Environ. Sci. Technol. 1987, 21 754-756 I
An Abundant Chlorinated Furanone in the Spent Chlorination Liquor from Pulp Bleaching Lars M. Stromberg," Flllpe de Sousa, Pierre Ljungqulst, Bruce McKague, and Knut P. Krlngstad STFI (Swedish Pulp and Paper Research Institute), P.O. Box 5604, S-114 86 Stockholm, Sweden
A large peak always occurring in gas chromatograms (with electron capture detection) [GC (ECD)] when spent pulp chlorination liquors are analyzed for chlorinated phenols was identified as being caused by the presence of 3,4-dichloro-5-(dichloromethyl)-5-hydroxy-2-furanone. The compound exhibits weak mutagenic activity, has a slightly elevated bioaccumulation propensity, but is chemically rather unstable. Introduction
In recent years, available information on the chemical compositon of spent liquors from the bleaching of chemical pulp has increased (1). It has been well established that such liquors may exert acute toxic and genotoxic effects due to the presence of various chlorinated and nonchlorinated compounds of low relative molecular mass (1, 2). One group of compounds present is comprised of phenols, catechols, and guaiacols chlorinated to various degrees. This group is of particular interest because the compounds contribute to the toxicity of spent bleaching liquors and show a tendency to bioaccumulate (3, 4). The standard procedure for the qualitative and quantitative determination of chlorinated phenolic compounds includes acetylation of the spent liquor and gas chromatographic (ECD) analysis of the products obtained (5). A large peak representing an unknown compound often appears in these chromatograms. The peak is also easily detectable when chlorination products from naturally occurring aquatic humic acid are analyzed (6, 7). Since the peak could not be attributed to any known chlorinated phenols, catechols, or guaiacols, we decided to isolate and characterize the responsible compound. Experimental Section
Spept Chlorination Liquor, A spent chlorination liquor was prepared from softwood kraft pulp as described previously (8). Quantitative determinations of chlorinated phenolic compodnds were carried out according to a procedure outlined previously (5). Workup Procedure. A total of 1700 mL of the spent chlorination liquor (natural pH of 1.8) was extracted with 400 mL of diethyl ether [May and Baker Ltd. (pro analysis)] in a liquid-liquid extractor for 24 h. The extract containing a mixture of neutral, acidic, and phenolic compounds was then concentrated to a volume of about 25 mL. The extract obtained was subsequently treated with 2 x 10 mL of a 0.5 M NaHC03 solution, and the aqueous phase was acetylated essentially as previously described (5, 7). A small quantity of ascorbic acid was added to prevent oxidation. Gas Chromatography. The various hexane extracts obtained from the acetylations were injected (1-3 pL) into a Hewlett-Packard 5890 gas chromatograph equipped with an electron capture detector (ECD, 63 Ni). The column was an OV-1701 fused silica capillary column (30 m X 0.32 mm id.) manufactured by J & W Scientific Inc. (Cordova, CA). The column temperature was held constant at 190 754
