ECOTOXICOLOGY
AND
ENVIRONMENTAL
LETTERS
SAFETY
24,243-244
(1992)
AND NOTES TO THE EDITOR
Recently I received a note to the editor regarding the published manuscript “Chlorinated Benzo- 1,2-quinones: An Example of Chemical Transformation of Toxicants by M. Remberger, P. A. Hynning, and A. H. during Tests with Aquatic Organisms,” Neilson. Because of the critical nature of this note, I decided to ask A. H. Neilson and his associates to respond. Therefore, what follows is the text of the note for publication from A. A. Grey and A. B. McKague entitled “Reaction of Hexachlorocyclopentadiene with Sulfuric Acid.” Following the note is the rebuttal from A. H. Neilson. FREDERICK
COULSTON
Editor Reaction
of Hexachlorocyclopentadiene
with
Sulfuric
Acid
A recent publication in this journal (Remberger et al., 199 1) illustrates some of the difficulties encountered in the analysis of chemical constituents originating from pulp bleaching operations. The paper reported that tetrachlorobenzo- 1,2-quinone decomposed at pH 7.5 mainly to tetrachlorocatechol, chloranilic acid, and 3,4,Strichlorocyclopentene- 1,2-dione (Fig. 1). Identification of the trichlorocyclopentenedione was based on comparison with a standard prepared by reaction of hexachlorocyclopentadiene with sulfuric acid (Prins, 1946). In 1960, it was reported (Roedig and Markl) that the product obtained by Prins was not 3,4,5-trichlorocyclopentene-1 ,Zdione but rather 2,4,%ichlorocyclopentene1,3-dione (Fig. 1). This work was supported by conversion of the product to 2,2,4,5tetrachlorocyclopentene- 1,3-dione (Fig. 1) with hydrochloric acid and potassium chlorate. The “C NMR spectrum of the product has three signals occurring at 183.85, 15 1.13, and 56.29 ppm, consistent only with the symmetrical structure of 2,4,5-trichlorocyclopentene-1,3-dione. The chemical shifts are also consistent with those of 2,2,4,5tetrachlorocyclopentene-1,3-dione which occur at 179.52, 148.68, and 70.06 ppm (see also Hawkes et al., 1974). In addition, treatment of the product with aqueous chlorine converts it to the tetrachlorocyclopentene1,3-dione. The structure of the compound obtained by Prins is clearly 2,4,5-trichlorocyclopentene- 1,3-dione and not 3,4,5-trichlorocyclopentene1,2-dione. Therefore, the de-
Cl
0
3,4,5trichlorocyclopentene-I ,2-dione FIG.
0
2,4,5trichlorocyclopentene-I ,3-dione 1. Structural formulas 243
of chlorinated
2,2,4,5tetrachlorocyclopentene-1,3-dione diones. 0147-65
13192 $5.00
Copyright 0 1992 by Academic Press, Inc. All rights of reproduction in any form reserved.
244
LETTERS
AND NOTES TO THE EDITOR
composition product of tetrachlorobenzo- 1,2-quinone (Remberger et al., 199 1) must also be 2,4,5-trichlorocyclopentene1,3-dione. REFERENCES HAWKES, G. E., SMITH, R. A., AND ROBERTS, J. D. (1974). J. Org. Chern. 39, 1276-1290. PRINS, H. J. (1946). Syntheses of polychloro compounds with aluminium chloride. VI. The elimination of hydrogen chloride from polychloro compounds and the formation of cyclic compounds: The synthesis of perchlorocyclopentadiene. Rec. Trav. Chim. 65,455-467. REMBERGER,M., HYNNING, P.-A., AND NELSON, A. H. (1991). Chlorinated henzo-1,2quinones: An example of chemical transformation of toxicants during tests with aquatic organisms. Ecofoxicol. Environ. Saf 22, 320-336. ROEDIG, A., AND M.&RKL, G. (1960). fiber die perchlorderivate von cyclopenten-(I)-dion(3.5) pyron-(2) und protoanemonin. Annalen 636, l- 18. A. A. GREY
Carbohydrate Research Centre University of Toronto Toronto, Canada M5S IA4 A. B. MCKAGUE
CanSyn Chem. Corp. 200 College Street Toronto, Canada M5S IA4 Reply to the Comments of Grey and McKague
We thank Dr. McKague for pointing out that the structure of the reference compound we used in our study “Chlorinated Benzo- 1,2-quinones: An Example of Chemical Transformation of Toxicants during Tests with Aquatic Organism,” which was published in Ecotoxicol. Environ. SaJ 22, 320-336 (199 I), is in fact 2,4,5-trichlorocyclopentene- 1,3-dione and not the 3,4,5-trichlorocyclopentene1,2-dione which we assumed on the basis of the original description of the compound by Prins (1946). This undoubtedly correct observation does not, however, bear on the structure of the transformation product that we found, since we clearly stated that our product was not identical to the reference compound-although its mass spectrum was similar to but clearly not identical to that of the substance prepared by Prins (Fig. B)-irrespective of its structure. The statement by Dr. McKague that our compound is 2,4,5trichlorocyclopentene- 1,3-dione is therefore not supported by the evidence we provided which demonstrated that it was different from the reference substance now shown to be the 1,3-dione. The correct formulation of the structure of the reference compound in no way alters any of the conclusions of our paper, which was directed only tangentially to this compound. M. REMBERGER P. A. HYNNING A. H. NEILSON
