Benzol-1,2,4-tricarbonsure-1,2-anhydrid

1.55 at 68 °F (NTP, 1992) - Denser than water; will sink

1.55 at 68 °F

Crystals

Colorless solid

less than 1 mg/mL at 68 °F (NTP, 1992)

Sol at 25 °C: 0.002 g/100 g carbon tetrachloride; 0.06 g/100 g ligroin; 0.4 g/100 g mixed xylenes; 15.5 g/100 g dimethyl formamide; 49.6 g/100 g acetone; 21.6 g/100 g ethyl acetate

36.5 g/100 g 2-butanone at 25 °C; 38.4 g/100 g cyclohexanone at 25 °C; 0.06 g/100 g mineral spirits at 25 °C

Solubility in water: reaction

440.6 °F (NTP, 1992)

227 °C o.c.

440.6 °F

464 to 473 °F at 14 mmHg (NTP, 1992)

390 °C

Boiling point: 240-245 °C at 14 mm Hg

Boiling point 240-245 °C at 14 mm Hg

at 1.87kPa: 240-245 °C

464-473 °F at 14 mmHg

329 to 336 °F (NTP, 1992)

161-163.5 °C

161-163.5 °C

329-336 °F

322 °F

6.6 (NTP, 1992) - Heavier than air; will sink (Relative to Air)

Relative vapor density = 6.6 (air =1)

Relative vapor density (air = 1): 6.6

6.6

4e-06 mmHg at 77 °F (NTP, 1992)

0.00000986 [mmHg]

Vapor pressure: 4X10-6 mm Hg

Vapor pressure of liquid trimellitic anhydride = 2.25 mm Hg at 200 °C

Vapor pressure at 25 °C: negligible

0.000004 mmHg

FCS -> FDA Cumulative Estimated Daily Intake (CEDI)

FCS -> FDA Inventory of Food Contact Substances Listed in 21 CFR

FCS -> FDA Inventory of Effective Food Contact Substance (FCS) Notifications

FCS -> FDA Inventory of Effective Food Contact Substance (FCS) Notifications

FCS -> FDA Inventory of Effective Food Contact Substance (FCS) Notifications

FCS -> FDA Inventory of Effective Food Contact Substance (FCS) Notifications

Danger

H317: May cause an allergic skin reaction [Warning Sensitization, Skin]

P233, P260, P261, P264+P265, P271, P272, P280, P284, P302+P352, P304+P340, P305+P354+P338, P317, P319, P321, P333+P317, P342+P316, P362+P364, P403, P403+P233, P405, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for < 0.1% (1 of 1477) of reports.

Danger

H317 (99.9%): May cause an allergic skin reaction [Warning Sensitization, Skin]

Chemical: 5-Isobenzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo-

Hazard Traits - Respiratory Toxicity

Council Directive (EEC) No 109/1989 (Repealed by Reg. EC No 1935/2004 (amended))

5-Isobenzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of 5-Isobenzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo- are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Status: Active Update: 05-04-2023 https://echa.europa.eu/registration-dossier/-/registered-dossier/15095

Substance: Benzene-1,2,4-tricarboxylic acid 1,2 anhydride

This chemical is combustible. (NTP, 1992)

Combustible. Finely dispersed particles form explosive mixtures in air.