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"C. The quantification procedure was carried out with the internal standard method (response factors related to 2,6dibromophenol as internal standard). Retention times and quantification data were measured with a Trivector Scientific-Trilab 2000 chromatography data system. Gas Chromatography/Multistage Mass Spectrometry (GC/MS-MS). The GC/MS and GC/MS-MS investigations were conducted with a Finnigan TSQ-46C mass spectrometer system. The samples were introduced into the ion source (temperature 120 "C) via the gas chromatograph or a moving-belt LC interface. The conditions for the GC were as follows: oven temperature, 170 "C; injector temperature, 250 "C; GC interface temperature and transfer line temperature, 300 "C. The column used was a DB-1 fused silica capillary column (30 m X 0.252 mm i.d.) manufactured by J & W Scientific Inc. (Cordova, CA). Two ionization techniques were used, positive electron impact (EI, electron energy 70 eV) and positive chemical ionization with methane as a reactant gas (CI, electron energy 150 eV, ion source pressure 1.0 mTorr). Collision activation experiments (daughter ions) were carried out with the first quadrupole transmitting the ions of interest alternately. In the collision chamber (second quadrupole) these ions were collision-activatedwith argon at a pressure of 1.5 mTorr and a nominal collision energy of 10 eV. Collision-induced fragments were separated by scanning the third quadrupole from mass m/z 40 to mass m / z 400 in 240 ms in E1 and from mass m/z 100 to mass m/z 400 in 240 ms in CI. Spectroscopic Methods and Equipment. The lH NMR and 13CNMR spectra were run on a Bruker WP 200 (200 MHz) and a Varian CFT-20 spectrometer, respectively. The UV and IR spectra were run on a Cary Model 118C UV spectrophotometer and a Perkin-Elmer Model 983 infrared spectrophotometer, respectively. Synthesis. Two ways of preparing the furanone compounds were used. In the first, leading to the acetyl derivate 3,4-dichloro5-(dichloromethyl)-5-acetyl-2-furanone (Figure 1A), chlorine water (4.0 L, containing 15 g of Clz) was added to a stirred solution of tetrachloro-o-benzoquinone(5.0 g, in 500 mL of acidified water, pH 2) in an amber bottle. The mixture was stirred at room temperature for 4 h and then extracted 3 times with ether (400 mL). After concentration, the extract (50 mL) was shaken twice with 2 X 50 mL of 0.5 M NaHC03 solution. The resulting aqueous phase was acetylated and extracted with hexane to obtain a crude product mixture. The pure compound was obtained by fractionation on SiOz (40 g), eluting with hexane-etherethanol (10:5:1). The compound was crystallized twice from acetone: white crystals; mp 90-91 "C; IR (KBr pellet) ,V 2990,1815,1780,1635,1370,1185,1080,990,950 cm-l; UV (methanol) ,A, 238 nm (9700); lH NMR (CDC13) 6 2.19 (3 H, S, CH,CO), 6.04 (1 H, S, -CHClJ; 13C NMR (CDCl,) 6 20.98 (CS), 70.82 (C6), 102.79 (c5), 126.24 (c3), 146.72 (C4), 161.75 (CZ), 167.85 (C7). Spectra recorded with reduction of decoupling effect "off resonance" showed a doublet (C6) and a quartet (C8). The GC retention time of the acetate relative to the internal standard was 1.13.
0013-936X/87/0921-0754$01.50/0
0 1987 American Chemical Society
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Figure 1. Structural formula for the chlorinated furanones 3,4-dlchloro-5-(dichloromethyl)-5-acetyl-2-furanone (A) and 3,4-dichloro-5(dlchloromethyl)-5-hydroxy-2-furanone (B). T
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Figure 2. Mass spectrum (EI) of the acetate of 3,4-dichloro-5-(dichloromethyl)-5-hydroxy-2-furanone. The C I mass spectrum sf the compound showed the molecular ion was m l z 292. Data for some daughter ion spectra of the molecular ion and fragment ions are presented under Experimental Section.
