The fluorination of Butane over cobalt trifluoride

Journal of Fluorine Chemistry, 40 (1988)

THE

FLUORINATION

JAMES

BURDON,

OF

BUTANE

SALEH

Department

of

Birmingham

B15 2TT

T.

Chemistry,

283-3

OVER

EZMIRLY

283

18

COBALT

and

TRIFLUORIDE*

THOMAS

The University

of

N.

HIJCKERBY

Birmingham,

I? O.Box

363,

trifluoride

has given

(U.K.)

SUMMARY The fluorination mixture

of

partially

identified, butanes

of

l-2%

over

were

utility.

secondary

C-H was converted

of

of

perhaps

for

H replacement

the

former.

the

51 of

these

products.

into

model

because

the

and in part

then

H was reduced the

fluorination

fluorination

via

alkenes:

a complex

been polyfluoro-

The reaction in the

C-F more easily

of

have

Most were

was some selectivity

a particular

A computer

successful,

compounds:

99% of

There

replacement

fluorines.

cobalt

polyfluoro-2-methylpropanes.

synthetic

ease

over

fluorinated

comprising but

butane

primary,

by geminal was only

proceeded

and the and vicinal

partially

in part

the model

has no

fluorination:

only

by simple

allowed

F

for

INTRODUCTION

Although

there

fluorination fluorides neither the [I],

is

positions but

a reasonably

aromatic

(CoF3, so well

well-studied

*

of

in the

the

MnF3, etc), studied

of

nor

residual aliphatic

cases

are

satisfactory

substrates

[1]

mechanism

over

fluorination

of

so well

understood.

hydrogens

and double

there those

of

is

not

ethane

bonds

ethene

to

the

transition

aliphatic In the

much data [2].

for

high-valency

metal

compounds aromatic

is

area.

can be rationalized go on. [2].

The only

and

Dedicated to Emeritus Professor W.K.R. Musqrave on the occasion of his 70th birthday.

0022-l 139/88/$3.50

0 Elsevier Sequoia/Printed in The Netherlands

284 2methylpropane fluorinated last

[3]: products

tertiary

was.

the

was almost

H was replaced

More recently

rearrangements for

octane

straight-chain

cobalt

over

of

trifluoride the

or C8-cyclic

the

partial

is

(88

as compared

turned

out

fluorinated with

to

be the

butanes

only

about

for

the

aliphatics: 50% of

fluorination

fluorination

to

of

partially

we have

cobalt

optical

identified

trifluoride

fluorinated

than

over that

of

fluorinated

counting

40.

of

butane

more complex

possible

case:

in the

20 partially

H

skeletal

perfluorinated

potentially

much greater

This

primary

saturated

only

being

and in the

than

extensive

of

mechanism

number of

one).

that

partially

compounds.

a usable

case

faster

gave

rest

the

is

two cases.

first

fluorination

because

butanes

the

clear

the

This

in the

has become

investigated

trifluoride.

2-methylpropane

hydrogens

10 times

cobalt

developing

we have

compared

random in

during

C8-isomers

hope

partially

it

of

by F about

perfluoro-octane.

branched-chain

aliphatics

[4].

can occur

example.

In the

distribution

pairs

about

product

2-methylpropanes

as

40

as

[3].

RESULTS

The crude into

fluorination

16 fractions

fractions

were

identified

mixture

(Table then

6).

The major

separated

(many were

still

was separated

mixtures

- see

combination

of

spectroscopic

of

lgP and 1~ nmr spectra

to

approximate

percentage of

later)

also

the

are

the

approximate fluorination

each

confidence

of D-P)

the

individual

or glc

mixture.

normally

contained

its

would

enabled

in Table

reaction

change

if

the

and an

was calculated

fractions it

1, where

can be claimed

composition

A-C):

careful many minor

mixture.

structure

distillation

(fractions

In addition.

fraction

in the

which

then

‘7) by a straightforward

summarized

compound

with

these

and were

should

a different

(see from

as determined only

be regarded

temperature

by as

of

employed.

problem

reaction

is

glc

Table

each

distillation

from many of

methods.

of

The overall

and in any case were

The major

of

This

presented.

compositions

nmr (fractions

and chemical

be identified.

assessment

peaks

by preparative-scale

examination components

by fractional

in

identification

Even those at best

very

is

components small

the

great

which

amounts

of

complexity

were single minor

of peaks

coaponents,

the on glc amounts

285

TABLE 1

Compounds Identified in the CoF3/butane Reaction

Compound

Compound Distillation No.

fractiona in

How Identifiedb

Identification categoryC

which present

% in

reaction mixtured

in greatest amount

CFQCF~CF~CFQ

1

A

CFQCF~CF~CF~H

2

A

CFQCF~CFHCFQ

3

A

CF3CF2CF2CFH2

4

C

Sep(C)

a

1.7

CF3CF2CFHCF2H

5

C

Sep(C)

a

3.0

CFQCFHCF~CF~H

6

E

Sep(D)

a

11.4 5.8

Sep(Al Sep(B) j

a

0.2

b

4.8

b

3.1

CF2HCF2CF2CF2H

7

G

Sep(G)

a

CFQCF~CH~CFQ

8

B

Sep(C)

a

1.0

CF3CFHCFHCF3(m)

9

B

Synth(C)

b

2.0

CF3CPHCFHCF3(+)

10

E

Synth(E)

e

1.8

F

F

f

0.2

F

G

b

3.4

Sep(I)

a

5.5

Sep(H)

C

2.4

Sep(H)

C

2.5

Synth(1)

a

14.0

CF3CF2CFHCPH2

11

CF3CFHCF2CFH2

12

CF2HCF2CF2CFH2

13

J

CF3CFHCFHCF2H-A:

14

H

CF3CFHCFHCF2H-Be

15

H

CF2HCF2CFHCF2H

16

I

CFQCH~CF~CF~H

17

F

G

C

1.9

CF3CPHCH2CF3

18

C

Sep(C)

C

0.7

CF2HCF2CP2CH3

19

F

F

e

1.7

CF3CFHCFHCFH2

20

M

M

I2

0.2

CF2HCF2CFHCFH2

21

M

CF3CH2CF2CFH2

22

H

CF2HCFHCF2CFH2

23

M

CFH2CF2CF2CFH2

24

M

CF2HCF2CH2CF2H

25

K

CF3CH2CFHCF2H

28

I

CF2HCFHCFHCP2H-A: 27

L

CF2HCFHCFHCF2H-Be 28

N

CF2HCFHCF2CH3

K

29

e

1.2

f

0.4

b

6.6

M

d

3.0

J

f

0.7

I

f

0.5

Sep(L)

b

4.6

Sep(N)

a

3.9

g

0.4

Sep(L) H Sep(L)

J

(continuedoverleaf)

286 TABLE 1

(Cont.)

30

G

CF2HCFHCFHCFH2-Ae 31

P

CF2HCFHCFHCFH2-Be 32

P

CFH2CF2CFHCFH2

33

0

CF2HCH2CF2CFH2

34

CF2HCFHCH2CF2H

35

CFH2CF2CF2CH3

G

d

2.1

Sep(P)

b

1.3

b

1.3

Sep(0)

b

2.5

0

0

e

0.8

P

0

f

0.5

3

b

0.4

b

0.4

f

0.6

CFH2CFHCFHCFH2-Ae 36

P

CFH2CFHCFHCFH2-Be 37

P

3

Sep(P1 F

38

F

(CF3 13CF

39(l)f

A

Sep(A)

CF3CFfCF2H12

40(71

D

CF3CF(CF2H)CFH2

41(8)

(CF312CHCFH2 ICF2H13CF

CH3CF2CFHCH3

gg

tr.

D

f

0.1

F

F

f

0.3

42(8a)

F

F

g

tr.

43112a)

H

I

f

0.4

CF3CH(CF2H12

44(13)

H

H

f

0.1

CF3CH(CF2HlCFH2

45(14a)

J

J

f

tr.

(CF2Hl2CFCFH2

46(121

I

I

f

0.4

CF3CF(CH3)CFH2

47(8b3)

F

F

g

tr.

