Characterization by NMR of reactants and products of hydrofluoroether isomers, CF3(CF2)3OCH3 and (CF 3)2C(F)CF2OCH3, reacting with isopropyl alcohol

Article abstract of DOI:10.1002/mrc.3964

The 3M Company product Novec 71IPA DL, a mixture of methoxyperfluorobutane, methoxyperfluoroisobutane and 4.5 wt.% isopropyl alcohol, has been found to be very stable at ambient temperature, producing fluoride at the rate of ～1 ppm/year. Our earlier kinetic and theoretical studies have identified the reaction mechanism. This paper identifies the ¹H and ¹⁹F NMR chemical shifts, multiplicities, and coupling constants of reactants and the major products that result from aging the mixture in sealed Pyrex NMR tubes for periods up to 1.8 years at temperatures from 26 °C to 102 °C. Chemical shifts and coupling constants of fluorine and hydrogen atoms on the hydrofluoroethers and isopropyl alcohol are traced through the reactions to their values in the products - esters, isopropylmethyl ether, and HF. These spectral positions, multiplicities, and coupling constants are presented in table format and as figures to clarify the transformations observed as the samples age. Copyright 2013 John Wiley & Sons, Ltd. The titled hydrofluoroether isomers react slowly with isopropyl alcohol in a two-step process yielding isopropylmethyl ether, the corresponding isopropyl ester isomers, and HF. ¹⁹F and ¹H NMR chemical shifts, multiplicities, and coupling constants are assigned to the reactants and major products in this paper. Copyright

Full text of DOI:10.1002/mrc.3964

Research Article
Received: 19 December 2012
Revised: 4 April 2013
Accepted: 12 April 2013
Published online in Wiley Online Library: 23 May 2013
(wileyonlinelibrary.com) DOI 10.1002/mrc.3964
Characterization by NMR of reactants and
products of hydrofluoroether isomers,
CF (CF ) OCH and (CF ) C(F)CF OCH ,
3
2 3
3
3 2
2
3
reacting with isopropyl alcohol
a
a
b
Howard C. Knachel, * Vladimir Benin, William E. Moddeman,
b
c
d
Janine C. Birkbeck, Thomas A. Kestner and Tanya L. Young
™
The 3M Company product Novec 71IPA DL, a mixture of methoxyperfluorobutane, methoxyperfluoroisobutane and 4.5 wt.%
isopropyl alcohol, has been found to be very stable at ambient temperature, producing fluoride at the rate of ~1 ppm/year.
1
19
Our earlier kinetic and theoretical studies have identified the reaction mechanism. This paper identifies the H and F NMR
chemical shifts, multiplicities, and coupling constants of reactants and the major products that result from aging the mixture
ꢀ
ꢀ
in sealed Pyrex NMR tubes for periods up to 1.8 years at temperatures from 26 C to 102 C. Chemical shifts and coupling
constants of fluorine and hydrogen atoms on the hydrofluoroethers and isopropyl alcohol are traced through the reactions
to their values in the products – esters, isopropylmethyl ether, and HF. These spectral positions, multiplicities, and coupling
constants are presented in table format and as figures to clarify the transformations observed as the samples age. Copyright ©
2013 John Wiley & Sons, Ltd.
Supporting information may be found in the online version of this article.