There are three syndromes caused by trimellitic anhydride (TMA) based on its ability to irritate and sensitize lung tissue. Sensitized workers can develop upon re-exposure 1) asthma-rhinitis; 2) late respiratory systemic syndrome (LRSS); or very rarely 3) pulmonary disease anemia syndrome (PDA). [Grammer LC et al. Review of trimellitic anhydride (TMA) induced respiratory response. Allergy Asthma Proc 1997 Jul-Aug;18(4):235-7] Workers exposed to less than 0.002 mg/m3 are at low risk for developing disease. [Grammer LC et al. A Clinical and Immunologic Study to Assess Risk of TMA-Induced Lung Disease as Related to Exposure. JOEM 1999 Dec;41(12):1048-51] TMAN is a potent sensitizer after inhalation of either dust or fume. It causes IgE and IgG mediated disease (asthma/rhinitis, late respiratory systemic syndrome, pulmonary disease anemia, and late arthralgia myalgia). Symptoms include sneezing, rhinitis, dry throat, watery eyes, conjunctivitis, and dyspnea. Dermal contact may cause or exacerbate respiratory sensitization. When workers are not exposed to >2 ug/m3, there are no cases of disease or IgG against TM-HAS (Human Serum Albumin), but there are still cases of non-diseased workers with IgE against TM-HAS (9% incidence). TMAN cause both immediate and delayed dermal sensitization in animal studies. [ACGIH] Danger of airway sensitization; [MAK] TMA skin testing provides an alternative and potentially more practical method for monitoring TMA-exposed workers for developing IgE sensitization. [PMID 21915071] See ACID ANHYDRIDES.

European Chemicals Bureau; IUCLID Dataset, Benzene-1,2,4-tricarboxylic acid 1,2-anhydride (CAS No.552-30-7) (2000 CD-ROM edition). Contains information on usage patterns, toxicology, and ecological effects submitted by industry to the European Union. Available from the database query page: http://ecb.jrc.it/esis/esis.php as of August 28, 2006.

TRIMELLITIC ANHYDRIDE reacts exothermically with water. This reaction is expected to be slow, but can become vigorous if local heating accelerates it. Reaction with water is accelerated by acids. Incompatible with acids, strong oxidizing agents, alcohols, amines, and bases. Incompatible with strong oxidizing agents, strong acids or strong bases. (NTP, 1992).

Fires involving this material should be controlled using a dry chemical, carbon dioxide or Halon extinguisher. (NTP, 1992)

Use water spray, powder.

Fresh air, rest. Refer for medical attention.

Remove contaminated clothes. Rinse skin with plenty of water or shower.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Give one or two glasses of water to drink. Refer for medical attention .

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

(General first aid procedures)

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then you should dampen the solid spill material with 60-70% ethanol and transfer the dampened material to a suitable container. Use absorbent paper dampened with 60-70% ethanol to pick up any remaining material. Seal the absorbent paper, and any of your clothes, which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Solvent wash all contaminated surfaces with 60-70% ethanol followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

... Ozone (3 ppm for 3 hr) caused an increase in -log PC300 at 1 hr after exposure, with return of -log PC300 to control levels at 8 hr. Ozone also increased baseline RL at 8 hr. trimellitic anhydride (TMA) challenge increase -log PC300 in TMA-sensitized guinea pigs at 8 hr after challenge from 3.85 +/- 0.09 to 4.11 +/- 0.09. Ozone exposure prior to TMA challenge prevented the induction of airway hyperresponsiveness with a mean -log PC300 of 3.51 +/- 0.20, which was not different from that of control TMA-sensitized group. Baseline lung resistance was significantly higher in ozone-pretreated animals after TMA challenge when compared to those of either control or challenged with TMA alone. Ozone had no effect on TMA challenge-induced BAL eosinophilia and neutrophilia.

... Before challenge, sensitized animals were pretreated iv with inhibitors of different mediators: pyrilamine (antihistamine: 2 mg/kg, indomethacin (cyclooxygenase inhibitor: 10 mg/kg), OKY-046 (thromboxane synthetase inhibitor: 30 mg/kg), ICI-198,615 (leukotriene receptor antagonist: 10-6 mol/kg), ketanserin (5-HT2 receptor antagonist: 1 mg/kg), or azelastine ("antiallergic agent": 1 mg/kg). Intratracheal instillation of trimellitic anhydride conjugated to guinea pig serum albumin (TMA-GPSA) induced a slowly progressing increase in lung resistance (RL) and produced extravasation of Evans blue dye at all airway levels in sensitized animals. Pyrilamine and azelastine abolished the increase in RL induced by TMA-GPSA until 2.5 min after the challenge. Indomethacin and OKY-046 significantly attenuated the increase in RL 3 min after the challenge. ICI-198,615 and ketanserin did not significantly affect the increase in RL. Extravasation of Evans blue dye induced by TMA-GPSA was decreased by pyrilamine, azelastine and ICI-198,615 in main bronchi and intrapulmonary airways. Indomethacin, OKY-046 and ketanserin did not significantly affect the extravasation of dye into the airway tissue.

