E J Goethals

M F Dubreuil

T Vanrenterghem

T J Loontjens

English

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 University of Groningen
Synthesis of α-amino-ω-carboxypolytetrahydrofuran
Vanrenterghem, T.; Dubreuil, M.F.; Goethals, E.J.; Loontjens, T.J.
Published in:
Polymer International
DOI:
10.1002/(SICI)1097-0126(199905)48:5<343::AID-PI184>3.0.CO;2-T
IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from
it. Please check the document version below.
Document Version
Publisher's PDF, also known as Version of record
Publication date:
1999
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):
Vanrenterghem, T., Dubreuil, M. F., Goethals, E. J., & Loontjens, T. J. (1999). Synthesis of α-amino-ω-
carboxypolytetrahydrofuran. Polymer International, 48(5), 343-345. https://doi.org/10.1002/(SICI)1097-
0126(199905)48:5<343::AID-PI184>3.0.CO;2-T
Copyright
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Download date: 06-10-2021
Rapid Report
Synthesis of a-amino- v-carboxy-
polytetrahydrofuran
T Vanrenterghem,1 MF Dubreuil,1 EJ Goethals1* and TJ Loontjens2
1Department of Organic Chemistry, Polymer Division, University of Ghent, Krijgslaan 281, 9000 Ghent, Belgium
2DSM Research, P.O. Box 18, 6160 MD Geleen, The Netherlands
INTRODUCTION
Telechelic polymers are important building blocks for
the design of new macromolecular architectures.1 In
some cases hetero-telechelic polymers, linear polymers
containing two different functional end-groups on
each polymer chain, may be of interest. In this paper
we report a convenient method for the synthesis of
a-amino-o-carboxy-polytetrahydrofuran based on a
combination of functional initiation and end-
capping.
RESULTS AND DISCUSSION
In a previous paper we reported that a combination of
a functionalized alcohol and tri¯uoromethanesulfonic
acid anhydride (tri¯ic anhydride, Tf2O) can be used as
a functional initiator system for the polymerization of
tetrahydrofuran (THF).2 This method was now
applied with ethyl-6-hydroxyhexanoate (EHH) as
functional alcohol leading to polyTHF carrying an
ester end-group which can be hydrolyzed to the
corresponding carboxylate-terminated polymer.
Scheme 1
Polymer International Polym Int 48:343±345 (1999)
* Correspondence to: EJ Goethals, Department of Organic Chemistry, Polymer Division, University of Ghent, Krijgslaan 281, 9000 Ghent,
Belgium
(Received 22 February 1999; accepted 24 February 1999)
# 1999 Society of Chemical Industry. Polym Int 0959±8103/99/$17.50 343
To introduce the amino function at the other chain
end it is, in principle, possible to end-cap the living
polymer with ammonia. However, it was observed that
this reaction leads to a substantial fraction of coupling
product resulting from reaction of the ®rst formed
primary amine with the oxonium end-group of another
living polymer. A convenient method leading to the
pure primary amino end-group was found to be end-
capping of the living polymer with hexamethylene
tetramine followed by acid hydrolysis.3 The ester
function, introduced by the initiator system, was
hydrolyzed to the carboxylic function by treatment
with anhydrous potassium hydroxide, as reported.4
The complete reaction sequence for the synthesis of
the heterotelechelic polymer is given in Scheme 1.
Figure 1 shows the 1H NMR spectrum of a polymer
with number average molecular weight 3500. The
presence of multiplets of equal intensities at 2.35 and
3.1ppm are in agreement with the presence of
carboxylate and ammonium end-groups in stoechio-
metric amounts. As reported earlier,2 the molecular
weight of the polymers can be varied by changing the
initiator concentration and/or the polymerization time.
Molecular weight distributions (Mw/Mn) are typically
below 1.2 (Table 1).
EXPERIMENTAL PART
Materials
Tf2O and EHH were puri®ed by distillation. CH2Cl2
was puri®ed by general methods and used after
distillation over calcium hydride. Trichloromethane
was used after distillation over calcium hydride. THF
was puri®ed by general methods and used after
distillation over sodium in the presence of benzo-
phenone. 2,2-Di-tert-butylpyridine (DTBP) was used
as received.
Synthesis
A typical synthesis of the polymer is as follows. In a
dried two necked-¯ask of 50mL, 7mL of CH2Cl2,
500mL of DTBP (2.23 10ÿ3 mol) and 250mL of Tf2O
(1.49 10ÿ3 mol) were thermostatted at 20°C. 239mL
of EHH (1.47 10ÿ3 mol) was added dropwise under
stirring. After one hour, the polymerization was started
by introducing 20mL of THF (0.247 mol). After 15
minutes, the polymerization was terminated with a
solution of 0.522g of HMTA (3.73 10ÿ3 mol) in
25mL of trichloromethane. After 10minutes stirring
at room temperature the solvents and unreacted THF
were evaporated. The residue was dissolved in 10mL
of toluene, 15mL of methanol and 1.2g of concen-
trated sulfuric acid and the solution was re¯uxed for 2
hours. The mixture was neutralized by adding a 50%
NaOH/water solution, the salts were ®ltered off and
the ®ltrate was stripped to dryness on a rotary
evaporator leaving 4.1g of a-amino-o-ester-termi-
nated polyTHF.
4.1g (1.18 10ÿ3 mol) of the residue was added to a
stirred cooled suspension (0°C) of 2.73g (11.75 10ÿ3
mol) of potassium tert-butoxide in 40mL of dry THF
and 55mL (3 10ÿ3 mol) of water. The ice-bath was
removed and after three hours at room temperature
the mixture was acidi®ed with concentrated hydro-
chloric acid. The salts were ®ltered off and the polymer
Figure 1. 360MHz1H NMR spectrum of
a-amino-o-carboxy-polyTHF (Mn 3500g
molÿ1, solvent CDCl3).
Table 1. Molecular weight and molecular weight
distributions of a-amino-o-carboxy-polytetrahydro-
furan as a function of polymerization time.
[THF]=11.26molLÿ1, [EHHOTf]=0.0525molLÿ1,
solvent CH2Cl2. Values obtained by gel permeation
chromatography
Polymerization time (min) Mn Mw/Mn
7 2000 1.19
15 3600 1.17
344 Polym Int 48:343±345 (1999)
T Vanrenterghem et al
was precipitated in cold water, ®ltered off, and dried
under vacuum (yield 100%).
ACKNOWLEDGEMENTS
T Vanrenterghem thanks the I.W.T. (Vlaams Instituut
voor de Bevordering van het Wetenschappelijk-Tech-
nologisch onderzoek in de industrie) for a scholarship.
REFERENCES
1 Goethals EJ, Telechelic Polymers: Synthesis and Applications, CRC
Press, Boca Raton (1989)
2 Dubreuil MF and Goethals EJ, Macromol. Chem. Phys. 198:3077±
3087 (1997)
3 Leir CM, Hoffmann JJ and Stark JE, EP 0 296 852 A2, 3M (1988)
4 Gassman PG and Schenk WN, J. Org. Chem. 42:918±920 (1977)
Polym Int 48:343±345 (1999) 345
Synthesis of a-amino-o-carboxy-polytetrahydrofuran