1
19
™
™
Keywords: NMR; H; F; hydrofluoroethers; isopropyl alcohol; Novec 7100; Novec 71IPA
1
9
We have been unable to observe the F NMR resonance for
Introduction
[
2]
the acyl fluorides in the region +10 to +60 ppm because of their
Recently, a number of cleaning agent replacements for environ-
mentally undesirable materials have been developed and are
currently in use. One specific cleaning agent designed for removing
light soils is an azeotrope of methoxyperfluorobutane isomers,
rapid reaction with IPA. In general, acyl halides, in the presence of
[
3]
alcohols, react rapidly at ambient temperatures to form esters
ꢁ
3
with rate constants on the order 10 /s. Our measured rate
[
1]
ꢁ15
ꢁ12
constants for the slow step are between 10
and 10 /s
™
ꢀ
C F –O–CH (Novec 7100DL) and isopropyl alcohol (IPA). This
for temperatures of 26 to 90 C. Thus, the rate constant for the
4
9
3
ꢁ
3
9
12
solvent combination has been the object of our recent work that
reaction in Eqn (2), 10 /s, would be between 10 and 10 times
faster than that in Eqn (1). In our multiple-pulse experiments –
where samples were examined at room temperature after
removal from their respective heating media – the lifetime of
the acyl fluoride was too short for NMR detection.
The identification of a single F resonance in the range ꢁ140
to ꢁ180 ppm attributable to HF is also problematic. Interaction
™
addressed the stability of Novec 7100DL in the presence of
™
several different concentrations of IPA. Novec 71IPA DL is an
isomeric mixture containing the normal-isomer, CF (CF ) OCH ,
3
2 3
3
the iso-isomer, (CF ) CFCF OCH in ~40/60 ratio, a chiral isomer
3
2
2
3
19
(
<0.025 wt.%), and IPA at ~4.5 wt.%. Density functional theory
[1]
calculations for the reaction of the two major isomers with IPA
predicted that isomeric acyl fluorides, C F CO(F), isopropylmethyl
3
7
ether (IME), (CH ) CH–OCH , and HF are produced in the rate-
3
2
3
determining step (Eqn (1)). Our predicted and measured
{
* Correspondence to: Howard C. Knachel, University of Dayton, Department of
Chemistry, 300 College Park, Dayton, OH 45469-2357, United States. E-mail:
hknachel1@udayton.edu
thermodynamic activation parameters (ΔHpred. = 24.6kcal/mol and
{
ΔHobs. = 25 kcal/mol) are indicative of a slow reaction at ambient
temperatures. The second, and faster, reaction occurs between acyl
fluoride and another molecule of IPA, producing isomeric isopropyl
esters and a second molecule of HF (Eqn (2)).
a University of Dayton, Department of Chemistry , 300 College Park Dayton, OH
[
1]
45469-2357, United States
slow
b B&W Pantex, LLC, Amarillo, TX 97120, United States
C4F9OCH3 þ ðCH3Þ CðHÞOH ! C3F7C ¼ OðFÞ þ ðCH3Þ CðHÞOCH3 þ HF
2
2
(1)
c 3M Center, Building 0236-02-B-11 St. Paul, MN 55144-1000, United States
d Ohio State University, Chemistry Department, Columbus, OH 43210, United
States
fast
C3F7C ¼ OðFÞ þ ðCH3Þ CðHÞOH ! C3F7COOCHðCH3Þ þ HF (2)
2
2
Magn. Reson. Chem. 2013, 51, 407–413
Copyright © 2013 John Wiley & Sons, Ltd.

H. C. Knachel et al.
between the HF and the OH of IPA and/or water (if present) leads to
6. Acetone-d , 99.9%D, obtained from Norell, Inc. (Landisville,
6
+
ꢁ
complex equilibria involving H F and/or (HF) F species where n is
NJ 08326, USA) Lot No. 8276.
2
n
between 1 and 3. These broad resonances change position and
7. Special Pyrex 5-mm NMR tubes procured from Norell, Inc.
(Landisville, NJ 08326, USA) Part No. S-5-300-8 constricted
(for sealing).
8. Tetramethylsilane, 99.9+%, NMR grade, A.C.S. reagent, pur-
chased from Sigma-Aldrich (Atlanta, GA 30353-5182, USA)
Stock No. T24007-100G, Batch No.11418EE.
9. Hamilton Company (Reno, NV 85920-0012, USA) glass syrin-
ges with stainless steel needles were used in the preparation
of samples.
intensities as a function of heating time and cannot be specifically
[4]
attributed to non-complexed HF as the dominant molecular entity.
