Synthesis of a series of dichloroamino- and dihalosulfonamido-1,3,5-triazines and investigation of their hindered rotation and stereodynamic behaviour by NMR spectroscopy

Article abstract of DOI:10.1039/a808753i

Mono-substituted 1,3,5-triazines (s-triazines) have been prepared and characterised by NMR spectroscopy. The room temperature ¹³C NMR spectra of dichloroamino-s-triazines show three signals for the triazine ring, clearly indicating that C(2) and C(3) are in inequivalent environments. At elevated temperatures, two of the signals broaden and coalesce. Conversely, a number of dihalosulfonamido-s-triazine compounds were found to display only one signal for C(2) and C(3), indicating that the degree of π-bonding in the exocyclic C-N bond in these compounds is less significant. The low temperature exchange limits for the dihalosulfonamido-s-triazine compounds are reported.

Full text of DOI:10.1039/a808753i

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Synthesis of a series of dichloroamino- and dihalosulfonamido-
1,3,5-triazines and investigation of their hindered rotation and
stereodynamic behaviour by NMR spectroscopy
Stuart A. Brewer,* Helen T. Burnell, Ian Holden, Brian G. Jones and Colin R. Willis
DERA, CBD Porton Down, Salisbury, Wiltshire, UK SP4 0JQ
Received (in Cambridge) 9th November 1998, Accepted 29th March 1999
Mono-substituted 1,3,5-triazines (s-triazines) have been prepared and characterised by NMR spectroscopy. The
room temperature 13C NMR spectra of dichloroamino-s-triazines show three signals for the triazine ring, clearly
indicating that C(2) and C(3) are in inequivalent environments. At elevated temperatures, two of the signals broaden
and coalesce. Conversely, a number of dihalosulfonamido-s-triazine compounds were found to display only one
signal for C(2) and C(3), indicating that the degree of π-bonding in the exocyclic C–N bond in these compounds is
less significant. The low temperature exchange limits for the dihalosulfonamido-s-triazine compounds are reported.
Table 1 13C NMR data for dichloroamino-s-triazine compounds and
Introduction
estimated values of the free energy of rotation (∆G‡)
Cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) is an
H
R
N
extremely important compound that finds widespread appli-
cation in dye chemistry,1 agriculture2 and the textile industry.3
Displacement of the chlorine atoms by nucleophiles such as
amines, alcohols and phenols has been well documented4 and a
wide range of substitution products may be prepared. Con-
sidering the simplicity and widespread application of these
compounds, it is somewhat surprising that so little has been
reported on their stereodynamics. All studies to date have
investigated restricted rotation in the more complicated di- and
tri-amino-substituted s-triazines5 (s-triazine = 1,3,5-triazine)
and to our knowledge no reference has been made to the
simpler mono-amino derivatives. During the course of our
research on low surface energy textile treatments for cellulose, a
number of dichloroamino-s-triazine derivatives were required.
We now report their synthesis and stereodynamics as studied by
NMR spectroscopy.
N
1
N
3
2
Cl
N
Cl
δC/ppm (proton
decoupled)
∆G‡/
kJ
No.
