17O-NMR study of polyfluorinated alcohols and ethers

Journal of Fluorine Received:

17

September

0-NMR

KONRAD

31 ( 1986) 183 -196

10, 1985; accepted:

183

December

STUDY OF POLYFLUORINATED

2. 1985

ALCOHOLS

AND ETHERS

VON WERNER

Hoechst

BERND

Chemistty,

AG, Werk

Gendorf,

filr Anorganische

MeiserstraBe

Burgkirchen

(F.R.G.)

+

WRACKMEYER

Institut

D-8269

1, D-8000

Chemie,

Munich

der Universitat

MLlnchen

2 (F.R.G.)

SUMMARY

cc70 ethers. tuents

values The

position.

CHFzCFz data

"O-nuclear

in y-position

comparison

phenyl

are reported

shielding

with

e-interactions

group

is attached

are supported

fluorine

"B-

are greatly

and

alcohols

fluorine

and

substi-

than expected

substituents

oxygen

to the oxygen.

by 13C-,

with

(much more

between

CoC,/B - unsaturation)

group

increases

and it decreases

513 C -values)

with The

for 16 polyfluorinated

in

and a vinyl reduced

Conclusions

2gSi-chemical

by

p-

or a

if a

from

&'O-

shifts.

INTRODUCTION The dramatic last decade

have

of fundamental

?# Author

improvements stimulated

importance

instrumentation

during

the study of such nucleides in chemistry

to whom correspondence

0022-1139/86/$3.50

in NMR

should

but which

which

the are

have unfavourable

be addressed

0 Elsevier Sequoia/Printedin The Netherlands

184 nuclear

magnetic

"O-nucleus

(natural

abundance:

only

in the last 5-6 years,

work

by Christ

of "0-NMR shows

et al.

studies

As a consequence

parameters

much

empirical

values

structure. ethers

171, that there

3"

C-values

ROR'/RCHzR' effects

for both

reflected later,

corroborated

oxygen

compounds

(PC,@

-unsaturated

Our current polyfluorinated NMR as a probe alkyl

chain

hydrocarbons

Furthermore,

in various

"0-NMR

studies

[8,9], of carboxonium and aromatic)

only

scant

of only three

still

"0-NMR

&"O)

in order models.

between

that

J "O-

(ROH/RCH3

ions

161,

on structural

r-interactions suggested

are

in ref.

[l] and,

[2-51,e.g.of boron-

[I01 and of

ethers

[ll].

in NMR spectroscopic

compounds

for studying

of

dependance

first

organic

work

161 and dialkyl

correlations

a similar

of oxygen

in the electronic

6 "O-values,

in alcohols

have received values

are linear

[2-51).

[2-51 it is evident

in case of alcohols

interest

types

shifts,

to changes

of corresponding

by the

compounds)

and to test theoretical

sensitive

nuclei.

number

in "0-NMR

available

[7]), indicating

and it is

see ref.

and classification

trends

shown

growing

of different

"O-chemical

is the

the pioneering

(for reviews

amount

already

are very

Is was

after

or of labelled

of the activity

(in particular

the information

CT "0

and

of the vast

on the collection

to establish From

abundance

for this

and I = 5/2),

ca. 20 years -

of this method

available

concentrates

0.037%

example

[I], that a steadily

(natural

the potential

compounds

A typical

properties.

[12] prompted

the influence

properties us to use

of "O-

of the polyfluorinated

and ethers.

So far, compounds

of this type

attention.

To our knowledge,

the

compounds

have been

reported.

These

s"Oare shifted

185

3. 170.

-23.6

Al7 0:

-29.5

[61

J”O:

carried

It is shown

with

"o(a):

(A"0).

+96.0[131

"0-NMR

oxygen

influence

q-carbon

if the

: -28.0

A systematic

is a shielding

0

to the 3"O-values

respect

out for polyfluoroaromatic

is observed

\ H.”

A"0

analogues

that there

but deshielding

3

-28

to low frequency

of their hydrocarbon

0

[ill

+56

A"0:

considerably

has been

F'm~::2",,,,

CHF~CHFCHZ-0-CH=CHz

CF~CHZ-O-H

study

derivates

[141.

of the C6Fs-group,

is substituted

with

fluorine:

B

1 70.

