Multiblock copolymer synthesis via controlled radical polymerization in aqueous dispersions. Part 1: Synthesis of S-tert-alkyl-N,N- alkoxycarbonylalkyldithiocarbamates

Article abstract of DOI:10.1016/j.tet.2004.11.052

In a novel two- or three-step synthetic route, S-(1,4-phenylenebis(propane- 2,2-diyl)) bis(N-methyldithiocarbamate) is reacted at low temperature with various alkyl chloroformates to form various S-tert-alkyl-N,N- alkoxycarbonylmethyl-dithiocarbamate RAFT

Full text of DOI:10.1016/j.tet.2004.11.052

Tetrahedron 61 (2005) 1167–1174
Multiblock copolymer synthesis via controlled radical
polymerization in aqueous dispersions. Part 1: Synthesis of
S-tert-alkyl-N,N-alkoxycarbonylalkyldithiocarbamates
*
Raf Bussels and Cor E. Koning
Laboratory of Polymer Chemistry, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
Received 19 July 2004; revised 26 October 2004; accepted 18 November 2004
Available online 15 December 2004
Abstract—In a novel two- or three-step synthetic route, S-(1,4-phenylenebis(propane-2,2-diyl)) bis(N-methyldithiocarbamate) is reacted at
low temperature with various alkyl chloroformates to form various S-tert-alkyl-N,N-alkoxycarbonylmethyl-dithiocarbamate RAFT agents.
Also an alternative and novel synthetic route towards S-(1,4-phenylenebis(propane-2,2-diyl)) bis(N-methyldithiocarbamate), is proposed.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
moiety (e.g., butyl), then two polymerization steps are
required to obtain a (multi)block copolymer. If Z is a
macromolecular moiety, then only one polymerization step
is required. Recently, the synthesis of sequence ordered
polystyrene via compound 2 was reported by Motokucho.25
However, these authors reported that the synthesis of
In a forthcoming series of papers, the synthesis of multi-
block copolymers via controlled radical polymerization in
aqueous dispersions will be discussed. These polymers can
be used, for example, as compatibilizers for polymer blends
and composites, or as pressure-sensitive adhesives, which
can be applied to the substrates directly from the water-
borne latex. Various techniques have been reported in
literature for the synthesis of (multi)block copolymers, for
example, anionic polymerization,1 polycondensation of
telechelic polymers,2,3 the iniferter method4,5 and more
recently several techniques allowing controlled (or ‘living’)
radical polymerization.6–10 However, of these techniques
only the RAFT process allows the well-controlled synthesis
of (multi)block copolymers in aqueous dispersions.9,11–14
Therefore, the RAFT process has been utilized in this work.
The number of polymerization steps needed to create
multiblock copolymers is dependent on the number of
RAFT moieties per controlling molecule/polymer chain.
Most of the research in block copolymer synthesis via the
RAFT process has been performed employing mono- and
bifunctional RAFT agents.15–24 The concept of this work,
however, has been to employ multifunctional RAFT agents,
which allow the synthesis of multiblock copolymers in one
or two polymerization steps, depending on the nature of the
Z group (see Fig. 1). If Z in compounds 1 (dithiocarbox-
ylate) or 2 (trithiocarboxylate) is a low molecular weight
Keywords: Block copolymer synthesis; Alkyl chloroformates; Dithio-
carbamates; Living radical polymerization.
* Corresponding author. Tel.: C31 40 2472840; fax: C31 40 2463966;
e-mail: c.e.koning@tue.nl
Figure 1. Multiblock copolymer synthesis via a multifunctional RAFT
agent. (a) Multiblock copolymer synthesis starting from a symmetrical,
multifunctional RAFT agent 1. (b) Multiblock copolymer synthesis starting
from a symmetrical multifunctional trithiocarbonate 2.
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.11.052

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R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
compound 2 is cumbersome. Moreover, only primary alkyl
leaving groups have been used, leading to relatively high
polydispersities of the resulting polymers.
will be discussed in two forthcoming papers. Compounds 4
[poly(S-(1,4-phenylenebis(propane-2,2-diyl)) bis(N,N-
alkoxycarbonylmethyldithio-carbamate))] are the multi-
functional RAFT agents. The synthesis of multiblock
copolymers with this compound will be discussed in two
future papers. These compounds do not suffer from the
disadvantages of the traditional RAFT agents. Whereas the
more classical RAFT agents exhibit a dark red to pink color
and an extremely bad smell, the S-alkyl-N,N-alkoxycarbo-
nylalkyldithiocarbamates described in this work are only
slightly yellow and have a faint, sweet smell.
