml (0.044 mol), was added to a warm
solution of 1.000 g (3.9 mmol) of 2-(4-methylpiper-
azin-1-yl)-1,4-naphthoquinone in 40 ml of ethanol, and
the mixture was left to stand for 15 days in a closed
vessel in the dark at room temperature. The precipitate
was filtered off, washed with ethanol, and dried. Yield
0.401 g (28%), mp 243–245°C. IR spectrum, ν, cm–1:
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-
2-yl)-1-methyl-1-pentylpiperazinium iodide (IIIb).
Reaction time 9 days. Yield 83%, mp 233–236°C. IR
spectrum, ν, cm–1: 2951, 2869 (C–H); 1672, 1641
1
(C=O). H NMR spectrum (CD3CN), δ, ppm: 0.96 t
(3H, CH3), 1.37 m (4H, CH2), 1.80 m (2H, CH2),
3.13 s (3H, NCH3), 3.40 m (2H, NCH2), 3.50 m (4H,
NCH2), 3.85 m (4H, NCH2), 7.82 m (2H, 6-H, 7-H),
8.08 m (2H, 5-H, 8-H). Electronic absorption spectrum
(EtOH): λmax 465 nm (logε 3.48). Found, %: C 49.38;
H 5.72; Cl 7.12; I 26.00; N 5.81. C20H26ClIN2O2. Cal-
culated, %: C 49.13; H 5.32; Cl 7.25; I 26.00; N 5.73.
1
1676, 1621 (C=O). H NMR spectrum (CD3CN), δ,
ppm: 1.32 s (3H, CH3), 3.03 s (3H, NCH3), 3.45 m
(6H, NCH2), 3.71 s (2H, NCH2), 3.85 m (2H, NCH2),
6.10 s (1H, 3-H), 7.74 m (2H, 6-H, 7-H), 7.98 m
(2H, 5-H, 8-H). Electronic absorption spectrum:
λmax 429 nm (logε 3.39). Found, %: C 55.23; H 5.89;
Br 21.92; N 7.69. C17H21BrN2O2. Calculated, %:
C 55.89; H 5.75; Br 21.90; N 7.67.
4-(3-Chloro-1,4-dioxo-1,4-dihydronaphthalen-
2-yl)-1-heptyl-1-methylpiperazinium iodide (IIIc).
Reaction time 10 days. Yield 53%, mp 233–236°C. IR
spectrum, ν, cm–1: 2928, 2857 (C–H); 1672, 1652
1,1-Dimethyl-4-(1,4-dioxo-1,4-dihydronaphtha-
len-2-yl)piperazinium iodide (IIIk) was synthesized
as described in [10]. Methyl iodide, 0.2 ml (2 mmol),
and triethylamine, 0.18 ml (1.3 mmol), were added to
a warm solution of 0.243 g (0.001 mol) of 2-(piper-
azin-1-yl)-1,4-naphthoquinone in 10 ml of methanol.
The mixture was kept for 5 days in a closed vessel in
1
(C=O). H NMR spectrum (CD3CN), δ, ppm: 0.92 t
(3H, CH3), 1.37 m (8H, CH2), 1.78 m (2H, CH2),
3.14 s (3H, NCH3), 3.39 m (2H, NCH2), 3.52 m (4H,
NCH2), 3.85 m (4H, NCH2), 7.82 m (2H, 6-H, 7-H),
8.06 m (2H, 5-H, 8-H). Electronic absorption spectrum
(EtOH): λmax 463 nm (logε 3.55). Found, %: C 50.81;
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

BEREZHNAYA et al.
1830
the dark at room temperature, an additional portion of
methyl iodide, 0.2 ml, was added, and the mixture was
kept for 5 days more. The precipitate was filtered off,
washed with methanol, and dried. Yield 0.340 g (85%),
mp 253–255°C (decomp.). IR spectrum, ν, cm–1: 2955
4-[3-(3-Acetylphenylamino)-1,4-dioxo-1,4-dihy-
dronaphthalen-2-yl]-1,1-dimethylpiperazinium
iodide (VIIIb). Methyl iodide, 1 ml (16 mmol), and
three drops of triethylamine were added to a warm
solution of 0.195 g (0.5 mmol) of compound VIIb in
30 ml of ethanol, and the mixture was left to stand for
24 h in a closed vessel at room temperature. The mix-
ture was evaporated to dryness, the tarry residue was
treated with 1 ml of benzene and 1 ml of petroleum
ether, and the precipitate was filtered off and washed
with petroleum ether (bp 40–70°C). Yield 0.26 g
(98%), mp 128–130°C. IR spectrum, ν, cm–1: 3304
1
(C–H); 1672, 1637 (C=O). H NMR spectrum
(CD3CN), δ, ppm: 3.15 s (6H, NCH3), 3.48 m (4H,
CH2), 3.76 m (4H, CH2), 6.15 s (1H, 3-H), 7.75 m (2H,
6-H, 7-H), 7.97 m (2H, 5-H, 8-H). Electronic absorp-
tion spectrum (H2O): λmax 443 nm (logε 3.21). Found,
%: C 48.23; H 4.69; I 31.89; N 7.34. C16H19ClIN2O2.