-

+8.0

[I41

5

A"0:

-37.0

A"0:

We have measured alcohols

the

(1) and ethers

of the oxygen In addition,

1’0. *

atoms

"O-chemical

we looked

and of the CRFzCF2-group

+31.5

(anisole),

+68.5

(CsFsOCH3)

of 16 polyfluorinated

to represent

to the structures

at the mutual on the

[I41

shifts

(2,3) in order --

corresponding

+76.5

influence

"O-chemical

of

shift

the surrounding of type A, - g, 2. o<,fi -unsaturatio (compounds

zp,YS,f). - -CFz-CFz-0' 4

-CFz-CFz-CHz-0' B =

-CFz-CFz-CHz-C&-O C Y.z

186 RESULTS

AND DISCUSSION

"O-chemical

shifts,

1, together

in Table

differences,

A"0,

with

with

exerted

by the CHFzCF2-

similar

as evidenced

and those

given

in Table other

influence 15,161

by

d13C-data

(13C or

2, and also by kg,

"0)

in structures

This

However,

of Table

is always

to the reduced alcohols. "O-nucleus the other

is apparent (_1~, z!

observe

a shows

(see entries

fluorine removed small

atoms

or negligible

from A13C data

6"O

values

or

from the nucle

(OCH,), &3&f). ----

[12,

That means,

very

close

For type $

is observed; substituent.

shielding

of hydrogen

(compounds

than

structures

For the alcohols

for the silanes

isg

$5.

for lab --- must be attributed

bonding

in the polyfluorinated

2) a decrease

its magnitude

that

In case of the latter

in shielding.

is larger

of the increased tendency

immediately

distinguished.

an increase

in shielding

part

Therefore,

[12,15,16]

analogue.

of type $ and g are readily

the increase

data

have only a very

of type C - we will

An inspection

d"O

nucleides

is very

obtained

or further

small Al70 values

to the hydrocarbon

(g) there

23~). ---

will

on its shielding.

and from

of neighboured

previously

J-position

in

hydrocarbon

or the CsF '3- and C,F15-group

1 for compounds

in question

to the corresponding

on the shieldinq

in Table

substituents

1 - 2 are given

A 3 l/2' and the shift

the line widths,

respect

The influence

analogues.

0, of compounds

5"

depends

in shielding

of the

on the nature

of

187 The A"0-values indicating

+ 2 ppm), caused

solely

compounds result

2de with ===

pair

other

the

analoques

at the terminal

vinylic

The comparison shows

sensitive atom.

A crude

estimate

N

position

for

"CH*-groups

crude

estimate

study

shows

produces

a fluorine of the

at the

"O-nucleus

by the

of the

/s -carbon

[Ill ).

which

reduces

at the

for

charge

density

[12,15,16]

at the of

d-carbon

by -10 2 3 ppm

w

+3 5 1

a-position) (i.e. in

(i.e. in

in this /$-position)

('p-effect?),

y -position) 'y

y -

A similarly

compounds

(the wellknown

[12,

fi -carbon

alkanes.

/v + 36 + 5 ppm

(i.e. in

alkanes

qives

p-carbon

for comparable

(zd). _=

is much more

bc- or

(i.e. in

w-

d13C-data

"O-nucleus

atom at the

effect

in

for these

of polyfluorinated

d-carbon

from A" O-values

a deshielding

pairs

in polyfluorinated

that a fluorine

cited

[Ill

the CHCFzCF2-group

from Al3 C-values

-3.5 + 1 per fluorine

by "0-NMR

%-electron

substitution

atom at the

are

(le) _= and at the oara-carbon

that the shielding

ppm per fluorine and

a reduced

J13 C-values

to the fluorine

If the

r-contributions

that the

lone electron

carbon

with

lone

w-interactions

(see references

is supported

reflect

is the

x-system.

group

Therefore,

of the oxyqen

(Table 2) which

this

for

55 - 75 ppm in the hydrocarbon

by Aca

in 2&.

is

changes

the oxygen

shown qualitatively

suggest

This argument

situation

between

(58

of oxygen

or the aromatic

methods

constant

ppm. Clearly,

by an ethyl

physical

are reduced

interactions.

