Synthesis of Fluorinated Polycyclic Aromatic Hydrocarbons Through a Photochemical Cyclization
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This article was downloaded by: [RMIT University]On: 21 March 2013, At: 22:16Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK
Polycyclic Aromatic CompoundsPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/gpol20
Synthesis of Fluorinated Polycyclic AromaticHydrocarbons Through a Photochemical CyclizationUwe Weis a & Jan T. Andersson ba Department of Analytical and Environmental Chemistry, University of Ulm, Ulm, Germanyb Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, GermanyVersion of record first published: 27 Oct 2010.
To cite this article: Uwe Weis & Jan T. Andersson (2002): Synthesis of Fluorinated Polycyclic Aromatic Hydrocarbons Througha Photochemical Cyclization, Polycyclic Aromatic Compounds, 22:1, 71-85
To link to this article: http://dx.doi.org/10.1080/10406630210376
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Polycyclic Aromatic Compounds, 22:71–85, 2002
Copyright c© 2002 Taylor & Francis
1040-6638/02 $12.00 + .00
SYNTHESIS OF FLUORINATED POLYCYCLICAROMATIC HYDROCARBONS THROUGH APHOTOCHEMICAL CYCLIZATION
Uwe WeisDepartment of Analytical and Environmental Chemistry,University of Ulm, Ulm, Germany
Jan T. AnderssonInstitute of Inorganic and Analytical Chemistry, Universityof Munster, Munster, Germany
Chromatographic determination of polycyclic aromaticcompounds (PACs) is commonly performed with internalstandards. Presently, perdeuterated PACs are widely usedas internal standards, although they possess severaldisadvantages. Fluorinated PACs can be used instead toavoid those drawbacks. The synthesis of 12 three- tofive-ring PACs containing up to three fluorine atoms isdescribed here together with extensive spectral data.
Keywords fluorinated polycyclic aromatic compounds, internal standard,photocyclization, Wittig-Horner-Emmons
Polycyclic aromatic compounds (PACs) are routinely determinedusing chromatographic techniques, which necessitates the use ofstandards—either (surrogate) internal standards (IS), which are addedto the sample, or external, which may be the analytes themselves. Verycommon as IS are PACs, which are supposed not to occur in the sample,or perdeuterated analogues of compounds in the sample. Although
Received 3 January 2001; accepted 28 May 2001.The authors thank Karin Weißenhorn and Hendrik M¨uller for their support with recording
the NMR data.This article was taken from the Ph.D. thesis of Uwe Weis, University of Ulm, Ulm, Germany,
1994.Address correspondence to Jan T. Andersson, Department of Analytical Chemistry, Uni-
versity of Munster, Wilhelm-Klemm-Strasse 8, D-48149 M¨unster, Germany. E-mail: [email protected]
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72 U. Weis and J. T. Andersson
perdeuterated PACs (d-PAC) are widely used, they possess several dis-advantages that make their use less than ideal. First, there is a limitednumber of them commercially available. Also, there is little variationpossible so that if a d-PAC is found to coelute with another samplecomponent, a mass-selective detector has to be used to quantitate theIS. Although the desirable purity of an IS is 100%, the purity of thecommercially available d-PACs usually ranges between 98% and99%.
In an attempt to circumvent those problems, we investigated fluori-nated PACs (F-PACs) as IS and found that they indeed present many ad-vantages (1–3). For each parent structure, several fluorinated derivativesare imaginable, which means that an IS can be selected for each sampleso that coelution does not occur. There are so many F-PACs available thatseveral can be used in the same analysis, thereby providing an internalmethod for checking for coelution problems (2). They also can be easilysynthesized for specialized analytical problems. An example of this isprovided in a work that reported on the determination of dimethylben-zothiophenes in crude oils; here, 5-fluoro-2, 7-dimethylbenzothiophenewas synthesized as an ideal IS (3).
Although our main interest in these compounds is their use as chro-matographic standards, it should be noted that they invoke interest inother fields also. Thus, many fluorinated polycyclic aromatics have beenused in carcinogenicity studies (4).
Since few F-PACs can be purchased from chemical supply houses,they presently must be synthesized in the laboratory. In this article, wereport on the synthetic procedures we have used for mono- to tri-fluoro-PACs with three to five aromatic rings, and we present extensive spectraldata on them.
RESULTS AND DISCUSSION
Syntheses
We selected the synthetic target molecules so that they are distributedthroughout the gas chromatographic elution range in a typical PAC anal-ysis covering compounds with two to six aromatic rings. Since fluori-nated naphthalenes are commercially available, they are not consideredhere. As has been shown in previous works (1, 2), it is highly desirableto use several standards, so that several fluorinated congeners for eachparent group are prepared.
For most compounds synthesized here, a photochemical ring closureof a suitably substituted stilbene was the central step in the synthesis
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Synthesis of Fluorinated PAHs 73
FIGURE 1. Synthesis of the fluoroarenes.
