Pyrrole

log Kow = 0.75

0.75

0.75

0.9698 @ 20 °C

0.955-0.975

0.9698 @ 20°C

Colorless liquid when fresh

Yellowish or brown oil

Soluble in alcohol, ether and dilute acids. Also soluble in most organic chemicals.

Water solubility: 4.5X10+4 mg/l @ 25 °C

45 mg/mL at 25 °C

Soluble in most fixed oils; Slightly soluble in water

Soluble (in ethanol)

Warning

H226 (10.7%): Flammable liquid and vapor [Warning Flammable liquids]

P210, P233, P240, P241, P242, P243, P264, P270, P280, P301+P317, P303+P361+P353, P330, P370+P378, P403+P235, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 1442 reports by companies from 11 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Warning

H226: Flammable liquid and vapor [Warning Flammable liquids]

Chemical: 1H-Pyrrole

Commission Regulation (EC) No 1565/2000 (Repealed by Com. Implementing Reg. (EU) No 872/2012)

Status: Active Update: 22-05-2020 https://echa.europa.eu/registration-dossier/-/registered-dossier/31075

1H-Pyrrole: Does not have an individual approval but may be used under an appropriate group standard

A CNS depressant; May cause liver injury; Effects of high doses administered by IP injection in dogs include convulsions and liver injury; [HSDB] Safe when used as a flavoring agent in food; [JECFA] Causes convulsions and muscle contractions in oral lethal-dose studies of rabbits; [RTECS]

2 - Materials that, under emergency conditions, can cause temporary incapacitation or residual injury.

2 - Materials that must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur. Materials would not under normal conditions form hazardous atmospheres with air, but under high ambient temperatures or under moderate heating could release vapor in sufficient quantities to produce hazardous atmospheres with air.

0 - Materials that in themselves are normally stable, even under fire conditions.

Flam. Liq. 3 (10.7%)

Flammable liquids - Category 3

... CAN REACT WITH OXIDIZING MATERIALS.

Violent reaction with 2-nitrobenzaldehyde.

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

0.32 [mg/m3]

3.5 [mg/m3]

21 [mg/m3]

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 61(SRC), determined from a log Kow of 0.75(2) and a regression-derived equation(3), indicates that pyrrole is expected to have high mobility in soil(SRC). Volatilization of pyrrole from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 1.8X10-5 atm-cu m/mole(4). The potential for volatilization of pyrrole from dry soil surfaces may exist(SRC) based upon a vapor pressure of 8.35 mm Hg(5). Pyrrole does not readily undergo biodegradation in water unless there exists bacteria that have had previous exposure to pyrrole. Given this need for acclimation, the decomposition of pyrrole may be very slow(6).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 61(SRC), determined from a log Kow of 0.75(2), indicates that pyrrole is not expected to adsorb to suspended solids and sediment in water(SRC). Volatilization from water sources is expected(3) based upon a Henry's Law constant of 1.80X10-5 atm-cu m/mole(4). Volatilization half-lives for a model river and model lake are 42 hrs and 368 hrs, respectively(SRC), using an estimation method(3). According to a classification scheme(5), an estimated BCF of 2(3,SRC) from a log Kow of 0.75(2) suggests the potential for bioconcentration in aquatic organisms is low. Experiments have shown that pyrrole is actually degraded by gasoline-adapted ground water cultures when present as a single substrate. Adaption time was 480 hrs and degradation time was 600 hrs(6). Pyrrole was not degraded in a mixture of compounds in water after 1100-1300 hrs at 10 °C and at a concentration of 0.2-1 mg/l(6).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), pyrrole, which has a vapor pressure of 8.35 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase pyrrole 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 4 days(SRC) from its rate constant of 1X10-10 cu cm/molecule sec(3). In a comparison of room temperature rate constants and loss rates of selected organics in the presence of 7.2X10+11 molecule/cu cm of ozone, 5X10+5 molecule/cu cm of hydroxyl radicals, and 2.4X10+8 molecules/cu cm of NO3 radicals, pyrrole displayed the following rate constants: 1.6X10-17 cu cm/molecule sec with a loss rate of 1 day, 1.2X10-11 cu cm/molecule sec with a loss rate of 5.2 days, and 4.9X10-11 cu cm/molecule sec with a loss rate of 1000 days, respectively(4).

Pyrrole has been detected in "popped" popcorn at a level of 26 ug/kg in a dry capture method and 44 ug/kg in a wet capture method(1). Fresh chicken breast with bone was cut into 1.5 inch cubes, coated with flour and fried in Fri-al shortening. During a 48 hour period in which the chicken was fried, pyrrole was detected (detection level not specified)(2).

Results of a study of several sites show that prior to coal gasification by ground water, pyrrole was not detected (limits of detection were 0.1 ppb). However, once coal gasification began, pyrrole was detected at 208 ppm in Hanna, Wyoming and 111 ppm Gillete, Wyoming. Pyrrole was not detected from low-Btu gasification of Rosebud coal but was detected at 23 ppm from an in situ oil shale process (limits of detection were 0.1 ppb)(1). Two retort wastewaters selected for study were produced from January to May, 1979 in the modified in situ retort 6 at the Occidental Oil Shale, Inc. facility at Logan Wash, CO. In the condensate retort water, 4.9 mg/l of pyrrole was detected while no pyrrole was detected at the process retort water (detection limits not specified)(2). Pyrrole was detected from shale oil wastewaters used to cool hot spent shale, both in gas condensate water and process retort water units not specified(3).