CF2HCF(CFH2)2

48(161

M

M

f

0.1

CF2HCF(CFH2lCH3

49(14)

K

L

f

0.1

h

50(17/181

0

0

f

0.1

h

51(17/181

0

0

f

0.1

a See Table

6.

b Sep = Separated

fraction

in parenthesis

spectrum

with

synthesised ir

identified signals

soae 4).

letter

then

in the

the

nar

of

fraction

identified

by picking

c = as b, but 30-40%:

:

f = as b.

but

or CH3) visible signals

were

d Obtained

from

out

g = as f.

(20.29)

or signals

the

its

obscured

out

of

of

of

ir =

either

by

its

c a = compound

20-30%:

of

from

some mixture fraction): those

e = as b.

only

(In

compounds

individual

of

the

but

one nmr peak

weak (42,471 other

its

Synth

compound was

a distillation

either

the

distillation

and analysing

as 40-90%

very

of

the

fraction.

but

but

by those

compositions

that

ninr signals

d = as b,

(10%:

usually

whole present cut

the

in parehthesis

by picking

or a glc

from

by comparison

by nmr analysis.

indicates

the

b = compound

or

fraction

etc)

fraction

signals

glc

either

specimen

(F,G,

distillation

a distillation

compound

(CF3

identified

in >90% purity:

(either

10-202:

from

by prep-scale identified

an authentic

A single

in that

.Isolated

mixture

of

and then

or nmr.

nrr

that

and then

cases - see

fractions:

b-f. Table these

287 TABLE

were

1 (fOOtIIOtSS Cont.)

analysed

for

A.E.

either

numbers

given

a mixture

to

with

they

were

fA.B.C)

or nmr (the

in parentheses

1 solely

two compounds not

there

were

basis

of

identical but

to

are

e See text

refer

in ref.

on the

identified

remainder).

(1.8a.etc.j

polyfluoro-2-methylpropanes

compound

h these

r51. 3:

by glc

f The numbers

to

3.

the

the

compound

g Identified

ir

peak

compounds

at

in

1000 cm-1

17 and 18 of

ref.

undoubtedly

polyfluoro-2-methylpropanes.

which

were

a small sample

insufficient

amount of of

8.

to

19.

and 7)

at worst

in addition

Literature several

[5]

enabled

present

as simple

28 to

XIII

(Table

7)]

with

21 and 23 (glc

is

a major

ones

spectra

by ir

is

9.

for

the

single

the

several

major

of

identification glc of

main

most

10.

pure

was

contained

Re-synthesis [it

example.

7).

pure

and 27 by finding peak XII).

product,

sufficed

(2.3).

(for

when an apparently

peaks

(Table

as virtually

mixtures

be identified

peak

analyses

some single

to minor

infrared

compounds or

elemental

CF3CFHCF2CF2H. which

dehydrofluorinated): components

affect

CF2HCF2CF2CH3, was revealed

peaks

component

nmr peaks

and 18 have

1

27 and 28 [8]

(>90%)

its

of

(compounds

been

of

glc

in a mixture

synthesised

unambiguously:

LiAlH CF3CC&CCNF3

x3+

CF3CFCfiCFCNF3

4

CF3CFHCFHCF3 (9 and 10)

LiAlH CF2HCF2CFCPCF2CP 2

CF2IiCF2CF=CF2 -L1p2/h-~

CF2HCF2CFHCF2H (18)

9 and 16 were major was identified fraction KOH:

E.

it

elimation

by picking

out

all

9 was distinguished

reacted it

components

is

about therefore

2-3

single

its

slower.

plausibly

glc

peaks

19 F nmr signals

from

times most

of

(V and XI) in distillation

10 by dehydrofluorination and assuming the

and 10

with

trans-periplanar

meso-isomer:

288 F CF H *

less

more stable

(+

funreactive)

F3 H

stable alkene) 10

9

The 1~ and lgF spectra [7]:

glc

peak

parameters. chemical

6.

are

9 or

spectral

details.

chemical

shifts

although

One of

9 or

(no couplings there

is

22 and 26 have between

also

detected

our

no physical

The remaining

been

or

spectral

polyfluoro-2-nethylpropanes identified

nmr signals

problem

when all

components

the

this

several

signals

is

signals

their

from

unrecorded.

of

are

point

signal

is

(76.7)

for

of

triplets

that the

even only

visible.

true

CF3-CFH: (10Hz).

cases

range

4 where

it

is

It

split

and these

all

into

couplings

good

picking

with

is

not

in the

lost.

a doublet

the a

minor

from

CHF. CH2F

The essence

are

these 20 the

20 to

(Table

of

doublet

(Table

2)

of

make

CF3

place

(J-1.5Hz)

of

have

compounds

recorded With

typical

out

major

components

correct

were

was not

the

so narrow.

examples

is

of

1~ signals

some minor

is

are

This

by those of

All

new.

However,

The two worst

in such

is

the

necessitated

invariably

one visible.

for

reaction

by a mixture.

(CP3CFHCFHCPH2) and 29 (CP2HCFHCF2CH3) and we have the

here

shift.

Compound 38 has

completely

usually

shift

there

nmr

were given.

obscured

Table

proton

in a complex

commonly

chemical

apparent

later)

the given

the

of

[9] or

[lo]:

[ll]:

exception

presented

were

were

with

and the mentions

those

reported.

component

this

those

was almost

and CHF2 because problem

from

some signals

components:

the

- see

by nmr spectrocopy:

relevant

amiss

literature same

properties

with

synthesised

the

also

reported

properties

(with

[8]

are

physical

best

and those

as a minor

compounds

agree

the

literature There

10 has been

something

also

the

4.

in the

essentially

but without

parameters

[12]

in

given)

clearly

described

with

in Table

11 and 12.

10.

agreement

mixture;

recorded

included

Compounds

been

compound 4 are a spectrum

Compound 8 is shifts

compounds

10,

of

IV contained

CF3

2) (6Hz) with

289

CF3 with

an F on 4. We do not

pretend

what else

the

threo

an H on 2.

that

this

compound might

or erythro

- but

and CF3 with

is

conclusive

be.

that

is

There beyond

Fs on 2 and 3.

- but is,

it

is

respectively.

difficult

of

course,

speculation

with

the

to

suggest

question

the

of

evidence

available.

The second

example

of

a very

speculative

(CF2HCFHCF2CH3) where

only

expected

position

a CH3CF2.

coupling

in addition

for

to

the

the

the

spectrum

though

the

contained

of

CFH2 regions

did

given

assignments

to

in
possible

to write

similar

confidence.

The reassuring by nmr is

the in

vary

very

simple

valuable

almost

been

studies.

is

no overlap

the

reaction

was in the

the

doublet

CF3 or CFH2 peaks

structure

CF2H region

whereas

probable

that

in

as 29 even

J the

components

most

AB cases

they

and CFlI2 because certain

firmly

two most

the

the

for

CF3 and

missing

signal

structural the

the

established

the

other

- any CF2 in

are

relatively

are

even

of 2):

parameter

types

of

the

useful

ranges

signal

are

(as

coupling

signals

relatively

there

is

(these

can

as a CFH can

The least from

for

other

also

useful

are

compounds

involved.

- CFH2CF2CF2CH3 - and 38 - CH3CF2CFHCH3) by homo- and hetero-nuclear

is

data

group

CH3 and CH2 are

uncommon.

it

and with

polyfluorobutanes

same molecule

with

unknowns

though

literature

The most

situations).

overlapping

(30

(Table

our values.

CF3:

remaining

20 and 29.

and no second-order

when mixtures

structures

the

determination

parameters

with

structural

unassigned,

them as with

of

with

speculative

we leave

mixture)

of

and C-CF2H).

because

Two unusual have

it

as an AB - to more complex

CFH. CFS, is

accord

purposes

C-CF2-C

from

present

in the

feature

is

of

down structures

complete

there

between

fraction

show what can be done,

consistancy

identification narrow,

making

some details

just

- each

also

thus

the

in

29

(J = 2.9Hz)

(19.5Hz):

given

from major

this

doublet

no unassigned

visible:

compound

a CF2H.