(5) (step 3 in Figure 1). This reaction has proven to be useful for otherfluorinated PACs, e.g., monofluorobenzo[c]phenanthrenes (6) but, withthe exception of 1,3-difluorobenzo[c]phenanthrene (7), does not seem tohave to been used for di- or higher F-PACs. Of the compounds describedhere, only 3-fluorophenanthrene appears to have been made previouslyusing this synthetic approach (5). Halogen loss occasionally has beenreported to occur on photolysis of halogenated aromatics, but we didnot encounter troubling problems with the present systems. Only whena halogen atom in the ortho-position of the stilbene is present can a de-halogenation occur together with the ring closure at the halogenatedposition; this dehalogenation has been used for chlorinated systems(8–10).
The stilbenes were routinely prepared from a benzaldehyde and adiethyl benzylphosphonate according to Wittig-Horner-Emmons (11,12) (step 2 in Figure 1). The gas chromatographic (GC) analysis of thestilbenes indicated a purity of at least 99% for the sum of the E- andZ-isomers. Fluorobenzylphosphonates were prepared in a Michaelis-Arbuzov reaction from triethyl phosphite and the corresponding benzylhalide (13, 14) (step 1 in Figure 1).
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TAB
LE1.
Syn
thes
isof
Flu
orin
ated
Pol
ycyc
licA
rom
atic
Hyd
roca
rbon
s(F
-PA
Hs)
—Y
ield
and
Mel
ting
Poi
nt
Yie
ldM
eltin
gpo
int
Sol
vent
for
Dur
atio
nof
Com
poun
d(%
)(◦ C
)re
crys
taliz
atio
nra
diat
ion
(hr)
3-F
luor
ophe
nant
hren
ea
7582
–84
Eth
anol
14.0
1,2-
Difl
uoro
phen
anth
renea
4110
8–11
1E
than
ol16
.03,
6-D
ifluo
roph
enan
thre
nea64
139–
141
Eth
anol
16.0
2,4,
6-T
rifluo
roph
enan
thre
nean.
d.98
–102
Eth
anol
18.0
1,3-
Difl
uoro
benz
o[c]p
hena
nthr
enea
5712
8–13
0E
than
ol12
.01,
2-D
ifluo
roch
ryse
neb27
228–
230
Ben
zene
:eth
anol
1:1
3.5
1,3-
Difl
uoro
chry
seneb
4121
4–22
0B
enze
ne:e
than
ol1:
14.
01,
4-D
ifluo
roch
ryse
neb41
157.
5–15
8.5
Cyc
lohe
xane
1.0
2,4-
Difl
uoro
chry
seneb
5614
5–14
5.5
Ben
zene
:eth
anol
1:1
3.5
11-F
luor
oben
zo[g]ch
ryse
neb
6712
5–12
8B
enze
ne3.
013
-Flu
orob
enzo
[g]ch
ryse
neb
5715
2–15
4B
enze
ne:e
than
ol1:
11.
512
,14-
Difl
uoro
benz
o[g]c
hrys
eneb
4216
2–16
3B
enze
ne:e
than
ol1:
12.
0
n.d.
,not
dete
rmin
ed.
aP
hoto
cycl
izat
ion
usin
gai
ras
oxid
anta
ccor
ding
to(1
6).
bP
hoto
cycl
izat
ion
usin
gio
dine
asox
idan
tacc
ordi
ngto
(15)
.
74
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Synthesis of Fluorinated PAHs 75
The stilbene mixture was used directly for the photochemical ringclosure in benzene with iodine as oxidant and propylene oxide presentto capture the hydrogen iodide formed (15) (step 3 in Figure 1). Theyield in this reaction was in most cases around 50% (Table 1). If thereis a choice of different positions, bond formation takes place accordingto statistical frequency.
Spectral Data
The ultraviolet (UV), infrared (IR), nuclear magnetic resonance(NMR), and mass spectroscopic (MS) data are collected in Tables 2and 3, and yields, boiling points, and refractive indices in Table 4. TheUV data of the synthesized fluoroaromatics are included as they are use-ful for the selection of the optimum wavelength for high-performanceliquid chromatography (HPLC) detection.
The mass spectra are dominated by the parent ion, which is always thebase peak. A fragment corresponding to (M-20)+ (loss of HF) is of vari-able intensity, ranging from 3% for 11-fluorobenzo[g]chrysene to 22%for 1,3-difluorobenzo[c]phenanthrene. The doubly charged M2+-ion hasapproximately the same intensity as the (M-20)+. Finally it should benoted that the ion (M-20)2+ was clearly observable for the compoundswith four and five rings (mass 138 cluster).
EXPERIMENT
The equipment for the characterization of the compounds is listed inTable 5. The commercially available compounds from Aldrich, Fluka,or Merck (Germany) were used without further purification. Solventsfor the syntheses were of technical grade and were also used withoutpurification. Their purity was determined by GC and was in all cases>99%. Benzene was redistilled to a purity>98%.
Analysis
Sample Preparation
The course of the photocyclization was followed chromatographically(Table 5). One mL of reaction solution was filled into a 2 mLvial and0.5 mL of a 0.05M sodium thiosulfate solution was added. The vialwas shaken until the iodine color disappeared. The aqueous layer wasdiscarded, and the organic layer was used for chromatographic analysis.