The Koc of pyrrole is estimated as approximately 61(SRC), using a log Kow of 0.75(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that pyrrole is expected to have high mobility in soil.

SOURCE DOMINATED: Pyrrole was detected at <1 ng/ml of air above 1 ml of water in 10 ml samples from two process retort wastewaters collected at Laramie Energy Technology Center during May 1982 and at the Logan Wash site of Occidental Oil Shale Inc. during December 1987; it was also detected in the gas-condensate retort wastewaters at 3.1 and 5.0 ng/ml of air above 1 ml of water at both sites(1). Pyrrole has been found in stock emission during incineration of municipal waste units not specified(2). URBAN/SUBURBAN: Pyrrole was not detected in ambient air at either Logan Wash, CO or at Boulder, CO(1).

IT HAS A DEPRESSANT ACTION ON THE CENTRAL NERVOUS SYSTEM AND, IN SEVERE INTOXICATION, IS INJURIOUS TO THE LIVER.

NO CASES OF OCCUPATIONAL DISEASE DUE TO PYRROLE HAVE BEEN REPORTED; HOWEVER TESTS INDICATE THAT IT HAS A MODERATE CUMULATIVE TOXICITY.

AEROBIC: Pyrrole was not degraded in a mixture of compounds in water after 1100-1300 hrs at 10 °C and at a concentration of 0.2-1 mg/l. Experiments have shown that pyrrole is actually degraded by gasoline-adapted ground water cultures when present as a single substrate. Adaption time was 480 hrs and degradation time was 600 hrs. Pyrrole inhibits benzene biodegradation strongly even at pyrrole concentrations of 100-200 ug/l(1). Degradation of pyrrole seems to be enhanced with the concomitant degradation of other compounds in an aqueous environment. No degradation of pyrrole was observed under denitrifying conditions during 846 days of incubation(2). In an aerobic enrichment culture that originated from groundwater at a creosote-contaminated aquifer in Fredensbury Denmark, pyrrole was completely removed after 49 days. It is suggested that microorganisms have to adapt to pyrrole before they can begin to degrade it and that the lag phase can be very long(3).

ANAEROBIC: Anaerobic research of pyrrole using primary digestive sludge, having an average inflow of 100 cu m/day and a mean retention time of 20 days, displayed negative gas production during the first 11 weeks of incubation. This corresponds to no biodegradation of pyrrole under anaerobic conditions(1).

Found in coal tar and bone oil; [Merck Index] Used as an intermediate (pharmaceuticals, dyes, herbicides, and perfumes) and curing agent for resins; [HSDB]

Intermediate especially in drug manufacture

CHEM INT FOR DYES, HERBICIDES, PERFUMES, CROSS-LINKING AGENT FOR RESINS

REACTION OF AMMONIA AND ACETYLENE OR BUTADIENE

Fractional distillation of bone-oil with sulfuric acid. Later converted into the potassium compound (C4H4NK), washing with ether, and treatment with water, followed by drying and distillation.

Thermal decomposition of ammonium mucate with glycerol or mineral oil. Also formed on heating of albumin; on heating sheep's wool with aqueous barium hydroxide solution; by pyrolysis of gelatin.

Flavouring Agent -> FLAVOURING_AGENT -> JECFA Functional Classes

Flavoring Agents -> JECFA Flavorings Index

Flavouring Agent -> FLAVOURING_AGENT -> JECFA Functional Classes

Flavouring Agent -> FLAVOURING_AGENT -> JECFA Functional Classes

Flavouring Agent -> FLAVOURING_AGENT -> JECFA Functional Classes

1H-Pyrrole: ACTIVE

STUDY OF FREE RADICALS PRODUCED IN PYRROLE BY X IRRADIATION & TRITIUM ATOM DECAY.

A constituent of coal tar & bone oil ... .

Pyrrole was found to be potentially useful as a tracer for determining the contribution of environmental tobacco smoke to concentrations of volatile organic compounds in indoor environments with smoking.

The ability of 10 pyrroles to block the acidic nitrosation of morpholine has been determined by using an assay that measures their effectiveness in the presence of a 10-fold excess of amine. The log (% N-nitrosomorpholine) formed is a linear function of blocking agent concentrations ranging from 0.0 to 1.5 times the equivalents of initial nitrate. The negative slopes of these plots allow a ranking of the effectiveness of the blocking agent. Several of the pyrroles have been found to be much more effective than establishing blocking agents such as ascorbic acid. The following order blocking ability has been determined: 2,5-dimethylpyrrole = 1-benzyl-2,5-dimethylpyrroleic acid = 1,2-phenylenediamine = pyrrole > 1,2,5-tribenzylpyrrole = 1-benzylpyrrole = octamethylporphine hydrazine = 2,5-diphenylpyrrolecarboxylic acid. Pyrroles give complex mixtures devoid of N-nitroso compounds upon nitrosation.