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Dimethyl carbonate (DMC) is an
organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
with the
formula In science Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe."... modern science is a discovery as well a ...
OC(OCH3)2. It is a colourless, flammable liquid. It is classified as a
carbonate ester A carbonate ester (organic carbonate or organocarbonate) is an ester An ester is a derived from an (organic or inorganic) in which at least one –OH group is replaced by an –O– () group, as in the substitution reaction of a and an . s ...

carbonate ester
. This compound has found use as a
methylating agent In the chemical sciences, methylation denotes the addition of a methyl group A methyl group is an alkyl derived from methane, containing one carbon atom chemical bond, bonded to three hydrogen atoms — CH3. In chemical formula, fo ...
and more recently as a solvent that is exempt from the restrictions placed on most
volatile organic compound Volatile organic compounds (VOC) are organic chemicals , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abilit ...
s (VOCs) in the US. Dimethyl carbonate is often considered to be a green reagent.


Production

World production in 1997 was estimated at 1000 barrels a day. Production of dimethyl carbonate worldwide is limited to Asia, the Middle East, and Europe. Dimethyl carbonate is traditionally prepared by the reaction of
phosgene Phosgene is the organic chemical compound , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, mo ...

phosgene
and
methanol Methanol, also known as methyl alcohol, amongst other names, is a chemical A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. ...

methanol
.
Methyl chloroformate Methyl chloroformate is the Methyl group, methyl ester of chloroformic acid. It is an oily colorless liquid, although aged samples appear yellow. It is also known for its pungent odor. Preparation Methyl chloroformate can be synthesized using ...

Methyl chloroformate
is produced as an intermediate: : COCl2 + CH3OH → CH3OCOCl + HCl : CH3OCOCl + CH3OH → CH3OCO2CH3 + HCl This synthesis route has been largely replaced by oxidative carbonylation. In this process,
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom. It is the simplest molecule of the oxocarbon family. In ...

carbon monoxide
and an oxidizer provide the equivalent of CO2+: :: CO + 1/2 O2 + 2 CH3OH → (CH3O)2CO + H2O It can also be produced industrially by a
transesterification In organic chemistry Organic chemistry is a branch of that studies the structure, properties and reactions of s, which contain in .Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Stu ...

transesterification
of ethylene carbonate or
propylene carbonate Propylene carbonate (often abbreviated PC) is an organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carb ...
and
methanol Methanol, also known as methyl alcohol, amongst other names, is a chemical A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. ...

methanol
, which also affords respectively ethylene glycol or
propylene glycol Propylene glycol (IUPAC name In chemical nomenclatureA chemical nomenclature is a set of rules to generate systematic names for chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecu ...
.


Reactions and potential applications


Methylating agent

Dimethyl carbonate methylates
aniline Aniline is an organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior an ...

aniline
s,
carboxylic acid A carboxylic acid is an organic acid that contains a carboxyl group (C(=O)OH) attached to an R-group. The general formula of a carboxylic acid is R−COOH or R−CO2H, with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
s, and
phenols In organic chemistry Organic chemistry is a branch of chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, prope ...
. Sometimes these reactions require the use of an
autoclave An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure/Ambient temperature, temperature. Autoclaves are used in medical applications to perform ...

autoclave
. : Dimethyl carbonate's main benefit over other methylating reagents such as
iodomethane Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from ...

iodomethane
and
dimethyl sulfate Dimethyl sulfate (DMS) is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held toget ...

dimethyl sulfate
is its low toxicity. Additionally, it is biodegradable. Unfortunately, it is a relatively weak
methylating agent In the chemical sciences, methylation denotes the addition of a methyl group A methyl group is an alkyl derived from methane, containing one carbon atom chemical bond, bonded to three hydrogen atoms — CH3. In chemical formula, fo ...
compared to these traditional reagents.