R
Solvent
T/ЊC C(1)
C(2)/C(3)
molϪ1
1
2
3
C8H17
C2H5
CDCl3
CDCl3
26
20
29
166.5 170.2, 171.3 78
165.4 169.2, 170.8
166.8 170.6, 171.6 79
167.5 171.2
—
CH2C7F15 CDCl3
C6D5NO2
120
limitation of the instrument. The fluorinated analogue 3 dis-
plays a lower coalescence temperature and the fast exchange
limit for this compound was observed at 120 ЊC. The fluxional
behaviour exhibited by these triazines is indicative of restricted
rotation about the exocyclic C–N bond, due to π-bonding, and
is comparable to that displayed by amides. In the case of 3, the
lower coalescence temperature indicates that the inductive
effect of the perfluoroalkyl chain is sufficient to diminish the
degree of double-bond character, despite the presence of the
Results and discussion
Dichloroamino-s-triazine compounds, 1, 2 and 3 were prepared
by the treatment of cyanuric chloride with the corresponding
alkylamine. Mono-substitution can be attained at 0 ЊC owing
to electron-donation from the exocyclic nitrogen atom in the
product increasing the electron density of the ring, which stabil-
ises the remaining C–Cl bonds. The dichlorosulfonamido-s-
triazine derivatives are prepared by the reaction of cyanuric
chloride with the sodium salt of the corresponding sulfon-
amide. However, unlike the mono-amino derivatives, consider-
able care is needed in the preparation of the mono-sulfonamido
analogues. The C–Cl bonds in these compounds remain labile
to further substitution owing to the electron-withdrawing effect
of the sulfonamide group6 and low temperatures are required
to avoid formation of the di- and tri-substituted derivatives.
The degree of π-bonding in the exocyclic C–N bond in these
compounds was therefore predicted to be much less than
that in the mono-amino derivatives. Evidence for this is clearly
discernible from the NMR data.
methylene spacer group (cf. CH3CH2NH2, Kb = 4.5 × 10Ϫ4
CF3CH2NH2, Kb = 5.0 × 10Ϫ9).7
,
The room temperature proton decoupled 13C NMR data for
the sulfonamide derivatives 4, 5, 8† and 9 displayed only two
resonances for the triazine ring, indicating that C(2) and C(3)
are equivalent owing to free rotation of the sulfonamide group
about the exocyclic C–N bond (fluorine coupling in 8 and 9
causes C(2)/C(3) to appear as a doublet of doublets and C(1)
as a triplet). Therefore, in contrast to the amino analogues,
relatively little double bond character exists between the sulfon-
amide nitrogen and the triazine ring. The free energies of acti-
vation for rotation (∆G‡) were estimated and are presented in
Tables 1 and 2. The ∆G‡ values for the sulfonamide derivatives
were significantly lower than those obtained for the amino-
triazines.
The room temperature proton decoupled 13C NMR spectrum
of 1, 2 and 3 displayed three distinct signals for the triazine ring
(Table 1) indicating inequivalence of C(2) and C(3). Increasing
the temperature revealed that for 1 and 2, the C(2) and C(3)
resonances coalesce at approximately 120 ЊC. The fast exchange
spectrum could not be recorded owing to the temperature
† A pure sample of triazine 8 could not be obtained, however the
signals corresponding to the impurities were remote from the area of
interest.
J. Chem. Soc., Perkin Trans. 2, 1999, 1231–1234
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Table 2 13C NMR data for dihalosulfonamido-s-triazine compounds (b: broad, t: triplet, dd: doublet of doublets) and estimated values of the free
energy of rotation (∆G‡)
C2H5
SO2R
N
1
N
N
3
2
X
N
X
δC/ppm (proton decoupled)
No.
R
X
Solvent
T/ЊC
C(1)
C(2)/(3)
∆G‡/kJ molϪ1
4
C8H17
Cl
d8-THF
0
Ϫ70
Ϫ90
24
Ϫ50
Ϫ90
24
Ϫ70
2
Ϫ60
20
Ϫ50
Ϫ90
24
Ϫ60
Ϫ90
166.1
165.9
165.8
165.1
164.8
164.6
166.2
166.1
170.6 (t)
170.5 (t)
170.3 (t)
170.0 (t)
170.0 (t)
169.3 (t)
168.9 (t)
168.8 (t)
171.3
44
171 (b), 172 (b)
170.2, 171.4
171.1
170 (b), 172 (b)
169.8, 171.2
172.1
171.8
172.4 (dd)
172.2 (dd)
172.0 (dd)
173 (b), 170 (b)
171.2 (dd), 172.1 (dd)
171.8 (dd)
170 (b), 173 (b)
171.0 (dd), 171.9 (dd)
5
C6H4CH3
Cl
d8-THF
—
6
7
8
C8F17
C8F17
C8H17
Cl
F
d8-THF
d8-THF
d8-THF
—
—
44
F
9
C6H4CH3
F
d8-THF
44
In an attempt to observe the fluxional behaviour of the
sulfonamide group, low-temperature 13C NMR spectra were
recorded. The C(2)/C(3) resonance in 4, 5, 8 and 9 broadens as
the temperature decreases and almost disappears at approxi-
mately Ϫ50 ЊC. At Ϫ70 ЊC, C(2) and C(3) appear as two
individual resonances and slow exchange is observed at
approximately Ϫ90 ЊC.