Although NMR was used to measure rates at a variety of
[
1]
temperatures and reactant concentrations in our previous study,
1
9
few spectral details were included. This current paper reports
F
1
and H NMR chemical shifts and coupling constants of the two
major methoxyperfluorobutane isomers and 4.5 wt.% IPA, and
ꢀ
the major products of their reaction at 90 C in a mixture that
was aged for 363 days.
10. Melting point capillary tubes used for NMR standards and
deuterium lock were procured from Kimax (Vineland,
NJ 08362-1502, USA), Stock No. 34500 99, 1.5–1.8 ꢂ 100 mm.
Experimental
Sample preparation
Instrumentation
NMR samples
1
19
Several NMR spectrometers were used in measuring H and
signals. A Bruker 400 MHz was used for multiple-pulse
F
F
™
19
Samples for NMR included both new and aged Novec 7100DL and
new and aged mixtures of Novec 7100DL with IPA. Because IPA is
™
measurements, and a Burker 500 MHz was used for multiple-
1
hygroscopic, all samples were prepared in a nitrogen-purged,
pulse H measurements including COSY and TOCSY experiments.
[
1]
dry box. The mixtures ranged from 51.0 to 97.25 wt.% of
An Anasazi EFT 60 was used to measure T values of fluorine
atoms in the two major isomers of methoxyperfluorobutane.
1
methoxyperfluorobutane isomers with the remainder being IPA.
[1]
The NMR test samples, with sealed capillaries containing
acetone-d or CDCl used for lock signals, were prepared and
attached to a vacuum line, chilled with either liquid nitrogen or a
dry ice/alcohol slush, evacuated, back filled with 150 Torr O , and
sealed with a torch. The addition of purified oxygen provided a para-
magnetic material to shorten the NMR longitudinal relaxation time (T
6
3
Materials
2
The following chemicals and materials were used in the preparation
of the samples and standards needed for this study.
1
)
™
™
[5]
of hydrogen and fluorine nuclei. The samples were sealed with a torch,
instead of capped, to permit long-term heating of the samples with-
out loss of volatile components. At appropriate time intervals, samples
were removed from the heating medium, and H and F multiple-
pulse experiments were performed. After analyses, the NMR test
sample was returned to the heating medium to continue aging.
1
. Novec -7100 Lot No. 24448, Novec 7100DL Lot Nos.
2
2
™
0221 and 20224, and Novec 71IPA Lot Nos. 22038 and
2121 provided by 3M Company (Saint Paul, MN 55144-1000,
USA. A typical analysis provided by 3M Company shows that
the three Novec 7100 isomers and IPA comprise ~99.84 wt.%
of the mass of Novec 71IPA, the remaining 0.16 wt.% of the
1
19
™
™
sample is a proprietary composition.
. 2-Propanol (IPA), 99.5%; anhydrous, <0.005% water purchased
from Sigma-Aldrich (Atlanta, GA 303553-5182, USA) Batch No.
Data collection
2
3
™
To avoid potential reactions between the components of Novec
0
4750TE.
7100DL and a solvent, or with internal standards, such as TMS
and CFCl , the NMR tubes used in the aging experiments
3
. No vendor could be found to provide an authentic sample of
IME to compare its resonances to those present in our
samples. See Eqn (1). Therefore, IME was synthesized using
the Williamson reaction. An approximate 2 : 1 molar excess
of powdered sodium isopropoxide (Alfa Aesar (Ward Hill,
MA 01835, USA) Stock No. 89446 and Lot No. C06U026)
was mixed with methyl iodide (Fisher Scientific Pittsburgh,
PA 15275, USA (Certified M2121-100, Lot No. 084930))
under vacuum conditions. After 3 days at room temperature,
the volatile IME was vacuum transferred to an NMR tube
™
contained only the neat liquid reactants, Novec 7100DL and
IPA. This resulted in very intense NMR signals. In addition, the
reactions were very slow. The combination made it impossible
to measure the disappearance of reactants in a reasonable time.
