Synthesis and characterization of novel quaternary ammonium RAFT agents

Article abstract of DOI:10.1080/00397910701568751

Synthesis of three new cationic thio compounds suitable to control free-radical polymerization according to the reversible addition fragmentation chain transfer (RAFT) process (reversible addition fragmentation transfer) is presented. Among them, two bear

Full text of DOI:10.1080/00397910701568751

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Synthesis and Characterization of Novel
Quaternary Ammonium RAFT Agents
Austin Samakande a , Ronald D. Sanderson a & Patrice C. Hartmann a
a Department of Chemistry and Polymer Science, UNESCO Associated Centre
for Macromolecules, University of Stellenbosch, Matieland, South Africa
Version of record first published: 19 Oct 2007.
To cite this article: Austin Samakande , Ronald D. Sanderson & Patrice C. Hartmann (2007): Synthesis and
Characterization of Novel Quaternary Ammonium RAFT Agents, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 37:21, 3861-3872
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Synthetic Communicationsw, 37: 3861–3872, 2007
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701568751
Synthesis and Characterization of Novel
Quaternary Ammonium RAFT Agents
Austin Samakande, Ronald D. Sanderson,
and Patrice C. Hartmann
UNESCO Associated Centre for Macromolecules, Department
of Chemistry and Polymer Science, University of Stellenbosch,
Matieland, South Africa
Abstract: Synthesis of three new cationic thio compounds suitable to control free-radical
polymerization according to the reversible addition fragmentation chain transfer (RAFT)
process (reversible addition fragmentation transfer) is presented. Among them, two bear
a quaternary ammonium group in the R group [i.e., N,N-dimethyl-N-(4-(((phenylcarbo-
nothionyl)thio)methyl)benzyl)ethanammonium bromide and N-(4-((((dodecylthio)
carbonothioyl)thio)methyl)benzyl)-N,N-dimethylethanammonium bromide, a dithioester
and a trithiocarbonate, respectively]. The synthesis of a trithiocarbonate bearing an
ammonium group in the Z group [i.e., 2-((11-((benzylthio)carbonothioyl)thio)undeca-
noyl)oxy)-N,N,N-trimethylammonium iodide] is also presented. Another three thio co
mpounds,
namely
1,4-phenylenebis(methylene)dibenzenecarbodithioate,
dido
decyl-1,4-phenylenebis(methylene)bistrithiocarbonate, and 11-(((benzylthio)carbono
thioyl)thio)undecanoic acid, identified as other potentially interesting mono-or
difunctional RAFT agents, which were obtained as side products or intermediates,
were isolated and fully characterized.
Keywords: cationic transurf, dithioester, RAFT, trithiocarbonate
INTRODUCTION
The industrial demand for novel synthetic materials with specific properties is
constantly growing. From an academic point of view, this has resulted in
Received in the USA March 30, 2007
Address correspondence to Patrice C. Hartmann, UNESCO Associated Centre for
Macromolecules, Department of Chemistry and Polymer Science, University of Stel-
lenbosch, Private Bag X1, 7602 Matieland, South Africa. E-mail: hartmann@sun.ac.za
3861