Calculated, %: C 48.24; H 4.77; I 31.91; N 7.04.
1
(NH); 1678, 1642 (C=O). H NMR spectrum (CDCl3),
1,1-Dimethyl-4-(1,4-dioxo-1,4-dihydronaphtha-
len-2-yl)piperazinium hexafluorophosphate(V)
(IIIl). Piperazinium iodide IIIk, 0.203 g (5 mmol),
was dissolved in a mixture of 35 ml of water and 10 ml
of acetonitrile, the solution was filtered, and a solution
of 0.196 g (1 mmol) of KPF6 in 10 ml of water was
added dropwise under stirring. After 1 h, the mixture
was diluted with 60 ml of water for more complete
precipitation. The precipitate was filtered off, washed
with ice water, and dried. Yield 0.186 g (89%),
mp 289–291°C (decomp.). IR spectrum, ν, cm–1: 2955
δ, ppm: 2.64 s (3H, CH3), 3.26 (4H, NCH2), 3.32 s
(6H, NCH3), 3.41 m (4H, NCH2), 7.31 m (1H, 6′-H),
7.49 m (1H, 5′-H), 7.56 m (1H, 2′-H), 7.65 m (1H,
4′-H), 7.68 s (1H, NH), 7.72 m (2H, 6-H, 7-H), 8.10 m
(2H, 5-H, 8-H). Electronic absorption spectrum:
λmax 503 nm (logε 3.36). Found, %: C 54.03; H 5.12;
I 23.90; N 7.34. C24H26IN3O3. Calculated, %: C 54.34;
H 4.90; I 23.92; N 7.91.
4-[3-(3-Methoxyphenylamino)-1,4-dioxo-1,4-di-
hydronaphthalen-2-yl]-1,1-dimethylpiperazinium
iodide (VIIIc). Methyl iodide, 2 ml (32 mmol), and
three drops of triethylamine were added to a warm
solution of 0.247 g (0.66 mmol) of compound VIIc in
20 ml of ethanol, and the mixture was left to stand for
5 days in a closed vessel at room temperature. The
mixture was then evaporated to dryness, and the
residue was crystallized from petroleum ether (bp 40–
70°C). Yield 0.263 g (77%), mp 70–73°C. IR spec-
trum: ν 1641 cm–1 (C=O). 1H NMR spectrum (CDCl3),
δ, ppm: 3.07 (6H, NCH3), 3.35 m (4H, NCH2), 3.82 s
(3H, OCH3), 6.59 m (1H, 2′-H), 6.68 m (1H, 4′-H),
6.78 m (1H, 6′-H), 7.29 m (1H, 5′-H), 7.48 s (1H, NH),
7.68 m (2H, 6-H, 7-H), 8.02 m (2H, 5-H, 8-H). Elec-
tronic absorption spectrum: λmax 500 nm (logε 2.97).
Found, %: C 52.73; H 5.04; I 25.08; N 7.83.
C23H26IN3O3. Calculated, %: C 53.18; H 5.01; I 24.47;
N 8.09.
1
(C–H); 1672, 1637 (C=O). H NMR spectrum
(CD3CN), δ, ppm: 3.15 s (6H, NCH3), 3.48 m (4H,
CH2), 3.76 m (4H, CH2), 6.15 s (1H, 3-H), 7.75 m (2H,
6-H, 7-H), 7.97 m (2H, 5-H, 8-H). Electronic absorp-
tion spectrum (EtOH): λmax 430 nm (logε 1.71). Found,
%: C 46.61; H 4.55; F 27.43; N 6.46; P 7.16.
C16H19N2O2 ·PF6. Calculated, %: C 46.15; H 4.57;
F 27.40; N 6.73; P 7.16.
1,1-Dimethyl-4-[3-(4-methylphenylamino)-1,4-
dioxo-1,4-dihydronaphthalen-2-yl]piperazinium
iodide (VIIIa). Methyl iodide, 3 ml (48 mmol), and
five drops of triethylamine were added to a warm
solution of 1.441 g (4 mmol) of compound VIIa in
50 ml of ethanol, and the mixture was left to stand for
2 days in a closed vessel in the dark at room tempera-
ture. The precipitate was filtered off, washed with eth-
anol, and dried. Yield 1.45 g (72%), mp 233–236°C.
IR spectrum, ν, cm–1: 3335 (NH); 1656, 1640 (C=O).
1H NMR spectrum (CDCl3), δ, ppm: 2.37 s (3H, CH3),
3.04 (4H, NCH2), 3.28 m (4H, NCH2), 3.34 s (6H,
NCH3), 6.97 d (2H, 2′-H, 6′-H, 3J = 8 Hz), 7.17 d (2H,
4-[3-(N-Acetyl-3-methoxyphenylamino)-1,4-di-
oxo-1,4-dihydronaphthalen-2-yl]-1,1-dimethylpi-
perazinium iodide (VIIId). Methyl iodide, 2 ml
(32 mmol), and three drops of triethylamine were
added to a warm suspension of 0.419 g (1 mmol) of
compound VIc in 30 ml of ethanol, and the mixture
was kept for 7 days in a closed vessel at room tem-
perature. The precipitate was filtered off, washed with
ethanol, and dried. Yield 0.437 g (78%), mp 206–
209°C. IR spectrum, ν, cm–1: 1678, 1642 (C=O).