AND
ENVIRONMENTAL
LETTERS
SAFETY
24,243-244
(1992)
AND NOTES TO THE EDITOR
Recently I received a note to the editor regarding the published manuscript “Chlorinated Benzo- 1,2-quinones: An Example of Chemical Transformation of Toxicants by M. Remberger, P. A. Hynning, and A. H. during Tests with Aquatic Organisms,” Neilson. Because of the critical nature of this note, I decided to ask A. H. Neilson and his associates to respond. Therefore, what follows is the text of the note for publication from A. A. Grey and A. B. McKague entitled “Reaction of Hexachlorocyclopentadiene with Sulfuric Acid.” Following the note is the rebuttal from A. H. Neilson. FREDERICK
COULSTON
Editor Reaction
of Hexachlorocyclopentadiene
with
Sulfuric
Acid
A recent publication in this journal (Remberger et al., 199 1) illustrates some of the difficulties encountered in the analysis of chemical constituents originating from pulp bleaching operations. The paper reported that tetrachlorobenzo- 1,2-quinone decomposed at pH 7.5 mainly to tetrachlorocatechol, chloranilic acid, and 3,4,Strichlorocyclopentene- 1,2-dione (Fig. 1). Identification of the trichlorocyclopentenedione was based on comparison with a standard prepared by reaction of hexachlorocyclopentadiene with sulfuric acid (Prins, 1946). In 1960, it was reported (Roedig and Markl) that the product obtained by Prins was not 3,4,5-trichlorocyclopentene-1 ,Zdione but rather 2,4,%ichlorocyclopentene1,3-dione (Fig. 1). This work was supported by conversion of the product to 2,2,4,5tetrachlorocyclopentene- 1,3-dione (Fig. 1) with hydrochloric acid and potassium chlorate. The “C NMR spectrum of the product has three signals occurring at 183.85, 15 1.13, and 56.29 ppm, consistent only with the symmetrical structure of 2,4,5-trichlorocyclopentene-1,3-dione. The chemical shifts are also consistent with those of 2,2,4,5tetrachlorocyclopentene-1,3-dione which occur at 179.52, 148.68, and 70.06 ppm (see also Hawkes et al., 1974). In addition, treatment of the product with aqueous chlorine converts it to the tetrachlorocyclopentene1,3-dione. The structure of the compound obtained by Prins is clearly 2,4,5-trichlorocyclopentene- 1,3-dione and not 3,4,5-trichlorocyclopentene1,2-dione. Therefore, the de-
Cl
0
3,4,5trichlorocyclopentene-I ,2-dione FIG.
0
2,4,5trichlorocyclopentene-I ,3-dione 1. Structural formulas 243
of chlorinated
2,2,4,5tetrachlorocyclopentene-1,3-dione diones. 0147-65
13192 $5.00
Copyright 0 1992 by Academic Press, Inc. All rights of reproduction in any form reserved.
244
LETTERS
AND NOTES TO THE EDITOR
composition product of tetrachlorobenzo- 1,2-quinone (Remberger et al., 199 1) must also be 2,4,5-trichlorocyclopentene1,3-dione. REFERENCES HAWKES, G. E., SMITH, R. A., AND ROBERTS, J. D. (1974). J. Org. Chern. 39, 1276-1290. PRINS, H. J. (1946). Syntheses of polychloro compounds with aluminium chloride. VI. The elimination of hydrogen chloride from polychloro compounds and the formation of cyclic compounds: The synthesis of perchlorocyclopentadiene. Rec. Trav. Chim. 65,455-467. REMBERGER,M., HYNNING, P.-A., AND NELSON, A. H. (1991). Chlorinated henzo-1,2quinones: An example of chemical transformation of toxicants during tests with aquatic organisms. Ecofoxicol. Environ. Saf 22, 320-336. ROEDIG, A., AND M.&RKL, G. (1960). fiber die perchlorderivate von cyclopenten-(I)-dion(3.5) pyron-(2) und protoanemonin. Annalen 636, l- 18. A. A. GREY
Carbohydrate Research Centre University of Toronto Toronto, Canada M5S IA4 A. B. MCKAGUE
CanSyn Chem. Corp. 200 College Street Toronto, Canada M5S IA4 Reply to the Comments of Grey and McKague
We thank Dr. McKague for pointing out that the structure of the reference compound we used in our study “Chlorinated Benzo- 1,2-quinones: An Example of Chemical Transformation of Toxicants during Tests with Aquatic Organism,” which was published in Ecotoxicol. Environ. SaJ 22, 320-336 (199 I), is in fact 2,4,5-trichlorocyclopentene- 1,3-dione and not the 3,4,5-trichlorocyclopentene1,2-dione which we assumed on the basis of the original description of the compound by Prins (1946). This undoubtedly correct observation does not, however, bear on the structure of the transformation product that we found, since we clearly stated that our product was not identical to the reference compound-although its mass spectrum was similar to but clearly not identical to that of the substance prepared by Prins (Fig. B)-irrespective of its structure. The statement by Dr. McKague that our compound is 2,4,5trichlorocyclopentene- 1,3-dione is therefore not supported by the evidence we provided which demonstrated that it was different from the reference substance now shown to be the 1,3-dione. The correct formulation of the structure of the reference compound in no way alters any of the conclusions of our paper, which was directed only tangentially to this compound. M. REMBERGER P. A. HYNNING A. H. NEILSON