3862
A. Samakande, R. D. Sanderson, and P. C. Hartmann
tremendous effort being put into the research and development of new
methods of polymerization that yield polymers with tailored structures and
the desired properties. Many nanocomposite materials have inorganic nanofil-
lers dispersed in an organic polymer continuous matrix. Emphasis is most fre-
quently on the control of the nature, the shape, and the dispersion of the
inorganic nanoparticles.[1,2] In nanocomposites, the control of the polymer
structure itself is generally neglected. Good control of the polymer architec-
ture can influence the morphology of the nanofiller.[3–5] This is the case in
the preparation of polymer-clay nanocomposites using in situ intercalative
polymerization methods. Here, as the polymerization takes place, the chain
growth itself is one of the main driving forces of clay exfoliation.[1] Good
control of the macromolecular chain growth could therefore directly impact
the degree of exfoliation of clay, as long as the polymerization takes place
inside the clay galleries.
Preparation of polymers with fairly controlled architectures can be
achieved by making use of controlled polymerization techniques such as
ionic polymerization, nitroxide-mediated polymerization (NMP), atom
transfer radical polymerization (ATRP), and lately, reversible addition frag-
mentation chain transfer polymerization (RAFT).[6] Of all these methods,
RAFT polymerization is often reported as being the most versatile, as it is
fairly tolerant to impurities and can be used with a wide range of
monomers. The control in RAFT-mediated polymerization is achieved by
using thiocarbonyl thio compounds.
Thiocarbonyl thio compounds are unstable when exposed to heat, light,
oxygen, basic media, or amines (primary and secondary). However, because
of the central role their structure plays in controlling (or not) the polymeriz-
ation of specific monomer systems, great efforts have been made to prepare
tailored RAFT agents with a variety of structures. Very good reviews are
available in the literature, in which many different RAFT agents with
various R and Z groups are summarized.[7–9]
Only a few RAFT agents bearing an ionic group have been used in
controlled free-radical polymerization. Among them, anionic R group–contain-
ing compounds have been described, for example, sodium carboxylate,[10–13]
sodium sulfonate,[14,15] or carboxylic acid.[11,14,16–24] Compounds able to
form an anionic charge (i.e., with a carboxylic acid group, if dissociated) in
the Z group have also been reported.[14,16,17]
To our knowledge, only two RAFT agents containing a quaternary
ammonium group have been reported to date.[5,25] The first reference
describes the synthesis of 4-(N,N-diethyldithiocarbamylmethyl)-benzyltri-
methylammonium bromide, its use in the modification of montmorillonite
clay, and the preparation of polymer-clay nanocomposites by in situ inter-
calative free-radical polymerization of methacrylic monomers and styrene.[5]
The second reference describes the synthesis of a RAFT agent containing a
morpholinium cationic group in its R group and its use in controlling the
free-radical polymerization of N-vinylbenzyl-N,N,N-trimethylammonium

Quaternary Ammonium RAFT Agents
3863
chloride in aqueous solution.[25] There is no report on the use of any
thiocarbonyl thio compound with a cationic group in the Z group suitable
for RAFT-mediated free-radical polymerization. A dithioester with a
cationic quaternary ammonium group situated in what would be the Z
group (if this molecule was a RAFT agent suitable for free-radical polymer-
ization) has been prepared for protein thioacetylation purposes.[26] However,
here the R group would be an ethyl group, making this compound a poor
candidate as a RAFT agent for the free-radical polymerization of vinylic
monomers.
This article deals with the preparation of thiocarbonyl thio compounds
with quaternary ammonium groups (either in the R or the Z group). These
compounds should be able to attach onto the surface of clay as well as to
control the free-radical polymerization of monomers according to the RAFT
process. However, because the compounds described in the present article
are also watersoluble and present surface-active properties, they may also
be used in the controlled polymerization of water soluble monomers or as
transfer surfactants (“transurf”) in emulsion polymerizations.
MATERIALS
Materials were obtained as follows: magnesium turnings, dodecanethiol,
thionyl chloride, 32% HCl, and methyl iodide (Riedel-de-Haen); iodine
crystals, bromobenzene, benzylbromide, N,N-dimethylethylamine, N,N-
dimethylethanol amine, and a,a-dibromo-p-xylene (Fluka); carbon disulphide
and 11-mercaptoundecanoic acid (Aldrich); Aliquote 336 (Acros); and NaOH
pellets and anhydrous magnesium sulphate (Merck). Dry tetrahedrofuran
(THF) was obtained by distillation of THF high performance liquid chromato-
graphy (HPLC) grade (sigma) over lithium aluminiumtetrahydride; all the
other solvents were used as received from Sigma (pro analysis (p.a.) grade
or higher).
ANALYTICAL EQUIPMENT
Nuclear magnetic resonance (NMR) spectroscopy was performed at 208C
using a Varian VXR-Unity (300 MHz). Fourier transform infrared spec-
troscopy (FTIR) was carried out on a Nexus FTIR instrument, by
averaging 32 scans, with a wave number resolution of 4 cm21. Electrospray
mass spectroscopy (ESMS) and electron impact mass spectroscopy
(EIMS) were carried out using a Waters-Micromass QTOF Ultima API
instrument and AMD 604 high-resolution mass spectrometer, respectively.
Melting points were carried out on a Stuart melting-point SMP 10 instru-
ment, and a Perkin Elmer Lambda 20 UV spectrometer was used for UV
analysis.

