Reactions involving fluoride ion. Part 28[1]. Cyclisation and formation of dimers from perfluoro-2,5-diazahexa-2,4-diene

Journal of‘ Fluorine Chemistry, 24 (1984)2 11-2 18

211

Received: March25, 1983;accepted: May 6, 1983

REACTIONS INVOLVING FLUORIDE ION. PART 28rl-j. CYCLISATION AND FORMATION OF DIMERS FROM PERFLUORO-2,5-DTAZAHEXA-2,4-DIENE

R.N. BARNES, R.D. CHAMBERS, M.J. SILVESTER, C.D. HEWITT Department of Chemistry, University Science Laboratories, South Road, Durham, DHl 3LE (U.K.)

and E. KLAUKE Bayer A.G., Zentrale Forschung, 5090 Leverkusen, Bayerwerk, (F.R.G.)

SUMMARY

A variety

of dimers

is formed by reaction

of perfluoro-2,5-diazahexa-

2,4-diene (2) with metal fluorides; product composition depends on the reactivity of the fluoride source and the reaction conditions i.e. product may be under kinetic or equilibrium control. Cyclisation of (2) occurs, over hot caesium fluoride, in a flow process. A nitranion, generated by fluoride ion, has been trapped with iodomethane.

INTRODUCTION

So far, in this series of papers, we have concentrated on the chemistry of fluorinated carbanions that are generated by reactions of fluoride ion with fluorinated alkenes and, here, we describe chemistry of some nitranions generated from perfluorinated aza-alkenes. We [2] and others [3] have described some chemistry of nitranions generated from fluorinated azacyclohexenederivatives and some chemistry of the anion derived from perfluoroazapropenehas also been reported [4,5]. Generally, fluorinated aza-alkenes are not readily accessible but a good synthesis of perfluoro-2,5-diazahexa-2,4-diene (2), starting from the fluorinated amine cl), has been reported [6] and this followed an earlier, more esoteric synthesis [7]. Here, we describe some reactions of the diazadiene (2) with fluoride ion, to generate corresponding nitranions, both in solution and on the surface of metal fluorides.

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212

(i)

fCCl,-N=CC12)2

>

(ii)

fCF2-NH-CF3)2

)

~CF=N-c~3)2 (2)

(1) (ii) NaF, SO'C.

(i) HP;

Preliminary published

reports

on the formation

[8] and we have investigated

temperature

and metal

the formation

fluoride

and structures

of dimers

on these systems.

of dimers

detected.

However,

we find that the products the metal

the effect

fluoride

of

We are able to confirm

(5) and (lo), reported

together with a small amount of the Spiro-dimer

with conditi0nsi.e.

from (2) have been

in some detail

earlier,

(ll), not previously

obtained

vary dramatically

used and the temperature

(see Table).

TABLE Reaction

products

sulpholane(room

(X composition)

from (2) plus metal

fluoride

in

temp.)

MF

5

10

11

NaF

76

24

NaF'

35

65

K_F

43

50

7

CsF

37

57

6

CsFb

94

6

a At 120°C b At -23'C

Probable

mechanisms

shown in Schemes involves might

1 - 3

anticipate,

step 2i.e

over the competing

temperatures

or using

to note that formation

bimolecular

less reactive

that the intramolecular

of (10)

(7)-'(8), at an early stage, and we

fluoride

cyclisation with

process would

step (3)-+(4), involved

of (S), i.e. Scheme

(7)-t(8) is an example

(51, (10) and (11) are

that this unimolecular

This is, in fact, quite consistent because

of dimers

It is important

therefore,

However,formation

implies

.

an intramolecular

preferred 1.

for the formation

1, is preferred sources

of a formally

in Scheme

at lower

(see Table) and this

step (7)+(8)

the Baldwin

be

is not easy.

rules for cyclisation

disfavoured

5-endo-trigonal

213

CF3

CF3 IQ N

3

(2) (2) m-+F '

Y

CF3N

Scheme

(3)

1

&

F2

F2 F

_-A

F 2

(6)

X=CF 2

(I

.$CF3 (88)

(7)

+

(8b)

(8a) + (8b)

Scheme 2

$!!k

214

CF3

CF;

CF I3

Scheme

3

cyclisation

[9].

Scheme

this is an example

of a favoured

at high temperatures preferred

a cyclisation

5-exo-trigonal

or with more reactive

(see Table)

and, therefore,

1 also involves

showing

step (4)+(51 but

process

fluoride

[9].

sources,

Conversely, dimer

that (7)+(8) will occur at higher

this must be a rare example

of a formally

(10) is

temperatures

disfavoured

process. The preferred since a mixture

formation

of (10) with

been anticipated. (5) with caesium

fluoride

(3) with F

(5) G

(51, the low temperature

We established,

new dimer of probable nitranion

of (10) at 1OO'C is, at first sight, surprising

however,

product,

would have

that further heating

of dimer

at 120°C gave (lo), together with a further

structure

(12), apparently

formed by reaction

(8b).