In this work, the S-alkyl-N,N-alkoxycarbonylmethyldithio-
carbamate RAFT moiety has been employed, for three
major reasons. The first reason is that this type of RAFT
agent has a high transfer constant.25–32 The second reason
involves the incorporation of a macromolecule into the
RAFT agent during synthesis: the classical synthetic routes
towards RAFT agent synthesis10,33,34 imply the incorpor-
ation of a macromolecule into the RAFT agent during the
first synthesis step. Since RAFT agent synthesis generally
involves three reaction steps, this renders purification of the
macromolecular RAFT agent extremely difficult. However,
in this paper a novel synthetic route towards S-alkyl-N,N-
alkoxycarbonylalkyldithiocarbamate RAFT agents is
reported that allows the incorporation of macromolecules
during the final reaction step. The third reason for choosing
the S-alkyl-N,N-alkoxycarbonylmethyldithiocarbamate
moiety is related to the synthesis of multifunctional RAFT
agents: the classical synthetic routes towards RAFT agents
generally involve low to medium yield reaction steps, which
subsequently implies a low final yield. The synthetic route
that is reported in this paper allows the synthesis of a linear,
symmetrical multifunctional RAFT agent, via the step-
growth polymerization principle.
The novel, extremely versatile synthetic route is based on
two bifunctional precursors, which upon condensation form
the RAFT moiety. This approach avoids the cumbersome
three-step reaction towards most RAFT agents and reduces
the total number of synthetic steps needed. Moreover, this
synthetic route allows the incorporation of a tertiary leaving
group in high yield. The novel synthetic route is based on
the route proposed by Allainmat et al.,35 which implies the
reaction of a chloroformate with a primary S-alkyl
dithiocarbamate. This route is depicted in Figure 3, applied
to the RAFT agents that have been synthesized in this work.
Employing this route, the synthesis of a macromolecular or
a multifunctional RAFT agent can be performed in a
maximum of three convergent reaction steps: the synthesis
of bifunctional dithiocarbamate 5, the synthesis of chloro-
formates 6b and 7a–b (6a, that is, butyl chloroformate, is
commercially available), and the (poly)condensation reac-
tion of dithiocarbamate 5 with chloroformates 6a–b or 7a–
b. Unfortunately, Allainmat et al.35 only reported the use of
primary S-alkyl dithiocarbamates, and not of tertiary S-alkyl
dithiocarbamates in this synthetic route. In the following
sections the syntheses of compound 5, 6b and 7a–b are
described in detail. Then, the synthetic route proposed by
Allainmat et al.35 is modified and applied to the synthesis of
S-tert-alkyl-N,N-alkoxycarbonylalkyldithiocarbamates.
The RAFT agents that have been used in our study on the
polymerization of acrylic monomers are depicted in Figure
2. Bifunctional RAFT agents 3 [S-(1,4-phenylenebis(pro-
pane-2,2-diyl)) bis(N,N-alkoxycarbonylmethyldithiocarba-
mate)] were synthesized because the mini-emulsion
polymerization of acrylic monomers mediated with an S-
alkyl-N,N-alkoxycarbonylalkyldithiocarbamate RAFT
agent has not yet been described. These polymerizations
Two of the RAFT agents, of which the synthesis is described
in this paper, are based on either Kratonw L-1203 or on
Kratonw L-2203. Kraton is the trade name of fully
hydrogenated, linear poly(butadiene), carrying primary
hydroxyl groups on either one (L-1203) or both (L-2203)
chain ends. The number average molar mass of both
polymers, according to the manufacturer, is 4000 g molK1
.
Both non-crystalline Kraton grades have a glass transition
temperature below K50 8C, and, because of their low molar
masses, both compounds are viscous liquids.
2. Results and discussion
2.1. Synthesis of S-(1,4-phenylenebis(propane-2,2-diyl))
bis(N-methyldithiocarbamate)
For the synthesis of S-(1,4-phenylenebis(propane-2,2-diyl))
bis(N-methyldithiocarbamate), that is, compound 5, the
route reported by Monde et al.36 was employed. Using this
method, sodium alkylthiolate salts were reacted with
various isothiocyanates, resulting in excellent yields while
short reaction times were employed. To the best of our
knowledge, however, no reports are available on the
reaction of tertiary thiolate salts with isothiocyanates.
Figure 2. Bi- and multifunctional S-tert-alkyl-N,N-alkoxycarbonylalkyl-
dithiocarbamates studied in this work. Bifunctional RAFT agents 3, with
varying length of the Z group are used to study the viability of the S-tert-
alkyl-N,N-alkoxycarbonylalkyldithiocarbamate moiety to control polym-
erization of various acrylates in solution and emulsion. RAFT agents 4,
either with a low molecular weight or a macromolecular Z group are studied
on their ability to synthesize multiblock copolymers.