Having

are

not

signals

not,

are

is

was observed: was a small

CH3CF2 triplet

There

is

many strong

There

J and we have

CF2H signal

was indeed

(-5

fraction

CH3 signal

larger

must be a J4 H-F coupling.

assignment

decoupling

290

TABLE 2

Chemical Shift (lgF and 1HI and Coupling Constant Ranges in Polyfluorobutanes

Group

lgF shift rangea

CF3-CF2

81.5-83.9

CF3-CFH

74.9-81.2

CF3-CH2

62.0-65.2

CF2Ij-CF2

134.2-144.2b

CF2H-CFH -CF2&CH2

130.6-134.1

lH shift range (7)

3.97-4.26

114.5-117.9

m2-CF2

235.0-244.1

5.17-5.5

-2-CFH

233.8-237.6

5.1

-CF2-

105.4-132.4"

-CFH-

mi.5-22o.5d

5.05-5.6

8.26-8.30

CJ3_CF2 CH3-CFH

8.64

-CH2-

7.18-7.8

a In ppm upfield from CFC13.

b If centres of AB spectra are taken

instead of chemical shifts of individual fluorines, the range is 136.8-139.2.

c The lowest field signals occur when there is a

neighbouring CH2 or CH3: without these groups, the range is 121.9-132.4.

System

d As for c;

range would be 203.2-220.5.

Coupling range:

System

(Hz)

Coupling rangee (HaI

CF2Hfgem)

51.0-55.3

CF2H-C-C-CF

CPH2fgemI

45.7-47.4

CPH2-CF2

14.0-15.0

CFHfgem)

44.3-45.5

CFH2-CEH

20.4-24.8

O-2.8

(continuedoverleaf)

291

TABLE 2

(Cont.)

-0

CF3-CF2

CFH2-CFIJ

11.3-15.8

CF3-CFH

9.9-10.6

CF3-CPU

5.6-6.5

CFH2-C-C-CF

1.2-2.8

CF3-CH2

9.4-10.4

CFH2-C-CH

1.8-2.1

CF3-C-CF

9.4-ll.lf

CH3-CF2

18.9-19.5

O-2.6

CH3-CFH

24.1

<4-5.7%

CH3-CFH

6.3

CF3-C-C-CF CF2H-CF2

CFH2-C-CF

4.5-5.7

CF2H-CFH

8-12.6

CH3-C-CF

W2H-CFfl

10-12.6

CH3-C-C-CF

15.7-16.3

CI+2F-CF

2.8-12.8

C!!F2-CF CljF2-CH

2.8-8.4 3.6-4.6

W2H-CH2 CI?2H-C-CFH

<4-10.2g

CF2H-C-CF2

5.8-9.5

o-2.9 o-1.5

e Scme couplings were unobtainable and some of those given are probably composite values rather the simple couplings implied: in both cases this is due to second-order effects, particularly with couplings involving CF2H and -CF2-.

f Compounds 18 and 26 had 7.4Hz and 7.3Hz for this

coupling.

g Bottom of range may be zero - not clear because of

second-order effects.

Some dehydrofluorinationshelped to confirm a few of the structural assignments.

CF3CF2CF2CF2H (2) +

CFQCF~CF~CF~H KOH,

+ CF3CF=CFCF3

CFQCF~CFHCFQ (3)

CFQCF~CFHCF~H (5)

KOH,

CF3CFHCF2CF2H (6)

KOH,

(Z)-CF3CF2CF=CFH

(Z)-CF3CF=CFCF2H + (El--CF3CP=CFCF2H

292

CF2HCF2CF2CFH2

(13)

KOH,

(Z)-CF2HCF2CF=CFH

(Zl-CFH=CFCF2CFH2 +

CF2HCFHCF2CFH2 (231 +

KOH_

CF2HCF=CFCFH2 +

CF2HCFHCFHCF2H(271

(Zl-CF2HCH=CFCF2H

: The nmr spectra

of

the

polyfluorobutenes

are

in accord

with

expectation.

the

typically

large

(-120Hz)

the

large This

all were

JHF of leaves

had been

obtained

identified

since

these

are

Nevertheless regarded

compounds

‘A’

or

‘B’

attempted

Table

1 gives

has been amount the

identity

of

certainty, it. from

in

About

This

the

there

compounds

certain

and

reaction.

They

igF nmr signals: fingerprints.

in some cases.

It

component

because

of

All

31,32;

are

36.37)

pairs

of

must be

the

based

has been

certainty on the

with

none are

other

been and we

which that

the

less

likely

with

varying

degrees

of

they

comprise

over

99% of

presence

is

clear

amount than

0.1%

mixture:

unidentified

present

(their

smaller

it

is

that

require

without

u

we have of

distorting

its

missed

peaks

any of

to them.

DISCUSSION

It

is

trifluoride

surely is

obvious virtually

that

the

valueless

fluorination for

the

that

in several

in greater

unlikely

would

components

the

established.

extremely this

a structure

argument

51 compounds,

reaction

is

have

stereoisomers

CF3. CEH2. or CH3 signals

mixture.

by those

of

as reasonable

in a mixture,

remain

unattributed fractions):

obscured

is

butane/CoF3

the

significant

of

identified

distillation reaction

or

them.

is

compound

we have

five

by group

polyfluoro-2-methylpropanes

21,28;

1.

an assessment

the

otherwise

(14.15:

distinguish

a substance

In summary,

serve while

in Table

to

established.

of

all

in others.

of

not

are

from a (CH3)3CH/CoF3

they

5:

distinguished

shown by a w-CF=CF

work by comparison

identifications,

pairs

designated

[Sl

present

were

in Table

[143.

All

39-51.

complex,

as tentative

Four

have

quite

such

(-30Hz)

previously

in the

recorded

7. and E isomers JFF-coupling

a m-CH=CF compounds

are

of

preparative

butane

over

purposes.

cobalt In

of

any be

293

a case

extremis,

might

be nade

and CF2HCF2CFHCF2H (16) have.

in fact,

purpose

been

by the

point

arose

ethane

for

the

tested

route

fluorination

although

CF3CFHCF2CF2H (6).

need would

as anaesthetics

fluorination

in the

[Z],

but

the

described of

to

be very

Cl53

and were

in this

of

great

[33

CFH2CFH2 from

(6 and 7

prepared

paper.

2-methylpropane

production

CF2HCF2CF2CF2H (7),

have

for

that

The same

and even with

the

latter

might

just

be viable. With higher

less,

for

since This

partially

skeletal

with

trifluoride

C6Fi6H2

provides

Any interest

in the

it

fluorination. is

(2)

Why is

the

The first (i)

is

point

every

the

equally three

types

even

does

not

containing with

without

the

(e.g.

of

pattern

example.

some of

the

in

the

paper: random?

skeletal

the

rearrangement

hydrogens

all

H’s

the

so

since

two fluorines

to

(ii)these

in which of

it

fluorines

not

program

alkenes.

(iv)

related

are

badly (see

and,

also

does

number of by

of

and none 1.4% of

while not

the

as defined

amounts

comprise

(e.g.

Are hydrogens the

be present,

only

with

C4F5H5 isomers)

of

significant

would

likely

molecules

same molecule

reactive?

did

are

H’s

the

irrespective

definitions

them is

a computer

intervention

if

mean:

C4FgI-I equally

Random fluorination

one or

four

could

in all

in all

in the

reactive,

molecule?

or

It

from C4HI6 to

Are all

occur.

three

‘random’.

hydrogens

equally

of

accepting

We have written fluorination

say,

according

be shown later,

lies

by fluorine

molecule (ii)

Are all

Cases

mixture.

fluorination

for

and to

in this

H in CF2HCF2CFHCF2H) equally

rest

compounds

reaction

in every

(iii)

in the

clearly

compounds

C41.

CoF3/aliphatics

P-methylpropane

some discussion

fluorines

CF2H groups,

fluorines (i)

of

C6FIIR

be even

as well

benzene,

therefore of

hydrogen

t-----,

by fluorine?

reactive?

in all

trifluoride to

(ml%)?

requires

same number of

to

be addressed

of

butane

hydrogen

be replaced

route

mechanism

will

replacement the

with

fluorination

on the

insignificant

to

a viable

cobalt

likely

ClSJ.