Synthesis of α‐amino‐ω‐carboxy‐polytetrahydrofuran

  
 University of Groningen
Synthesis of α-amino-ω-carboxypolytetrahydrofuran
Vanrenterghem, T.; Dubreuil, M.F.; Goethals, E.J.; Loontjens, T.J.
Published in:
Polymer International
DOI:
10.1002/(SICI)1097-0126(199905)48:5<343::AID-PI184>3.0.CO;2-T
IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from
it. Please check the document version below.
Document Version
Publisher's PDF, also known as Version of record
Publication date:
1999
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):
Vanrenterghem, T., Dubreuil, M. F., Goethals, E. J., & Loontjens, T. J. (1999). Synthesis of -amino--
carboxypolytetrahydrofuran. Polymer International, 48(5), 343-345. https://doi.org/10.1002/(SICI)1097-
0126(199905)48:5<343::AID-PI184>3.0.CO;2-T
Copyright
Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the
author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).
Take-down policy
If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately
and investigate your claim.
Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the
number of authors shown on this cover page is limited to 10 maximum.
Download date: 21-01-2020
Rapid Report
Synthesis of a-amino-v-carboxy-
polytetrahydrofuran
T Vanrenterghem,1 MF Dubreuil,1 EJ Goethals1* and TJ Loontjens2
1Department of Organic Chemistry, Polymer Division, University of Ghent, Krijgslaan 281, 9000 Ghent, Belgium
2DSM Research, P.O. Box 18, 6160 MD Geleen, The Netherlands
INTRODUCTION
Telechelic polymers are important building blocks for
the design of new macromolecular architectures.1 In
some cases hetero-telechelic polymers, linear polymers
containing two different functional end-groups on
each polymer chain, may be of interest. In this paper
we report a convenient method for the synthesis of
a-amino-o-carboxy-polytetrahydrofuran based on a
combination of functional initiation and end-
capping.
RESULTS AND DISCUSSION
In a previous paper we reported that a combination of
a functionalized alcohol and tri¯uoromethanesulfonic
acid anhydride (tri¯ic anhydride, Tf2O) can be used as
a functional initiator system for the polymerization of
tetrahydrofuran (THF).2 This method was now
applied with ethyl-6-hydroxyhexanoate (EHH) as
functional alcohol leading to polyTHF carrying an
ester end-group which can be hydrolyzed to the
corresponding carboxylate-terminated polymer.
Scheme 1
Polymer International Polym Int 48:343±345 (1999)
* Correspondence to: EJ Goethals, Department of Organic Chemistry, Polymer Division, University of Ghent, Krijgslaan 281, 9000 Ghent,
Belgium
(Received 22 February 1999; accepted 24 February 1999)
# 1999 Society of Chemical Industry. Polym Int 0959±8103/99/$17.50 343
To introduce the amino function at the other chain
end it is, in principle, possible to end-cap the living
polymer with ammonia. However, it was observed that
this reaction leads to a substantial fraction of coupling
product resulting from reaction of the ®rst formed
primary amine with the oxonium end-group of another
living polymer. A convenient method leading to the
pure primary amino end-group was found to be end-
capping of the living polymer with hexamethylene
tetramine followed by acid hydrolysis.3 The ester
function, introduced by the initiator system, was
hydrolyzed to the carboxylic function by treatment
with anhydrous potassium hydroxide, as reported.4
The complete reaction sequence for the synthesis of
