4,4′-Methylenebis(2-chloroaniline) (also known as MOCA, MBOCA, and bisamine) is a substance used as a curing agent in
polyurethane
Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...
production. MOCA is an
aromatic
In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...
amine
In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...
which is structurally similar to
benzidine
Benzidine (trivial name), also called 1,1'-biphenyl-4,4'-diamine (systematic name), is an organic compound with the chemical formula, formula (C6H4NH2)2. It is an aromatic amine. It is a component of a test for cyanide. Related derivatives are ...
, a known human bladder carcinogen. MOCA has been shown to cause
hepatoma
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide.
HCC most common ...
s in mice and rats, lung and mammary carcinomas in rats and bladder cancer in dogs. It is a proven human
carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...
standing on the WHO
List of IARC Group 1 carcinogens
IARC group 1 Carcinogens are substances, chemical mixtures, and exposure circumstances which have been classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC). This category is used when there is sufficien ...
, with a current
threshold limit value of 0.01 ppm in the industrial atmosphere. Animal studies have resulted in tumor growth in the
liver
The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...
, lung, and
bladder
The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...
.
[
It is a ]weak base
A weak base is a base that, upon dissolution in water, does not dissociate completely, so that the resulting aqueous solution contains only a small proportion of hydroxide ions and the concerned basic radical, and a large proportion of undissocia ...
with a slight odor and is reactive to active metals such as sodium, potassium, magnesium and zinc.[
]
Toxicity
Employee exposure is often monitored by measurement of urinary MOCA in free and/or conjugated form. This is the best currently available indicator of MOCA absorption, which is estimated by spot measurement of concentration in urine, creatinine-corrected. Urine concentration is a proxy variable - the measurement is of unmetabolised MOCA - and creatinine-correction affects accuracy. Dose-response curves are also lacking. But despite such limitations the method is a reasonable means of monitoring the effectiveness of engineering controls, personal protective equipment and work practices including education. MOCA levels are usually higher at the end of the shift and reflect exposure over the preceding two to three days. The biological half-life Half-life is a mathematical and scientific description of exponential or gradual decay.
Half-life, half life or halflife may also refer to:
Film
* Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang
* ''Half Life: ...
of MOCA in urine is approximately 23 hours.
Regulation
In December 2023, the US EPA announced that it was prioritizing MBOCA "for risk evaluation under the Toxic Substances Control Act
The Toxic Substances Control Act (TSCA) is a United States law, passed by the Congress in 1976 and administered by the United States Environmental Protection Agency (EPA), that regulates chemicals not regulated by other U.S. federal statutes, ...
(TSCA)" along with four other toxic chemicals.
See also
* Methylene diphenyl diisocyanate
Methylene diphenyl diisocyanate (MDI) is an aromaticity, aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widel ...
* Toluene diisocyanate
Toluene diisocyanate (TDI) is an organic compound with the formula CH3C6H3(NCO)2. Two of the six possible isomers are commercially important: 2,4-TDI (CAS: 584-84-9) and 2,6-TDI (CAS: 91-08-7). 2,4-TDI is produced in the pure state, but TDI is oft ...
References
{{DEFAULTSORT:Methylenebis(2-chloroaniline), 4,4'-
Anilines
Chloroarenes
IARC Group 1 carcinogens