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TAB
LE2.
Spe
ctro
scop
icD
ata
ofth
eF
luor
inat
edP
olyc
yclic
Aro
mat
icH
ydro
carb
ons
(F-P
AH
s)
Com
poun
dM
etho
dS
pect
rosc
opic
data
3-F
luor
ophe
nant
hren
e1H
-NM
R7.
34(1
H,d
t,3J=
8.3
Hz,
4J=
2.5
Hz)
;7.6
3(4
H,m
);7.
88(2
H,m
);8.
29(1
H,d
d,3J=
10.8
Hz,
4J=
2.4
Hz)
;8.5
4(1
H,d
d,3J=
9.2
Hz,
4J=
2.5
Hz)
13C
-NM
R10
7.64
;107
.94;
115.
45;1
15.7
7;12
2.87
;126
.14;
126.
30;1
26.6
3;12
7.18
;128
.64;
130.
51;1
30.6
2;13
2.29
;163
.29
19F
-NM
R−1
13.5
9M
S19
7(1
7%);
196
(100
%);
194
(13%
);17
6(4
%);
175
(3%
);98
(9%
)IR
1,60
0(s
);1,
507
(s);
1,45
2(m
);1,
205
(m);
1,17
7(m
);86
6(m
);83
5(s
);73
9(s
)U
V29
1(0
.33)
;249
(1.7
9);2
11(0
.99)
1,2-
Difl
uoro
phen
anth
rene
1H
-NM
R7.
45(1
H,m
);7.
65(2
H,m
);7.
82(1
H,d
,3J=
9.2
Hz)
;7.9
1(1
H,m
);7.
99(1
H,d
,3J=
9.2
Hz)
;8.3
8(1
H,m
);8.
57(1
H,d
,3J=
7.5
Hz)
13C
-NM
R11
6.05
;117
.96;
118.
86;1
22.6
4;12
3.17
;127
.01;
127.
46;1
27.6
5;12
8.54
;128
.94;
129.
47;1
31.5
1;14
5.69
(d,
1J=
250
Hz)
;147
.65
(d,1J=
247
Hz)
19F
-NM
R−1
41.0
8;−1
48.4
7M
S21
5(1
5%);
214
(100
%);
212
(12%
);19
4(6
%);
193
(6%
);10
7(6
%);
106
(5%
)IR
1,63
8(m
);1,
476
(s);
1,28
0(m
);1,
255
(m);
889
(m);
811
(s);
777
(m);
754
(s)
UV
294
(0.1
1);2
51(0
.45)
;207
(0.2
6)1,
2-D
ifluo
roch
ryse
ne1H
-NM
R7.
51(1
H,q
,3J=
7.5
Hz)
;8.0
1(1
H,m
);8.
25(1
H,d
,3J=
9.4
Hz)
;8.4
9(1
H,m
);8.
59(1
H,d
,3J=
9.4
Hz)
;8.7
8(2
H,m
)13
C-N
MR
116.
35;1
16.5
7;11
8.57
;119
.54;
120.
83;1
22.7
5;12
3.09
;123
.43;
126.
77;1
27.0
7;12
7.59
;127
.95;
128.
30;1
28.6
4;13
0.38
;132
.13;
145.
43(d
,1J=
250
Hz)
;14
7.19
(d,1J=
248
Hz)
ppm
19F
-NM
R−1
41.3
0;−1
48.6
5M
S26
5(2
0%);
264
(100
%);
263
(11%
);26
2(2
5%);
244
(6%
);13
2(9
%)
IR1,
636
(m);
1,43
8(m
);1,
375
(m);
1,28
1(s
);1,
010
(m);
822
(m);
803
(s);
750
(s)
UV
266
(0.9
0);2
57(0
.56)
;217
(.33
)
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1,3-
Difl
uoro
chry
sene
1H
-NM
R7.
11(1
H,m
);7.
69(2
H,m
);8.
00(2
H,m
);8.
17(2
H,m
);8.
47(1
H,d
,3J=
9.3
Hz)
;8.
70(1
H,d
,3J=
9.3
Hz)
;8.7
6(1
H,q
,3J=
6.8
Hz)
13C
-NM
R10
1.28
;101
.57;
101.
86;1
03.7
6;10
4.01
;118
.97;
120.
86;1
21.0
7;12
3.32
;127
.02;
127.
90;1
28.6
3;12
9.31
;130
.30;
132.
50;1
32.6
3;15
9.71
;(d,
1J=
255
Hz)
;16
0.75
(d,1J=
246
Hz)
19F
-NM
R−1
10.9
7;−1
18.1
0M
Sn.
m.
IR1,
634
(m);
1,59
6(m
);1,
429
(m);
1,11
2(s
);99
4(m
);81
5(s
);74
7(s
);74
3(s
)U
V26
7(1
.09)
;258
(0.6
1);2
19(0
.29)
3,6-
Difl
uoro
phen
anth
rene
1H
-NM
R7.
34(2
H,d
t,3J=
8.3
Hz,
4J=
2.4
Hz)
;7.6
3(2
H,s
,4+
5−H
);7.