equation: ∆G‡ = RTc[23 ϩ 2.3log10(Tc/∆ν)] where Tc = coales-
cence temperature (K), ∆ν = frequency separation (Hz) and R =
gas constant (J molϪ1).9 Mass spectra were obtained by positive
liquid secondary ion mass spectrometry (LSIMS) using a
Micromass Autospec SQ Mass Spectrometer. Melting points
are uncorrected.
The perfluoroalkyl derivatives 6 and 7 displayed a similar
trend to that observed for 3, where the coalescence temperature
of the respective class of triazine was lowered by the strong
electron-withdrawing capacity of the perfluoroalkyl group.6,8
Unfortunately, the solution became gelatinous on further cool-
ing and the slow exchange spectrum of 6 and 7 could not be
recorded.
In conclusion, the syntheses and stereodynamic behaviour
of various dichloroamino-s-triazines and dihalosulfonamido-s-
triazines are reported. The 13C NMR data provides useful
information about the distribution of electron density in a
range of s-triazines. The data correlate well with the greater
reactivity of the C–Cl bond in dichlorosulfonamido-s-triazines
relative to dichloroamino-s-triazines. Surprisingly, although
difluoro-s-triazines display greater reactivity relative to the
dichloro-analogues, significant differences in their fluxional
NMR behaviour were not observed. A more detailed study of
coalescence temperature is therefore required. The dihalo-s-
triazines containing a perfluorosulfonamido-group exhibited
the lowest coalescence temperature of the compounds investi-
gated.
Solvents and reagents
Analytical grade solvents were used as supplied. Cyanuric
chloride (Aldrich) was recrystallised from chloroform. Cyanuric
fluoride and N-ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadeca-
fluorooctane-1-sulfonamide (Fluorochem) were used as sup-
plied. 4-Methylbenzenesulfonyl chloride and octanesulfonyl
chloride (Aldrich) were used as supplied. N-Ethyloctane-1-
sulfonamide and N-ethyl-4-methylbenzenesulfonamide were
prepared from the corresponding sulfonyl chloride and ethyl-
amine gas in dichloromethane.
N-Octyl-4,6-dichloro-1,3,5-triazin-2-amine 1. Cyanuric chlor-
ide (2.86 g, 15.5 mmol), dissolved in chloroform (100 cm3), was
added to a solution of sodium carbonate (1.64 g, 15.5 mmol)
dissolved in water (40 cm3). The two-phase mixture was stirred
vigorously and cooled to 0–5 ЊC. Octylamine (2.00 g, 15.5
mmol) dissolved in chloroform (5 cm3) was added dropwise.