15,161

w20

as was

"O-nucleus

shielding

This

e-interaction

A"0-values

the availability

2de ===

in

is replaced

smaller

deshield

A"0-values

undisturbed

and by many

The

that the reduced

and the vinylic

CHF2CF2-group virtually

zab_c_are fairly

by the CHFzCFz-group.

of changes

electron

for compounds

causes

whereas

shielding

-effect'

[171).

188 TABLE "0

1

Chemical

shifts

a

to their

Nr.

hydrocarbon

and line widths

( &170)

Hz) of polyfluorinated

alcohols analogues

Compound

and ethers

b,

(A"0)

61'0

HCFZCF~CHZ-OH

(A31/2

in comparison

A)'?/2 Solvent/'C

A" 0

-26.8

410

-27.6

170

-28.0

>700

CDC13/60

-27.0c

-7.0

630

CDC1,/30

-6.0'

+34.0

100

CsDs/28

+55.0(a)

200

-28.3(b)

165

+60.0

155

CDC13/50

i58.5

HCFzCFz-O-CsHs

+101.0

390

CsD.5/30

+23.0

HCFzCFz-0-CH=CH~

+107.0

120

c6D6/30

+19.0

HCFZCFZ-0-CH=C=CH2

+152.5

250

CsD6/28

--

C3F7-O-CF=CF2

+95.0

175

CDC13/30

+11

HCF2CF2CH2-O-Si(CH,)3

-13.8

110

CDCls/28

-18.0g

+92.0

480

CDC13/30

-26g

C7F15CH2-0-Si(CH3)3

-17.0

700

CDC13/30

-20.09

/O\ CGF~~CHZ-CH-CH~

-20.0

440

CDC13/30

+oh -

+6.0

700

CDC11/30

+og -

+116.0

>800

CDC1,/30

209

C~F,~CHZ-OH C~FI~CH~CHZ-OH

HCFzCFz-0-CH3

CDC13/28 CDCls/55

-27.0'

+56.5d

(a)

(b) HCFZCFZ-0-CHzCHz-0-CH3

CDC13/50

HCFZCFZ-0-CHzCH=CH*

HCFZCFZCH~-0-BC,H,,

i

CsF1xCH2CH2-O-Si(CH3)3 CsF13CHzCHz-0-BCsHir

i

+60.0e

(a)

-1.3e

(b)

f f f

.o f

189 Footnotes a

to Table

A positive the

1

sign denotes

"O-resonance

values

depends

a high

of external

< 200 Hz, + 0.5 ppm; > 600 Hz 2 5 ppm. + 3 ppmi Approximate

error:

< 600 Hz, + 70 Hz; C d e

Ref.

[6].

Ref.

[7a].

This work;

respect

of the

< 400 Hz, rfi1.5 ppm;

to

&"O-

< 600 Hz,

A 3 l/2 < 200 Hz, + 20 Hz; < 400 Hz, + 40 Hz; > 600 Hz, + 100 Hz.

CHxO-CHzCHz-0-CHzCHz-0-CHx

-5.0

$70:

shift with

the accuracy

on the line widths:

Av1/2

b

frequency HzO;

(CH~-O-~H~),

in CsDs/28'C;

A 3 l/2 = 185 HZ;

-27.0

(CH3-0-CH1),

A 9 l/2 = 105 Hz. Ref.

[l?].

B.Wrackmeyer, 3 "0

"0-NMR

of 1,2-butylenoxide:

BC~H,~

-18.0

measurements. [7b].

= 9-borabicyclo[3.3.1]nonyl.

If the changes

(’ 3c, "0) local

unpublished

in the magnetic

can be accounted

paramagnetic

shielding

for both

for by Pople's

screening

constants

nuclei

approximation

(eqn. (1)) [la],

of the the ratio

-3 of the radial expansion terms for oxygen and carbon < r >1 2P -3 2.96 [7a], to < r >13 (theoretically 2.74, experimentally 2P c 3.83 [6, 7b]) should explain the main part of the different

To

sensitivity.