R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
1169
Figure 3. Allainmat’s synthetic route applied to the RAFT agents that have been studied in this work. Bifunctional dithiocarbamate 5 is reacted with
monofunctional chloroformate 6a–b to form bifunctional RAFT agents 3a–b. By using a bifunctional chloroformate 7a–b, a polycondensation reaction of this
compound with bifunctional dithiocarbamate 5 allows the synthesis of multifunctional RAFT agent 4a–b.
However, we successfully modified Monde’s route, thereby
enabling it to synthesize tertiary S-alkyl dithiocarbamates.
This method, however, requires the use of tertiary sodium
thiolate salts. These compounds were synthesized according
to the procedure reported by Lee et al.37 This procedure
involves the reaction of a tertiary alkyl alcohol with
thiourea, and subsequent hydrolysis to form the sodium
thiolate salt.
reactor were passed through a solution of sodium hydroxide
in order to destroy phosgene and hydrogen chloride passing
along with the argon. Various mono- and bifunctional
(macromolecular) alcohols were treated with a 20%
phosgene solution in toluene. The reaction mechanism and
the various synthesized chloroformates are depicted in
Figure 5. It should be noted that the formation of the
The entire synthetic route towards compound 5 is depicted
in Figure 4. In the first reaction step, diol 8, thiourea and
hydrobromic acid were reacted according to the procedure
reported by Lee et al.,37 to form bifunctional dithiouronium
salt 9. The method reported by Lee et al.,37 then implies the
hydrolysis of bifunctional dithiouronium salt 9 to the dithiol
with 2 equiv of aqueous sodium hydroxide. However, as
was mentioned above, the route proposed by Monde et al.,36
implies the addition of a sodium thiolate salt to an alkyl
isothiocyanate. The tertiary dithiol, formed via Lee’s
procedure,37 should therefore be hydrolyzed to dithiolate
salt 10 in a separate reaction step. We found that it was also
possible to hydrolyze dithiouronium salt 9 directly to
dithiolate anion 10, using 6 equiv of aqueous sodium
hydroxide. Moreover, a methanolic solution of methyl
isothiocyanate could be added to the dithiolate anion 10
solution without isolating the dithiolate sodium salt first.
After addition of methyl isothiocyanate to the reaction
mixture, dithiocarbamate 5 readily precipitated out of the
solution and could be collected easily by filtration. After
recrystallization, the product was pure and compound 5 was
obtained in an overall yield of 60%. With this approach, we
thus succeeded in reducing the number of reaction steps
required for this synthesis from three to two.
2.2. Chloroformate synthesis
In this work, we opted for the use of a phosgene solution in
toluene. To ensure safe reaction conditions, all reactions
involving a phosgene solution were performed under strict
exclusion of air by having a stream of argon passing through
the reaction mixture at all times. All gases that left the
Figure 4. Novel synthetic route towards S-tert-alkyl-N-
alkyldithiocarbamates.

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R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
S-alkyl-N-alkyldithiocarbamates, we found that the reaction
pathway did require some optimization, especially in the
reaction of dithiocarbamate
chloroformates.
5
with bifunctional
The synthetic route towards bifunctional S-tert-alkyl-N,N-
alkoxycarbonylmethyl-dithiocarbamates is depicted sche-
matically in Figure 6, together with the optimal reaction
conditions. Dithiocarbamate 5 was reacted with monofunc-
tional chloroformates 6a–b to form bifunctional RAFT
agents 3a–b. In this reaction, triethylamine was used to trap
the hydrogen chloride that is formed upon reaction.
Triethylamine hydrochloride precipitated from the solution,
thus forcing the reaction equilibrium towards the reaction
products. The highest yield (85–90%) was obtained when
performing the reaction at K20 8C in THF for 48 h, using
5 equiv of triethylamine as the proton trap. The remaining
10–15% of the obtained crude reaction mixture was
compound 11a–b, which resulted from addition of only
one chloroformate molecule to dithiocarbamate 5. The
extended reaction times that were required can be explained
by the fact that the reaction in Figure 6 proceeds via
intermediate N-alkoxycarbonyl triethylammonium chloride,
which is formed by the reaction of triethylamine with a
chloroformate, and in which the carbonyl group is activated
for reaction with 5. The N-alkoxycarbonyl triethylammo-
nium chloride salt is only moderately soluble in tetrahy-
drofuran, and precipitated partially out of the solution. This
salt gradually redissolved and thus ensured complete
reaction.
Figure 5. Chloroformate synthesis employing a 20% phosgene solution in
toluene. A slight excess of phosgene must be used in order to prevent the
reaction between the chloroformate and the alcohol to form a carbonate.
respective carbonates or polycarbonates, formed by a
reaction of two alcohol molecules with one phosgene
molecule, cannot be entirely avoided, since for safety
reasons only a slight excess of phosgene was used. After the
reaction, in all cases the yields were close to 100%. In the
case of Kratonw chloroformate 6b, a minor amount of
di(Kratonw) carbonate was found after the reaction with
GPC analysis. However, this is only a few percent, and
could not be observed in the 1H NMR and 13C NMR spectra,
due to the low end-group concentration in the sample. The
reaction of various alcohols with a phosgene solution was
performed with and without the use of a proton trap, but no
differences could be observed in reaction yield or product
purity.