3
3′-H, 5′-H, J = 8 Hz), 7.46 s (1H, NH), 7.61 t and
7.71 t (1H each, 6-H, 7-H), 8.00 m (2H, 5-H, 8-H).
Electronic absorption spectrum: λmax 488 nm
(logε 3.23). Found, %: C 54.29; H 5.26; I 25.61;
N 8.36. C23H26IN3O2. Calculated, %: C 54.87; H 5.17;
I 25.25; N 8.35.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

SYNTHESIS OF PHOTOACTIVE 1-METHYL-1-R-4-(1,4-DIOXO-1,4-DIHYDRO...
1831
1H NMR spectrum (CDCl3), δ, ppm: 2.13 s (3H, CH3),
3.15 (6H, NCH3), 3.37–3.58 m (8H, NCH2), 3.79 s
(3H, OCH3), 6.91 m (3H, 2′-H, 4′-H, 6′-H), 7.31 m
(1H, 5′-H), 7.83 m (2H, 6-H, 7-H), 8.11 m (2H, 5-H,
8-H). Electronic absorption spectrum: λmax 455 nm
(logε 3.45). Found, %: C 52.71; H 4.92; I 22.01;
N 7.25. C24H25IN3O4. Calculated, %: C 53.48; H 4.99;
I 22.64; N 7.49.
2. Shishkina, R.P. and Berezhnaya, V.N., Usp. Khim.,
1994, vol. 63, p. 145.
3. Gritsan, N.P., Bazhin, N.M., Golovacheva, V.G., Erosh-
kin, V.I., and Fokin, E.P., USSR Inventor’s Certificate
no. 679925, 1979; Byull. Izobret., 1979, no. 30, p. 171.
4. Do Minh, T., Fleming, J., and Lindstrom, M., US Patent
no. 4684599, 1987; Chem. Abstr., 1988, vol. 108,
no. 85322s.
5. Shishkina, R.P., Ektova, L.V., Matoshina, K.I., and
Fokin, E.P., Izv. Sib. Otd. Akad. Nauk SSSR, Ser. Khim.
Nauk, 1982, issue 12, no. 5, p. 136.
6. Shishkina, R.P., Mamatyuk, V.I., and Fokin, E.P., Izv.
Akad. Nauk SSSR, Ser. Khim., 1985, no. 4, p. 855.
Determination of light sensitivity of materials
based on quaternary (1,4-dioxo-1,4-dihydronaph-
thalen-2-yl)piperazinium salts. Light-sensitive layers
were prepared from solutions of piperazinium salts in
acetonitrile containing 15 vol % of water (c = 3×
10–4 M). An oxidized aluminum plate was immersed in
a solution containing a piperazinium salt and was dried
at room temperature to remove residual moisture under
nonactinic light. The sample was exposed with a fila-
ment lamp (adaptation illuminance E = 1200 lx) over
different periods of time. The exposed material was
treated with a 0.002 M solution of palladium(II)
chloride in water to activate development. The sample
was developed over a period of 5 min with a solution
for chemical precipitation of silver with the following
composition: 0.1 g of OP-7 surfactant, 39 g of Mohr’s
salt, 19 g of iron(III) nitrate, 9 g of citric acid, 4.5 g of
silver nitrate, and distilled water (up to 500 ml). The
optical density was measured using a DO-1 optical
densitometer. Characteristic curves were plotted for
each substance on the basis of the optical density
values. The light sensitivities were determined from
the characteristic curves by the formula S0.2 = 1/H,
where H is the exposition necessary to obtain an op-
tical density higher by 0.2 unit than that of fog.
7. Shishkina, R.P., Mamatyuk, V.I., Ektova, L.V., and
Fokin, E.P., Izv. Akad. Nauk SSSR, Ser. Khim., 1985,
no. 11, p. 2524.
8. Shishkina, R.P., Korobeinicheva, I.K., and Ektova, L.V.,
Sib. Khim. Zh., 1991, no. 4, p. 102.
9. Weygand–Hilgetag Organisch-chemische Experimen-
tierkunst, Hilgetag, G. and Martini, A., Eds., Leipzig:
Johann Ambrosius Barth, 1964, 3rd ed. Translated
under the title Metody eksperimenta v organicheskoi
khimii, Moscow: Khimiya, 1968, p. 423; Organikum.
Organisch-chemisches
Grundpraktikum,
Berlin:
Wissenschaften, 1976, 15th edn. Translated under the
title Organikum. Praktikum po organicheskoi khimii,
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The authors thank L.V. Ektova for providing
a sample of 2-(3-acetylphenylamino)-3-chloro-1,4-
naphthoquinone (IVb).
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Sib. Otd. Akad. Nauk SSSR, Ser. Khim. Nauk, 1987,
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