GpAA

uO

uo2’ruB . AE

=

= permeability

AE = average r2p =

radius

imbalance

-1

-
of free space,

excitation

E:

Q

)

(1)

A+BAB

By= Bohr magneton

energy

of the valence

of electronic

+

p electrons,

charge.

ZQ

represents

the

190

z

3

61718

a

gf

8

ll,12,13h

i

from Ref.

= +59.0,

= 59.9 Hz.

AV l/2 = 250 Hz.

'J("Si"C)

12.

= +19.4;

'J(29Si13C)

= 58.9 Hz.

"B = i-57.8; Au l/2 = 280 Hz. d BCaH14 = 9-borabicyclo[3.3.1]nonyl

Jz9Si

24.5(11)

-1.4(11)

45.1(10)

63.0(3)

J. Fluorine

gz

ro.21

89.8(6)

(1984) 275.

see Ref.

23.0(8)

J('9F'3C)

23.2(13)

33.1(7)

constants

33.3(12)

24.3(6)

-1.4(6)

lo.11

202.4(5)

Chem.

and coupling

58.0(8)

C7F,5-groupS

33.7(7)

55.0(8)

44.6(8)

-1.5(12)

115.0(2)

= 60.0 Hz. :: 29Si = +23.9; 'J(29Si"C) M.-J.Stebe and J.-J.Delpuech, G.Serratrice,

"B

c$29Si = 23.7;

Data

For the d'3C-values of C6Fq3-, and Ref. cited therein.

C~F,~CHZCH>-O-BC~H,~

7

34.6(7)

C6F,3~Hz~Hz-O-Si;dH3)3g

Z$

f 35.5(7)

61.1(8)

7 B/10 9 C~F,~CH~-CH-CHZ

e

&j

12

109.5(l)

C7F15CH2-O-Si(CHa)3

di

60.8(3)

(2)

115.5

109.4(l)

110.7(4) [-Il.01

[52.5]

[93.41

(2)

117.1

108.1(l)

&

8

HCFZCFZCHZ-0-BCsH,d

1

H~F2~F2~H2-O-Si(&H3)3C

25

1g

H;F2:F2-O-dH=c=GH2

;g

12

CDClj

CDC13

C6Ds

CDClj

CDCl,

CDC13

C6D6

192

the ratio

Apparently, are in the order

of magnitude

expansion

However,

terms.

FY ’ 3CH2

_

-

i

c

C

10

A13C

+3 + 1

large

in case of the

flicting

to be more

the ’ p

contrast, bond"

and,

The latter presence with other

bond'

-effect'

mechanism

G-bonds.

relevant

Q-terms

should

'(3 -effects!

Although of the

even more

Therefore,

at all in the case of

is much con-

-effect' space'

efficiently

at the oxygen

is believed

effect.

'through

"O-shielding

atom

as compared

for the discussion

with

fluorine

space'.

in the

(Es.(l)),

the AE approximation

In

'through

that changes

approximation

into account

In particular,

-10 + 3

efficiently

it is likely

in Pople's

A"0

there

‘y

I&

to be more effective

lone pairs

be taken

+36 f 5

may be operative

is expected

terms

17 /

-c-Lo

than an 'through

cases,

of polarizable

C-H

Al70

[17], the nature

in special

is very

?

‘d

&-

"O-shielding.

a 'through

of the radial

r/j

-3.5 + 1

13C

FF

1

_

and

of fluorine

FR

13CHz-

_

“0

for

by the ratio

(/3- effect'

(M

A13C

evidence

-effects'

predicted

the

’

_

‘y

of the

of the AE, and the of the

may not be valid atoms

in

/3-

position. Another changes Thus,

description

in orbital

energies

the low frequency

effect')

unaffected. n-G

or

and the ’

reduce

"O-

leaving

paramagnetic

and increase

,& -effect'invokes

by the fluorine

of stabilization

G*-orbitals

This will GeG*

induced

shift of the

may be the result

(C-O, C-C, C-H) vs 2

*

of the ’ y -’

substituents.

or '3C-resonances of n- or the radial

c-orbitals term almost

circulations

the magnetic

(' r-

shielding.

from the type Although,

193

the analogous be more more,

effect

than offset

the C-F

oxygen

G

of fluorine

field

produce

a marked

in ref.

induced

[19])

deshielding

Both,

of 2~s ____

indicate alkyl

the

5

of the

0- and

%,

"B-values.