That is, the uncertainty in the intensity measurement was larger
than the intensity difference achieved over, for example, a period
ꢀ
of a month at 90 C. However, it was possible to monitor the
growth of product signals above base line by increasing the
signal-to-noise ratio through the use of multiple-pulse experiments.
To avoid saturating these weak signals, it was necessary to
determine the longitudinal relaxation times, T , for the F nuclei
1
in question. To determine the optimum pulse angle and pulse
1
using liquid nitrogen. The H NMR spectrum was recorded at
19
300MHz in the same medium used for NMR measurements
™
of aged samples (i.e. 4.5 wt.% IPA in Novec 7100DL). The
chemical shifts matched. They are as follows: (CH doublet at
.1 ppm, CH septet at 3.4 ppm, and OCH singlet at 3.3 ppm,
)
3 2
delay, the Ernst equation was employed. Values of T for samples
of the hydrofluoroethers were determined by the inversion–
1
1
3
with the intensities matching the expected pattern of 6 : 1 :
. Chloroform-d, 99.8% D, stabilized with silver foil, 0.03 v/v%
TMS, obtained from Acros Organics (Pittsburgh, PA, USA),
Code No. 368651000, Lot No. A0274197.
recovery Fourier transform method for samples with and without
4
5
O present. The results are shown in Table 1.
2
1
19
The H and F NMR chemical shift scales were referenced
to 3.700ppm for the methoxy group of (CF ) CFCF OCH and
3
2
2
3
. Fluorotrichloromethane, CFCl , 99+%, purchased from Sigma-
ꢁ81.660 ppm for the perfluoromethyl group of CF CF CF CF OCH .
3
3
2
2
2
3
Aldrich (Atlanta, GA 30353-5182, USA) Stock No. 254991-
The reasons for these choices are as follows: First, the values were
consistent with those in the 3M data base, which were referenced
800ML, Batch No. 03706ME.
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Copyright © 2013 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2013, 51, 407–413

NMR characterization of hydrofluoroether reactions with isopropyl alcohol
1
9
Table 1. Longitudinal relaxation times of F NMR resonances for
Novec 7100 recorded at 56.46 MHz
In short, the degradation of the two major isomers of
™
methoxyperfluorobutane, described herein, do not belong to
ꢀ
any of the classic ether reactions up to 100 C. The high activation
Chemical species
T
1
with O
2
(s)
T
1
2
without O (s)
barrier of 25 kcal/mol is responsible for the long-term ambient
™
(
CF
3
)
2
iso-isomer
1.7
1.7
6.8
6.3
stability of Novec 71IPA.
CF
3
n-isomer overlapping
As discussed previously, although the methoxyperfluorobutane
isomers are very stable at ambient conditions, they do react with
IPA when aged at elevated temperatures, albeit slowly. The
following sections recount the details of our NMR findings regarding
chemical shifts, multiplicity, and coupling constants attributable
to reactants and major products in aged samples. The figures
presented later show both the NMR signal of atoms in the starting
material and that of the same atom, or atoms, as they appear in
the reaction products. Finally, the correlations achieved using a
–
–
–
CF
CF
CF
2
2
2
–OCH
–OCH
3
iso-isomer
3
n-isomer
1.7
1.8
6.1
7.2
2
–CF – n-isomer
overlapping peaks
C–F iso-isomer
2.5
10.2
1
19
to internal TMS and CFCl signals; and second, the H and
chemical shifts of reactants and products remained unchanged
over 411 days at 90 C. During this experiment, only 0.27% of the
F
3
1
H COSY experiment are presented.
ꢀ
starting material was consumed. This small change in the composi-
tion of the solution was insufficient to change the bulk magnetic
susceptibility of the sample.