Two points

(1)

of is

can occur

fluorination:

butane

provides

utility

compounds

rearrangements

aromatic

and C6FgR3 isomers

information

preparative

fluorinated

substantial

contrasts

cobalt

the

aliphatics.

fluorination

are:

the

random occur.

as will

wrong. Appendix)

replaced

which

one at a time

can model by F’s

a

294

That

is

:-

Wm-lFn* C4HmFn

or

+

-

C4Hm-IFn+i

C4Hm-lFnC ln=lO-m) The model

(i)

the

contains

five

reactivity

disposable

ratio

between

parameters: a single

H in a CH2 to

a single

H in

a CH3: the

(ii)

amount by which

reduced

(or

reactivity (iii)

(iv)

the

increased) of

amount by which

increased)

by the of

(v)

by introducing

the

reactivity

introduction

be released

so appear

of

of of

CII3CH2 as compared

two parameters

might

reactivity

an H in a CH2 (or

CH3) is

a geminal

the

one H in a CH2 as compared

reactivity and

the

in the

to

allow

from

the

for

the

surface

H in a CHF);

reduced

F (e.g.

(or the

CIl3CHF); ease

of

F (e.g. the

an H is

a vicinal with

with

the

with

which

cobalt

a compound

trifluoride

and

products.

TABLE 3

Comparison Partially

between

Observed

Fluorinated

and Calculateda

Isomer

Distributions

in

Butanes

%C

Compoundb Observed

Compound!

%C Observed

Calc.

Calc.

Nonafluorobutanes 2

60

50

3

40

50

23

Octafluorobutanes 4

4

3

7

21

5

11

16

8

4

2

6

43

47

9+10

14

8

d

0

14+15

16

17

Heptafluorobutanes CF3CP2CF2CH3

(continued

overleaf)

295

TABLE

3

(Cont.)

11

1

1

16

46

12

11

11

17

6

13

18

10

18

2

d

1

CFQCF~CFHCHQ

d

0

23

36

35

CF3CFHCF2CH3

d

1

24

11

3

19

7

0

d

0

20

1

4

21

9

11

22

2

5

CFQCF~CH~CF~H

Hexafluorobutanes

CF3CF2CH2CFH2

CFQCFHCH~CF~H

d

1

25

3

8

26

2

2

27+28

28

29

d

0

CF3CH2CH2CF3

Pentafluorobutanes 29

4

5

33

30

24

30

24

1

34

9

18

31+32

30

40

35

6

8

100

44

CF2HCH2CF2CH3

d

9

CF2HCH2CFHCFH2

d

18

e

Tetrafluorobutanes 3&37

CFH2CF2CH2CH2P

d

CFH2CF2CFHCH3

d

f

Trifluorobutanes 100

3

CFH2CFHCFHCH3

d

34

CF2HCH2CFHCH3

d

I

CFH2CFHCH2CFH2

d

36

CFH2CH2CF2CH3

d

19

38

a See Appendix. C

b See Table 1 for identities of numbered compounds.

The figures are X,

(e.g.:

g

with each set of isomers being treated separately

the sum of all the C4F7H3 isomers = 100: the sum of all the

CqF8H2 isomers = 100:

etC).

d Not

and none predicted to occur to >2%. isomers detected or predicted.

detected.

e No other isomer detected

f As e. but none >4%.

g No other

296

The best notable data

set

of

exceptions

and the

involved.

Since the

the

isomer

major

CqF5H5 (33) is

each

of

the

steps

sets

this

(e.g.

at the

then

the

the

the

(but

see

only

in the Table

measuring

large

observed

of

36 + 37 are

errors a small

and since (e.g.

even

the

major

way we have 3)

the

differences

acceptable

later)

the

likely

extent

c of

of

With

comprise

a small

results

difficulty

apparently

between the

CqF5H5 at 8.9%).

only

100% (footnote

compounds

fit

isomers

to

3.

shown in Table

given

can be quite

main path

shown before

of

expressing

isomers

Add to

results

later),

may occur

and ‘observed’

Part

the

these

then

of

the

reasonable

mixture

accurately,

‘calculated’

quite

a set

2.5%),

set

any errors.

of

is

some of

of

gives

be discussed

reaction

at

quantities

(the

(to

calculated

amount of

that

parameters

-

- magnifies

many small between

as a test

fluorination

of

then

speculative

the

model.

becomes

and are

not

part

model):

co3+ (_e,

CH3CH2CH2CH3

co3+ (_e)

>

23.

Scheme

1

There

are,

would

not

27.

of

directly intervention

However. badly. They are:

F-

___,

_

course.

in to

+ 37)

28

appear

particularly

[CH3CH2CH2CH3]’

CH3CH2CH+CH3

CFH2CFHCPHCFH2(36

_

>

CH3CH2CFHCH3

repeat

.

+ 32)

etc.

other

compounds

later

stages

fluoro-compounds of

> CH3CH2EHCH3

CP2HCFHCFHCFH2(31

in any products), the

*

-H+

on the

and it of

the

is

full

main path

quite

possible

fluorination,

(R + CoF3 +

RF + CoF2)

of

for

(or

CH2 groups

that,

radicals without

could

go

the

carbocations.

there

are

a set

compounds

which

the

model

fails

very

297

Calc.

Observed

CH3CF2CFHCH3

(38)

100

3

24

1

CFH2CF2CF2CH3

(30)

CF2HCF2CF2CH3

(19)

7

0

CFH2CF2CF2CFH2 (24)

11

3

structurally

related.

These

compounds

share

the

24)

predicted

to

occur of

amounts.

were

the

at so,

amount

early

then

- about

that

just

possible

the

.

positions

speculate

but

amounts,

also

CoF3 !+F2)

is

not

in

H (there

the

expected

be

present

of

might

it

CH~CFHCF~CFH~,

calculated set

since

present

Fraction

which 30.

are

obvious,

given

anomalously

large

which

could1 be a

are

CH3 and CFH if

couplings): in

anomalously

this large

10%. compounds

is

Perhaps

present.

form:

* CH3CH=CHCH3 cop3 (+F2)

-H+

+

the

10)

are

showing

alkenes

CH3CH-CFCH3

Simple F for H replacement

these

that

why this

fluorination

observed

in

would to

compounds

18 vs

they

occurs

compound

Scheme 1)

-HF

set,

Other

CFH2CF2CFHCFH2 (33:

significant

20% compared

only

in the

quite

expected

CH3CH2CHCCH3 (See

are

model,

anomalous

the

One can

in

the

is also

It

member of

pattern

and CFH2CF2CF2CF2H (13.

crudity

signals

clearly

same structural

predicted

the

are

-

CHQCFHCFHCHQ

CH3CFHCF2CH3

(38)

one - compounds

with

33.30,etc.

Scheme 2

This quite

sequence

cannot

common (-8.5%

of

the model of

the

calculations

more highly

observed, anomalously

whatever largs

be the the

total

with fluorinated the

choice

amounts

only

of

reaction

38 gives

product):

predictions

products

which

of

parameters

the

compounds

furthermore, for

are

the

very

in the which

CH2 groups

model.

could

starting

amounts

far

from If

are

of those

the

be formed

by

many

2

298

:“m . . v)LD

(0

m

8

11

12

1 234.5 67 CF3CFHCF2CPH2

Lit.[lO]

10

9e

Lit.[E]

1 2.3 45 67 CP3CF2CFHCPH2

(*)

1 23 CF3CFHCFHCF3

(meso)

1 23 CF3CPHCFHCF3

12 3 4 CFQCF2CH2CgQ d

d 113.8

4.25

5.28

5.53

7.47

d 81.9

f

f

231.2

119.4 125.6 239.8

125.1 131.1 208.6

75.2 215.4

83.9

75.6 221.3

77.8 220.5

78.1 211.4

88.3

f

f

567 = 46 (continuedoverleaf)

. * = 288; J46 = J56 = 14.6;

;t,z=J:fl==2J:5 ;,j":3;,";3 =

56'7= 46.2

514 = 10.1: J16 = 2; J23 =2g4

doublet (6.OHz) couplings

apparent triplet (9.4Hz) and

JXX = 1.5. The 77.8 signal shows

45.1; JAX~ = 22.6;Jfi = 2.6;

AA'XX' sub-spectrumwith JAX =

The -CFHCFH- segment forms an

and doublet (6.1Hz) couplings.

shows apparent triplet (9.4Hz)

523 I 51. The 78.1 signal

534 = 9.5

513 = 0.7: 523 = 16.2: 524 =

$

u, t

*

4

1

m

VI

v) I

(u

3 7-l

f:

s

W WI ii?

