4-Hydroxyazobenzol

INSOL IN WATER; VERY SOL IN ALC & ETHER; SOL IN BENZENE, CONCN SULFURIC ACID & DIL ALKALI (YELLOW)

Soluble in acetone, ethanol, benzene and ether

In water, 90 mg/l @ 20 °C

4.7 [ug/mL] (The mean of the results at pH 7.4)

0.00000023 [mmHg]

2.31X10-7 mm Hg @ 25 °C

Warning

H315 (97.8%): Causes skin irritation [Warning Skin corrosion/irritation]

P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 46 reports by companies from 6 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

LC50 Pimephales promelas (fathead minnow) 110 (1.07-1.13) mg/l 72 hr, wt 100 mg, flow-through bioassay, dissolved oxygen 7.4 (4.6-8.8) mg/l, water hardness 44.9 (42.4-46.6) mg/l as CaCO3, pH 6.9-7.7, alkalinity 42.9 (39.6-61.4) mg/l CaCO3, temp: 26.4 +/- 1.4 °C, Purity 90%+

LC50 Pimephales promelas (fathead minnow) 1.09 (1.05-1.13) mg/l 96 hr, wt 100 mg, flow-through bioassay, dissolved oxygen 7.4 (4.6-8.8) mg/l, water hardness 44.9 (42.4-46.6) mg/l as CaCO3, pH 6.9-7.7, alkalinity 42.9 (39.6-61.4) mg/l CaCO3, temp: 26.4 +/- 1.4 °C, Purity 90%+

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 3200(SRC), determined from a structure estimation method(2), indicates that 4-hydroxyazobenzene is expected to have slight mobility in soil(SRC). The pKa of 4-hydroxyazobenzene is 8.2, indicating that the undissociated form will exist in neutral and acidic soils. In basic soils, the anion form will predominate and is expected to have higher mobility than the undissociated species. Volatilization of 4-hydroxyazobenzene from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 6.7X10-10 atm-cu m/mole(SRC), derived from its vapor pressure, 2.31X10-7 mm Hg(3), and water solubility, 90 mg/l(4). 4- Hydroxyazobenzene is not expected to volatilize from dry soil surfaces(SRC) based on a vapor pressure of 2.31X10-7 mm Hg at 25 °C(3). 4-Hydroxyazobenzene persists in some wastewater treatment systems and degrades in others, which suggest that biodegradation may be an important fate process in soils(5).

THE URINE OF RABBITS GIVEN 4-HYDROXYAZOBENZENE CONTAINED 2-ACETAMIDOPHENOL, 4-ACETAMIDOPHENOL, CONJUGATED 4-AMINOPHENOL, CONJUGATED 2-AMINOPHENOL, & 4-HYDROXYAZOBENZENE GLUCURONIDE.

The azoreduction of phenylazo-2-naphthol (Sudan I), 5-(phenylazo)-6-hydroxynaphthalene-2-sulfonic acid (aniline subsidiary color of FD&C Yellow No. 6 (ANSC)), and phenylazophenol (Solvent Yellow 7 (SY7)) in skin during percutaneous absorption was measured and the contributions of cytosolic and microsomal reductions were characterized. By using a series of azo dyes with a common U-14C-labeled phenylazo moiety, percutaneous absorption and metabolism were measured in vitro in flow through diffusion cells with Sencar mouse, hairless guinea pig, and human skin. Azoreductase assays using subcellular fractions from skin of all species were used to examine intracellular rates and distribution for the series of dyes. The absorption of the lipophilic dyes Sudan I and SY7 from a finite surface dose of 5 ug/sq cm was extensive in all species. In mouse, 32.8 + or - 2.8% of the applied Sudan I Jose and 64.1 + or - 3.3% of the applied SY7 Jose were absorbed in 24 hr. In the hairless guinea pig, 57.6 + or - 5.9% of the applied Sudan I dose and 67.8 + or - 4.6% of the applied SY7 dose were absorbed in 24 hr. Human skin was least permeable, with 26.4 + or - 6.7% of the applied Sudan I Jose and 36.1 + or 4.5% of the applied SY7 dose absorbed in 24 hr. Sudan I and SY7 were extensively reduced in skin of all species during percutaneous absorption (29.5 and 26.5%, respectively, of the absorbed dose in human skin and greater than 50% of the applied Jose in other species). ANSC was the least absorbed, with 5% or less penetrating. SY7 was preferentially reduced in the skin cytosol of all species, whereas Sudan I was equally reduced in the skin cytosol and microsomal fractions. The site of azoreduction in the cell may affect the metabolic fate of the liberated arylamine. The extensive azoreduction observed during percutaneous absorption may modulate the toxicities of these compounds and must be considered when effective doses are determined for quantitative risk assessments from dermal exposures.

A study was made of the chemical structural requirements for binding to microsomal cytochrome p450 and enzymic reduction of the azo linkage in p-dimethylaminoazobenzene (DAB) and related azo dye carcinogens. Liver microsomes were prepared from male Wistar rats, some of which had been pretreated with microsomal enzyme inducers. Dimethylaminoazobenzene, its corresponding primary and secondary amines, and p-hydroxyazobenzene showed high substrate reactivity for reduction by microsomes. ... Active substrates showed type I (p-hydroxy derivative) or type 11 binding spectra, while inactive substrates showed only weak binding with microsomes. When two inactive compounds were incubated with microsomes under aerobic conditions, allowing preliminary hydroxylation to occur, there was marked facilitation of azoreduction. /It was/ concluded that p-substituted azobenzenes with electron donating groups facilitate azo dye reduction by rat liver microsomes, with good correlation between cytochrome p450 binding and substrate reactivity. Hydroxylation facilitates reduction of otherwise nonreactive compounds.