82(2
H,d
d,3J=
8.9
Hz,
4J=
5.9
Hz)
;8.0
9(2
H,d
d,3J=
10.7
Hz,
4J=
2.4
Hz)
13C
-NM
R10
7.95
;116
.28;
125.
51;1
28.9
2;13
0.65
;131
.20;
161.
53(d
,1J=
246
Hz)
19F
-NM
R−1
13.3
8M
S21
5(1
4%);
214
(100
%);
212
(9%
);19
4(8
%);
193
(7%
);10
7(9
%)
IR1,
600
(m);
1,44
1(s
);1,
203
(s);
1,16
9(s
);85
6(s
);84
1(m
);55
3(m
)U
V28
9(0
.13)
;248
(0.8
5);2
10(0
.44)
2,4,
6-T
rifluo
roph
enan
thre
ne1H
-NM
R7.
14(1
H,m
);7.
36(2
H,m
);7.
60(1
H,d
d,3J=
8.8
Hz,
4J=
2.7
Hz)
;7.7
4(1
H,d
,3J=
8.8
Hz)
;7.8
6(1
H,d
d,3J=
8.8
Hz,
4J=
6.2
Hz)
;8.6
7(1
H,t
d,3J=
12.4
Hz,
4J=
3.5
Hz)
13C
-NM
R10
3.33
;109
.10;
112.
46;1
15.7
3;11
6.00
;125
.11;
128.
69;1
28.9
1;12
9.34
;130
.39;
135.
38;1
60.4
2(d
,1J=
249
Hz)
;161
.76
(d,1J=
245
Hz)
;161
.78
(d,1J=
257
Hz)
19F
-NM
R−1
05.6
7;−1
11.7
1;−1
11.8
6M
S23
3(1
4%);
232
(100
%);
230
(6%
);21
2(7
%);
211
(5%
);11
6(7
%)
IR1,
450
(s);
1,41
7(s
);1,
211
(s);
1,11
0(s
);99
4(s
);85
4(s
);82
4(s
);56
4(s
)U
V29
5(0
.20)
;245
(1.0
6);2
04(0
.46)
(Co
ntin
ue
do
nn
extp
age
)
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TAB
LE2.
Spe
ctro
scop
icD
ata
ofth
eF
luor
inat
edP
olyc
yclic
Aro
mat
icH
ydro
carb
ons
(F-P
AH
s)(C
on
tinu
ed
)
Com
poun
dM
etho
dS
pect
rosc
opic
data
1,4-
Difl
uoro
chry
sene
1H
-NM
R7.
26(2
H,m
);7.
70(2
H,m
);8.
02(2
H,m
);8.
25(1
H,d
d,3J=
9.8
Hz,
4J=
2.2
Hz)
;8.
80(1
H,d
,3J=
8.8
Hz)
;8.8
5(1
H,d
,3J=
8.8
Hz)
;9.1
2(1
H,d
d,3J=
9.9
Hz,
4J=
4.4
Hz)
13C
-NM
R11
0.16
;112
.38;
118.
93;1
20.9
2;12
2.80
;123
.25;
123.
52;1
24.9
1;12
6.45
;126
.75;
126.
96;1
28.0
1;12
8.35
;129
.34;
129.
95;1
32.1
0;15
4.92
(d,
1J=
247
Hz)
;15
7.23
(d,1J=
254
Hz)
19F
-NM
R−1
14.1
5;−1
26.4
3M
S26
5(2
2%);
264
(100
%);
263
(11%
);26
2(2
4%);
244
(6%
);13
2(9
%)
IR1,
597
(m);
1,44
7(m
);1,
431
(s);
1,28
4(m
);1,
217
(m);
812
(s);
745
(s);
733
(s)
UV
265
(1.0
4);2
17(0
.36)
2,4-
Difl
uoro
chry
sene
1H
-NM
R7.
17(1
H,m
);7.
40(1
H,m
);7.
66(2
H,m
);7.
85(1
H,d
d,3J=
9.2,
4J=
2.5
Hz)
;7.
98(2
H,m
);8.
72(2
H,m
);9.
03(1
H,d
d,3J=
9.2
Hz,
4J=
3.4
Hz)
13C
-NM
R10
3.22
;103
.60;
103.
98;1
08.4
6;10
8.74
;123
.02;
123.
50;1
24.5
8;12
4.93
;126
.33;
126.
79;1
28.0
2;12
8.35
;130
.09;
131.
82;1
35.1
1;15
9.45
(d,
1J=
247
Hz)
;15
9.76
(d,1J=
248
Hz)
19F
-NM
R−1
04.4
4;−1
13.1
1M
S26
5(1
9%);
264
(100
%);
263
(10%
);26
2(1
9%);
244
(6%
);13
2(8
%)
IR1,
629
(s);
1,52
5(s
);1,
422
(s);
1,29
6(s
);1,
105
(s);
995
(s);
843
(s);
752
(s)
UV
262
(1.0
1);2
16(0
.31)
1,3-
Difl
uoro
benz
o[c]p
hena
nthr
ene
1H
-NM
R7.