> (3) G_(S)---3(10)

N 'CF3

of

215

Consequently,

formation

if sufficient

time has elapsed

of significant

amounts

of (12) can only occur

to set up an equilibrium

mixture

at high

temperatures. Only small amounts reactions obtained

carried

of cyclic compounds

out in solution

(8a) and (8b) were detected

[8] but these compounds

in high yield by the cyclisation

in

have now been

(7)4(E) over hot caesium

fluoride

in a flow system.

(3)

0

(8b) (16%)

+

(8a) (65%)

(i), CsF, 220°, N2 flow

As expected, rapidly

the cyclic

at room temperature,

via the nitranion the nitranion because

(8a) and (8b) form the dimer

in the presence

However,

(9) in the presence

reaction

iodomethane,

(9).

compounds

the dimer

of fluoride

(10)

obviously

(10) is also in equilibrium

of fluoride,

of (10) with caesium

sources,

with

even at room temperature,

fluoride,

followed

gave a high yield of the corresponding

by addition

N-methyl

of

derivative

(13). YH3 N (10)

+

CsF a

CH I 3_$

(9)

F

F2

2

(93%)

(13) Further

chemistry

of these interesting

systems

is in progress.

EXPERIMENTAL 19 EM360L

F and 'H n.m.r. spectrometer,

external

reference.

chromatography phthalate

Percentage

gas chromatography.

or tetramethylsilane

shifts are quoted as positive.

out using columns

as

Gas

packed with 20% di-isodecyl

P (Column A) or 20% 'Krytox' [lo] on Chromosorb yields

of by g.1.c. analysis

spectra were recorded

at 20°C using a Varian

trichlorofluoromethane

Upfield

was carried

on Chromosorb

(Column K). products

spectra were recorded

with

quoted were measured using a gas density

using a VG Micromass

either balance

12B spectrometer

W

by weighing detector.

Mass

linked with a

216

Dimerisation

of perfluoro-2,5-diazahexa-2,4-diene

(2)

(a) At 120°C A mixture

of perfluoro-2,5-diazahexa-2,4-diene

mmol),

sodium

heated

at 120°C for 3 days in a Carius

transferred liquid

fluoride

(1.12 g, 26.7 mmol),

under vacuum

tube.

into a trap cooled

(7.92 g, 91% recovery)

to consist

(2) (8.75 g, 38.4

and sulpholane Volatile

(25 ml) was

material

in liquid air.

was shown by g.l.c.-m.s.

was

The resultant

(Column K, 1OO'C)

of (5) (35%) and (10) (65%)[8].

(b) At room temperature (i) With

sodium

diazahexa-2,4-diene sulpholane material

(5 ml) was stirred

was

transferred

The resultant contain

liquid

1-ene

gave

potassium

identified

requires:

broad multiplet,

fluoride

perfluoro-2,5fluoride

(- 1.0 g), and Volatile

at room temperature.

into a trap cooled

by preparative

those reported

the dimers

in liquid air.

(Column A, 60°C) to scale g.1.c. gave the by comparison

in the literature

A similar

of

[8].

experiment

using potassium

(5) (43%) and (10) (50%), together with a third

as perfluorospiro-1,3,6,9-tetra-aza-3,6,9-trimethylnon-

(11) (nc) (7%);

CSF16N4

Separation

data with

(ii) With

component

for 70 hours

under vacuum

sodium

(5) (76%) and (10) (24%), identified

spectroscopic

fluoride

containing

(2.9 g) was shown by g.1.c.

two components.

known dimers

A mixture

fluoride

(2) (3.2 g, 14.0 mmol),

Analysis:

c, 21.1;

F, 66.7;

6, 9-F), 58.5(3F,

singlet,

4-F),

and 91.2

(2F, quartet,

C, 21.0;

F, 66.7;

N, 12.3%;

broad

83.4 (lF, broad singlet,

singlet,

N, 12.1%;

M, 456; 3-F),

M+ 456.

6, 57.8

(6~,

71.4 (2F, broad

2-F), 90.7 (2F, multiplet,

7-F),

J = 8.5 Hz, 8-F).

CF3 4

7 F2f3.&j7 BF2

9 b,

'

2

(11)

(iii) With fluoride

caesium

gave a mixture

fluoride

A similar

of dimers

(5) (37%),

experiment

using

caesium

(10) (57%), and (11) (6%).

217

(c)

At -23'C

At mixture mmolj,

caesium

stirred vacuum

of perfluoro-2,5-diazahexa-2,4-diene fluoride

at -23'C for 23 hours. into a trap cooled

removed.

The resultant

95'C) to contain

Isomerisation

dimers

g.l.c.-m.s.

1760 cm

Volatile

in liquid air.