3864
A. Samakande, R. D. Sanderson, and P. C. Hartmann
EXPERIMENTAL
N,N-Dimethyl-N-(4 (((phenyl-carbonothionyl)thio)methylbenzyl)
ethanammonium Bromide (5)
Dry tetrahydrofuran (THF, 5 g), magnesium (Mg0) turnings (1 g; 0.04 mol), a
small crystal of iodine, and bromobenzene (1 g; 0.0064 mol) were stirred with
gentle heating (colder than 408C) until the reaction started. Then additional
amounts of bromobenzene (5.28 g; 0.0336 mol) and THF (25 g) were added
dropwise while keeping temperature colder than 408C by using an ice bath.
After all the magnesium disappeared, 3.05 g of carbon disulphide
(0.04 mol) was slowly added over 30 min at 08C. The solution turned red,
and the contents were left to stir at room temperature for a further 15 min.
The resulting Grignard reagent solution was heated at 408C then added
dropwise over 2 h to a solution of a,a-dibromo-p-xylene (15.84 g;
0.06 mol) in dry THF (200 mL) kept at 608C. After the last drop of the
Grignard reagent was added, the reaction mixture was kept at 608C for a
further 2 h.
Ice-cold water (150 mL) was then added, and the resultant mixture was
extracted with ether (3 ꢀ 100 mL). The combined organic phases were
washed with water (100 ml) and brine (2 ꢀ 40 mL), then dried over
anhydrous magnesium sulfate. Solvent was evaporated off the organic phase
under reduced pressure, yielding a crude oil. Purification was performed
using column chromatography with hexane–chloroform (8:1) as eluent, and
the peach-colored band was collected. However, column chromatography is
not necessary because the impurities present (i.e., unreacted a,a-dibromo-
p-xylene and 1,4-phenylenebis(methylene)dibenzenecarbodithioate) do not
interfere with the next step.
The crude oil was dissolved in acetone, and an excess of dimethylethy-
lamine (26.28 g; 0.360 mol) was added dropwise to the solution. The
reaction was stirred at ambient temperature for 48 h. The solvent was
removed under reduced pressure. The obtained residue was washed
several times with ether. Dry acetone was used to extract the desired
product from the insoluble material (i.e., the biquaternary ammonium
compound). The acetone phase was collected and evaporated, and the
residual solid product was washed with ether and dried to yield hygroscopic
red crystals of the desired RAFT agent [i.e., N,N-dimethyl-N-(4(((phenyl-
carbonothionyl)thio)methylbenzyl)ethanammonium bromide (5) (10.88 g;
66.36% yield)].
The melting point could not be determined because the reagent was too
hygroscopic. 1H NMR (300 MHz, CDCl3) d (ppm): 7.98, 7.65, and 7.53
(d, d, and t, 5H, aromatic 55CH-), 7.40 (m, 4H, p-phenylene aromatic 55CH-
), 5.04 (s, 2H, S-CH2-F), 4.56 (s, 2H, F-CH2-Nþ), 3.66 (q, 2H, Nþ -CH2-
Me), 3.19 [s, 6H, Nþ(CH3)2], 1.40 (t, 3H, -CH3); 13C NMR (300 MHz,
CDCl3) d (ppm): 227.41 (C55S), 144.86, 138.80, 133.88, 133.00, 130.31,