16(1
H,m
);7.
43(1
H,d
dd,3J=
8.7
Hz,
4J=
2.6
Hz,
5J=
1.1
Hz)
;7.5
8(2
H,m
);7.
73(3
H,m
);7.
94(2
H,m
);8.
24(1
H,m
)13
C-N
MR
102.
80;1
08.1
4;12
4.80
;125
.02;
125.
78;1
26.2
1;12
6.33
;127
.46;
128.
35;1
28.7
8;12
9.34
;129
.56;
129.
90;1
31.1
1;13
3.03
;135
.64;
159.
73(d
,1J=
257
Hz)
;16
0.21
(d,1J=
248
Hz)
19F
-NM
R−9
4.44
;−11
3.20
MS
265
(21%
);26
4(1
00%
);26
3(2
6%);
262
(26%
);24
4(2
2%);
131
(14%
)
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P1: MRM
Polycyclic Aromatic Compounds TJ595-06 February 9, 2002 17:29
IR1,
630
(s);
1,52
4(m
);1,
124
(m);
996
(s);
849
(s);
822
(s);
743
(s);
661
(s)
UV
295
(0.2
0);2
80(0
.81)
;217
(0.4
8)11
-Flu
orob
enzo
[g]ch
ryse
ne1H
-NM
R7.
24(1
H,m
);7.
53(1
H,m
);7.
65(4
H,m
);8.
26(1
H,d
,3J=
9.8
Hz)
8.67
(5H
,m);
8.83
(1H
,d,3J=
8.1
Hz)
13C
-NM
R10
9.68
;109
.96;
116.
01;1
19.6
0;11
9.70
;121
.29;
123.
17;1
23.5
4;12
3.88
;124
.26;
124.
31;1
25.7
4;12
5.84
;126
.18;
126.
92;1
27.4
9;12
8.66
;129
.47;
130.
20;1
31.0
9;13
1.96
;159
.06
(d,1J=
251
Hz)
19F
-NM
R−1
22.6
9M
S29
7(2
2%);
296
(100
%);
295
(45%
);29
4(3
8%);
276
(3%
);14
7(1
5%);
138
(6%
)IR
1,60
9(m
);11
,442
(m);
1,41
0(m
);1,
236
(s);
838
(m);
807
(s);
748
(s);
718
(s)
UV
286
(1.1
5);2
76(1
.16)
;266
(0.9
6);2
09(0
82)
13-F
luor
oben
zo[g]ch
ryse
ne1H
-NM
R7.
29(1
H,m
);7.
61(4
H,m
);7.
87(2
H,m
);8.
43(1
H,d
,3J=
9.0
Hz)
;8.5
3(2
H,m
);8.
62(2
H,m
);8.
77(1
H,d
,3J=
9.9
Hz)
13C
-NM
R11
2.52
;112
.81;
115.
23;1
15.5
4;12
0.04
;123
.08;
123.
52;1
23.7
6;12
6.26
;126
.73;
127.
28;1
27.3
7;12
8.51
;128
.76;
129.
24;1
29.5
4;13
0.17
;130
.29;
130.
78;1
31.0
1;13
1.19
;161
.31;
(d,1J=
244
Hz)
19F
-NM
R−1
14.5
2M
S29
7(2
3%);
296
(100
%);
295
(46%
);29
4(3
9%);
276
(4%
);14
6(9
%);
138
(4%
)IR
1,62
5(m
);1,
452
(m);
1,43
2(m
);1,
184
(m);
835
(s);
752
(s);
744
(s);
720
(s)
UV
285
(1.8
2);2
75(1
.78)
;259
(1.4
4);2
09(1
.21)
12,1
4-D
ifluo
robe
nzo[g
]chr
ysen
e1H
-NM
R7.
13(1
H,m
);7.
44(1
H,d
dd,3J=
8.7
Hz,
4J=
2.6
Hz,
5J=
1.0
Hz)
;7.6
3(4
H,m
);7.
85(1
H,d
,3J=
9.3
Hz)
8.10
(1H
,m);
8.52
(2H
,m);
8.61
(1H
,d,
3J=
9.3
Hz)
;8.
68(1
H,m
)13
C-N
MR
102.
63;1
02.9
8;10
3.36
;107
.63;
107.
90;1
22.8
3;12
2.96
;123
.27;
123.
54;1
25.4
8;12
6.78
;126
.94;
127.
35;1
27.3
8;12
8.94
;129
.12;
130.
03;1
30.4
5;13
0.48
;135
.44;
156.
81(d
,1J=
258
Hz)
;160
.16
(d,1J=
248
Hz)
19F
-NM
R−9
4.24
;−11
3.06
MS
315
(23%
);31
4(1
00%
);31
3(2
4%);
312
(24%
);29
4(2
1%);
156
(12%
);14
7(9
%)
IR1,
629
(s);
1,57
4(m
);1,
122
(s);
993
(s);
859
(s);
755
(s);
744
(s);
720
(s)
UV
275
(1.0
8);2
09(0
.66)
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P1: MRM
Polycyclic Aromatic Compounds TJ595-06 February 9, 2002 17:29
TAB
LE3.