The reaction mixture was stirred vigorously for 1 h at 0–5 ЊC
and then allowed to warm to room temperature. The organic
layer was separated and washed with water (3 × 10 cm3) and
dried over sodium sulfate. Filtration and removal of the chloro-
form by evaporation under reduced pressure afforded N-octyl-
4,6-dichloro-1,3,5-triazin-2-amine 1 (3.66 g, 85%) as a white
solid, mp 58–60 ЊC (Found: C, 47.7; H, 6.6; N, 20.2; C11H18-
N4Cl2 requires C, 47.7; H, 6.5; N, 20.2%); δH (300 MHz;
C6D5NO2) 0.78 (3H, t, J 7 Hz, CH3), 1.16 [10H, m, (CH2)5], 1.60
(2H, m, CH2CH2N), 3.44 (2H, m, CH2N), 6.90 (1H, t, J 5.85
Hz, NH); δC (75 MHz; C6D5NO2) 14.4 (CH3), 23.3, 27.3, 29.5,
29.8, 29.9 and 32.4 (CH2), 42.2 (CH2N), 166.5 (triazine C–NH),
170.2 (triazine C–Cl), 171.3 (triazine C–Cl); m/z 277 [(M ϩ H)ϩ,
100%], 305 [(M ϩ C2H5)ϩ, 20], 291 [(M ϩ CH3)ϩ, 6], 241
[(M Ϫ Cl)ϩ, 54], 219 [(M Ϫ C4H9)ϩ, 6], 205 [(M Ϫ C5H11)ϩ, 6],
191 [(M Ϫ C6H13)ϩ, 8], 177 [(M Ϫ C7H15)ϩ, 38].
Experimental
Instrumentation
NMR spectra were measured using a JEOL Lambda 300 (1H
300.4 MHz; 13C 75.45 MHz), a JEOL 400 GXD (1H 399.65
MHz; 13C 100.4 MHz) and a JEOL Lambda 500 (1H 500 MHz;
13C 125.65 MHz; 19F 470.4 MHz) spectrometer. All spectra were
measured at ambient temperature (294 K) unless otherwise
noted. Typical acquisition parameters were 8 scans for 1H spec-
tra collected into 32768 data points, 500 scans for 13C spectra
collected into 32768 data points and 16 scans for 19F collected
into 65536 data points. The free energies of activation for
rotation (∆G‡/kJ molϪ1) were calculated using the following
N-Ethyl-4,6-dichloro-1,3,5-triazin-2-amine 2. Cyanuric chlor-
1232
J. Chem. Soc., Perkin Trans. 2, 1999, 1231–1234

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ide (1.00 g, 5.42 mmol), dissolved in chloroform (40 cm3), was
added to a solution of sodium hydrogen carbonate (1.37 g, 16.3
mmol) dissolved in water (15 cm3). Ethylamine hydrochloride
(1.30 g, 15.9 mmol) dissolved in water (5 cm3) was added drop-
wise and the two-phase mixture was stirred vigorously for 3 h at
ambient temperature. The organic layer was separated and
washed with water (3 × 10 cm3) and dried over sodium sulfate.
Filtration and removal of the chloroform by evaporation under
reduced pressure afforded N-ethyl-4,6-dichloro-1,3,5-triazin-2-
amine 2 (0.89 g, 85%) as a white solid: δH (400 MHz; CDCl3)
1.23 (3H, t, J 7.27 Hz, NHCH2CH3), 3.53 (2H, quintet, J 6.66
Hz, NHCH2CH3), 7.24 (1H, br, NHCH2CH3); δC (100 MHz;
CDCl3) 14.30 (CH3), 36.43 (CH2), 165.4 (triazine C–NH), 169.2
(triazine C–Cl), 170.8 (triazine C–Cl).