Quaternary Ammonium RAFT Agents
3865
128.74, 127.22, 66.72, 59.35, 49.06, 41.02, 8.54; ESMS m/e: 330.1350 (Mþ,
100); IR (neat): 1044 cm21 (C55S); UV: lmax 304 nm (C55S, p–pꢁ).
1,4-Phenylenebis(methylene)dibenzenecarbodithioate (3)
The ether soluble component (by-product) was evaporated to dryness to obtain
the neutral difunctional RAFT agent 1,4-phenylenebis(methylene)dibenzene-
carbodithioate (3) (4.950 g; 30.19% yield).
Melting point: 338C. 1H NMR (300 MHz, CDCl3) d (ppm): 8.02,
7.35–7.52 (d and m, 10H, aromatic 55CH-), 7.35 (s, 4H, p-phenylene
aromatic 55CH-), 4.58 (s, 4H, -CH2-F-CH2-);13C NMR (300 MHz, CDCl3)
d (ppm): 228.07 (C55S), 145.08, 135.03, 132.76, 129.97, 128.67, 127.22,
41.77; EIMS m/e: 410 (Mþ); IR (neat): 1044 cm21 (C55S); UV: lmax
305 nm (C55S, p–pꢁ).
N-(4-((((Dodecylthio)carbonothioyl)thio)methyl)benzyl)-N,–
dimethylethanammonium Bromide (10)
To a stirred solution of dodecanethiol (25.5 g; 0.126 mol) and Aliquote 336
(2 g) in a 160/60 mL acetone/water mixture, NaOH (11.16 g; 0.279 mol)
was added dropwise as a 50% aqueous solution. The resulting mixture was
further stirred at room temperature for 1 h, then cooled to 08C using an ice
bath. Carbon disulphide (9.88 g; 0.130 mol) was added very slowly over
30 min. The temperature was then slowly increased to 408C, and the
reaction mixture was held at that temperature for a further 15 min, resulting
in a reddish-tinted solution. The resultant solution was added dropwise to a
stirred solution of a,a-dibromo-p-xylene (50 g; 0.189 mol) in 250 mL of
THF maintained at 608C. Upon completion of the addition, the mixture was
immediately cooled (rt), then stirred at rt overnight. The solvents were
removed under reduced pressure, and the crude product was dissolved in
100 mL of chloroform–acetone (80:20 v/v). Dimethyethyl amine (55.29 g;
0.756 mol) was slowly added, and the resulting mixture was stirred for 48 h
at rt. The precipitate that formed was filtered off. The filtrate was collected
and washed with water, then concentrated under reduced pressure and preci-
pitated in ether. The obtained powder was washed several times with ether,
dried, and then recrystallized from acetone to yield yellow crystals of N-(4-
((((dodecylthio)carbonothioyl)thio)methyl)-benzyl)-N,N-dimethylethanammon
ium bromide (10) (25.63 g; 38% yield).
Melting point: 79–818C. 1H NMR (300 MHz, CDCl3) d (ppm): 7.63 and
7.38 (d and d, 4H, p-phenylene aromatic 55CH-), 5.04 (s, 2H, S-CH2-F), 4.59
(2s, 2H, F-CH2-Nþ), 3.66 (t, 2H, Nþ-CH2-), 3.34 (t, 2H, -CH2-S), 3.20 [s, 6H,
Nþ(CH3)2], 1.66 (m, 2H, -CH2-CH2-S), 1.37 [m, 5H, -CH2-and-CH3 (head
group)], 1.22 (m, 18H,-(CH2)9-), 0.83 [t, 3H, -CH3 (main chain)]; 13C NMR

3866
A. Samakande, R. D. Sanderson, and P. C. Hartmann
(300 MHz, CDCl3) d (ppm): 223.69 (C55S), 139.03, 133.88, 130.26, 126.96,
66.78, 59.30, 49.04, 40.29, 37.34, 31.88, 29.58, 29.52, 29.41, 29.30, 29.08,
28.91, 27.92, 22.62, 14.00; ESMS m/e: 454.2361 (Mþ, 100); IR (neat):
1060 cm21 (C55S); UV: lmax 309 nm (C55S, p–pꢁ).
Didodecyl-1,4-phenylenebis(methylene)bistrithiocarbonate (8)
The ether phases (obtained from the product washing) were combined and
evaporated to yield yellow crystals of a difunctional neutral RAFT agent (a
by-product) [i.e., didodecyl-1,4-phenylenebis(methylene)bistrithiocarbonate
(8) (5.469 g; 8.1% yield)].
1
Melting point: 63–648C. H NMR (300 MHz, CDCl3) d (ppm): 7.28
(s, 4H, p-phenylene aromatic 55CH-), 4.57 (s, 4H, -CH2-F-CH2-), 3.34
(t, 4H, -CH2-S), 1.66 (m, 4H, -CH2-CH2-S), 1.12–1.40 [m, 36H, -(CH2)9-],
0.84 (t, 6H, -CH3); 13C NMR (300 MHz, CDCl3) d (ppm): 223.41 (C55S),
134.61, 129.36, 40.66, 36.95, 31.74, 29.45, 29.37, 29.26, 29.16, 28.92,
28.73, 27.78, 22.51, 13.85; EIMS m/e: 658 (Mþ); IR (neat): 1062 cm21
(C55S); UV: lmax 311 nm (C55S, p–pꢁ).
11-(((Benzylthio)carbonothioyl)thio)undecanoic Acid (13)
A solution containing 11-mercaptoundecanoic acid (20.61 g; 0.094 mol),
Aliquote 336 (1.52 g), and THF (40 g; 44.5 mL) was prepared at rt. Sodium
hydroxide (7.55 g; 0.189 mol) was slowly added as a 50% aqueous solution
over 30 min. Then an additional volume of water (30 mL) was added, and
the clear brownish solution was stirred for an additional 30 min. The mixture
was cooled down to 08C using an ice bath, and carbon disulphide (7.17 g;
0.094 mol) was added slowly over 30 min. The resultant solution was stirred
at rt for a further 30 min. Benzyl bromide (16.73 g; 0.094 mol) was slowly
added, and the mixture was stirred for 24 h at rt. The aqueous phase was
acidified to pH 2 using 32% HCl and extracted using chloroform
(3 ꢀ 100 mL). The organic phases were combined, washed with 100 mL
water, dried over magnesium sulfate, and concentrated. The RAFT
compound was precipitated in a petroleum ether/ethyl acetate mixture (7:1),
and the precipitate dried under high vacuum to yield yellow crystals of 11-
(((benzylthio)carbonothioyl)thio)undecanoic acid (13) (31.23 g; 87.51%).
1
Melting point: 578C. H NMR (300 MHz, CDCl3) d (ppm): 7.27–7.35
(m, 5H, aromatic 55CH-), 4.59 (s, 2H, S-CH2-F), 3.35 (t, 2H, -CH2-S), 2.32
(t, 2H, -CH2-CO), 1.55–1.72 (m, 4H, S-CH2-CH2- and CH2-CH2-CO),
1.20–1.42 [m, 12H, -(CH2)6-]; 13C NMR (300 MHz, CDCl3) d (ppm):
224.42 (C55S), 135.50, 129.58, 129.01, 128.04, 37.08, 33.88, 29.28, 29.16,
29.03, 28.85, 27.96, 24.65; EIMS m/e: 474 (Mþ); UV: lmax 307 nm (C55S,
p–pꢁ).