Spe
ctro
scop
icD
ata
ofD
ieth
ylB
enzy
lpho
spho
nate
s
Com
poun
dM
etho
dS
pect
rosc
opic
data
Die
thyl
2-flu
orob
enzy
lpho
spho
nate
1H
-NM
R1.
40(6
,t);
3.35
(2,d
);4.
20(4
,q);
7.35
(4,m
)M
S24
6(1
2%);
198
(24%
);12
4(2
0%);
110
(23%
);10
9(1
00%
);83
(25%
);81
(34%
)IR
1,49
6(s
);1,
253
(s);
1,05
5(s
);1,
028
(s);
966
(s);
758
(m)
Die
thyl
4-flu
orob
enzy
lpho
spho
nate
1H
-NM
R1.
15(6
,t);
3.05
(2,d
);3.
95(4
,q);
6.90
(2,t
);7.
20(2
,m)
MS
246
(8%
);12
4(9
%);
110
(8%
);10
9(1
00%
);83
(13%
);81
(13%
)IR
1,51
1(s
);1,
226
(s);
1,05
5(s
);1,
028
(s);
966
(s);
856
(m);
797
(m);
561
(m)
Die
thyl
2,4-
diflu
orob
enzy
lpho
spho
nate
1H
-NM
R1.
05(6
,t);
2.95
(2,d
);3.
85(4
,q);
6.60
(2,m
);7.
15(2
,m)
MS
264
(16%
);21
6(1
6%);
127
(100
%);
109
(38%
);10
1(1
2%);
91(1
6%);
81(2
4%)
IR1,
507
(s);
1,27
2(s
);1,
253
(s);
1,05
4(s
);1,
028
(s);
968
(s);
850
(m)
Die
thyl
2,5-
diflu
orob
enzy
lpho
spho
nate
1H
-NM
R1.
10(6
,t);
3.00
(2,d
);3.
85(4
,m);
6.80
(3,m
)M
Sn.
d.IR
1,50
1(s
);1,
252
(s);
1,05
4(s
);1,
028
(s);
968
(s);
808
(m);
722
(m)
Die
thyl
3,4-
diflu
orob
enzy
lpho
spho
nate
1H
-NM
R1.
20(6
,t);
3.00
(2,d
);4.
00(4
,m);
7.00
(3,m
)M
S26
4(1
2%);
208
(13%
);12
7(1
00%
);10
9(4
6%);
91,(
12%
);81
(26%
)IR
1,51
9(s
);1,
250
(s);
1,05
5(s
);1,
029
(s);
967
(s);
799
(m);
620
(m)
Die
thyl
3,5-
diflu
orob
enzy
lpho
spho
nate
1H
-NM
R1.
20(6
,t);
3.00
(2,d
);4.
00(4
,m);
6.60
(1,m
);6.
75(2
,d)
MS
264
(26%
);20
8(2
4%);
127
(100
%);
109
(67%
);10
1(2
4%);
91(2
6%);
81(5
5%)
IR1,
598
(s);
1,11
9(s
);1,
055
(s);
1,02
8(s
);98
8(s
);68
6(m
);57
0(m
)D
ieth
yl1-
naph
thal
enyl
met
hylp
hosp
hona
te1H
-NM
R1.
00(6
,t);
3.50
(2,d
);3.
80(4
,m);
7.35
(4,m
);7.
65(2
,m);
7.95
(1,d
)M
S27
9(9
%);
278
(44%
);14
2(1
2%);
141
(100
%);
115
(24%
)IR
1,25
3(s
);1,
054
(s);
1,02
7(s
);96
3(s
);80
7(m
);77
8(s
)
n.d.
,not
dete
rmin
ed.
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P1: MRM
Polycyclic Aromatic Compounds TJ595-06 February 9, 2002 17:29
Synthesis of Fluorinated PAHs 81
Chromatography
The purity of solvents and the synthesized phosphonates was checkedby GC as detailed in Table 5. OneµL was injected at an oven temperatureof 50◦C/2 min, ramp at 10◦C/min to 240◦C, and held for 2 min.
The purity of the F-PACs was determined by GC with on-columninjection (Table 5). OneµL was injected at an over temperature of80◦C/2 min, ramp at 4◦C/min to 270◦C, and held for 5 min.
The course of the photocyclization reaction of the fluorophenan-threnes was monitored by GC using splitless/split injector in splitlessmode (Table 5) for 60 s. OneµL was injected at an oven temperature of80◦C/2 min, ramp at 10◦C/min to 270◦C, and held for 5 min.
Four- and five-ring F-PAHs were analyzed using reversed-HPLC(RP-HPLC) (Table 5). FiveµL of the analyte solution was injected.The mobile phase was 70/30 methanol/water for four-ring F-PAHs and75/25 for five-ring F-PAHs).
Syntheses
Arylphosphonates
Triethyl phosphite (60 mmole) and benzyl halide (50 mmol) wereplaced in a 100-mL round bottom flask fitted with a reflux condenserand a drying tube. Nitrogen was bubbled through the liquid for about15 min. Gas bubbles caused by the escaping ethyl halide indicated thestart of the reaction. After reflux for several hours, the product wasworked up by distillation through a short Vigreux column. The puritywas determined by GC. Yields, boiling points, and refractive indexesare listed in Table 4 and the spectroscopic data in Table 3.
