Methyl orange

327.33400

327.06500

208-925-3

6B4TC34456

3143

ORANGE-YELLOW POWDER OR CRYSTALLINE SCALES

2927000090

93.54000

4.15290

4-dimethylaminoazobenzene-4-sulfonic acid, sodium salt is an orange powder. (NTP, 1992)

1.468 g/cm³

>300 °C

100ºC

37 °C

In water= 200 mg/l at 25 deg C

Store at RT.

LD50 orally in Rabbit: 60 mg/kg

PH: 3.1 RED, 4.4 YELLOW.

Azo dyes can be explosive when suspended in air at specific concentrations. Insoluble in water.

Azo, Diazo, Azido, Hydrazine, and Azide Compounds

4-DIMETHYLAMINOAZOBENZENE-4-SULFONIC ACID, SODIUM SALT is an azo compound. Azo, diazo, azido compounds can detonate. This applies in particular to organic azides that have been sensitized by the addition of metal salts or strong acids. Toxic gases are formed by mixing materials of this class with acids, aldehydes, amides, carbamates, cyanides, inorganic fluorides, halogenated organics, isocyanates, ketones, metals, nitrides, peroxides, phenols, epoxides, acyl halides, and strong oxidizing or reducing agents. Flammable gases are formed by mixing materials in this group with alkali metals. Explosive combination can occur with strong oxidizing agents, metal salts, peroxides, and sulfides.

III

6.1

UN 2811

3

R10

S16-S24/25

OO3150000

T

Stable. Incompatible with strong oxidizing agents.

P301 + P310

H301

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.

... The mutagenicity of a number of azo dyes is reviewed in this paper.[Chung KT; Mutat Res 114 (3): 269-81 (1983)]

Excerpt from ERG Guide 151 [Substances - Toxic (Non-combustible)]: Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Containers may explode when heated. Runoff may pollute waterways. (ERG, 2016)

|Danger|H301 (100%): Toxic if swallowed [Danger Acute toxicity, oral]|P264, P270, P301+P310, P321, P330, P405, and P501|Aggregated GHS information provided by 122 companies from 4 notifications to the ECHA C&L Inventory.

Excerpt from ERG Guide 151 [Substances - Toxic (Non-combustible)]: SMALL FIRE: Dry chemical, CO2 or water spray. LARGE FIRE: Water spray, fog or regular foam. Move containers from fire area if you can do it without risk. Dike fire-control water for later disposal; do not scatter the material. Use water spray or fog; do not use straight streams. FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2016)

Excerpt from ERG Guide 151 [Substances - Toxic (Non-combustible)]: As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. SPILL: Increase, in the downwind direction, as necessary, the isolation distance shown above. FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2016)

SMALL SPILLS AND LEAKAGE: If you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then dampen the solid spill material with toluene, then transfer the dampened material to a suitable container. Use absorbent paper dampened with toluene to pick up any remaining material. Your contaminated clothing and absorbent paper should be sealed in a vapor-tight plastic bag for eventual disposal. Solvent-wash all contaminated surfaces with toluene 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. STORAGE PRECAUTIONS: You should store this material in a refrigerator. (NTP, 1992)

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

Methyl orange's production and use as a pH indicator and as a dye for textiles(1) may result in its release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 240(SRC), determined from a measured water solubility(2) and a recommended regression-derived equation(3), indicates that methyl orange will have moderate mobility in soil(SRC). Due to the ionic nature of methyl orange, the retention of the dye by ion-exchange processes(4,SRC), particularly on clay surfaces, and adsorption at mineral surfaces such as geothite(5,SRC), may slow down or prevent leaching(SRC). As methyl orange is an ionic compound, volatilization of this compound will not be important from moist soil surfaces(4,SRC). Based on limited data, methyl orange is expected to be resistant to aerobic biodegradation in soil(SRC). In an aqueous BOD screening test, this compound was not degraded over a 5 day period(6). This compound may be susceptible to biodegradation under anaerobic conditions(SRC); intestinal microflora were able to metabolize methyl orange, forming N,N-dimethyl-phenylene diamine(7).|AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 240(SRC), determined from a measured water solubility(2) and a recommended regression-derived equation(1), indicates that methyl orange should not adsorb to suspended solids and sediment in water(SRC). However, due to the ionic nature of methyl orange, the retention of the dye by ion-exchange processes(3,SRC), particularly on clay surfaces, and adsorption at mineral surfaces such as geothite(4,SRC), may lead to increased adsorption on some sediment and particulate surfaces(SRC). As methyl orange is an ionic compound, volatilization from water surfaces is not expected(3,SRC). According to a classification scheme(5), an estimated BCF value of 30(1,SRC), from a measured water solubility(2), suggests that bioconcentration in aquatic organisms is low(SRC). Based on limited data, methyl orange is expected to be resistant to aerobic biodegradation in water(SRC). In an aqueous BOD screening test, this compound was not degraded over a 5 day period(6). This compound may be susceptible to biodegradation under anaerobic conditions; intestinal microflora were able to metabolize methyl orange, forming N,N-dimethyl-phenylene diamine(7).|ATMOSPHERIC FATE: The ionic state of methyl orange makes this compound essentially non-volatile(1,SRC); therefore, this compound should exist in the particulate phase in the ambient atmosphere. Particulate-phase methyl orange may be physically removed from the air, mainly by wet deposition(SRC).