the heterotelechelic polymer is given in Scheme 1.
Figure 1 shows the 1H NMR spectrum of a polymer
with number average molecular weight 3500. The
presence of multiplets of equal intensities at 2.35 and
3.1ppm are in agreement with the presence of
carboxylate and ammonium end-groups in stoechio-
metric amounts. As reported earlier,2 the molecular
weight of the polymers can be varied by changing the
initiator concentration and/or the polymerization time.
Molecular weight distributions (Mw/Mn) are typically
below 1.2 (Table 1).
EXPERIMENTAL PART
Materials
Tf2O and EHH were puri®ed by distillation. CH2Cl2
was puri®ed by general methods and used after
distillation over calcium hydride. Trichloromethane
was used after distillation over calcium hydride. THF
was puri®ed by general methods and used after
distillation over sodium in the presence of benzo-
phenone. 2,2-Di-tert-butylpyridine (DTBP) was used
as received.
Synthesis
A typical synthesis of the polymer is as follows. In a
dried two necked-¯ask of 50mL, 7mL of CH2Cl2,
500mL of DTBP (2.23 10ÿ3 mol) and 250mL of Tf2O
(1.49 10ÿ3 mol) were thermostatted at 20 ° C. 239mL
of EHH (1.47 10ÿ3 mol) was added dropwise under
stirring. After one hour, the polymerization was started
by introducing 20mL of THF (0.247 mol). After 15
minutes, the polymerization was terminated with a
solution of 0.522g of HMTA (3.73 10ÿ3 mol) in
25mL of trichloromethane. After 10minutes stirring
at room temperature the solvents and unreacted THF
were evaporated. The residue was dissolved in 10mL
of toluene, 15mL of methanol and 1.2g of concen-
trated sulfuric acid and the solution was re¯uxed for 2
hours. The mixture was neutralized by adding a 50%
NaOH/water solution, the salts were ®ltered off and
the ®ltrate was stripped to dryness on a rotary
evaporator leaving 4.1g of a-amino-o-ester-termi-
nated polyTHF.
4.1g (1.18 10ÿ3 mol) of the residue was added to a
stirred cooled suspension (0 ° C) of 2.73g (11.75 10ÿ3
mol) of potassium tert-butoxide in 40mL of dry THF
and 55mL (3 10ÿ3 mol) of water. The ice-bath was
removed and after three hours at room temperature
the mixture was acidi®ed with concentrated hydro-
chloric acid. The salts were ®ltered off and the polymer
Figure 1. 360MHz1H NMR spectrum of
a-amino-o-carboxy-polyTHF (Mn 3500g
molÿ1, solvent CDCl3).
Table 1. Molecular weight and molecular weight
distributions of a-amino-o-carboxy-polytetrahydro-
furan as a function of polymerization time.
[THF]=11.26molLÿ1, [EHHOTf]=0.0525molLÿ1,
solvent CH2Cl2. Values obtained by gel permeation
chromatography
Polymerization time (min) Mn Mw/Mn
7 2000 1.19
15 3600 1.17
344 Polym Int 48:343±345 (1999)
T Vanrenterghem et al
was precipitated in cold water, ®ltered off, and dried
under vacuum (yield 100%).
ACKNOWLEDGEMENTS
T Vanrenterghem thanks the I.W.T. (Vlaams Instituut
voor de Bevordering van het Wetenschappelijk-Tech-
nologisch onderzoek in de industrie) for a scholarship.
REFERENCES
1 Goethals EJ, Telechelic Polymers: Synthesis and Applications, CRC
Press, Boca Raton (1989)
2 Dubreuil MF and Goethals EJ, Macromol. Chem. Phys. 198:3077±
3087 (1997)
3 Leir CM, Hoffmann JJ and Stark JE, EP 0 296 852 A2, 3M (1988)
4 Gassman PG and Schenk WN, J. Org. Chem. 42:918±920 (1977)
Polym Int 48:343±345 (1999) 345
Synthesis of a-amino-o-carboxy-polytetrahydrofuran


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Synthesis of α‐amino‐ω‐carboxy‐polytetrahydrofuran

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