=1 Y

m

b a

N 0,

b

b-b

zi

m

L,

CL

0 . 0

VI .

.cu . c

M

29

30h

12 3 4 5 CFH2CF2CF2CH3

28

12345 8 CF2HCFHCF2CH3

(B)'

1 2 34 CF2HCFHCFHCF2H

(A)

1 2 34 CF2HCFHCFHCF2H

3458

244.1

f

132.7

131.9

4.27

f

4.04

4.07

8.0

85.0

12

27e

7.5

85.1

28

Lit.[ll]

CF3CH2CFHCF2H

58 f

4

138.5

123

25

f

CP2HCF2CH2CF2H

243.9

24e

12 3 CPH2CP2CP2CFH2

TABLE 4 (cont.)

125.3

f

218.8

220.4

202.0

201.5

115.2

125.7

f

108.2

f

5.3

5.22

8.28

f

134.4

8.3

4.8

133.88 131.4.

f 5.8

f

114.5

7.48

l

55; J34+J38

= 41

= 13: 535 = 1.5: 545 = 19.2

4.5: 515 = 1: 523 = 12.8; 534

512 = 48.2; 513 = 14.1: 514 =

J38 = 2.9; J58 = 19.5

512 = 53; 534 = 45

512

53.8(48)

J58 =

11); 513 = 7.3:

535 = 545 = 12.8(12.2):

512 = 10.4(Lit.

512 = 53.4: 515 = 1.9: 534 = 545 = 15.9: 535 = 5.8: J48 = 4.8

512 = 45.7

fs N

33

34

35

123 4 56 CF2HCH2CF2CFH2

12345 67 CF2HCFHCH2CF2H

32i

311

CFH2CF2CPHCPH2

12 3.4 56 78

(6)

1 2 34 56 78 CF2HCPHCPHCPH2

(A)

1 2 34 56 78 CP2HCFHCPHCFH2

132.1

116

240.7

134.1

132.0

f

3.97

5.1

-4

-4

205.3

7.46

118.9

217.2

219.2

f

107.8

125.1

-5

-5

7.8

240

206.3

205.2

211.5

117.9

5.17

5.57

-5

-5

f

236.5

237.8

234.5

5.5

-5.5

"5.5

567 = 55.3

(continued overleaf)

557 = 4.5 (other one cl);

J56 = 16.3: two of 535. 545,

523 = 4.6: 535 = 1.8; J56 = 46

512 = 54.1: 513 = 534 = 15.7:

11.3: 578 = 45

556 = 47; 557 = 20.4; 567 =

534 = 263: 545 = J46 = 14.2:

= 535 = J36 = 10.7: 524 = 7.0:

512 = 46: 513 = 514 = 14.2: 523

12.4: J78 = 47.4

512 = 53.6; 557 = 22.5: 567 =

46.2

11.5; 557 = 567 = 15.6: 576 =

= J56 = 45: J35 = 545 = J58 =

512 = 53.6: 513 = 514 = 10: 534

i

38h

37

36

central

strong

of

attributed.

in almost

equal

189.3

-5.1

-5.1

it

is

decoupling.

the

as if

e Spectrum

not

i These therefore

out

very

entirely

are

were

half

CFCP3.

order.

J46 = 24.1:

the

signals

inseparable

obscured.

(10

are

in a signal

by stronger

have

(see

that

been

correctly

becomes

not

and

with

a

about

obscured analysed

it

Experimental)

h Spectrum

are or overlapping

J-values

symmetrical

f Signal

are Omitted

which

show some

lH shifts

on neat

J56 = 6.3

535 =

525 = 5.6 534 = 8.8;

c Many spectra

b Figures

second-order.

present

obscured

markedly

certain

two compounds

8.5:

514 =

514 =

514 = 2.4; 524 = 7.6;

J26 = J36 = 1:

523 = 255:

compounds first are

were

of

internal those

lower

534 = 45-50

513 = 20.7;

512 = 513 = 18.9:

14.7:

513 = 24.8:

534 = 45-50

512 = 46.8:

10.2:

512 = 47.3:

XL100 [~OOMHZ(~H) or 94.1(1gF)] on the XLlOO.

signals

they

from

so many couplings

relevant

AB spectrum;

and (iii)

of

carried

or a Varian

8.64

particularly

analysed

d Not measured.

present;

g Upper half

is

when (i)

have been

were

f

in ppm upfield

AB situation),

shifts

experiments lgp

omitted

all

simple

are

amounts:

homo- and hetero-nuclear

signal.

hump.

second-order

have been

nevertheless

they

or overlapping

were present

the aid

(ii)

zero:

C-C bond:

incompletely-resolved

by larger

broad,

signals:

neccessarily

the

the

107.9

203.2

206.6

GOMHz(lH) or 56.4MHz( lgF)]

102.9

-5.5

-5.5

Decoupling

figures

(beyond

remaining

featured

8.41

237.6

233.8

R12B [at

or CC)4 solutions.

7 scale;

second-order

on the

compounds

a Run on a Perkin-Elmer

1 2.3 45 6 CH3CF2CFHCH3

(B)

12 34 CFH2CFHCFHCPH2

(A)

12 34 CFH2CFHCFHCFH2

TABLE 4 (cont.)

g

305

5 (cont.)

b,

E)

TMS.

d As Table

or

h External

a0

(Z

CF2HCF=CFCFH2f

4.

c Omitted

d

126.4

123 456 (Z)-CP2HCF=CHCF2He

456

158.5

12 34 58 (Z )-CFH=CFCP2CPH2,e

123

120.7

d

123 45 (Z)-CF2HCF=CFCF3f

123 45 (E)-CF2HCF=CPCF3g

TABLE

values

4.03h

3.46

3.10

3.&’

4.ooh

are

d

124.0

156.5

149.3

d

not

d

d

114.5

263.3

57.9

d

necessarily

4.33

117.8

151.3

d

zero.

4.71

3.92

5.39

= 50;

= 52.1;

= 7:

523

J56

513

534

f

= 3.5

534

545

=

545

524

= 47.5

g Neat.

556

523 = 12.3

= 32.7;

= 1.4:

523

J45

= 4.5;

= 15.4;

515 = 8:

= 21.9;

= 7;

J36

solution.

J46

523

= 46.3

= 1;

535

= 12.4:

= 2.5:

514

C6P6

= 11.5;

= 54.2

= 16.4;

J56

535

= 7.6;

= 11.2;

= 15.7;

513

e CCP4 solution.

512

J46

= 52.8:

= J46

512

19.3:

534

= 69.4:

= 1:

512

= 1:

514

524

= 1.5:

= 12.6;

= 19.8:

523

513 524

= 51.3;

=16.0;

512

J12

:

307 Scheme 2

are

proceeded

down this

three the

added

then

about

since

or more hydrogens, Scheme 1 or Alkenes

the

could

fluorination

it

alkenes

is

quite

could

that

that

of

stages

in the ion

the

only

small

of

alkene

they

are

a few compounds

to

substantial

amount

for

Only (Taken

isomers; is

at early

as but-2-ene. to

a judiciously

to

the

compound

38

chosen

frow

“anomalous”

24%;

route

figures

of

are

are

mixture.

Calc.

if

the

C H F set then 4 5 5 this correction

as discussed from 38.

the

present

in

particularly

31 and 32,

present for

anomalous

in 31+32;

compound

the’observed’ is

33 (CFH2CF2CFHCFH2) also

if.

of

much greater

are

If

39%.

(i.e.

is

(20.22.25.34)

However, the

composition

amount predicted

these

2.6%

from

final

well.

compounds

amount of

observed

the

30%).

to

the

quite

observed

together.

omitted

the

compared

where

two,

obs.

31 and 32 rises

pentafluoro-isomers

the

give

dominant

as well

in a way similar with

model,

Most of

and so the

error.