An estimated BCF value of 30 was calculated for methyl orange(SRC), using a measured water solubility(1) and a recommended regression-derived equation(2). According to a classification scheme(3), this BCF value suggests that bioconcentration in aquatic organisms is low(SRC).

The Koc of methyl orange is estimated as approximately 240(SRC), using a measured water solubility of 200 mg/l(1) and a regression-derived equation(2,SRC). According to a recommended classification scheme(3), this estimated Koc value suggests that methyl orange has moderate mobility in soil(SRC). Due to the ionic nature of the dye, the retention of methyl orange by ion-exchange processes(4,SRC), particularly on clay surfaces and adsorption at mineral surfaces such as geothite(5,SRC), may slow down or prevent leaching(SRC).

Since methyl orange is an ionic compound, volatilization from water and moist soil surfaces will not be important(1,SRC).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 23,943 workers (3,278 of these are female) are potentially exposed to methyl orange in the US(1). Occupational exposure may be through inhalation of dusts and dermal contact with this compound at workplaces where methyl orange is produced or used(SRC). The general population may be exposed to methyl orange via dermal contact with products containing this compound(SRC).

Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant and Hackh's Chemical Dictionary, 5th ed, p301, p499) (See all compounds classified as Indicators and Reagents.)

KINETIC ANALYSIS OF BILIARY EXCRETION OF IV DOSE OF [(3)H]METHYL ORANGE & PRODUCTS OF DEMETHYLATION (MONO- & DI-) SHOWED THAT SUCCESSIVE REMOVAL OF METHYL GROUP RESULTED IN MUCH FASTER BILIARY EXCRETION OF CMPD.|BILIARY EXCRETION OF IV ADMIN METHYL ORANGE & METABOLITES, 4'-SULFO-4-METHYLAMINOAZOBENZENE & 4'-SULFO-4-AMINOAZOBENZENE, BY RATS WAS USED TO ILLUSTRATE A ONE-COMPARTMENT PHARMACOKINETIC MODEL IN WHICH A DRUG UNDERWENT 2 SUCCESSIVE METABOLIC REACTIONS.

YIELDS 4'-METHYLAMINOAZOBENZENE-4-SULFONIC ACID IN RAT, IN MOUSE. /FROM TABLE/|METHYL ORANGE IS CONVERTED TO N,N-DIMETHYL-P-PHENYLENEDIAMINE BY INTESTINAL ANAEROBIC BACTERIA. SULFANILIC ACID IS ANOTHER METABOLITE.

Excerpt from ERG Guide 151 [Substances - Toxic (Non-combustible)]: Highly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution. (ERG, 2016)

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. SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment. INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing. INGESTION: DO NOT INDUCE VOMITING. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Be prepared to transport the victim to a hospital if advised by a physician. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital. (NTP, 1992)

C.I. 13025

As pH indicator in 0.1% aq soln

Benzenesulfonic acid, 4-[2-[4-(dimethylamino)phenyl]diazenyl]-, sodium salt (1:1): ACTIVE|Methyl orange is very seldom used in textile applications because it is fugitive and sensitive to acids; however, on occasion, it has been used to dye wool and silk from an acid bath.