... Both IgE and IgG anti-trimellitic anhydride antibodies started to rise between weeks 1 and 3 after immunisation, reached their highest levels 7 weeks after sensitisation with 3% of TMA and then started to decline. Betamethasone and cyclosporin A (CsA) given orally over the time of sensitisation (8 days in total) inhibited the development of specific IgE and IgG anti-TMA antibodies. Betamethasone given 10-17 days after sensitisation attenuated the IgE and IgG antibody responses as well while treatment with CsA after sensitisation had no effect on the production of specific antibodies. Levels of total IgE and IgG were not affected except for a small decrease in total IgE using medium-dose betamethasone after sensitisation.

... Guinea pigs pretreated with cobra venom factor (CVF) had significantly reduced amounts of complement component C3 in the lavage fluid 24 hours after trimellitic anhydride (TMA) conjugated to guinea pig serum albumin challenge. Pretreatment with CVF did not affect the immediate TMA-induced bronchoconstriction nor the TMA-induced microvascular leakage. In animals depleted of the complement system by pretreatment with CVF the TMA-induced increase in mononuclear cells, total white blood cells, red blood cells, and EPO activity in the bronchoalveolar lavage was significantly reduced.

... Exposure to 0.5 mg/cu m trimellitic anhydride produced hemorrhagic foci of the lung and increased antibody levels in rats treated for six hours/day, five days/week for two weeks ... Estrogen treatment reduced the number of lung foci in both male and female rats, while testosterone treatment had no effect.

TERRESTRIAL FATE: Based on the structural similarities to phthalic anhydride, trimellitic anhydride is expected to have a similar hydrolysis rate(SRC). Phthalic anhydride has been reported to hydrolyze rapidly in water(1) and estimated half-lives of approximately 1.5 minutes and 2.7 minutes were calculated(SRC) using reported observed rate constants of 7.9X10-3/sec(2) and 4.3X10-3/sec(3), respectively. Based upon this hydrolysis rate, trimellitic anhydride is expected to hydrolyze in moist soils(SRC). Volatilization from soil surfaces and adsorption to soil are not expected to be important processes because of hydrolysis(SRC).

AQUATIC FATE: Based on the structural similarities to phthalic anhydride, trimellitic anhydride is expected to have a similar hydrolysis rate(SRC). Phthalic anhydride has been reported to hydrolyze rapidly in water(1) and estimated half-lives of approximately 1.5 minutes and 2.7 minutes were calculated(SRC) using reported observed rate constants of 7.9X10-3/sec(2) and 4.3X10-3/sec(3), respectively. Therefore, volatilization from water surfaces, adsorption to suspended solids and sediments, biodegradation, and bioconcentration of trimellitic anhydride are not expected to be important in aquatic systems based on hydrolysis(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), trimellitic anhydride, which has an extrapolated vapor pressure of 9.86X10-6 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase trimellitic anhydride is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 20 days(SRC), calculated from its rate constant of 7.97X10-13 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase trimellitic anhydride may be physically removed from the air by wet and dry deposition(SRC).

The substance can be absorbed into the body by inhalation and by ingestion.

inhalation, ingestion, skin and/or eye contact

/AQUATIC SPECIES/ No signs of toxicity were observed in Daphnia magna (water flea) exposed to TMA/TMLA nominal concentrations of 130, 220, 350, 600, or 1,000 mg/L for 48 hours under static conditions ... Based on measured concentrations, the 96 hr NOEC was > 792 mg/L.