Stilbenes
Benzene (25 mL) and tetrabutylammonium hydrogen sulfate (350 mg)as phase transfer catalyst were placed in a 100 mL round bottom flask.A sodium hydroxide solution (50%, 25 mL) was added to the stirredbenzene solution. Diethyl benzylphosphonate (25 mmol) and aldehyde(25 mmol) were dissolved in 5 mL benzene. The mixture was added tothe flask and then refluxed for 1 hr with continued stirring. After attain-ing room temperature, the phases were separated and the organic layerwashed three times with water and dried over magnesium or sodiumsulfate.
The filtered solution was concentrated to 25 mL on a rotary evapo-rator. The product was purified through open column chromatography
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P1: MRM
Polycyclic Aromatic Compounds TJ595-06 February 9, 2002 17:29
TAB
LE4.
Die
thyl
Ben
zylp
hosp
hona
tes—
Sta
rtin
gC
ompo
unds
,Yie
ld,a
ndM
easu
red
Phy
sica
lCon
stan
ts
Sta
rtin
gco
mpo
und
Pro
duct
Yie
ld(%
)B
.p.
an D
b
2-F
luor
oben
zylb
rom
ide
Die
thyl
2-flu
orob
enzy
lpho
spho
nate
90.1
82◦ C
at4
Pa
1.48
43-
Flu
orob
enzy
lchl
orid
eD
ieth
yl3-
fluor
oben
zylp
hosp
hona
te66
.781
◦ Cat
4P
a1.
482
4-F
luor
oben
zylc
hlor
ide
Die
thyl
4-flu
orob
enzy
lpho
spho
nate
78.6
103
◦ Cat
4P
a1.
480
2,4-
Difl
uoro
benz
ylbr
omid
eD
ieth
yl2,
4-di
fluor
oben
zylp
hosp
hona
ten.
d.c
n.d.
c1.
463
2,5-
Difl
uoro
benz
ylbr
omid
eD
ieth
yl2,
5-di
fluor
oben
zylp
hosp
hona
te75
.273
◦ Cat
5P
a1.
472
3,4-
Difl
uoro
benz
ylbr
omid
eD
ieth
yl3,
4-di
fluor
oben
zylp
hosp
hona
te59
.487
◦ Cat
4P
a1.
470
3,5-
Difl
uoro
benz
ylbr
omid
eD
ieth
yl3,
5-di
fluor
oben
zylp
hosp
hona
ten.
d.c
n.d.
c1.
465
1-C
hlor
omet
hyln
apht
hale
neD
ieth
ylna
phth
alen
ylm
ethy
lpho
spho
nate
83.8
140
◦ Cat
4P
a1.
565
aB
oilin
gpo
int.
bR
efra
ctiv
ein
dex
at20◦
C.
c Not
dete
rmin
ed.
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P1: MRM
Polycyclic Aromatic Compounds TJ595-06 February 9, 2002 17:29
Synthesis of Fluorinated PAHs 83
TABLE 5. Equipment Used
Method Apparatus
1. Refractive index Refractometer 1 T from Atago (Tokyo, Japan)connected with a cryostate TP F20HC from Julabo(Seelbach, Germany)
2. Melting point Thermovar (Reicheit, Sande, Germany)3. UV spectra UV-2100 from Shimadzu (Duisburg, Germany);
quartz cuvettes, methanolic solutions, d= 1 cm4. IR spectra IFS 113V from Bruker (Karlsruchen, Germany);
fluids were measured as film solids as KBr-pellet5. NMR spectra ARX 300 (AM 360a) from Bruker; 5 mm tubes,
solution in deuterochloroform withtetramethylsilane as internal standard1H 300.13 MHz (360.14 MHza)13C 75.47 MHz (90.57 MHza)19F 282.37 MHz
6. Mass spectra (GC-MS) HP 5890 A with on-column injector fitted witha HP 5970 B from Hewlett Packard (Waldbronn,Germany)
Column: J&W (Boblingen, Germany) DB-5—25 m;0.32 mm; 0.25µm
Carrier gas: Helium7. Purity check, solvents (GC) Delsi Di200 (Houston, Texas, USA) with splitless/
split injector and two flame ionization detectorsand hydrogen as carrier
Columns: J&W DB-5—30 m; 0.32 mm; 0.25µm;J&W DBWAX—30 m; 0.32 mm; 0.25µm
8. Reaction control (GC) Pye Unicam type PU 4500 (Kassel, Germany) withsplitless/split injector and flame ionization detector
Column: SGE (Damestadt, Germany) BP-5—25 m;0.22 mm; 0.25µm
Carrier gas: Hydrogen9. Reaction control (HPLC) Pump type 64 from Knauer (Berlin, Germany);
injection valveRheodyne (Bensheim, Germany) type 7125Detector: Altex UV detector,254 nm Column: RP-C18—120 mm; 4 mm 10µm
UV, ultraviolet; IR, ; NMR, ; GC-MS, ; GC, ; HPLC, high-performance liquid chromatography.aFor 1,2-difluorophenanthrene, 2,4,6-trifluorophenanthrene, 1,2-Difluorochrysene, 1,3-Difluo-
rochrysene, and 1,4-Difluorochrysene.