2.3. Synthesis of S-alkyl-N,N-alkoxycarbonyl-
methyldithiocarbamates
The full potential of the synthetic route introduced above is
shown when it is applied to the synthesis of multifunctional
RAFT agents. As was mentioned earlier, it is possible to
synthesize multifunctional RAFT agents starting from S-
(1,4-phenylenebis(propane-2,2-diyl)) bis(N-methyldithio-
carbamate) 5, and bifunctional chloroformates 7a–b via
a polycondensation reaction. The reaction scheme is
presented in Figure 7. In a first series of experiments,
equimolar quantities of 1,4-butanediol bischloroformate
After describing the synthesis of all the required compounds
for the (poly)condensation reaction between bifunctional
dithiocarbamate 5 and various mono- and bifunctional
chloroformates, we will focus on the condensation reaction
itself. As was reported earlier, Allainmat et al., only used
primary S-alkyl-N-alkyldithiocarbamates in this reaction.35
Although not much difference in reactivity towards
chloroformates was expected between primary and tertiary
Figure 6. Synthesis of bifunctional RAFT agents. The reaction proceeds optimally when performed at K20 8C over 48 h, employing 5 equiv of the proton trap.

R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
1171
Figure 7. Synthesis of multifunctional RAFT agents. The reaction proceeds optimally when performed at K20 8C over 48 h, employing 5 equiv of the proton
trap. However, the chain length of the Z group has a major influence on the conversion of the functional groups.
(commercially available) and bifunctional dithiocarbamate
5 were reacted at K20 8C, together with a sixfold excess of
triethylamine. However, after 48 h, no reaction had taken
place. Here, the bifunctional N-alkoxycarbonyl triethyl-
ammonium dichloride salt was formed as an intermediate of
this reaction, but this compound was virtually insoluble in
tetrahydrofuran. Thus, the reaction was fully inhibited, due
to the absence of activated bischloroformate in the solution.
However, by employing 1,10-decanediol bischloroformate
7a instead, a polycondensation reaction occurred. In this
reaction again the dichloride salt was formed, but in this
molecule the N-alkoxycarbonyl triethylammonium moieties
were further separated from each other, and the more apolar
character of this compound enhanced its solubility in
tetrahydrofuran. Therefore, solubility was less affected,
and only partial precipitation took place. The dichloride
salt derived from 1,10-decanediol bischloroformate 7a
gradually redissolved during the reaction, allowing the
synthesis of a multifunctional RAFT agent.
targeted compound) towards these compounds, based on a
procedure reported by Allainmat et al.35 We have modified
this procedure in such a way that it now allows the synthesis
of S-tert-alkyl-N,N-alkoxycarbonylalkyldithiocarbamates.
Also, we have developed a novel synthetic route towards
S-tert-alkyl-N-alkyldithiocarbamates, as the synthetic
routes reported in literature were only suitable for the
synthesis of primary and secondary S-alkyl-N-alkyldithio-
carbamates. This novel route successfully combines the
synthetic route towards tertiary thiols reported by Lee et
al.,37 with the synthetic route towards primary S-alkyl-N-
alkyldithiocarbamates reported by Monde et al.,36 to
synthesize S-tert-alkyl-N-alkyldithiocarbamates in two
steps with a good overall yield. These compounds are
intermediates in the synthesis of S-tert-alkyl-N,N-
alkoxycarbonylmethyldithiocarbamates.
4. Experimental
In a similar fashion, macromolecular multifunctional RAFT
agent poly(Kratonw-RAFT) was synthesized from Kratonw
L-2203 bischloroformate 7b and bifunctional dithiocarba-
mate 5. Here also, a dichloride salt was formed upon
reaction of Kratonw bischloroformate 7b with triethyla-
mine, but this was not a problem here, due to the small
influence the end-groups had on the solubility of the
macromolecule in the reaction medium.
4.1. Materials and methods
Thiourea, a,a,a0,a0-tetramethyl-1,4-benzenedimethanol,
HBr 48% in water, sodium hydroxide, methylisothiocya-
nate, a 20% phosgene solution in toluene, 1,10-decanediol,
triethylamine and n-butyl chloroformate were purchased
from Aldrich, and were used as received. Kratonw L-1203
and L-2203 were purchased from Kraton BV, Amsterdam
and were used as received. All solvents were purchased
from Biosolve BV, and were dried and purified before use
over a Grubbs apparatus, that is, an apparatus in which the
solvent is passed under pressure over an alumina catalyst in
order to dry and deoxygenate the solvent, except for
methanol, which was used as received. Dichloromethane
was used as received for column chromatography. All
glassware was dried overnight at 150 8C before use, except
in the synthesis of S-(1,4-phenylenebis(propane-2,2-diyl))
bis(N-methyldithiocarbamate).