/AQUATIC SPECIES/ No signs of toxicity were observed in Scenedesmes subspicatus (green algae) exposed to TMA/TMLA nominal concentrations of 62.5, 125, 250, 500, or 1,000 mg/L for 96 hours under static conditions ... Based on measured concentrations, the NOEC was > 739 mg/L.

/AQUATIC SPECIES/ No signs of toxicity were observed in Leuciscus idus melanotus (Golden Orfe) exposed to TMA/TMLA nominal concentrations of 130, 220, 350, 600, or 1,000 mg/L for 96 hours under static conditions ... Based on measured concentrations the 96 hour NOEC > 896 mg/L.

/AQUATIC SPECIES/ Because TMA rapidly hydrolyzes to form trimellitic acid (TMLA) in water, following pH adjustment TMLA and sodium trimellitate salts are the actual form of the chemical evaluated in aquatic toxicity tests.

Cough. Headache. Nausea. Shortness of breath. Wheezing. Symptoms may be delayed.

Redness. Pain.

Redness. Pain.

Nausea. Abdominal pain. Burning sensation. Vomiting. Diarrhoea.

irritation eyes, skin, nose, respiratory system; pulmonary edema, resp sensitization; rhinitis, asthma, cough, wheezing, dyspnea (breathing difficulty), malaise (vague feeling of discomfort), fever, muscle aches, sneezing

The following link will take the user to the National Toxicology Program (NTP) Test Agent Search Results page, which tabulates all of the "Standard Toxicology & Carcinogenesis Studies", "Developmental Studies", and "Genetic Toxicity Studies" performed with this chemical. Clicking on the "Testing Status" link will take the user to the status (i.e., in review, in progress, in preparation, on test, completed, etc.) and results of all the studies that the NTP has done on this chemical. [http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm?fuseaction=ntpsearch.searchresults&searchterm=552-30-7]

This article described our clinical and immunologic experience in assessing workers exposed to trimellitic anhydride (TMA) in three industrial settings. Since 1977 /the authors/ have had engaged in a prospective study of workers involved at the site of manufacture of TMA. These studies demonstrate that serologic measurements of total antibody to trimellityl human serum albumin (TM-HSA) and IgE antibody to TM-HSA are predictive of the development of an immunologically mediated respiratory illness and are useful in monitoring workers removed from TMA exposure, in identifying asymptomatic workers who may be at risk in the future, and in defining the nature of sensitization of the work force. In a different industrial setting, /the authors/ have been able to study workers who mixed previously manufactured TMA powder with epoxy resins. This study indicated that clinical assessments by a plant physician with a standardized questionnaire, along with serologic tests, could establish the presence or absence of an immunologic respiratory illness caused by the inhalation of TMA dust. In a third industrial situation, workers were exposed to both TMA and phthalic anhydride (PA). Here workers were interviewed by a local physician with minimal experience with TMA-related respiratory illness. In this situation a more detailed questionnaire was utilized, along with serologic tests utilizing the enzyme-linked immunosorbent assay to establish the presence of a TMA- or PA-related syndrome. Immunologic studies demonstrated in workers exposed to both TMA and PA that the antibody responses elicited showed little crossreactivity between antibodies directed against TM-HSA or PA-HSA.

... A practical approach that has significantly reduced the incidence of immune disease due to trimellitic anhydride is periodic surveillance of exposed worker populations with serum antibody studies and questionnaires. Workers who have significant levels of antibody, report significant symptoms on questionnaires, or both, are further evaluated to determine the clinical diagnosis and whether any interventions are needed.

Based on the structural similarities to phthalic anhydride, trimellitic anhydride is expected to have a similar hydrolysis rate(SRC). Phthalic anhydride has been reported to hydrolyze rapidly in water(1) and estimated half-lives of approximately 1.5 minutes and 2.7 minutes were calculated(SRC) using reported observed rate constants of 7.9X10-3/sec(2) and 4.3X10-3/sec(3), respectively. Based upon this hydrolysis rate, trimellitic anhydride adsorption to soil and leaching are not expected to be important processes(SRC).