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84 U. Weis and J. T. Andersson
(20 g silica gel 60, 0.063–0.2 mm) with cyclohexane as eluent. Theeffluent was diluted to 100 mL and used directly for the photocyclization.
Fluoroaromatics
An aliquot of the stilbene solution containing 0.2 mmol stilbene, aniodine solution (5 mL; 40 mM in benzene), and benzene (700 mL) wereplaced in the photoreactor fitted with a high-pressure quartz mercuryvapor lamp (Hanau, 150 W). Nitrogen was bubbled through the solutionfor 20 min. Five mL propylene oxide was added and the irradiationstarted. The reaction was followed by GC for the phenanthrenes and byRP-HPLC for the other PACs. For mean irradiation time, see Table 1.This procedure was repeated until all the available stilbene solution hadreacted.
The combined batches were concentrated on the rotary evaporator.Iodine was removed by shaking with a sodium thiosulfate solution. Theorganic solution was washed and dried with magnesium or sodium sul-fate, and the product was purified by column chromatography and re-crystallization. Solvents, yields, and melting points are listed in Table 1.
REFERENCES
1. J. T. Andersson and U. Weis, Fluorinated internal standards for the quantitationof polycyclic aromatic compounds in a chimney ash sample, inPolycyclic Aro-matic Compounds: Synthesis, Properties, Analytical Measurements, Occurence andBiological Effects, ed. P. Garrigues and M. Lamotte (Gordon & Breach, 1993),85–91.
2. J. T. Andersson and U. Weis, Gas chromatographic determination of polycyclicaromatic compounds with fluorinated analogues as internal standards.Journal ofChromatography A659 (1994):151–161.
3. J. T. Andersson and K. Sielex, Dimethylbenzothiophenes and methyldibenzothio-phenes in crude oils from different sources.Journal of High Resolution Chromatog-raphy19 (1996):49–53.
4. S. Amin, E. H. Weyand, K. Huie, E. Boger, E. Neuber, S. S. Hecht, and E. J.Lavoie, Effects of fluorine substitution on benzo[b]fluoranthene tumorigenicity andDNA adduct formation in mouse skin, inPolynuclear Aromatic Hydrocarbons:Measurements, Means, and Metabolism, ed. M. Cooke, K. Loening, and J. Merritt(Columbus, Ohio: Battelle Press, 1991), 25–35.
5. F. B. Mallory and C. W. Mallory, Photocyclization of stilbenes and related molecules,in Organic Reactions 30, ed. W. G. Dauben (New York: John Wiley & Sons, 1984),1–217.
6. Y. Ittah and D. M. Jerina, Synthesis of monofluorobenz[c]phenanthrenes.Journalof Fluorine Chemistry16 (1980):137–144.
7. M. J. Plater, Synthesis of benzo[ghi]fluoranthenes from l-halobenzo[c]phenan-threnes by flash vacuum pyrolysis.Tetrahedron Letters35 (1994):6147–6150.
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to Cl3−dibenzothiophenes.Chemosphere38 (1994):3529–3539.9. R. Cosmo and S. Sternhell, Steric Effects. Inversion of 4,5-disubstituted 9,10-
dihydrophenanthrenes.Australian Journal of Chemistry40 (1987):35–47.10. J.-K. Luo, H. Kudo, R. F. Federspiel, and R. N. Castle, The synthesis of novel
polycyclic heterocyclic ring systems via photocyclization. 15, [1]benzothieno[3′,2′-4,5]thieno[2,3-c]quinoline, [1]benzothieno[3′,2′-4,5]thieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline, [1]benzothieno[3′,2′-4,5]thieno[2,3-c]tetrazolo[1,5-a]quinoline,thieno[3′,2′-4,5]thieno[2,3-c][1,2,4]trianolo[4,3-a]quinoline, and thieno[3′,2′-4,5]thieno[2,3-c]tetrazolo[1,5-a]quinoline. Journal of Heterocyclic Chemistry, 32(1995):317–322.
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12. J. Boutagy, and R. Thomas, Olefin synthesis with organic phosphonate carbanions.Chemical Reviews74 (1974):87–99.
13. H. G. Henning and G. Hilgetag, M¨oglichkeiten und grenzen der Michaelis-Arbusow-reaktion.Zeitschrift fur Chemie7 (1967):169–176.
14. B. C. Saunders, G. J. Stacey, F. Wild, and I. G. E. Wilding, Esters containing phos-phorus. Part V. Esters of substituted phosphonic and phosphonous acids.Journalof the Chemical Society(1948): 699–703.
15. L. Liu, B. Yang, T. J. Katz, and M. K. Poindexter, Improved methodology forphotocyclization reactions.Journal of Organic Chemistry56 (1991):3769–3775.
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