stirring in ethanol (20 cm3) and N-ethyl-4-methylbenzene-
sulfonamide (0.79 g, 3.96 mmol) was added portion-wise. The
resulting solution was stirred for 30 min and then evaporated to
afford a sticky solid. Tetrahydrofuran (20 cm3) was added and
the suspension was cooled to Ϫ10 ЊC under argon. Cyanuric
chloride (0.73 g, 3.96 mmol) dissolved in tetrahydrofuran
(5 cm3) was added to the reaction mixture dropwise. After the
addition, the reaction mixture was allowed to warm to room
temperature over a 1 h period. The solvent was removed by
evaporation and the resulting residue was dissolved in dichloro-
methane (40 cm3). The solution was filtered through a pad of
Celite and the solvent was removed by evaporation under
reduced pressure. Purification of 0.51 g of the crude material
by chromatography on silica gel (chloroform) afforded 4,6-
dichloro-2-(N-ethyl-4-methylbenzenesulfonamido)-1,3,5-tri-
azine 5 (0.45 g, 88%) as a white solid (Found: C, 41.6; H, 3.4;
N, 16.1; C12H12N4Cl2O2S requires C, 41.5; H, 3.5; N, 16.1%);
δH (300 MHz; CDCl3) 1.43 (3H, t, J 7 Hz, CH3), 2.44 (3H, s,
CH3C6H4), 4.26 (2H, q, J 7 Hz, CH2N), 7.33 (2H, d, J 8.4 Hz,
Ar CH), 8.00 (2H, d, J 8.4 Hz, Ar CH); δC (75 MHz; CDCl3)
14.5 (CH3), 21.6 (CH3C6H4), 42.6 (CH2N), 129.1 (8-C and 4-C),
129.6 (Ar 7-C and 5-C), 135.3 (Ar 6-C), 145.4 (Ar 9-C), 163.8
(triazine C–NSO2), 170.5 (triazine C–Cl); m/z 347 [(M ϩ H)ϩ,
100%], 375 [(M ϩ C2H5)ϩ, 6], 361 [(M ϩ CH3)ϩ, 6], 311 [(M Ϫ
Cl)ϩ, 18].
N-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctyl)-4,6-
dichloro-1,3,5-triazin-2-amine 3. Cyanuric chloride (0.93 g, 5.00
mmol), dissolved in chloroform (20 cm3), was added to a solu-
tion of sodium hydrogen carbonate (0.46 g, 5.50 mmol) dis-
solved in water (10 cm3). The two-phase mixture was stirred
vigorously and cooled to 0–5 ЊC. N-(2,2,3,3,4,4,5,5,6,6,7,7,
8,8,8-Pentadecafluorooctyl)amine (2.00 g, 5.00 mmol) dissolved
in chloroform (5 cm3) was added dropwise. The reaction mix-
ture was stirred vigorously for 1 h at 0–5 ЊC and then allowed to
warm to room temperature. The organic layer was separated
and washed with water (3 × 10 cm3) and dried over sodium
sulfate. Filtration and removal of the chloroform by evapor-
ation under reduced pressure afforded an oil, which on tritur-
ation with cyclohexane yielded a white solid. Evaporation of
the cyclohexane gave N-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-penta-
decafluorooctyl)-4,6-dichloro-1,3,5-triazin-2-amine 3 (2.30 g,
84%) as a white solid, mp 79–80 ЊC (Found: C, 24.1; H, 0.5; N,
10.4; C11H3N4Cl2F15 requires C, 24.2; H, 0.55; N, 10.2%);
δH (500 MHz; CDCl3) 4.31 (2H, dt, J 6.41 Hz, J 14.95 Hz, CH2),
6.93 (1H, t, J 6.41 Hz, NH); δC (126 MHz; CDCl3) 41.1 (t,
J 23.8 Hz, CH2N), 110.7–118.4 [CF3(CH2)6], 166.8 (triazine
C–NH), 170.6 (triazine C–Cl), 171.6 (triazine C–Cl); δF (470
MHz; CDCl3; CFCl3) Ϫ79.9 (CF3), Ϫ116.8, Ϫ120.8, Ϫ121.0,
Ϫ121.8, Ϫ122.2 and Ϫ125.2 (CF2); m/z 574 [(M ϩ H)ϩ, 64%],
575 [(M ϩ C2H5)ϩ, 6], 561 [(M ϩ CH3)ϩ, 6], 527 [(M Ϫ F)ϩ,
100], 177 [(M Ϫ C7F15)ϩ, 14].