Trimellitic anhydride (CAS# 552-30-7) was evaluated for teratogenicity. The test substance was administered via inhalation to pregnant rats during gestation days 6-15 for 6/hrs/day at a concentration of 500 ug/cu m. Half of the animals were sacrificed for pathological evaluation and the other half were given a single "challenge" exposure of 500 ug/cu m for 6-hours. Pathological findings concluded there was a significant increased in the number of hemorrhagic lung foci and an increased level of trimellitic anhydride (TMA) specific serum antibody in all rats. There were no significant treatment-related differences in litter size, litter viability, variations, or malformations.

Trimellitic anhydride (CAS# 552-30-7) was evaluated for teratogenicity. The test substance was administered via inhalation to pregnant guinea pigs during gestation days 6-26 for 6/hrs/day at a concentration of 500 ug/cu m. Half of the animals were sacrificed for pathological evaluation and the other half were given a single "challenge" exposure of 500 ug/cu m for 6-hours. Pathological findings concluded there was a significant increase in the number of hemorrhagic lung foci and an increased level of trimellitic anhydride (TMA) specific serum antibody in 2/7 guinea pigs. There were no significant differences in litter size, litter viability, variations, or malformations.

Subchronic inhalation toxicity and sensitization potential were evaluated in groups of 15 rats (sex and strain not reported) exposed to a single 6-hour dose of trimellitic anhydride at a level of 0, 0.3, 1.6, 7.7, 23.9 or 135 micrograms/cu m with a second 6-hour dose to 500 micrograms/cu m 3 weeks later. The method of atmosphere generation and compound concentration measurement was not reported. There were no mortalities or clinical observations reported. Necropsy revealed a dose-dependent increase in hemorrhagic foci in the lungs of treated animals.

... Trimellitic anhydride (TMA) and trimellitic acid (TMLA) are structurally similar ... Studies on stability of TMA in water suggest complete hydrolysis occurs in less than ten minutes. Since TMA rapidly forms TMLA under the conditions used to test its toxicity, the toxicities of TMA and TMLA are believed to be the same with a few exceptions. Specifically, the alergic symptoms (both respiratory and dermal sensitization) of TMA are directly attributable to the reaction of TMA with free amines within proteins to form haptens, which when present at sufficiently high levels in tissues can produce sensitization. TMLA does not react with proteins to form haptens ... In addition to the immunological differences, there may be some slight quantitative differences in reactions at the site of contact. While both materials cause slight irritation of the skin and are severe eye irritants, there appears to be a difference in the magnitude of response. This difference in the magnitude of irritation may be attributable to the heat of hydrolysis of the anhydride. With the exception of the immunological and site of contact effects, all other endpoints are expected to be the same.

Occupational inhalation of trimellitic anhydride (TMA) apparently results in an antibody response with specificity for unique new antigenic determinants which arise from the coupling of TMA with autologous resp tract proteins.

... Sensitization with trimellitic anhydride (TMA) led to decreased lung function parameters during and within 1 hr after challenge as compared to non-sensitized rats. Alveolar macrophages (AM) depletion alleviated the TMA-induced drop in lung function parameters and induced a faster recovery compared to sham-depleted TMA-sensitized rats. It also decreased the levels of serum IgE 24 hr after challenge, but did not affect the sensitization-dependent increase in lung lavage fluid IL-6 and tissue TNF-alpha levels. AM depletion augmented the TMA-induced tissue damage and inflammation 24 hr after challenge.