3. Conclusions
Employing the RAFT process always implies the synthesis
of the organic chain transfer agents that are necessary to
mediate the RAFT polymerization. However, for the
objective of this work, the classical synthetic routes towards
RAFT agents were not useful. It was shown that there is one
type of RAFT moiety which can be synthesized in a
different way than the classical synthetic routes towards
RAFT agents, allowing the introduction of a macromolecule
in the chain, and allowing the synthesis of a multifunctional
RAFT agent: the versatile S-tert-alkyl-N,N-alkoxycarbonyl-
alkyldithiocarbamate moiety. We have successfully devel-
oped a two- or three-step synthetic route (depending on the
NMR analysis was performed on a Varian Gemini-2000
300 MHz or a Varian Mercury-Vx 400 MHz spectrometer.
Samples of the various compounds were dissolved in
deuterated chloroform (Cambridge Isotope Laboratories).

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R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
GPC analysis was carried out using a Waters model 510
pump, a model 410 refractive index detector (at 40 8C) and a
model 486 UV detector (at 254 nm) in series. Injections
were done by a Waters model WISP 712 autoinjector, using
an injection volume of 50 mL. The columns used were a
PLgel guard (5 mm particles) 50!7.5 mm column, followed
by two PLgel mixed-C or mixed-D (5 mm particles) 300!
7.5 mm columns at 40 8C in series. Tetrahydrofuran
(Biosolve, stabilised with BHT) was used as eluent at a
flow rate of 1.0 mL minK1. Calibration has been done using
5 8C using an ice bath. Methyl isothiocyanate (15.8 g,
0.22 mol) was dissolved in the minimum amount of
methanol needed, and this solution was added dropwise to
the red thiolate solution. S-(1,4-Phenylenebis(propane-2,2-
diyl)) bis(N-methyldithiocarbamate) 5 readily precipitated
out as a white solid. The resulting slurry was left to stir for
1 h to ensure complete reaction, and was then filtered over a
Bu¨chner funnel and washed with cold water. The white solid
was recrystallized twice from ethanol and dried under
1
vacuum. The overall yield was 60%. H NMR: d 1.83 (s,
ꢀ
polystyrene standards (Polymer Laboratories, Mn Z580 to
12H, C–(CH3)2), 2.95 (d, JZ4.7 Hz, 6H, NH–CH3), 6.65 (s
broad, 2H, N–H), 7.64 (s, 4H, aromatic H). 13C NMR: d
29.92 (C–CH3), 33.18 (NH–(CH3)2), 54.37 (C–(CH3)2),
127.27 (aromatic, 2-, 3-, 5-, 6-C), 143.96 (aromatic, 1-, 4-
C), 196.01 (C]S). LC–MS (ESI): m/z calcd for (MCNa)C
C16H24N2S4Na 395.07; found 395.01.
7.1!106 g molK1). Data acquisition and processing were
performed using Waters Millennium32 (v3.2 or 4.0) soft-
ware. Before injection, the samples were filtered over a
13 mm!0.2 mm PTFE filter, PP housing (Alltech).
HPLC-ESI MS analysis was carried out on an Agilent
Technologies 1100 series system, using a G1311A qua-
ternary pump, a G1313A autosampler, a G1315B UV-DAD
detector at 254 nm and an Agilent MDS type SL G1946D
mass spectrometer with atmospheric pressure electrospray
ionization. All data were processed with HP Chemstation
software. The column used was a Supersphere 100RP-18E;
150!3 mm; dp 4 mm (Bischoff) using a methanol (HPLC
grade, Biosolve)/water 50:50 to methanol gradient in
25 min at a flow of 0.4 mL minK1 at 25 8C. Samples were
dissolved in methanol (HPLC grade, Biosolve) at a
concentration of 10 mg mLK1. Typical injection volumes
were 1 mL.
4.1.2. Kratonw chloroformate (6b). A 250 mL three-
necked flask was equipped with a stirrer, a 100 mL dropping
funnel with stopper and 2 septa equipped with needles. The
flask was placed under Ar atmosphere through the first
septum, and the second septum was connected to a washing
bottle containing a 1 M aqueous NaOH solution, to destroy
all phosgene escaping from the reaction vessel. Phosgene
solution (2.5 g, 5.2 mmol) was injected into the flask
through the septum, using a 10 mL syringe. The flask was
then cooled to 0 8C with an ice bath. Monohydroxyfunc-
tional Kratonw L-1203 (Mn Z4000 g molK1, 20.0 g,
ꢀ
5 mmol) was dissolved in toluene (30 mL) and the solution
was brought into the dropping funnel, and slowly added to
the phosgene solution. The mixture was left to stir at 0 8C
for 4 h. The mixture was then purged with Ar for 2 h to
remove the excess phosgene. Toluene was removed under
reduced pressure. Kratonw chloroformate was used without
further purification. Yield 98% (calculated from 1H NMR).