N-(4,6-Dichloro-1,3,5-triazin-2-yl)-N-ethyl-1,1,2,2,3,3,4,4,5,
5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfonamide 6. Sodium
(5.00 g, 0.22 mol) was dissolved with stirring in ethanol (210
cm3) and N-ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadeca-
fluorooctane-1-sulfonamide (114 g, 0.22 mol) was added
portion-wise. The resulting solution was stirred for 30 min and
then evaporated to dryness. The resulting sticky solid was dis-
solved in acetone (200 cm3) and cooled to Ϫ78 ЊC under argon.
Cyanuric chloride (39.9 g, 0.22 mol) dissolved in acetone
(300 cm3) was added to the reaction mixture dropwise such that
the temperature did not rise above Ϫ75 ЊC (1 h). After the
addition, the reaction mixture was allowed to warm to room
temperature over a 1 h period. The precipitated solid was
removed by filtration and the orange solution dried over
sodium sulfate. Filtration and evaporation under reduced pres-
sure afforded N-(4,6-dichloro-1,3,5-triazin-2-yl)-N-ethyl-1,1,2,
2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfon-
amide 6 (125 g, 86%). The product can be purified by precipi-
tation from a chloroform–industrial methylated spirit (IMS)
solvent mixture. In a typical purification procedure, the crude
product (58.6 g) was dissolved in chloroform (150 cm3) and then
precipitated into IMS (400 cm3). The precipitate was collected
by filtration and dried under vacuum at 25 ЊC to afford triazine
6 (42.3 g, 72%) as a fine white solid, mp 92–93 ЊC (Found: C,
23.2; H, 0.7; N, 8.3; C13H5N4Cl2F17O2S requires C, 23.1; H,
0.75; N, 8.3%); δH (300 MHz; THF-d8) 1.42 (3H, t, J 7.0 Hz,
CH3), 4.26 (2H, q, J 7.0 Hz, CH2N); δC (75 MHz; THF-d8)
14.7 (CH3), 47.0 (CH2N), 110–118 (m, C8F17), 166.4 (triazine
C–NSO2), 172.2 (triazine C–Cl); m/z 675 [(M ϩ H)ϩ, 100%], 703
[(M ϩ C2H5)ϩ, 4], 689 [(M ϩ CH3)ϩ, 6], 193 [(M Ϫ SO2C8F17)ϩ,
98].
N-(4,6-Dichloro-1,3,5-triazin-2-yl)-N-ethyloctane-1-sulfon-
amide 4. Sodium (0.13 g, 5.65 mmol) was dissolved with stirring
in ethanol (20 cm3) and N-ethyloctane-1-sulfonamide (1.19 g,
5.38 mmol) was added portion-wise. The resulting solution was
stirred for 30 min and then evaporated to dryness. The resulting
solid was dissolved in acetone (60 cm3), cooled to Ϫ60 ЊC and
added to a cold (Ϫ60 ЊC) solution of cyanuric chloride (1.00 g,
5.42 mmol) dissolved in acetone (20 cm3). The temperature of
the reaction mixture did not rise above Ϫ55 ЊC during the add-
ition. After the addition, the reaction mixture was allowed to
warm to room temperature. Sodium chloride was removed by
filtration and the acetone was removed by evaporation under
reduced pressure. The resulting sticky solid was purified by col-
umn chromatography on silica gel (hexane:diethyl ether; 7:1)
to afford N-(4,6-dichloro-1,3,5-triazin-2-yl)-N-ethyloctane-1-
sulfonamide 4 (1.30 g, 65%) as a white solid, mp 68–69 ЊC
(Found: C, 42.5; H, 6.1; N, 15.3; C13H22N4Cl2O2S requires C,
42.3; H, 6.0; N, 15.2%); δH (300 MHz; CDCl3) 0.87 (3H, t, J 7.0
Hz, CH3), 1.28 [8H, m, (CH2)4], 1.35 (3H, t, J 7.0 Hz, CH3),
1.44 (2H, m, CH2), 1.80 (2H, m, CH2CH2S), 3.70 (2H, m,
CH2S), 4.12 (2H, q, J 7.0 Hz, CH2N); δC (75 MHz; CDCl3) 14.0
(CH3), 14.5 (CH3), 22.5, 23.2, 27.9, 28.8 and 31.6 (CH2), 42.6
(CH2N), 55.3 (CH2S), 165.1 (triazine C–NSO2), 171.0 (triazine
C–Cl); m/z 369 [(M ϩ H)ϩ, 100%], 397 [(M ϩ C2H5)ϩ, 6], 333
[(M Ϫ Cl)ϩ, 16].