... In the TNF-alpha knockout TNF-alpha-/- (B6;129S-Tnftm1Gk1) mice, the repetition of the trimellitic anhydride (TMA) challenges enlarged the extent of the late phase of contact hypersensitivity (CHS), but less than those in TNF-alpha+/+ mice. Injection of anti-TNF-alpha antibody into the peritoneal cavity of Balb/c mice significantly decreased the extent of the late phase of CHS. Subcutaneous injection of anti-IgE antibody into Balb/c mice also decreased the extent of the late phase of CHS in dose-dependent manner. Histologically, infiltration of polymorphonuclear leukocytes and eosinophils was more pronounced in repeatedly TMA-challenged TNF-alpha+/+ and Balb/c mice than in the TNF-alpha-/- mice and anti-TNF-alpha or anti-IgE antibodies treated Balb/c mice.

For more Mechanism of Action (Complete) data for TRIMELLITIC ANHYDRIDE (6 total), please visit the HSDB record page.

... Biological half-lives /in rats/ ranging from 3 to 46 days were estimated ... Specific half-lives for trimellitic anhydride in the lungs were estimated to be 21 days in male rats and 16 days in female rats ... In lung associated lymph nodes, half-lives of 13 and 33 days were estimated for male and female rats, respectively ...

Tissue concentration time-course data were collected for rats exposed to 0.95 mg/cu m trimellitic anhydride (TMA) for 45 min ... Animals were sacrificed 3 hr, 1, 2, 4, 8, 16, and 32 days following exposure. In general, the highest tissue concentrations were obtained at the first time point (T-max<3 hr). A second T-max of eight days was reported for lung lymph nodes in male rats, suggesting a possible role in the gender differences observed for lung toxicity ...

Used primarily as a curing agent for alkyl and epoxy resins; [Rom p. 1213] Used in the synthesis of, or as a curing agent for, epoxy resins, plasticizers, paints, wall and floor coverings, and insulation for cable and wire; [ACGIH]

Semiconductor Manufacturing [Category: Industry]

In prepn of resins, adhesives, polymers, dyes, printing inks

Plasticizer for polyvinyl chloride; high-temp plastics; wire insulation; gaskets; automotive upholstery.

Chem int for trimellitate plasticizers, poly(amide-imide) & poly(ester-imide) resins, alkyd coating resins (primarily water-based), dyes & printing inks

The largest amount of trimellitic anhydride is used to make plasticizers for poly(vinyl chloride). ... The anhydride is an important curing agent in the production of epoxy resins. Polyester resins of trimellitic anhydride are widely used as paint resins for water-based and solvent-based coatings.

2023: 50,000,000 - <100,000,000 lb

This chemical is listed as a High Production Volume (HPV) (65FR81686). Chemicals listed as HPV were produced in or imported into the U.S. in >1 million pounds in 1990 and/or 1994. The HPV list is based on the 1990 Inventory Update Rule. (IUR) (40 CFR part 710 subpart B; 51FR21438).

(1977) MORE THAN 2.27X10+6 G-AS ACID CHLORIDE

(1979) MORE THAN 2.27X10+6 G-AS ACID CHLORIDE

Production volumes for non-confidential chemicals reported under the Inventory Update Rule. [Table#4906]

By oxidation of pseudocumene to trimellitic acid followed by dehydration

Prepared by subliming trimellitic acid above its melting point; ... by heating crude trimellitic acid with V2O5: McKinnis, US 2998431 (1959 to Union Oil of California).

3-Xylene is carbonylated with carbon monoxide in the presence of boron trifluoride and hydrogen fluoride to form 2,4-dimethylbenzaldehyde. 2,4-Dimethylbenzaldehyde is decomplexed from the acids, purified, and oxidized to trimellitic acid. Trimellitic acid is subjected to normal dehydration and purification steps to obtain high quality trimellitic anhydride.

... Liquid-phase catalytic oxidation of 1,2,4-trimethylbenzene (pseudocumene) with air (Amoco method). An alternative process involves oxidation with 7% nitric acid at 170-190 °C and 2MPa, but it is inefficient compared with the air oxidation method.

Plastics Material and Resin Manufacturing

5-Isobenzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo-: ACTIVE