19
F Spectral Assignments
19
All of the F resonances shown in Figs 1 and 2 were collected using
a Bruker 400 operating at 376.463 MHz on a sample of Novec 71IPA
aged for 363 days at 90 C utilizing 1433 scans and the Bruker pulse
™
Results and Discussion
ꢀ
Usually ethers are unreactive in the presence of organic com-
pounds, and so they are often used as solvents for reactions.
Classic reactions of ethers include the following: (i) the oxidation
of ethers in air to form peroxides, (ii) interaction with strong
acids, such as HBr, to produce alkyl halides and alcohols, and
experiment zgfhigqn. The deuterium lock signal was provided by
inserting a sealed capillary tube, containing acetone-d
6 3
, CFCl , and
6 6
C H , inside the NMR tube. In Figs 1 and 2, the lower spectrum is
of the methoxyperfluorobutane isomer, and the upper spectrum is
that of its corresponding isopropyl ester. See Eqn (2).
(iii) Lewis acid–base interactions, such as the complex formed
between BF and diethyl ether, called the BF :etherate.
3
3
™
The iso-isomer in Novec 7100 – Fig. 1
The Material Safety Data Sheets, created by 3M Company for
™
™
3
Novec 71IPA and Novec 7100, suggest that these materials are
The CF groups are converted from a doublet of triplets ( J = 5.8Hz
3
FF
ꢀ
4
3
stable below 300 C. A colorimetric test for peroxide was conducted
and J =9.8Hz) centered at ꢁ73.84 ppm to a doublet ( J =7.3Hz)
FF
FF
™
at room temperature and up to the boiling point for Novec 7100
centered at ꢁ74.92 ppm. The CF multiplet shifted from ꢁ187.38 ppm
[
6]
3
on samples aged for several weeks. These tests were all negative.
Testing was also run with older samples of Novec fluids that had
been stored at room temperature for 1 year or more, and again,
no detectable level of peroxide was found. Furthermore, thermal
to a septet centered at ꢁ181.48 ppm ( J = 7.3 Hz). The –CF doublet
FF
2
ꢀ
degradation above 160 C of related compounds, for example,
4 9 2 5
hydrofluoropolyethers and C F –OC H studied by Marchionni
[7]
et al. in air, never formed peroxides but did include nonclassical
ether reaction products, such as perfluorinated acid fluorides and
2
CO . In our work, there was no evidence of peroxide formation in
™
aged sealed mixtures of IPA and Novec 7100 heated at tempera-
ꢀ
tures as high as 102 C for periods up to 632 days in a partial
2
pressure of 150 Torr O . Additionally, the Novec fluids have been
[
8]
in use for 16 years, and no one, including the Smithsonian, has
reported issues with peroxide formation.
™
To investigate the reaction of Novec 71IPA with strong acids, HCl
™
(
g) and HBr(g) were separately added to Novec 71IPA. No alkyl
halides or methanol was detected by NMR as would have been
expected of classical ether reactions with strong acids. However, IME
and esters were found, and their rates of formation from the reaction
of the two isomers of methoxyperfluorobutane and IPA (i.e. Eqn (1)
and Eqn (2)) increased by a factor of two. It is believed the reaction
described in Eqn (1) is catalyzed by the strong acids, as opposed to
the acids serving as reagents typical of classic ether reactivity.
Another case of a possible catalytic effect – this time in a Lewis
acid–base interaction in the presence of AlF – was discussed in a
3
quantum mechanical study of the decomposition of the
perfluoroethers, CF OCF and CF CF OCF CF . The AlF formed
19
3
3
3
2
2
3
3
Figure 1. The F NMR spectrum of: methoxyperfluoroisobutane (lower)
and isopropylperfluoroisobutyrate (upper). Each tie mark within a spectral
segment represents a change in chemical shift of 0.05 ppm.
the etherate-like complexes, AlF :O(CF ) and AlF :O(C F ) ,
3
3 2
3
2 5 2
[
9]
which are more typical of classic ether reactions.