Solvent

In the US, dimethyl carbonate was exempted under the definition of
volatile organic compound Volatile organic compounds (VOC) are organic chemicals , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abilit ...
s (VOCs) by the U.S. EPA in 2009. Due to its classification as VOC exempt, dimethyl carbonate has grown in popularity and applications as a replacement for
methyl ethyl ketone Butanone, also known as methyl ethyl ketone (MEK), is an organic compound , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, com ...
(MEK) and , as well as ''tert''-butyl acetate until it too was exempted. Dimethyl carbonate has an ester- or alcohol-like odor, which is more favorable to users than most hydrocarbon solvents it replaces. Dimethyl carbonate has an evaporation rate of 3.22 (butyl acetate = 1.0), which slightly slower than MEK (3.8) and
ethyl acetate Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), million ...

ethyl acetate
(4.1), and faster than
toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon Aromatic compounds are those chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular enti ...

toluene
(2.0) and
isopropanol Isopropyl alcohol (International Union of Pure and Applied Chemistry, IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a Transparency and translucency, colorless, Flammability, flammable chemical compound (chemical formula CH ...
(1.7). Dimethyl carbonate has solubility profile similar to common
glycol ether Glycol ethers are a group of solvent A solvent (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, know ...
s, meaning dimethyl carbonate can dissolve most common coating resins except perhaps rubber based resins. Hildebrand solubility parameter is 20.3 MPa and Hansen solubility parameters are: dispersion = 15.5, polar = 3.9, H bonding = 9.7. Dimethyl carbonate is partially soluble in water up to 13%, however it is hydrolyzed in water-based systems over time to methanol and CO2 unless properly buffered. Dimethyl carbonate can freeze at same temperatures as water, it can be thawed out with no loss of properties to itself or coatings based on dimethyl carbonate.


Intermediate in polycarbonate synthesis

A large captive use of dimethyl carbonate is for the production of through
transesterification In organic chemistry Organic chemistry is a branch of that studies the structure, properties and reactions of s, which contain in .Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Stu ...

transesterification
with
phenol Phenol (also called carbolic acid) is an aromatic forms of benzene (top) combine to produce an average structure (bottom) In chemistry, aromaticity is a property of cyclic compound, cyclic (ring (chemistry), ring-shaped), plane (geometry), p ...

phenol
. Diphenyl carbonate is a widely used raw material for the synthesis of
bisphenol-A Bisphenol A (BPA) is an organic synthetic compound with the chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classi ...

bisphenol-A
-polycarbonate in a melt polycondensation process, the resulting product being recyclable by reversing the process and transesterifying the polycarbonate with phenol to yield diphenyl carbonate and bisphenol A.


Alternative fuel additive

There is also interest in using this compound as a fuel oxygenate additive.{{cite journal , doi = 10.1021/ef9600974 , journal = Energy & Fuels , title = Review of Dimethyl Carbonate (DMC) Manufacture and Its Characteristics as a Fuel Additive , year = 1997 , last1 = Pacheco , first1 = Michael A. , last2 = Marshall , first2 = Christopher L. , volume = 11 , pages = 2–29


Safety

DMC is a flammable liquid with a
flash point In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo durin ...
of 17 °C (63 °F), which limits its use in consumer and indoor applications. DMC is still safer than
acetone Acetone, or propanone, is an organic compound , CH4; is among the simplest organic compounds. In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, ...

acetone
,
methyl acetate Methyl acetate, also known as MeOAc, acetic acid methyl ester or methyl ethanoate, is a carboxylate ester An ester is a chemical compound derived from an acid (organic or inorganic) in which at least one –OH hydroxyl group is replaced by an ...

methyl acetate
and methyl ethyl ketone from a flammability point of view. DMC has a
recommended exposure limit A recommended exposure limit (REL) is an occupational exposure limit An occupational exposure limit is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials. It i ...
(REL) limit of 100 ppm by inhalation over an 8-hour work day, which is similar to that of a number of common industrial solvents (
toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon Aromatic compounds are those chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular enti ...

toluene
, methyl ethyl ketone). Workers should wear protective organic vapor respirators when using DMC indoors or in other conditions where concentrations exceed the REL. DMC is metabolized by the body to
methanol Methanol, also known as methyl alcohol, amongst other names, is a chemical A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. ...

methanol
and carbon dioxide, so accidental ingestion should be treated in the same manner as
methanol poisoning Methanol toxicity is poisoning A poison In biology, poisons are Chemical substance, substances that can cause death, injury or harm to organs, Tissue (biology), tissues, Cell (biology), cells, and DNA usually by chemical reactions or other ...
.


See also

* Dimethyl dicarbonate


References

Methylating agents Carbonate esters Methyl esters