N-(4,6-Difluoro-1,3,5-triazin-2-yl)-N-ethyl-1,1,2,2,3,3,4,4,5,
5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfonamide 7. Sodium
(0.85 g, 37.0 mmol) was dissolved with stirring in methanol
(30 cm3) and N-ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadeca-
fluorooctane-1-sulfonamide (19.5 g, 37.0 mmol) was added
portion-wise. The resulting solution was stirred for 1 h and then
evaporated to dryness. Cyanuric fluoride (5.00 g, 37.0 mmol)
was dissolved in acetone (40 cm3) and cooled to Ϫ78 ЊC under
an atmosphere of argon. The sodium salt of the sulfonamide
prepared above, was dissolved in acetone (20 cm3) and added
slowly to the cyanuric fluoride solution over a 1 h period. After
2 h, the reaction mixture was allowed to warm to room tem-
4,6-Dichloro-2-(N-ethyl-4-methylbenzenesulfonamido)-1,3,5-
triazine 5. Sodium (0.09 g, 3.96 mmol) was dissolved with
J. Chem. Soc., Perkin Trans. 2, 1999, 1231–1234
1233

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perature and the solvent was removed by evaporation under
reduced pressure. Distillation (200 ЊC, 0.3 mbar) of 4.85 g of
the crude product afforded N-(4,6-difluoro-1,3,5-triazin-2-yl)-
N-ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-
1-sulfonamide 7 (1.50 g, 31%) as a white solid, mp 72 ЊC
(Found: C, 24.1; H, 0.95; N, 8.4; C13H5N4F19O2S requires C,
24.3; H, 0.8; N, 8.7%); δH (500 MHz; acetone-d6) 1.45 (3H, t,
J 7.0 Hz, CH3), 4.34 (2H, t, J 7.0 Hz, CH2N); δC (126 MHz;
acetone-d6) 14.3 (CH3CH2), 47.3 (CH3CH2), 170.3 (triazine
C–NSO2), 172.0 (dd, J 19.6 Hz, J 231 Hz, triazine C–F); δF (470
MHz; acetone-d6; CFCl3) Ϫ35.9 (triazine C–F), Ϫ80.6 (CF3),
Ϫ119.6, Ϫ120.0, Ϫ121.2, Ϫ121.4, Ϫ122.2 and Ϫ125.8 (CF2);
m/z 643 [(M ϩ H)ϩ, 100%], 671 [(M ϩ C2H5)ϩ, 4], 657 [(M ϩ
CH3)ϩ, 10], 159 [(M Ϫ SO2C8F17)ϩ, 56].