30(CH3CF2CF2CFH2) figure

do not

KCoF4).

in fact,

is,

form

single-P-for-H

quantities

C~H~F~

compounds

but-1-ene

starting

can be simulated

amount observed.

susceptible

40% of

in a fluorination.

can do over

formation

Indeed,

our

mixture

There

early

CH3CH2CF2CFH2. CH3CH2CFHCF2H. and CH3CFHCFHCFH2. and using

parameters

than

above,

made to rises

some of

CH3CF2CFHCH3). then

all

to

the

39%

33 arises this

fits

in

well.

Table

3 also

in

lists

With the the less

predicted

With the

isolated. <2X.

tetrafluoro. occur

with

by either

or by fluoride

fluorinated

(but

fluorination.

38.

occur

By invoking

1 and 2).

fluorination

been

have

compounds

be formed

in the early

thermally

only

highly

trifluoride

possible

in the

mixture

all

could

be formed either

processes

cobalt

Schemes

rather

less

could to

CH3CH=CHCH3

known [17]

over

stages

the

refers

with

CH3CH2CF2CPH2 and CHQCH~CFHCF~Hcould (see

fluorination

only

elimination:

Alkene-forming

is

the

Scheme 2 route.

alternatively

CHQCH~CHPCHQ \

It

of

estimate

those

by HF elimination,

catalysed

since

lo-25%

This

path.

than

hepta-.

tetra-

major half

values hexa,

for

the

the

‘predicted

awount

of

which

and penta-fluorobutanes.

and tri-fluoro.

isomer

some compounds

but the

figures

not

isomers

are

isolated’ which

have not these

higher: is

were

for

expected isolated.

are the to

300 and since

these

surprising.

case

a similar

point about

l-2%

fin

(although

the

the

5%. but

more accurate). being

of

to

both

lack

of is

samples

detection the

is

anomalous

not

too

one

(381

Why is

this

were

C4-hydrocarbon

and 60% 2-methylpropane over

carbocations, primary

results

CoF3. then

for

than

inevitably

either slow,

at

so slow

that

the

acid

or

to

clearly

is

it

about

of

40% not

involve

rearrange

then

true

rearrangement of

ions.

cannot,

amount of

This

tertiary

l-2%

C4-isomer.

mixture

these

they

the

either

since

that

must be due to and vice-versa

catalysed

[18].

this

suggests

pure):

with

form:

to

fluorination that

products

rearrangements

C4-isomer

the

feedstock,

as >99.5%

200°C

if

have

secondary

butane

Lewis

in

results

in an equilibrium

either

would

the

In the

2-methylpropanes:

[3]

we estimated

1%. starting

However,

carbocation

[3]

of

in the

amount so small?

butane

fluorinated

‘rearrangement’

purchased

either

happening

paper

these

about

rearrangement.

occurred

a reassessment

therefore

skeletal

are

butanes

original

Some of

is

is

products

some P-methylpropane

rearrangement

energy

the

detected

discuss

fluorinated

2-methylpropane

there

then

trifluoro-isomer

we wish

amount of

amount was about is

0.8%.

previously.

The other

of

comprise

The only

discussed

butane

only

to

the

are

other.

a

much higher

rearrangements

seems,

compete

in are

with

fluorination: CH3CH2CHFCH3 t

CH3CH2CH+CH3

M

+CH2FHCH3 CH3

Primary

carbocations

by invoking

protonated

fact,

during

occur

The C4-isomers - not

even

between

no other

reactions

avoid

protonated

isomerisation is

cyclopropanes.

fluorination

cannot

if

process

primary

(e.g. primary

with

longer

rearrangements octane

-25%;

are

if

invoked.

and 2-methylpentane

carbocations

alkanes

hexane carbocations

- such

chain

and extensive

cyclopropanes butane

competing via

can be avoided

only

as fluorination

take

they

“50% are

Lewis occurs

than

C4

do,

in

[4]).

to

rearrange

acid

catalysed

because

- and so the

there

slow

place.

EXPERIMENTAL Fluorination

of

Butane

(890

bed of

Cop3

(10

Butane

g)

was fluorinated

kg)

in a reactor

in 9 portions of

the

type

by passage

described

before

over

a stirred

[16]

at

309

140-230°C. dm3/h)

Residual

for

2.5h

collected were long)

in a trap

dried

over

packed

recorded

products

through

were

a trap

cooled

in

liquid

P2O5 and distilled

with

Dixon-gauze

in Table

swept

from

containing air.

reactor

with

(to

The combined

through

nickel

the

NaF pellets

spirals:

N2(20

remove

HF) and

products

(1921

a vacuum-jacketed

column

fractions

are

taken

(1.2

6.

TABLE 6

Summary of

Fraction

Fractional

Distillation

Wt(g)

b.range

57.6

Compoundsa

(OC)

<16.4

101.4

16.4-24.6

in Fraction

1, 2.

2.

9 (39)

2.

fi,

9 (18)

3.

104.2

24.6-32.2

50.0

32.2-33.8

(2).(3).$.5,6.8,9.18

151.6

33.6-35.7

128.9

35.7-42.8

6.7.10,(11),~,17,19,38.

G

149.6

42.8-48.6

~.(10),12.(14),(15).17,~.

Ii

131.8

46.6-55.0

7.(12),13,~.~.16,22,(26),

I

162.8

55.0-57.2

4.5.5,(9).18.

(40)

S,lO,(l8).(19)

(41),(42).(47)

(38),(41)

30,(43)(44),(4(S)

13.(14),(15).16.(25).

26).(2Q),

(43).(44).(46) 112.8

J

13 16 (25).(26).27. -*-.

57.2-57.9

(45). K

~,l6,23,25,(26).~

43.8

57.9-64.0

96.9

64.0-68.7

245.0

66.7-69.2

39.4

69.2-71.2

70.8

71.2-75.0

72.8

>vi.ob

29),(43).

(46) _.(29).(45),

(49)

a See Table

1 for

formulae

underlined

compound

is

compound

in parenthesis

24.28 -9-v 33 34,35.(50).(51) 31 32 33.34,35.36.37.(50).(51) _*-V

corresponding

present is

23 .-._I 24 28 33,(34).(48),(50).(51)

to

present

to

compound

>20% in a particular to

~3%.

b Pot

numbers. fraction:

residue.

An a

g) m

Separation

of

Five dinonyl unit

Distillation

columns

were

phthalate

used

each

separation,

inlet

pressure

the

Kel-P

x 5.5

2 - as unit

oil

unit

1;

gas the

no.,

(unit

unit

m. packed

1 but

on Celite

(1

with

75 mm dia.; unit

: 4):

5 - a Pye 104 instrument,

4 -

column

1.

N2 carrier

unit

(psi)

with

as unit

with

1 - 35 mm dia

: 2);

as unit

x 2 m, packed were

(1

packed

x 2 m. packed

1 cm dia All

1 but

by GPc

unit

employed:

on Celite

3 - as unit

15 mm dia

Fractions

5),

and katharometer

N2 flow-rate

and the

temp.

With

detection.

(dm3/h) (OC) are

(units

l-4)

stated,

or

in that

order.

Fraction (6.35

g).

evidenced mixture

A (13.0

the

peak at

[5]

to

C (32.0

0.7

(4,

no peak

by ir b.p. at

34-34.5OC, (C3P3W2+).

(see

30-31°C, 101

by ir

g)

of

g)

were

wae separated

(8,

5.2

2H. BlJ-octafluorobutane

g),

identified

B (25.9 rejected

be an approximately

g)

l@-octafluorobutane

identified

perfluorobutane as

[5]

and

(ii)

a

3:2

were

separated

and the mixture

second

of

lH-

(2;40; (18.2

g)

and

(2.3).

2I&octafluoropropane

8.6

(4.75

(i)

g).

main peaks

and third

OH-nonafluorobutanes

Fraction

(0.4

into

perfluoro-2-methylpropane

1000 cm-l.

The three

B

first

(1:9.25;58)

(
nonafluorobutanes

was shown by ir

of

was separated

a little

by an ir of

Fraction 57);

g)

containing

later) ms

at

g) (9)

(m/e)

(2:45;52)

b.p. b.p.

lE°C

27-28OC;

and nmr;

(v)

(bp

into [20]

(i) 18OC);

a mixture

2IJ, (ii) (6.3

and 2H,2&3l&heptafluorobutane

peaks

(CP3CFH,+);

as peaks

g)

at

(m/e)

(iv)

g,

101

~a.

