Synthesis of (α-T)polyacrylic acid

Full text of DOI:10.1002/jlcr.1185

Journal of Labelled Compounds and Radiopharmaceuticals
J Label Compd Radiopharm 2007; 50: 444–445.
Published online in Wiley InterScience
JLCR
(www.interscience.wiley.com). DOI: 10.1002/jlcr.1185
Short Research Article
Synthesis of [a-T]polyacrylic acidy
CRISTIAN POSTOLACHE* and LIDIA MATEI
Horia Hulubei National Institute for Physics and Nuclear Engineering, 407 Atomistilor, Magurele, Bucharest, 0077125, Romania
Received 12 July 2006; Revised 20 November 2006; Accepted 20 November 2006
Keywords: tritium; polyacrylic acid
Introduction
determination of melting point, TLC analysis and FTIR
ATR spectrometry. Dehydrohalogenation of the bromo-
derivative was realized using Ba(OH)2 in aqueous
medium. After finishing the reaction the Ba2+ was
removed from the reaction by acidification with H2SO4
(60%). The 2-bromoacrylic acid was extracted from
reaction medium with diethyl ether. The product
(37.49 g) was obtained with an extraction yield of
72%. The material was purified further by recrystalli-
zation from petroleum ether (25.12 g, 67%). The
product was characterized by determination of melting
point, TLC analysis and FTIR ATR spectrometry.
A polyacrylic acid (PAA) hydrogel with biotechnological,
medical and pharmaceutical application was obtained
by radio-polymerization of acrylic acid (AA) aqueous
solutions at NIPNE Magurele Romania.1 Due to its high
capacity of water absorption the PAA hydrogel may be a
good alternative for storage of low or medium-activity
tritium liquid wastes.2 The stability towards radiolysis
of PAA:H2O and self-radiolysis of PAA:HTO hydrogel
was analysed by RES spectrometry and gel/sol ratio
analysis using [T-G]PAA and [1-14C]PAA.3 For radio-
metric studies development and for confirmation of
RES spectra solving from previous studies it was
necessary to label the polyacrilic hydrogel in position
2. The labeled PAA was obtained in two main steps. In
the first step, the sodium [2-T]acrylate monomer was
obtained by catalytic hydrogenation of 2-bromoacrilyc
acid. In the second step, the hydrogel was produced by
radiopolymerisation of labeled monomer.
Synthesis of [2-D]acrylic acid and [2-T]acrylic acid
[2-D]Acrylic acid and [2-T]acrylic acid were obtained by
catalytic hydrogenation of 2-bromoacrylic acid. The
reaction took place at strongly alkaline pH (pH 11) in
dioxane. To protect the vinyl group were used the
Lindlar (Pd/BaSO4 partially poisoned with quinoline)
catalyst. The crude products were purified by TLC
using GF254 Silicagel and as eluent a mixture of
methyl isobutyl ketone:methanol:propanol:ammonia in
the ratio 64:10:40:25 (v/v/v/v). The deuterated pro-
duct was purified as sodium salt and was characterized
by FTIR spectrometry, 1H-RMN si HPLC.
Results and discussion
Synthesis of 2-bromoacrylic acid
The 2,3-dibromopropionic acid was obtained by bro-
mine addition in CCl4 medium to 0.5 mol of freshly
distillated acrylic acid. The crude product (114 g) was
obtained in 98% yield and purified by two recrystallisa-
tions from ethanol/cholorform. After purification we
obtained 93.5 g of white crystalline product (purifica-
tion yield 80%). The product was characterized by
After purification, the tritium labelled compound was
dissolved in methanol and characterized by determina-
tion of radioactive concentration and radiochemical
purity using radio TLC (Table 1). To 50 ml of methanolic
solution of 30 MBq/ml radioactive concentration was
added 0.5 g of sodium acrylate as carrier and the stock
solution was stored at 58C.
*Correspondence to: Cristian Postolache, Horia Hulubei National
Institute for Physics and Nuclear Engineering, 407 Atomistilor,
Magurele, Bucharest, 0077125, Romania. E-mail: cristip@nipne.ro
yProceedings of the Ninth International Symposium on the Synthesis
and Applications of Isotopically Labelled Compounds, Edinburgh,
16–20 July 2006.
Preparation of the [2-T]polyacrilyc acid
Labeled sodium acrylate (20 ml of the methanol solu-
tion) was evaporated to dryness under vacuum and the
Copyright # 2007 John Wiley & Sons, Ltd.

SYNTHESIS OF [a-T]POLYACRYLIC ACID 445
Table 1 Experimental data for [2-T]NaAA and [2-T]PAA
Radioactivity of crude labeled monomer (MBq)
Radioactivity of purified labeled monomer (MBq)
Radiochemical purity detected by TLC (%)
Purification yields (%)
4884
3626
90
74
Volume of labeled NaAA solution (ml)
50
Radioactive concentration of a monomer methanol solution (MBq/ml)
Total activity of monomer solution (MBq)
37
1850
Volume of AA solution used in isotopical dilution of labeled 2-T-NaAA (ml)
Radioactivity of labeled PAA washing solution (MBq)
Monomer’s and olygomer’s concentration in labeled PAA (%)
Radioactivity of purified [2-T]PAA (MBq)
20
199.8
10.8
1650
275
Specific activity (MBq/g)
residue redissolved in unlabelled acrylic acid solution
(20 ml of 30% v/v). The labelled polyacrylic acid was
obtained by radiopolymerization of this solution using
polyacrylic acid. The results obtained are illustrated in
Table 1.
a
60Co g source. The irradiation dose was 4.5 kGy and
REFERENCES
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removed by swelling in 500 ml deionized water followed
by dehydration with methanol. The radioactivity of
resulting solution was determined using a b-counter
and was used for correcting the total activity of labeled
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Copyright # 2007 John Wiley & Sons, Ltd.
J Label Compd Radiopharm 2007; 50: 444–445
DOI: 10.1002.jlcr