Synthesis of Fluorinated Polycyclic Aromatic Hydrocarbons Through a Photochemical Cyclization

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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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P1: MRM

Polycyclic Aromatic Compounds TJ595-06 February 9, 2002 17:29

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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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

)

76

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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

)

77

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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%

)

78

Dow

nloa

ded

by [

RM

IT U

nive

rsity

] at

22:

16 2

1 M

arch

201

3

P1: MRM


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)

79

Dow

nloa

ded

by [

RM

IT U

nive

rsity

] at

22:

16 2

1 M

arch

201

3

P1: MRM


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.

80

Dow

nloa

ded

by [

RM

IT U

nive

rsity

] at

22:

16 2

1 M

arch

201

3

P1: MRM



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

Dow

nloa

ded

by [

RM

IT U

nive

rsity

] at

22:

16 2

1 M

arch

201

3

P1: MRM


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.

82

Dow

nloa

ded

by [

RM

IT U

nive

rsity

] at

22:

16 2

1 M

arch

201

3

P1: MRM



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.

Dow

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] at

22:

16 2

1 M

arch

201

3

P1: MRM


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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ded

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arch

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8. K. Sielex and J. T. Andersson, Synthesis of Cl2− to Cl4− diphenylsulfides and Cl1−

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Synthesis of Fluorinated Polycyclic Aromatic Hydrocarbons Through a Photochemical Cyclization

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Transcript of Synthesis of Fluorinated Polycyclic Aromatic Hydrocarbons Through a Photochemical Cyclization