Magn. Reson. Chem. 2013, 51, 407–413
Copyright © 2013 John Wiley & Sons, Ltd.
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H. C. Knachel et al.
1
9
Figure 2. The F NMR spectrum of methoxyperfluorobutane (lower) and isopropylperfluorobutyrate (upper). Each tie mark within a spectral segment
represents a change in chemical shift of 0.05 ppm.
3
4
of septets centered at ꢁ82.44 ppm ( JFF =8.5Hz and JFF =9.8Hz)
does not have a corresponding resonance in the ester because the
2
carbon atom in the CF group is transformed to a carboxylate (–C
(
O)–O–). The splitting shown at ꢁ82.44 ppm is dependent on how
carefully the spectrometer is shimmed. A symmetrical octet is other-
wise obtained.
™
The normal-isomer in Novec 7100 – Fig. 2
5
The CF
3
group, a triplet of triplets at ꢁ81.66 ppm ( JFF = 2.2 Hz
4
4
and JFF = 9.6 Hz) converts to a triplet at ꢁ81.36 ppm ( JFF = 8.7
Hz) when the isopropyl ester is formed. No vicinal three-bond
[
10]
couplings were detected. Doblier
has reported fluorine–
fluorine coupling constants for perfluoroalkanes and concluded
that, ‘vicinal F–F coupling constants in perfluoroalkanes are often
very small, virtually negligible in comparison to longer-range
couplings’. The small triplet of triplets signal that overlaps the
1
Figure 3. The
H NMR spectrum of the methoxy groups of
methoxyperfluoroisobutane and methoxyperfluorobutane (left) being
converted to the methoxy group on isopropylmethyl ether (right).
13
ester triplet in the upper spectrum in Fig. 2 is due to the
C
satellite of the very strong resonance of the CF group of the
3
normal-ether isomer. The satellite to the right of the strong
1
resonance is not shown in the figure, but the JCF of 286.6 Hz
3
was measured and is consistent with the range for CF groups
[
10]
found on page 138 of Doblier.
The CF groups in the reactant chain are all multiplets, and
2
their resonances occur at ꢁ89.05, ꢁ126.21, and ꢁ126.59 ppm
as seen in Fig. 2. The fluorine atoms on the corresponding CF
2
groups in the product are as follows: a quartet centered at
4
ꢁ
119.74 ( J = 8.7 Hz) and a single resonance centered at
FF
ꢁ
127.21 ppm. The later resonance appears as a broadened
singlet resulting from coupling interactions being of the J variety.
FF
3
1
H Spectral Assignments
All of the resonances shown in Figs 3–5 were obtained with a
1
Figure 4. The H NMR spectrum of the methine hydrogen on IPA (center) as
Bruker 500 operating at 500.023 MHz on the same sample of
™
it is converted to the methine hydrogen on isopropylmethyl ether (right), and
to the methine hydrogen on each of the esters, isopropylperfluoroisobutyrate
and isopropylperfluorobutyrate (left).
Novec 71IPA discussed previously. The Bruker pulse experiment
zg30 was used for 128 scans.
™
Normal and iso isomers in Novec 7100 – Fig. 3
resonances at 3.700 and 3.697 ppm. The intensity ratio, iso/
The methoxy hydrogen atoms on each of the two
methoxyperfluorobutane isomers appear as single overlapping
normal, of 61/39 ꢃ 1 was determined by deconvolution of the
19
data in Fig. 3 and by using the integrated F intensities of the
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Copyright © 2013 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2013, 51, 407–413

NMR characterization of hydrofluoroether reactions with isopropyl alcohol
1
Figure 5. The H NMR spectrum of the methyl groups on isopropyl
alcohol (center) as they are converted to the methyl groups on
isopropylmethyl ether (right), and to the methyl groups on the esters,
isopropylperfluoroisobutyrate and isopropylperfluorobutyrate (left).
seven resonances in the lower portion of Figs 1 and 2. The details
of the second method are found in the Supporting Information.