2:l)

(18).

lH,2H-octafluorobutane

183(W+-19)

lH,3H-octafluorobutane 183(&f+-19).

1lJ.

nc

and 83 (CP2HCPH+), nc

(CF3CFH+ or

(8.

2.7

g).

(5, but b.p.

CF2HCF2+) and 95

311 TABLE 7

Compositions

of

Peak No

Main Components

I II III

Peak No

As displayed dinonyl

X

more than

are

one compound

approximately

the

concentrated

XVIII e XIX 3

in which

it

d A peak

appeared

is

listed

in the

between

displayed

15 psi,

for

minor

beside

a peak

time;

‘E ’ indicates

number,

lower-boiling

one concentrated V and VI in

as distinct

x 3.5m column

N2 pressure See text

relatively

and ‘L’

occurs,

36.37

(5 mm dia

(1:5),

listed.

same retention

mainly

e Although

31.32

)

on Celite

components

b,c

i4(E),15(E),13(L) 16(E),24(~) 27(E),21(L),23(L) 28 33 35

XI XII XIII XIV xv

on a Pye 104 instrument

phthalate

b Only major

Main Components

b,c

1

VI VII VII I IX

with

a

2.3 8 4 Q(B).lS(L) 5 6(E).lQ(L) lO(E),12,17,30(L 7

$

a

GPc Peaks

all

60°C). c Where

had

distillation

in the

these

ones.

a compound fractions

relatively it

some fractions:

peaks,

packed

temp.

compounds

higher.

was butane.

were not

separated.

Fraction g)

of

four

g)

of

(i)

G (35.0

(nmr analysis)

[19]

Fraction g)

several

of

43OC),

II (41.0 compounds

other

(2;68;52)

coaponents

and (iii)

and (iii);

44OC (Lit.

6.8

g) -gave

identified

g) 13,

compounds,

by ir

the

and

a mixture a mixture

(7.

11.9

g).

(9.7 (3.7 b.p.

[51.

(2;47;69)

and 15;

16 being

(ii)

(10.12,17.30):

lIJ,4IJ-octafluorobutane

separated 14.

(i)

two main peaks:

into (ii)

major.

(i)

a mixture

a mixture

(25.5

(s g)

1:2:2, of

312 Fraction gave

(i)

(iii);

I contained

two major

impure

compound

and (iii)

impure

13 (9.1

re-separation 57-56OC at

of

(iii)

165 (M-19),

gave

pure

This

L from

30.0

(a small

(synthesised

g),

N (23.7

71-72OC,

(ii)

and

(~a.

(ii)

mainly

Fraction (4.5

g)

(21.5

g,

in

g)

and (i)

gave

53-54OC: nc

C.26.1:

one peak.

l:l,

26.8

(16),

H.1.6%),

This g)

of

b.p.

ms peaks

was separated

mainly

(21)

consistent

literature

separated

contained

(unit

(ii)

1:l

4)

with [6])

(2;66;71)

two major

gave

g)

(i)

(23),

was detected

the

presence

(Found:

by

of

C,29.1:

27

H,2.4.

into

(i)

several

(28.

10.0

small g)

b.p.

Separation

of

peaks

proportion)

isomers

31 and 32 - b.p. H.3.4%).

(33)

which

- they 90°C

ms peak8

at

peaks.

a small

lIJ,2H,3&,4H-hexafluorobutane-B

was separated

two peaks

C.32.4;

in about

(2;69:103) were

were

(Found:

too the

80-90%

into

close

(i)

to

(28).

purity.

several

be fully

minor

separated

1,1.2,3,4-pentafluorobutane

C. 32.5;

H.3.1.

129 (M+-19:v.snall).

C4H5F5 requires

83(C2H2F3+).

65(C2H3F2+)

and 59(C3H4P+). A further (I)

all

separation

peak8

overlapping

contained

peaks

which

1,2,3,4-tetrafluorobutane (M+-19

: v.small),

g

by ir.

P (28.4 g);

(i) of

and lH,lH,3IJ,4H-hexafluorobutane

spectrum

in the

of

80.0

H,2.4%).

This

0 0.5

g)

of

and 83(CF2HCFH+).

of

(~a.

1.2,2.3.4-pentafluorobutane

peaks

b.p.

lH,2IJ,3&,4IJ-hexafluorobutane-B

identified

Fraction sample

90% purity,

lH,lIJ,2H,4&-hexafluorobutane an ir

C,28.9:

and

(16.3

lH.2H.4H-heptafluorobutane

(27)

as described

Fraction (9.1

of

(2:47;69)

Re-separation

g).

C4H3F7 requires

consisted

64OC, with

C4H4P6 requires

~a.

g as a mixture

proportion

b.p.

a mixture

95(C3H2F3+),

lIJ,2&.3H,4H-hexafluorobutane-A

nmr).

(ii)

16 (39.7

of

H.1.7.

lOl(CF2HCF2+),

Fraction (2:42;68)

(13)

C,26.5:

(Found:

g):

compound

lH,1&,4H-heptafluorobutane

Separation

peaks.

(5.15 in

(i)

were

psi.95) and (ii) isolated

isomers 65(C2H3F2+)

of

3.50 above

as a 1:l

36 and 37,

and 59(C3HqF+).

g in seven (2.44

g);

mixture b.p.

llO°C,

portion8

gave:

and (ii) (0.12

g)

two of

ms peaks

the at

111

313

2.3-Dichlorohexafluorobut-2-ene way over peak

CoP3(6

on glc.

compound

kg)

at

230-240°C.

Separation

(unit

of

The product 2)

suspension

at OOC.

After

dropwise.

of

distilled

into

(2;4.6;62)

to

(13.7 lithium

(76.5

mixed

g)

showed

isomers

of

183(M+-19).

and

(ii)

usual

one main

the

title

the

longer

nc

(9,

2.8

re-separated

(3:10;54)

to yield

2.8

41°C.

ms peak at

b.p.

Competitive

Dehydrofluorination

A mixture

(2:l

lh through

molten

at

consisted

-180°C.

top

pure

of

9 therefore

g)

(glc)

at

of

then

b.p.

compound

(50

cm3)

were

separated

by glc

ether):

25OC,

top

ms peak at

10 and ether

which

(+)-2H,3Soctafluorobutane

the

nc

0.45

2H,3H-octafluorobutane

g)

was passed

was (10,

starting

dehydrofluorinates

isomers,

about

2-3

Isomers

in a stream

The product

225OC.

the

flask

retained

g).

in ether

a

183(M+-19).

of

9 and 10,

KOH (26

of

g)

100 min to

30 cm3) was added

reaction

and were

to

(1:l)

a mixture

the

over

(4.2

(70X,

of

receiver

addition

dropwise

hydride acid

contents

(-78OC)

(in

was added

sulphuric

volatile

a cooled give

g)

neso-2H,3H-octafluorobutane

Isomer

the

aluminium

2h stirring,

The most

g),

gave

in the

2,3-Dichloro-octafluorobutane

The dichloro-compound

(I)

g) was fluorinated

(54.2).

Reduction

stirred

(80.7

(0.05 but

times

of

g).

in 5:l

slower

N2 over

collected ratio. than

ieoner

10. 1.2-Dichloro-4H-hertafluorobutane

QIJ-Heptafluorobut-1-ene irradiated (20

in a 30 cm sealed

CIB distant)

for

1.5h.

1,2-dichloro-IH-heutafluorobutane

[21] glass

(7.5

g)

tube

Distillation nc

and chlorine by two 20 watt of

(9.7

(2.9

g).

the

product

b.p.

g)

were

fluorescent

lamps

gave

80-82OC

(Found

: C,

314 18.9;

H.0.5;

CP, 27.7; This

F,52.8%). apparently

without

The Reduction

of

is

stirring

(0.75 to

g)

warm to

(15

to

residue (ii)

to

The mixture water

(24

but

out

the

the mixture

20 cm3) was added.