1H NMR: d (ppm) 0.80–1.80 (m, polymer chain H), 4.36 (t,
JZ7.0 Hz, –CH2–O(CO)Cl). 13C NMR: d 10.60–39.20
(polymer chain C), 71.16 (–CH2–O(CO)Cl), 151.10 (C]O).
MALDI-TOF MS analysis was carried out on a Voyager
DE-STR from Applied Biosystems. The matrix used was
trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]
malononitrile, which was synthesized according to the
procedure reported by Ulmer et al.38 Sodium, potassium or
lithium trifluoroacetate (Aldrich, 98%) was added to the
compounds as cationic ionization agent at a typical
concentration around 1 mg mLK1. The matrix was dis-
solved in THF (Biosolve) at a concentration of 40 mg mLK1
.
In a typical MALDI experiment, the matrix, salt and
polymer solution were premixed in the ratio: 5 mL sample:
5 mL matrix: 0.5 mL salt. Approximately, 0.5 mL of the
obtained mixture was hand spotted on the target plate. All
the spectra were acquired on the Voyager DE-STR in the
reflector mode.
4.1.3. 1,10-Decanediol bischloroformate (7a). A 250 mL
three-necked flask was equipped with a stirrer, a 100 mL
dropping funnel with stopper and 2 septa equipped with
needles. The flask was placed under Ar atmosphere through
the first septum, and the second septum was connected to a
washing bottle containing a 1 M aqueous NaOH solution, to
destroy all phosgene escaping from the reaction vessel.
Phosgene solution (33.0 g, 67 mmol) was injected into the
flask through the septum, using a 50 mL syringe. The flask
was then cooled to 0 8C with an ice bath. 1,10-Decanediol
(5.8 g, 33 mmol) was dissolved in a minimum amount of
THF and the solution was brought into the dropping funnel,
and slowly added to the phosgene solution. The mixture was
left to stir at 0 8C for 4 h. The mixture was then purged with
Ar for 2 h to remove the excess phosgene. Toluene was
removed under reduced pressure. 1,10-Decanediol bischloro-
formate was used without further purification. Yield 98%
(calculated from 1H NMR). 1H NMR: d 1.20–1.90 (m, –CH2–
4.1.1. S-(1,4-Phenylenebis(propane-2,2-diyl)) bis(N-
methyldithiocarbamate) (5). Thiourea (17.2 g, 0.23 mol)
and a,a,a0,a0-tetramethyl-1,4-benzenedimethanol (20.0 g,
0.10 mol) were mixed and added slowly with stirring to HBr
48% (41.7 g, 0.25 mol) in a 250 mL flask. The slurry was
heated to 50 8C with an oil bath for 5 min, after which the
slurry solidified. The white solid was cooled down, filtered,
washed with a 0.1 M aqueous HBr solution, and dried under
vacuum. The solid was then crushed to powder. A solution
of NaOH (24.7 g, 0.62 mol) in water (50 mL) was prepared
in a 250 mL three-necked flask, and heated to 40 8C with an
oil bath. The white powder was added to the NaOH solution
and was left to stir at 40 8C for 2 h. After this, the solution
had become clear and red. The solution was filtered over a
Bu¨chner funnel and the filtrate was transferred to a 250 mL
three-necked flask under Ar atmosphere, equipped with a
dropping funnel and a cooler, and the solution was cooled to
(CH2)8–CH2–), 4.38 (t, JZ6.7 Hz, –CH2–(CH2)8–CH2–). 13
C
NMR: d 25.36–29.13 (–CH2–(CH2)8–CH2–), 72.22 (–CH2–
(CH2)8–CH2–), 150.44 (C]O).