1
™
The reaction in Eqn (1) shows that the methoxy CH
3
groups on
Figure 6. The H COSY data taken on a sample of NOVEC 71IPADL that
ꢀ
had been heated at 90 C for 365 days.
both isomers end up as the methoxy CH group on the product,
3
isopropylmethyl ether, with a chemical shift of 3.265 ppm.
™
1.340 ppm and the septet centered at 5.266 ppm have been
Isopropyl alcohol in Novec 71IPA – Figs 4 and 5
assigned to the most abundant isomeric ester, the iso-isomer.
Their companion resonances belong to the normal-isomeric
ester. We refer the reader to the expanded scale spectra
illustrated in red in Figs 4 and 5. The integration of the methyl
and methine resonances are in a 6 : 1 ratio.
The third pair of coupled protons in Fig. 6, circled in green for
the doublet and cyan for the septet, deal with isopropyl methyl
ether, the product created in Eqn (1). The methyl hydrogens
and the methine hydrogen on the isopropyl group of IME appear
as a doublet, centered at 1.120 ppm, and a septet centered at
The reaction in Eqn (2) indicates that the isomeric acid fluorides
each react with a molecule of IPA yielding the corresponding
iso and normal esters. Figure 4 focuses on the methine hydrogen
atom in IPA as its chemical shift changes depending on whether
it is part of the isomeric ester structures, Eqn (2), or the IME
structure, Eqn (1). The methine hydrogen of IPA starts off as a
3
septet at 3.977 ppm ( JHH = 6.3 Hz) and is transformed to the iso-
3
ester as a septet at 5.266 ppm ( JHH = 6.3 Hz) and to the normal-
3
ester as a septet at 5.221 ppm ( JHH = 6.3 Hz). In transitioning to
IME, the IPA methine hydrogen is found as a septet at
3.431 ppm, respectively. They also integrate in the ratio 6 : 1.
3
3
.430 ppm ( JHH = 6.3 Hz).
Although the COSY data were useful in identifying the off-
diagonal peaks of the esters and IME, it did not relate the protons
Figure 5 focuses on the isopropylmethyl groups in IPA as their
chemical shift changes from IPA either to that of the isomeric
ester structures or to that of IME. Their resonance starts off as a
of methoxy hydrogens in IME (–O–CH ) to any of the methyl or
3
methine resonances. A selective TOCSY experiment was performed,
but it only confirmed the COSY results without adding anything
new about the methoxy group in IME.
3
doublet at 1.176 ppm ( JHH = 6.2 Hz) and is transformed to the
3
iso-ester as a doublet at 1.340 ppm ( JHH = 6.3 Hz) and to the
3
normal-ester as a doublet at 1.342 ppm ( JHH = 6.3 Hz), and to a
3
doublet at 1.120 ppm ( JHH = 6.3 Hz) in IME.
Conclusion
NMR Correlation SpectroscopY (COSY)
19
1
The F and H NMR chemical shifts, coupling constants, and
1
[11]
™
A two-dimension, H NMR COSY experiment was performed at
multiplicities of the components (Novec 7100DL and IPA) that
make up Novec 71IPA DL were identified and measured. These
™
™
5
00.023 MHz on the same Novec 71IPA sample as discussed
previously. Figure 6 shows the data. In the plot, the proton
NMR spectrum appears on each of the orthogonal axes. Peaks
with the same chemical shift on each axis intersect on the plot
diagonal. Off-diagonal signals correspond to H– H homonuclear
spin couplings. A PDF file, with scale expansion capability, is
available in the Supporting Information.