This provides

respect

and the delocalization

can also

"O-nucleus.

chains.

stronger

This

a compilation

withdrawing

ability

is, as expected,

greater

inter-

in 22, on the basis

by the more

negative

of the high

in "O-shielding,

to

of

A"0-value

frequency

can be assigned

that multinuclear

information

nuclei.

Thus,

are reflected

chemical

The great

to the presence

[9]). These

shift

'jr-inter-

as observed

in

r-interactions.

of the molecules shifts.

in ref.

in 2g than

Since part

increase

study has shown

for the various

data

in oxoboranes

reduced

interesting

(Table 2) of zkf are indicative

is supported

to $5.

a significant

established.

charges

the electron

(compare

This

"O-resonances

suggests

Further-

can be anticipated.

of these

5 "B-values

may be slightly

actions,

it may

in == 3e.

&'

for ZQ with

term.

Thus,

(Table 2) (compare with

of BO(pp) r-interactions actions

electrons

of the

-effect'

'lone pairs'

in energy.

circulations

of the polyfluorinated in 23~ --- than

the fluorine

'lone pair'

Si-values

Pg

in the radial

will be comparable

and oxygen

Magnetic

The

by an increase

-orbitals,

lone pairs

in case of the ’ fi

is expected

of fluorine

which

should

changes by

"B-,

in

resonance

be complementary

in the electronic

sensitivity atoms

magnetic

13C-, of the

/

"C-

and

structure 2gSi-

"O-nuclear

-position

has been

shielding firmly

194

EXPERIMENTAL

All NMR

17 0,

spectra

29Si) were

39.7 MHz

have been

concentrated references

carried

( d*'Si).

The

(acquisition

3

with

otherwise

( rv50-60%

(CzH5)*0-BF3

(CGDS) = 128.0,

50.3 MHz

in 20mm

W/V)

time

r/O.O2s,

angle

the end of the RF-pulse

acquisition

introduced

spectra

were

obtained Most

decoupling.

compounds

[21]. The silanes reaction

reacted heen

with

formed

9-borabicyclo[3.3

obtained

by the following

(ca,) 3c-~-cH2c~2-~~

.l]

= 35~s).

a straiqht base sequence

when

reaction

+ KOH/EtOH 80"

37'C

29Si-NMR

[20] with

'H-

procedures

yield

[22]. The vinyl

by the

The boranes @c_ --- are ether

z$ has

sequence:

(CH3)2C=CHz

(4-Me-CsH4-S03H,

(pyridine)

bp.

of

line.

the alcohols

+ SOClz

2~:

A delay

by standard

in quantitative

nonane

(CHs)rSi

IO4 to IO5 scans

1 HO-CHZCHZ-0-CF2CP2H

-

and

“C

+CF~=CF~CH~)~C-O-CH~CH~-~-CF~CF~H (DMF, KOH) -

CHz=CH-0-CFzCF2H

&

hexamethyldisilazane.

quantitatively

using

External

and the beginning

have been prepared

la&c_ ---- with

(&13C,

(s170),

~70'

the DEPT pulse

Jaqe --__ were obtained

of the alcohols

zg, 22 are also

to obtain

using

Hz0

between

of 35~s between was

(o.d.) tubes

(CH3)4Si

required

pulse

the measure-

in CsD6 or CDC13.

(a"B),

spectra

WP 200 NMR

in the Tables,

13C (CDC13) = 77.0),

170-NMR

13C, 27.1 MHz

a BRUKER

out at 27-28pC

solutions were

"B,

recorded

If not noted

spectrometer. ments

(64.2 MHz

ClCH2CH2-0-CF~CFZH

AT)

195

The yield

in the final dehydrochlorination

55 $ since Grob-fragmentation occured

under

step was only

formation

of vinyl

chloride

as a side reaction.

ACKNOWLEDGMENTS

This work was and the Fonds

supported

der Chemischen

by the Deutsche

Forschungsgemeinschaft

Industrie.

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1

H.A.Christ,

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2

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3

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R.Noyori, c)

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Table'

Academic

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~1-64,

1981.

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a

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