4.1.4. Kratonw bischloroformate (7b). A 250 mL three-
necked flask was equipped with a stirrer, a 100 mL dropping

R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
1173
funnel with stopper and 2 septa equipped with needles. The
flask was placed under Ar atmosphere through the first
septum, and the second septum was connected to a washing
bottle containing a 1 M aqueous NaOH solution, to destroy
all phosgene escaping from the reaction vessel. Phosgene
solution (5.4 g, 11 mmol) was injected into the flask through
the septum, using a 10 mL syringe. The flask was then
cooled to 0 8C with an ice bath. Bishydroxyfunctional
Ar atmosphere. The mixture was cooled to K20 8C using a
cryostate. S-(1,4-Phenylenebis(propane-2,2-diyl)) bis(N-
methyldithiocarbamate) (0.9 g, 2.5 mmol) and triethyl-
amine (1.3 g, 13 mmol) were dissolved in a minimum
amount of THF. This solution was added dropwise to the
Kratonw chloroformate solution with stirring. This mixture
was left to stir at K20 8C for 48 h, after which the mixture
was brought to room temperature. Triethylamine hydro-
chloride was filtered off, and THF was removed under
reduced pressure. Yield 86%. The resulting yellow viscous
oil was not further purified and was used as such in
Kratonw L-2203 (Mn Z4000 g molK1, 20.0 g, 5 mmol) was
ꢀ
dissolved in toluene (30 mL) and the solution was brought
into the dropping funnel, and slowly added to the phosgene
solution. The mixture was left to stir at 0 8C for 4 h. The
mixture was then purged with Ar for 2 h to remove the
excess phosgene. Toluene was removed under reduced
pressure. Kratonw bischloroformate was used without
further purification. Yield 98% (calculated from 1H
1
polymerizations. H NMR: d 0.80–1.80 (m, polymer chain
H), d 1.96 (s, 12H, C–(CH3)2), 3.57 (s, 6H, N–CH3), 4.35 [t,
JZ6.9 Hz, 4H, –O–CH2–), 7.47 (s, 4H, aromatic H). 13C
NMR: d 10.24–38.77 (polymer chain C, C–(CH3)2), 56.20
(N–CH3), 67.78 (–O–CH2–), 126.10 (aromatic, 2-, 3-, 5-, 6-
C), 142.84 (aromatic, 1-, 4-C), 153.98 (C]O), 206.22
(C]S).
1
NMR). H NMR: d 0.80–1.80 (m, polymer chain H), 4.36
(t, JZ7.0 Hz, –CH2–O(CO)Cl). 13C NMR: d 10.60–39.20
(polymer chain C), 71.16 (–CH2–O(CO)Cl), 151.10
(C]O).
4.1.7. Poly(decyl-RAFT) agent (4a). Poly(decyl-RAFT)
agent will be further used as the common name for poly(S-
1,4-phenylenebis(propane-2,2-diyl)) bis(N,N-1,10-decoxy-
carbonylmethyl-dithiocarbamate)).
4.1.5. Butyl-RAFT agent (3a). Butyl-RAFT agent will
be further used as the common name for S-(1,4-phenylene-
bis(propane-2,2-diyl)) bis(N,N-butoxycarbonylmethyldithio-
carbamate).
1,10-Decanediol bischloroformate (2.3 g, 11 mmol) was
dissolved in THF (10 mL) in a 100 mL double enveloped
flask, equipped with a stirrer and a 50 mL dropping funnel,
and placed under Ar atmosphere. The mixture was cooled to
K20 8C using a cryostate. S-(1,4-Phenylenebis(propane-
2,2-diyl)) bis(N-methyldithiocarbamate) (4.0 g, 11 mmol)
and triethylamine (6.7 g, 66 mmol) were dissolved in the
minimum amount of THF. This solution was added
dropwise to the 1,10-decanediol bischloroformate solution
with stirring. This mixture was left to stir at K20 8C for
48 h, after which the mixture was brought to room
temperature. Triethylamine hydrochloride was filtered off,
and THF was removed under reduced pressure. The
resulting viscous yellow oil was further purified by
preparative SEC. Yield 70%. 1H NMR: d 1.20–2.10
(m, –CH2–(CH2)8–CH2–, C–(CH3)2), 3.51 (s, N–CH3), 4.25
(t, JZ7.0 Hz, –CH2–(CH2)8–CH2–), 7.40 (s, aromatic H).