Three pairs of coupled protons are depicted in Fig. 6. The first
two pairs, circled in red and purple, are due to the isopropyl
groups on the two isomeric esters (Eqn (2)). Methyl resonances
components are very stable together but have been found to
react with each other very slowly producing hydrogen fluoride,
IME, and two esters, isopropyl perfluoroisobutyrate and isopropyl
perfluorobutyrate at rates of ~1 ppm/year at a laboratory
1
1
ꢀ
temperature of 20 C. The chemical shifts, coupling constants,
and multiplicities of these products have also been determined.
The detailed NMR spectra are shown, and the measurements
1
are summarized in Table 2. A H COSY experiment was used to
show the association of the methyl and methine hydrogens in
the products of the reaction. An authentic sample of IME was
synthesized using the Williamson synthesis. The chemical shifts,
thus obtained, were found to be identical to those found in the
(
centered at 1.340 and 1.342 ppm), circled in red, are doublets
split by the methine hydrogens. The methine resonances
centered at 5.266 and 5.221 ppm), circled in purple, are septets
(
™
split by the methyl hydrogens. The larger doublet centered at
aged samples of Novec 71IPA DL.
Magn. Reson. Chem. 2013, 51, 407–413
Copyright © 2013 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/mrc

H. C. Knachel et al.
wileyonlinelibrary.com/journal/mrc
Copyright © 2013 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2013, 51, 407–413

NMR characterization of hydrofluoroether reactions with isopropyl alcohol
[
4] (a) I. G. Shenderovich; H. H. Limbach, S. N. Smirnov, P. M. Tolstoy, G. S.
Acknowledgements
Denisov, N. S. Golubev, Phys. Chem. Chem. Phys., 2002, 4, 5488-5497;
(b) F. Y. Fujiwara, J. S. Martin, J. Am. Chem. Soc. 1974, 96(25), 7625-7631;
This work was supported under the Plant Directed Research and
Development (PDRD) Program of the US Department of Energy,
National Nuclear Security Administration at the Pantex Plant,
operated by B&W Pantex, LLC under contract number DC-AC54-
(
c) F. Y. Fujiwara, J. S. Martin, Can. J. Chem. 1971, 49, 3071-3073; (d) P. M.
Borodin, R. Singkh, V. A. Shcherbakov, Zhurnal Stukturnoi Khimii, 1968,
(6), 1078-1079; (e) K. Schaumburg, C. Deverell, J. Am. Chem. Soc. 1968,
0(10), 2495-2499; (f) R. Haque, L. W. Reeves, J. Am. Chem. Soc. 1967, 89
(2), 250-252.
9
9
0
0AL66620. The authors wish to express their appreciation to
™
™
[
5] Novec 7100DL is a higher purity version of Novec 7100. A
David A. Hesselroth and Thomas J. Brodbeck of 3M Company
™
™
typical analysis shows 99.84 wt % hydrofluoroethers and 0.16
for supplying the Novec 7100 and Novec 71IPA and Jason
Kehren of 3M Company for his discussions regarding the
fluorinated ethers. In addition, the authors wish to acknowledge
the support of Dr Daniel P. Kramer and Dr Chadwick D. Barklay
of the University of Dayton Research Institute regarding the
administrative details involved with this PDRD project.
™
wt
%
proprietary composition. Novec 7100DL is tightly-
™
controlled for ions, metals and non-volatile residue. All Novec
7100/IPA mixtures were made from the higher purity
hydrofluoroether.
[
[
6] J. M. Kehren, Private communication, 3M Center, St. Paul, MN 55144,
telephone 651 733 3644. Testing was done using EM quant peroxide
test from EM Industries, Inc. The test strips are capable of detecting
peroxide to 0.5 mg/L.
7] G. Marchionni, S. Petricci, P. A. Guarda, G. Spataro, G. Pezzin. J. Fluor.
Chem. 2004, 125, 1081–1086.
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Magn. Reson. Chem. 2013, 51, 407–413
Copyright © 2013 John Wiley & Sons, Ltd.
wileyonlinelibrary.com/journal/mrc