(60%.

remove

(unit

the

4)

to

distilled The

ether. yield

(i)

lIJ,2IJ,4IJ-heptafluorobutane separated

reduction

from

at higher

which

could

have

this

with

LiAlH4.

hydride

was allowed

and fractionally

to

by glc

of

of

acid

dropwise

aluminium

and

(16).

fraction

I.

temperature arisen

ether

or

in THF

by initial

alkene

ExDeriments

of

lH-

and ZH-Nonafluorobutane

(12.0

g)

(from

shaken

The organic (1.9

Fraction

together layer

g)

B).

(2 and 3)

potassium

in a sealed

was separated

identified

by ir,

hydroxide

tube

for

(2;43;62) and (ii)

(22 g)

23 days into

and

at room

(i)

lfl-nonafluorobutane

g).

(b)

This over

lH,2H-Octafluorobutane

compound

(3.2

40 min and the

(4;5.5;29) at

g)

reaction

octafluorobut-2-ene (2.2

(X.28.0:

[22].

cm3) was added lithium

-65OC.

(MgS04)

helices)

substance

products

cm3) were

temperature.

glass

the

carry

and then

Mixture

2h at

dried

(~0.1

with

Dehydrofluorination

(a)

(20 of

cm3) was separated

more complex

formation

in ether

and sulphuric

with

amount

to

H,0.4:

patent

given.

solution

After

cm3).

packed

by ir

Attempts lead

(50

g)

was separated,

0.5

a small

being

(-85OC)

room temperature

(ca -

identical

(2.5

a cooled

layer

cm column

C,19.0;

in a Russian

1.2~Dichloro-4H-hentafluorobutane

in ether

The ether

mentioned

any properties

The dichloro-compound with

C4HCP2F7 requires

F.53.1.

compound

gave

3110 and 1734

the

g)

(5)

was passed

products major

cm-l.

(1.6

corponent.

through g)

collected

molten at

KOH (30 g) -18OOC.

(Z)-lIJ-heptafluorobut-1-ene,

at

220°C

Separation ir

peaks

315

(c)

lH,3H-Octafluorobutane

This (19.0 (1;13;67)

g) was treated

gave (i)

as in (a),

unknown (0.6 g);

ir peak at 1725 cm-l: 1720 cm-l:

(6)

and (iv)

(iii)

starting

(1.0

g).

peak at

(19, 0.2 g).

as in (b) to give a product Separation

and one minor component.

(Z)-lH,4IJ-hexafluorobut-l-ene

1734 cm-I : and (ii)

g).ir

(13)

This butane (5.1 g) was treated (i)

(1.3

lIJ,lH,lIl,4&hexafluorobutane

one najor

Separation

10h at 100~~.

(Z)-lg-heptafluorobutane

(E)-lg-heptafluorobutane

(d) lH,lH,4H-Heptafluorobutane

containing

but for

(ii)

(0.4 g). material

(4.2 g)

(3;5.5.56)

gave

ir peaks at 3110. 2970, and

(2.1 g).

(e) Mixture of 1H,2H.3HW4H-A-(27) and lH,lH,3H,4H-(23)-Hexafluorobutanes This mixture for 44h.

but

g. s

1:l

The product

(10.1

(7.2

unknown (0.2 g);

(ii)

L) was treated

g) was separated

(1;13;57)

(Z)-lII,4IJ,4IJ-pentafluorobut-l-ene

at 3120. 2950. and 1732 cm-l: g).

from Fraction

ir peak at 1720 cm-l,

(iii)

(0.3 g).ir

(0.3

(i) peaks

(Z)-lH.2lJ,4IJ-pentafluorobut-2-ene

ms peaks at 146(M+), 127(M-19).

CHCPCP2H+).62(CF2HCP+), and 51(CP2H+); and (iv) lIJ,lII,4IJ-pentafluorobut-2-ene

as in (a). into:

g),

(2.1

95(CFCHCP2H+or

Z or E

ir peak at 1725 cm-i.

APPENDIX

A Comnutor Program for WodellinF Fluorination Each hydrogen in a fluorocarbon

is given a reactivity

H in a CH3 or a CPH2 or a CP2H) or 9 (each H in a modified

by multiplying

vicinal.

by p for each geminal fluorine

1 (each this

is

and X for each

For example, each hydrogen in the CFH2 group of a

CFH2CF2-moiety is assigned In a molecule, reactivities. g2v.

of either

CH2 or a CFH):

the total

a reactivity reactivity

of gv2. is the SUR of the individual

For example, CFH2CP2CFHCF2H has reactivity

The amount of a compound found in the final

amount formed and on the balance

between its

2gv2 + ngv4 +

product depends on the

reactivity

and the liklihood

316 of

its

release

release molecule

and not

has the the

from

the

by assuming

hence

further

all

on the

of

the

i in product

=

N = no.

of

is

pentafluorobutanes.

a compound

is

formed,

and release

from

Amt.

23 in product

of

in the

In the

release.

of

27 + 28 in

So. pair

even

case

amounts

formed

the

by

(In

the

have

+ ngv4

release

equal,

case

distributed

trifluoride

(and

A(i)

helps

parameter

to

balance

CFH2CF2CFHCF2H (23)

+ 2ngv2)p

amounts

were

is

a disposable

for

X

+ g2v)p

reactivity example:

Amt. of

23 formed

+ 5.RP

5.RP

the

example.

and 28):

X Amt. of

factors in the

the

are

the

product the

to a given

of

27 + 28 formed

+ 5.R1

because

The amount fluorinated given

of

=

though

cobalt

5.RP

(2g2v

27 and 28.

this

the

X

and R is

i,

=

For CF2HCFHCFHCF2H(27

product

in a

fluorine

+ N.RP

power R) which

(2gv2

Amt.

for

then

N.Rl

to

against

each

product):

fluorines

taken

fluorines

5RP.

in

(reactivity

number of

In our notation,

[reactivity(i)]p

where

We have modelled

surface.

only

distribution.

fluorination

appearance

Amt. of

trifluoride

depends

so that

factor,

an amount A(i)

between

it

on their

same Rp value.

same release If

cobalt

that

same for

would

not

reactivities

isomer

is,

23 and for

be equal,

the

even

if

the

differ. in this

model,

obviously

CFH2CF2CFHCF2H(23)--->CFZHCPZCPHCPZB(1B)

conversion):

Amt.

of from

16 formed 23

The amounts possible and the

=

Pgv2 + n&

(2w2

of

each

hexafluoro-isomer.

pentafluoro-isomers result

hexafluoro-isomers

expressed

+ g2v)p

and released as a percentage

released.

X Amt. of

23 formed

+ 5.RP

for

example.

into of

the

the

produced

product

total

are

amount of

from then

all summed

317 The best fit was obtained by trial and error by adjusting this gave B = 2; g = 0.25; 1 = 0.4; R, = 1: and p = 3.

E: are

given

in Table

variations

of

between

“predicted”

increasing

it

A similar

They are

2 to

program

5,

for

best

Here again

(CPH2)3CF It

is

(19

quite

of

from

types

of

fluorine

(or

number

:

for

to the

14 of

argue

cobalt

two CFH2 groups

towards

have

not

this

for

the

to B;

predictions.

fluorination g = 0.5;

compound:

reference

3)

that

than

of &! = 0.5; there

RP =

was much

predicted,

probability

the

should

and not

contribute

probability model

disposable

parameters

quite

CHF2. CF3.

CH2, CFH. and CF2) would

of

surface

in a molecule

in the

are

the

trifluoride

a CF2H group

from

allowed

for

were n = 10;

and

disparities

more sensitive

ridiculous

was an anomalous

hydrogen)

example,

here

large

relative

3).

reasonable

fluorohydrocarbon

gave

produce

and

The results

to Rp and p,

do not

constructed

there

ref.

sensitive

They are

values

more CH3(CF2H)CFCFH2 (compound to

very

and 0.7

example,

has been

[3]:

R = 3.

not

0.2

and “observed”.

from

2-methylpropane 100:

3.

g and y between

B.g,v.e,

of

because

merely

their

a different

a

on the

factor

Nevertheless

release.

(one

of

depend

we feel

more

enough:

release

should

that

each

we

five

for

CH3, CH2F,

be unreasonable.

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R.D.

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