The mass spectrum (EI) of the acetylated compound is presented in Figure 2. GC/MS-MS collision activation experiments (daughter ions) gave the following results: daughters (EI) of m/z 292 gave m/z 232 and 209, of mlz 233 gave mlz 205, and 177, of mlz 209 gave mlz 181, of m / z 198 gave mlz 170,142, and 107, and of mlz 167 gave m / z 139,111,103, and 95; daughters (CI) of mlz 295 gave mlz 235, 207, and 179. The second synthetic path yielded the underivatized compound 3,4-dichloro-5-(dichloromethyl)-5-hydroxy-2furanone (Figure 1B). A solution of 2,2,4,5-tetrachlorocyclopentene-1,3-dione (ICN Biomedical, 1.0 g) in ether (50 mL) was shaken with 0.1 M K2C03(200 mL) for a few minutes. The aqueous layer was cooled, acidified with 10% HCl, and extracted with ether. The extract was dried with anhydrous magnesium sulfate and evaporated to give the crude product as a semicrystalline solid. The reaction was also performed by stirring the dione in water overnight, extracting with ether, and evaporating the solvent. The crude product was fractionated on Si02(40 g), eluting with hexane-ether 1:l and ether. After evaporation of the solvent, trituration with hexane gave the product as tan crystals: mp 66-68 "C [lit. (9) mp 70-71 "C]; IR (KBr pellet),,v 3360,2990, 1763, 1630, 1378, 1240, 1175, 1015, 920 cm-l; UV (methanol) A,, 233 nm (8700); 'H NMR (CDC1,) 6 5.99 (5, -CHC12); 13CNMR (CDClJ 6 70.71 (C6), 103.54 (C5), 125.01 (C3), 148.19 (C4), 163.12 (C2). Spectra recorded with reduction of decoupling effect off resonance showed a doublet (C6). The mass spectrum (EI) of the compound is presented in Figure 3. GC/MS-MS collision activation experiments (daughter ions) gave the following results: daughters (EI) of m/z 250 gave m/z 167 and of mlz 167 gave m/z 139,111,103, and 95; daughters (CI) of mlz 251 gave mlz 233,205, and 177 and of m / z 233 gave m / z 205, 177, and 141. Acetylation as previously described gave the acetate (Figure 1A). Mutagenicity Tests. Ether solutions (20 pL/plate) of the underivatized synthesized compound were tested for
Flgure 3. Mass spectrum (EI) of 3,4-dichloro-5-(dichloromethyl)-5hydroxy-2-furanone. The C I mass spectrum of the compound showed the molecular Ion was m / z 250. Data for some daughter Ion spectra of the molecular ion and fragment ions are presented under Experimental Section.
mutagenicity with the Ames test (10). Salmonella typhimurium TA 100 and TA 98 were used without metabolic activation. All reported test values are mean values of six plates. As a positive control for the two strains, quercetin dihydrate (Fluka AG) was used. Determination of Bioaccumulation Potential. The determination of the bioaccumulation potential was carried out by the 1-octanol/water distribution coefficient (K0J method (11,lZ) and by the method based on reverse-phase thin-layer chromatography (RP-HPTLC), giving RL values (13-1 5).
Results and Discussion Figure 2 shows the mass spectrum of the compound responsible for the unknown peak as obtained in the GC (ECD) and GC/MS analysis of the hexane extract of the acetylated ether extract from spent chlorination liquor. From this spectrum and a spectrum obtained in separate experiments with high-resolution GC/MS (VG-7070 EQ, run at VG Analytical, Organic Mass Spectrometry Division, Manchester, U.K.), the following conclusions were drawn: chemical composition C7H404C14;acetylated; presence of a dichloromethyl group; and basic structure very likely a furanone. For further characterization, large quantities of the compound were produced by chlorinating tetrachloro-o-benzoquinoneand acetylating the reaction mixture as described under Experimental Section. Tetrachloro-o-benzoquinonewas selected as starting material because recent investigations suggested furanone derivatives as possible intermediates in the degradation of this particular lignin model compound type by chlorine (16). In this way the compound could be characterized by IH NMR, 13C NMR, UV, and IR spectroscopy. The results obtained are given under Experimental Section. Altogether the data suggest the compound to be the acetate of 3,4-dichloro-5-(dichloromethyl)-5-hydroxy-2-furanone as shown in