Quaternary Ammonium RAFT Agents
3867
2-((11-(((Benzylthio)carbonothioyl)thio)undecanoyl)oxy)-N,N,N-
trimethylammonium Iodide (16)
11-(((Benzylthio)carbonothioyl)thio)undecanoic
acid
(13)
(10.15 g;
0.025 mol) was dissolved in dry dichloromethane (50 mL). Thionyl chloride
(12.10 g; 0.102 mol) was added dropwise, then the solution was refluxed for
1 h. The solvent and excess thionyl chloride were removed under high
vacuum to yield a yellow viscous oil. An excess of N,N-dimethylethanolamine
(10.74 g; 0.121 mol) was then added very slowly to the crude oil, and the
reaction was allowed to run for 36 h at rt. The product was acidified using
32% HCl (13.75 mL; 0.1205 mol) and extracted four times using chloroform
(50 mL). The organic phases were combined and dried over anhydrous
magnesium sulfate. The solvents were removed under reduced pressure.
The solid product was washed several times with ether, redissolved in chloro-
form, washed with a 5% aqueous solution of sodium hydroxide, and dried over
magnesium sulfate, The chloroform was then removed under reduced
pressure. The residue was dissolved in 50 mL of ether. The ether solution
was maintained at 08C while methyl iodide (6.82 g; 0.048 mol) was slowly
added. The obtained precipitate was collected by filtration, dissolved in a
100-mL mixture of H2O/acetone (80:20 v/v), and extracted four times
using 50 mL of a mixture of chloroform/acetone (50:50 v/v). The organic
phases were dried over magnesium sulfate, and the solvent removed. The
product was precipitated into ether to yield a yellow powder, 2-((11-(((ben-
zylthio)carbonothioyl)thio)undecanoyl)oxy)-N,N,N-trimethylammonium
iodide (16) (3.477 g; 22.01% yield).
Melting point: 103–1058C. 1H NMR (300 MHz, CDCl3) d (ppm): 7.27–
7.35 (m, 5H, aromatic 55CH-), 4.51–4.56 (m, 4H, F-CH2-S and O-CH2),
4.06–4.09 (m, 2H, CH2-Nþ), 3.30 (t, 2H, -CH2-S), 3.50 [s, 9H, Nþ(CH3)3]
2.28–2.33 (m, 2H, -CH2-CO), 1.49–1.67 (m, 4H, S-CH2-CH2- and CH2-
CH2-CO), 1.16–1.38 [m, 12H, -(CH2)6-]; 13C NMR (400 MHz, CDCl3) d
(ppm): 223.75 (C55S), 172.73, 129.53, 128.99, 128.78, 128.02, 65.40,
57.68, 54.92, 41.36, 37.04, 34.09, 29.28, 29.13, 29.02, 28.81, 27.91, 24.58;
ESMS m/e: 470.2225 (Mþ, 100); IR (neat): 1076 cm21 (C55S), 1168 cm21
(C-O), 1742 cm21 (C55O); UV: lmax 308 nm (C55S, p–pꢁ).
DISCUSSION
RAFT Agent with a Positively Charged R Group
N,N-Dimethyl-N-(4-(((phenylcarbonothionyl)thio)methyl)benzyl)ethanammo
nium bromide (5) and N-(4-((((dodecylthio)carbonothioyl)thio)methyl)ben-
zyl)-N,N-dimethylethanammonium bromide (10) were prepared following a
simple strategy (cf. Schemes 1 and 2). Either a Grignard reagent (2)[27] or
sodium salt (7)[28] was first prepared following methods similar to those o