Vapour

and sulpholane

material

liquid

under vacuum

into

(2.05 gl was shown by

(10) (73%) and (12) (27%) [m/e by preparative

(C=N), 6, 57.7 (3F, C=N-CF3),

scale g.1.c.

showed

58.3 (6F, -I;-CF3). 61.4,

78.5 (2F, -CF2-),

85.1,

106 (2F, JAx = 166,

101.9 (IF, -dF-!.

phase reaction

of (2) over caesium

Perfluoro-2,5-diazahexa-2,4-diene through

a silica

(contact

in a trap cooled

in liquid air.

was shown by g.1.c. components

(65%) and (8b) (16%),

fluoride

identified

containing

through a silica

product was collected

liquid (8.8 g, 80% recovery)

as compounds

and (11) (6%) by comparison

to consist

of two

of spectroscopic

of dimers with (10) (27%),

fluoride

(8a)

data with

(contact

ion

(5) (67%), and (11) (6%)

tube (30 cm) containing

in a trap cooled

liquid (4.5 g) was shown by g.1.c. identified

at 22O'C in a

[8].

at 22O'C in a flew of nitrogen

components,

fluoride

scale g.1.c. gave compounds

by comparison

of a mixture

of dimers

(5.5 g) was passed

The resultant

by preparative

in the literature

phase reaction A mixture

caesium

time - 70 sets.) and the product was collected

(Column A, room temperature)

and separation

those reported

fluoride

(2) (10.9 g, 47.8 mmol) was passed

tube (30 cm) containing

flow of nitrogen

-r

(20 ml) was heated

was transferred

The resultant

76.3 (2F, JAK = 126.8, -CF2-), -CF2-),

layer

(Column K,

(5) (94%) and (101 (6%) (4.68 g),

A sample of (12) separated -1

under

(5)

(Column K, 1OO'C) to contain

437 (M-191].

was transferred

(5) (94%) and (10) (6%).

(0.82 g, 5.39 mmol),

at lCO°C for 3 days.

material

(25 ml) was

liquid (6.8 g) was shown by g.l.c.-m.s.

of dimers containing

fluoride

a trap cooled

Volatile

(2) (8.85 g, 38.8

and acetonitrile

in liquid air and the lower fluorocarbon

of compound

A mixture caesium

vmax

(0.8 g, 5.3 mmol),

caesium

time - 15 sets) and the

in liquid air.

The resultant

(Column A, 65'C) to contain

four

(8b) (lo%), (8a) (17%), (5) (67%),

of g.l.c.-m.s.

data.

218

Reaction

of nitranion

(9) with iodomethane

(8a)

Perfluoro-1,3-diaza-l-methylcyclopent-2-ene was stirred with dry caesium

fluoride

(3 ml) at room temperature.

After - 30 minutes

layer was observed only.

Methyl

stirred vacuum

22 hours.

into a trap cooled

was shown by g.1.c.

Volatile

22.9;

H, 1.2;

F, 65.3;

N, 10.6%;

liquid (2.2 g)

of one major

component.

N, 10.7%;

(13) (nc) (93%);

M+ 262.

M, 262;

C5H3F9N2

Analysis:

requires:

C,

6, 59.7 (3F, triplet

(J = 6 Hz), 3-F), 72.3 (ZF, quartet,

(J = 6 Hz) of triplets

triplet, J = 8 Hz, 5-F);

under

scale g.1.c. gave 1-methyl-3-trifluoromethyl-

F, 64.8;

(J = 7 Hz) of triplets 96.6 (2F, quartet

the dimer (10)

was transferred

The resultant

in liquid air.

(Column A, 8O'C) to consist

by preparative

H, 1.3;

to contain

material

2,2,4,4,5,5-hexafluoro-1,3-diazacyclopentane C, 23.1;

in sulpholane

a lower fluorocarbon

(1.35 g, 9.5 mm011 was added and the solution

for a further

Purification

(1.35 g, 9.5 mmol)

which was shown by n.m.r.

iodide

(2.1 g, 9.2 mmol)

(J = 8 Hz), 4-F),

J = 7 Hz, 2-F), 100.0 (2F,

6, 2.43 (N-CH3, singlet).

REFERENCES

Part 27.

S. Bartlett,

H.C. Fielding, submitted

R.D. Chambers,

J.R. Kirk, A.A. Lindley,

and R.L. Powell, J. Chem. Sot. Perkin Trans.

I,

for publication.

R.N. Barnes,

R.D. Chambers,

and R.S. Matthews,

J. Fluorine

Chem., -20

(1982) 307. A.R. Bailey, Chem.,

9

R.E. Banks, M.G. Barlow,

A.F. Gontar, USSR, 24

and M. Nickkho-Amiry,

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and I.L. Knunyants,

Bull. Acad.

Sci.

and I.L. Knunyants,

Bull. Acad.

Sci.

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A.F. Gontar,

E.G. Bykhovskaya,

USSR, 25 (1976) 205. H.J. Scholl

and E. Klauke,

P.H. Ogden

and R.A. Mitsch,

H.J. Scholl,

E. Klauke,

B.P. 1,325,619/1973. J. Amer.

Chem. Sot., -89 (1967) 3868.

and D. Lauerer,

J. Fluorine

Chem., 2 (1972/73)

203; 205. J.E. Baldwin,

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