Figure 1A. The availability of the pure acetylated compound made possible the quantitative determination of the furanone in spent chlorination liquors from the bleaching of softwood kraft pulps and oxygen-prebleached softwood kraft pulps. The results showed the content to vary between 5 and 10 g per ton of pulp depending upon the level of the K number of the pulp inspected. These quantities are of the same order of magnitude as those of chlorinated phenols, catechols, and guaiacols in spent bleach liquors. Information on possible genetic effects of the compound is of importance because a trichlorinated furanone derivative previously found in such liquors (C0.5g per ton of Environ. Sci. Technol., Vol. 21, No. 8, 1987 755
pulp) exhibits strong mutagenic effects as determined by the Ames test (17, 18). The unacetylated 3,4-dichloro5-(dichloromelthyl)-5-hydroxy-2-furanone could be obtained in high yield by hydrolyzing 2,2,4,5-tetrachlorocyclopentene-1,3-dione as described under Experimental Section. In some parallel investigations we thus found that the 1,3-dione very likely is an important intermediate in pulp chlorination (19). The identity of the isolated furanone was confirmed by lH NMR, 13CNMR, UV, and IR spectroscopy as can be seen from data given under Experimental Section and from the mass spectrium shown in Figure 3. The unacetylated furanone was tested by the Ames test with S. typhirnuriurn TA 100 as the test organism. The compound exhibits mutagenic activity corresponding to about 40 revertants per nanomole. This is considerably lower than the activity reported for the previously described trichlorinated furanone derivative (19). No response was obtained with the strain TA 98 up to a dose of 1 pg/plate. Measurement of the bioaccumulation potential showed the compound had an octanol/water distribution coefficient, log KO,, of about 2.40 at a water pH of 2. When the RP-HPTLC technique was used for the estimation of log KO,, a RG value of 2.26 was obtained. These results indicate a slightly elevated bioaccumulation propensity. Tests of the stability indicated that the major part (95%) of the compound in spent chlorination liquor disappeared after 24 h of storage at pH 8 and ambient temperature. At lower pH levels the compound was considerably more stable. Conclusions
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18, 236. (2) Kringstad, K. P.; Stockman, L. G.; Stromberg, L. M. J. Wood Chem. Technol. 1984, 4(3), 389. (3) Landner, L.; Lindstrom, K.; Karlsson, M.; Nordin, J.; Sorensson, L. Bull. Environ. Contam. Toxicol. 1977,18,663. (4) Renberg, L.; Svanberg, 0.; Bengtsson, B.-E.; Sundstrom, G. Chemosphere 1980, 9(3), 143. (5) Voss, R. M.; Wearing, J. T.; Wong, A. In Advances in the
(6) (7)
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Identificationand Analysis of Organic Pollutants in Water; Keith, L. M., Ed.; Ann Arbor Science: Ann Arbor, MI, 1981; Vol. 2, p 1059. Kringstad, K. P.; Ljungquist, P. 0.;de Sousa, F.; Stromberg, L. M. Environ. Sei. Technol. 1983, 17, 553. Kringstad, K. P.; de Sousa, F.; Stromberg, L. M. Environ. Sei. Technol. 1985, 19, 427. Kringstad, K. P.; Ljungquist, P. 0.;de Sousa, F.; Stromberg, L. M. Environ. Sei. Technol. 1981, 15, 562. Roedig, A,; MZirkl, G. Justus Liebigs Ann. Chem. 1960,636,
1. (10) Maron, D. M.; Ames, B. N. Mutat. Res. 1983, 113, 173. (11) Xie, T.-M.; Hulthe, B.; Folestad, S. Chemosphere 1984,13, 445. (12) OECD OECD Guidelines for Testing of Chemicals;Org(13) (14)
(15) (16) (17)
The tetrachlorinated furanone is a major compound that frequently can be observed when analyzing spent chlorination liquors for the content of chlorinated phenolic compounds. The furanone exhibits mutagenic activity and a slightly elevated bioaccumulation propensity. It may not, however, be a significant water pollutant as it is readily degraded under ambient conditions.
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Literature Cited (1) Kringstad, K. P.;Lindstrom, K. Environ. Sei. Technol. 1984,
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Received for review September 2, 1986. Revised manuscript received February 6, 1987. Accepted March 26, 1987.