3868
A. Samakande, R. D. Sanderson, and P. C. Hartmann
Scheme 1. Synthesis method A: 1,4-phenylenebis(methylene)dibenzenecarbodithio-
ate (3) and N,N-dimethyl-N-(4-(((phenylcarbonothionyl)thio)methyl)benzyl)ethanam-
monium bromide (5).
utlined in the literature. Separately, (2) and (7) were further reacted with
a,a-dibromo-p-xylene as described elsewhere.[29] One and a half equivalents
of a,a-dibromo-p-xylene [relative to (2) or (7)] were used to favor the fo
rmation of monofunctional adducts. Reaction of intermediates (4) or (9)
with dimethylethylamine yielded the quaternary ammonium salts (5) and
(10) respectively. The desired salts were purified by extraction using aceto
ne to remove traces of double salts originating from the reaction of dimethy-
lethylamine and a,a-dibromo-p-xylene (unreacted from the previous step).
RAFT Agent with a Positively Charged Z Group
Both 11-(((benzylthio)carbonothioyl)thio)undecanoic acid (13) and 2-((11-
(((benzylthio)carbonothioyl)thio)undecanoyl)oxy)-N,N,N-trimethylammonium
iodide (16) are RAFT agents with a trithiocarbonate group. The synthetic route
shown in Scheme 3 is versatile because it can be used to prepare RAFT agents
with a positive charge from already preexisting RAFT agents bearing any
carboxylic acid group.
Scheme 2. Synthesis method B: didodecyl-1,4-phenylenebis(methylene)bistrithio-
carbonate (8) and N-(4-((((dodecylthio)carbonothioyl)thio)methyl)benzyl)-N,N-
dimethylethanammonium bromide (10).

Quaternary Ammonium RAFT Agents
3869
Scheme 3. Synthesis method C: 11-(((benzylthio)carbonothioyl)thio)undecanoic
acid (13) and 2-((11-(benzylthio)carbonothioyl)thio)undecanoyl)oxy)-N,N,N-trimethy-
lammonium iodide (16).
11-(((Benzylthio)carbonothioyl)thio)undecanoic
synthesized following procedure similar to
acid
(13)
was
a
a strategy reported
elsewhere.[30–32] A tertiary amino group was introduced by reaction of the
activated acyl chloride (14) on N,N-dimethyl ethanolamine. As long as no
traces of water are present, tertiary amines do not provoke degradation of
di- and trithiocarbonates.
Difunctional RAFT Agents obtained as By-products
The synthetic pathways outlined for RAFT agents (in methods A and B)
also yielded by-products [i.e., R-CS2-CH2PhCH2-S2C-R (where R is
phenyl in method A or dodecyl in method B)], which are also potentially
interesting RAFT agents because they can be used in the preparation of
ABA block copolymer by controlled free-radical polymerization. They
have also been reported to be efficient in controlling the free-radical homo-
polymerization of styrene and butyl acrylate.[29] 1,4-Phenylenebis(methyle-
ne)dibenzenecarbodithioate (3) has been reported before,[29] whereas
didodecyl-1,4-phenylenebis(methylene)bis-trithiocarbonate (8) is a novel
RAFT agent.
CONCLUSION
Quaternary ammonium–functionalized RAFT agents were successfully syn-
thesized in acceptable yield and purity. The methods outlined are simple
and can easily be altered to yield other new RAFT agents by simply
changing the tertiary amine precursor of their head group.

3870
A. Samakande, R. D. Sanderson, and P. C. Hartmann
ACKNOWLEDGMENTS
The authors thank the National Research Foundation (NRF) of South Africa
and MONDI Packaging South Africa (MPSA) for funding.
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Preparation, properties and uses of a new class of materials. Mat. Sci. Eng. R
2000, 28, 1–63.
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