bient temperature for 2 d. Diethyl ether (100 cm3) was added
and the solution was washed with 2 M HCl (2 × 50 cm3), water
(2 × 50 cm3) and saturated aqueous sodium chloride (1 × 50
cm3). The organic layer was separated, dried over sodium sul-
fate, filtered and the solvent was removed by evaporation under
reduced pressure to afford 2-(N-ethyl-4-methylbenzenesulfon-
amido)-4,6-difluoro-1,3,5-triazine 9 (1.41 g, 60%). Further
purification of the product (0.90 g) was achieved by chrom-
atography on silica gel (diethyl ether) to give 2-(N-ethyl-4-
methylbenzenesulfonamido)-4,6-difluoro-1,3,5-triazine 9 (0.85
g, 95%) as a pale yellow liquid: δH (300 MHz; CDCl3) 1.44 (3H,
t, J 7 Hz, CH3), 2.44 (3H, s, CH3C6H4), 4.29 (2H, q, J 7 Hz,
CH2N), 7.33 (2H, d, J 8.4 Hz, Ar 3,5-H2), 7.98 (2H, d, J 8.4 Hz,
Ar 2,6-H2); δC (75 MHz; CDCl3) 14.5 (CH3), 21.7 (CH3), 43.2
(CH2N), 129.3, 129.5 (Ar 2,3,5,6-C4), 135.2 (Ar 4-C), 145.5 (Ar
1-C), 168.4 (t, J 16.8 Hz, triazine C–NSO2), 170.7 (dd, J 19.6 Hz,
J 231 Hz, triazine C–F); δF (470 MHz; CDCl3; CFCl3) Ϫ33.6
(triazine C–F); m/z 315 [(M ϩ H)ϩ, 100%], 343 [(M ϩ C2H5)ϩ,
8], 295 [(M Ϫ F)ϩ, 12].
N-(4,6-Difluoro-1,3,5-triazin-2-yl)-N-ethyloctane-1-sulfon-
amide 8. Sodium (0.037 g, 1.60 mmol) was dissolved with stirring
in ethanol (10 cm3) and N-ethyloctane-1-sulfonamide (0.39 g,
1.76 mmol) was added portion-wise. The resulting solution was
stirred for 30 min and then evaporated to dryness. Cyanuric
fluoride (0.44 g, 3.30 mmol) was dissolved in acetone (10 cm3)
and cooled to Ϫ78 ЊC under an atmosphere of argon. The
sodium salt of the sulfonamide prepared above, was dissolved
in acetone (10 cm3) and added slowly to the cyanuric fluoride
solution. The reaction mixture was allowed to warm to room
temperature and after a 2 h period, the solvent was removed by
evaporation under reduced pressure. Distillation (220 ЊC, 0.3
mbar) of the crude product afforded a mixture containing N-
(4,6-difluoro-1,3,5-triazin-2-yl)-N-ethyloctane-1-sulfonamide
8 (0.23 g, 48%) as a pale yellow oil. Further attempts at purifi-
cation by chromatography on silica gel led to decomposition of
the product: δH (500 MHz; CDCl3) 0.88 (3H, t, J 7 Hz, CH3),
1.30 (8H, m, (CH2)8), 1.36 (3H, t, J 7 Hz, CH3), 1.45 (2H, m,
CH2), 1.80 (2H, m, CH2CH2SO2), 3.71 (2H, m, CH2SO2), 4.14
(2H, q, J 7 Hz, CH2N); δC (126 MHz; CDCl3) 14.2 (CH3), 14.7
(CH3), 22.8, 23.4, 28.2, 29.1 and 31.9 (CH2), 43.2 (CH2N), 55.4
(CH2SO2), 169.4 (t, J 17.1 Hz, triazine C–NSO2), 171.3 (dd,
J 19.7 Hz, J 233 Hz, triazine C–F); δF (470 MHz; CDCl3;
CFCl3) Ϫ32.6 (triazine C–F).
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2-(N-Ethyl-4-methylbenzenesulfonamido)-4,6-difluoro-1,3,5-
triazine 9. Cyanuric fluoride (2.00 g, 14.8 mmol) and N-ethyl-4-
methylbenzenesulfonamide (1.50 g, 7.50 mmol) were dissolved
in acetone (10 cm3). 2,4,6-Trimethylpyridine (1.80 g, 14.9
mmol) was added and the reaction mixture was stirred at am-
Paper 8/08753I
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J. Chem. Soc., Perkin Trans. 2, 1999, 1231–1234