13C NMR: d 22.63–32.42 (–CH2–(CH2)8–CH2–, C–(CH3)2),
38.37 (C–(CH3)2), 56.14 (N–CH3), 67.39 (–CH2–(CH2)8–
CH2–), 126.38 (aromatic, 2-, 3-, 5-, 6-C), 142.97 (aromatic,
1-, 4-C), 154.07 (C]O), 203.12 (C]S). GPC (before
N-Butyl chloroformate (3.1 g, 23 mmol) was dissolved in
THF (10 mL) in a 100 mL double enveloped flask, equipped
with a stirrer and a 50 mL dropping funnel, and placed under
Ar atmosphere. The mixture was cooled to K20 8C using a
cryostate. S-(1,4-Phenylenebis(propane-2,2-diyl)) bis(N-
methyldithiocarbamate) (4.0 g, 11 mmol) and triethylamine
(5.4 g, 54 mmol) were dissolved in a minimum amount of
THF. This solution was added dropwise to the n-butyl
chloroformate solution with stirring. This mixture was left
to stir at K20 8C for 48 h, after which the mixture was
brought to room temperature. Triethylamine hydrochloride
was filtered off, and THF was removed under reduced
pressure. The resulting yellow oil was purified by column
chromatography using dichloromethane as the eluent and
1
yielded butyl-RAFT 3a as a yellow solid. Yield 85%. H
NMR: d 0.92 (t, JZ7.3 Hz, 6H, –CH2–CH2–CH2–CH3),
1.43 (m, 4H, –CH2–CH2–CH2–CH3), 1.70 (m, 4H, –CH2–
CH2–CH2–CH3), 1.88 (s, 12H, C–(CH3)2), 3.51 (s, 6H, N–
CH3), 4.26 (t, JZ6.6 Hz, 4H, –CH2–CH2–CH2–CH3), 7.40
(s, 4H, aromatic H). 13C NMR: d 13.64 (–CH2–CH2–CH2–
CH3), 19.12 (–CH2–CH2–CH2–CH3), 28.83 (C–(CH3)2),
30.52 (–CH2–CH2–CH2–CH3), 38.35 (C–(CH3)2), 56.15
(N–CH3), 67.42 (–CH2–CH2–CH2–CH3), 126.05 (aromatic,
2-, 3-, 5-, 6-C), 142.84 (aromatic, 1-, 4-C), 153.97 (C]O),
202.97 (C]S). LC–MS (ESI): m/z calcd for (MCNa)C
C26H40N2S4O4Na 595.84; found 595.76. HRMS (MALDI-
TOF MS): m/z calcd for (MCK)C C26H40N2S4O4K
611.151; found 611.135.
purification): Mn Z1800 g molK1, PDIZ1.80. GPC (after
ꢀ
purification and isolation of the high molecular weight
fraction): Mn Z3700 g molK1, PDIZ1.59.
ꢀ
4.1.8. Poly(Kratonw-RAFT) agent (4b). Poly(Kratonw-
RAFT) agent will be further used as the common name for
poly(S-(1,4-phenylenebis (propane-2,2-diyl)) bis(N,N-
Kratoncarbamoylmethyldithiocarbamate)).
Kratonw bischloroformate (4.0 g, 1 mmol) was dissolved in
THF (20 mL) in a 100 mL double enveloped flask, equipped
with a stirrer and a 50 mL dropping funnel, and placed under
Ar atmosphere. The mixture was cooled to K20 8C using a
cryostate. S-(1,4-Phenylenebis(propane-2,2-diyl)) bis(N-
methyldithiocarbamate) (0.37 g, 1 mmol) and triethylamine
(0.51 g, 5 mmol) were dissolved in a minimum amount of
THF. This solution was added dropwise to the Kratonw
chloroformate solution with stirring. This mixture was left
4.1.6. Kratonw-RAFT agent (3b). Kratonw-RAFT agent
will be further used as the common name for S-(1,4-
phenylenebis(propane-2,2-diyl)) bis(N,N-Kratoncarbamoyl-
methyldithiocarbamate).
Kratonw chloroformate (20.0 g, 5 mmol) was dissolved in
THF (30 mL) in a 250 mL double enveloped flask, equipped
with a stirrer and a 50 mL dropping funnel, and placed under

1174
R. Bussels, C. E. Koning / Tetrahedron 61 (2005) 1167–1174
15. Chong, Y. K.; Le, T. P. T.; Moad, G.; Rizzardo, E.; Thang,
S. H. Macromolecules 1999, 32, 2071–2074.
16. Taton, D.; Wilczewska, A. Z.; Destarac, M. Macromol. Rapid
Commun. 2001, 22, 1497–1503.
to stir at K20 8C for 48 h, after which the mixture was
brought to room temperature. Triethylamine hydrochloride
was filtered off, and THF was removed under reduced
pressure. Yield 80% (GPC). The resulting yellow oil was
not further purified and was used as such in polymerizations.
1H NMR: d 0.80–1.80 (m, polymer chain H), 1.95 (s, 12H,
C–(CH3)2), 3.59 (s, 6H, N–CH3), 4.36 (t, JZ7.0 Hz, 4H,
–O–CH2–), 7.45 (s, 4H, aromatic H). 13C NMR: d 10.20–
38.70 (polymer chain C, C–(CH3)2), 56.21 (N–CH3), 67.83
(–O–CH2–), 126.08 (aromatic, 2-, 3-, 5-, 6-C), 142.84
(aromatic, 1-, 4-C), 153.95 (C]O), 206.18 (C]S). GPC:
17. Donovan, M. S.; Lowe, A. B.; Sanford, T. A.; McCormick,
C. L. J. Polym. Sci., Part A: Polym. Chem. 2003, 41,
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18. Mayadunne, R. T. A.; Rizzardo, E.; Chiefari, J.; Krstina, J.;
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Mn Z21; 600 g molK1, PDIZ1.60.
ꢀ
20. de Brouwer, J. A. M.; Schellekens, M. A. J.; Klumperman, L.;
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¨
¨
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